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- Front Matter: Volume 6834
- Plenary Presentation
- Nano-and Micro-Optics
- Illumination System Design
- Astronomical and Space Optics
- Head-Mounted Display Design
- Compact Optics
- Interferometry in Optical Testing
- Testing for Aspheric Surfaces
- Novel System Design
- Wavefront Sensing and Coding
- Optical Measurement
- Optical System Analysis and Optimization
- Optical Testing and System Alignment
- Poster Session
Front Matter: Volume 6834
Front Matter: Volume 6834
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This PDF file contains the front matter associated with SPIE
Proceedings Volume 6834, including the Title Page, Copyright
information, Table of Contents, Introduction, and the
Conference Committee listing.
Plenary Presentation
The National Ignition Facility: the world's largest optical system
Show abstract
The National Ignition Facility (NIF), a 192-beam fusion laser, is presently under construction at the Lawrence Livermore
National Laboratory with an expected completion in 2008.1-5 The facility contains 7,456 meter-scale optics for
amplification, beam steering, vacuum barriers, focusing, polarization rotation, and wavelength conversion.6 A
multiphase program was put in place to increase the monthly optical manufacturing rate by up to 20x while
simultaneously reducing cost by up to 3x through a sub-scale development, full-scale facilitization, and a pilot
production phase. Currently 80% of the optics are complete with over 50% installed. In order to manufacture the high
quality optics at desired manufacturing rate of over 100 precision optics per month, new more deterministic advanced
fabrication technologies had to be employed over those used to manufacture previous fusion lasers.
Nano-and Micro-Optics
Nano-glass imprinting technology for next-generation optical devices
Junji Nishii
Show abstract
Sub-wavelength periodic structures are very attractive for several optical elements with functions such as polarization-independent
diffraction, isolation, antireflection, and phase control. In this paper I will review the fabrication of one- and
two-dimensional periodic structures upon the surface of oxide glasses using lithograph, etching and glass imprinting. A
4-channel demultiplexer and a superprism demultiplexer were fabricated upon silica plates. The latter exhibited a precise
linear relationship between the wavelength and the change of the output angle, which reached 4.8° with the incident
wavelength change of 1% for wavelengths of 1400-1500 nm. Fabrication of surface-relief gratings with high spatial
frequencies directly on optical glasses was possible using an imprinting process. One-dimensional and two-dimensional
periodic structures were formed reproducibly on a phosphate glass surface using thermally durable molds.
Technological strategy for advanced micro- and nano-structured optical elements
Show abstract
A wide variety of micro and nano-structured optical elements have been developed. Among other things, optical
elements with subwavelength structure surfaces are moving on the advanced stage for practical use. A camera lens with
antireflective structured surface and an achromatic birefringent wave-plate have been fabricated by plastic molding
process. Form-birefringent micro-reader array is used for a polarization imaging camera system. Recent research-and-developments
on subwavelength structured optical elements are oriented to practical applications and process
technologies for manufacturing. In this paper the current situation of the subwavelength structured optical elements have
been summarized and subjects of developments are discussed from the viewpoint of practical applications.
Bending insensitive optical curl cord patch cords based on Holey-fibers for FTTH
Show abstract
We experimentally demonstrate real practical optical curl patch cords based on holey fibers with bending insensitivity.
After making 6-hole holey fibers with the VAD method, the optical curl patch cord with the fabricated holey fiber is
developed.
Theoretical analysis of square GRIN lens
Show abstract
Square Gradient-index Selfoc lenses (GRIN) were successfully prepared by Tl+ and K+ ion-exchange. The ion
concentration equation in square class fiber was calculated by variable separation method. The refractive-index profile of
Square GRIN lenses analytic solution is got based on the linear relation between refractive-index and ion concentration.
The computation results are in good agreement with the measured ones. MATLAB partial differential toolbox was used
to numerically solve ion diffusion equation on square boundary conditions, this works is easy to be handled and redound
to the research on Square GRIN Lenses. The refractive-index analytic solution can be predigested and modeled by a
square law function with introducing the concept of incidence directions angle. Based on the function, the ray's
trajectory equation and Numerical Aperture were got. This work shows that the optical properties of Square GRIN lenses
are related to the directions angle.
Illumination System Design
Backlight pattern optimization
Show abstract
Backlight displays using edge lit light guides are found in many applications, including cell phones and compute lap
tops. The light guide extractor pattern is adjusted to provide the desired spatial distribution across the display. The
extractor pattern optimization can be performed using Monte Carlo simulations. Multiple examples are discussed.
Examples include backlights with multiple LEDs, a rod luminaire, a key pad illuminator, and a non-uniformly shaped
light guide.
Polarimetry of illumination for 193-nm lithography used for the manufacture of high-end LSIs
Show abstract
We have constructed a theory of polarimetry of illumination used in 193-nm lithography equipments, fabricated a
polarimeter mask, and demonstrated it for a hyper-NA (numerical aperture) lithography scanner. The polarimeter mask
comprises newly- developed polarizers and quarter-wave (λ/4) plates. The thin plate polarizers are made of calcite
(CaCO3), and the λ/4 plates are composed of two crystalline quartz (α-SiO2) plates and two sapphire (Al2O3) plates. A
light traveling through a window of the polarimeter mask reaches an image detector at the wafer level through projection
optics. Whereas the polarization states of the projection optics are unknown to us, Stokes parameters of the illumination
light are formulated without any influence from the projection optics.
A novel highly integrated light guide plate using micro optical technique
Show abstract
An integrated light guide plate(LGP) using micro optical technique is presented in this paper. Micro-prisms are
fused on the bottom surface which replace the plane reflective film at presented. By changing the bottom angles of
micro-prisms, the relationship between the bottom angle and the direction of peak luminance is analyzed systematically.
When the direction of peak luminance is concentrated on vertical angle(90°), the vertical direction luminance of LGP
without structure on the top surface is already closed to the 3M backlight module. while in the LGP which fused the
micro tapers with tiny concave on the top surface, the illuminance and the vertical direction luminance is about 2.28
times and 1.09 times compared to the 3M backlight module respectively. The result shows that the novel integrated
micro optical LGP can substitute for 3M crossed prism films and accorded with the tendency of integration ,frivolity and
high brightness in backlight system.
Rays propagation in optical tunnel
Show abstract
Optical tunnels are widespread in mircolithographic illumination systems. It reshapes the rays and illuminates masks
with dose-and-directional uniformity. Rays were focused the input end, reflected by the walls of the optical tunnel and
lapped over the output end. According to rays reflecting by walls, optical tunnel was expanded along the reflecting
walls. The approaches of rays' propagation in the optical tunnel were given. It indicates the luminance of the source is
important for the optical tunnel performance; the defect of small inclination between bottom and top walls are
neglectable for the uniformity of the output end. The taper of tunnel leads to the dissimilar of rays NA between output
end and input end. The relation of the NA was given. The indications were confirmed by the simulations. When a
collimated beam was focused on the input end, simulations show that the dropping of nonuniformity was unsmooth as
the optical tunnel length increasing. When the luminance turned to a Gaussian distribution, the uniformity improved
greatly. The uniformity of the output will be insensitivity with a fitting luminance. The nonuniformity would be less
than 0.7% when the radius diminished less than the half. The edges' defect degrade the uniformity greatly both
confirmed by the simulations and experiments. It shows that optical tunnels with sharp edges are excellent optical
integrators with fitting luminance sources.
Astronomical and Space Optics
Alignment induced aberration fields of next generation telescopes
Kevin Thompson,
Tobias Schmid,
Jannick Rolland
Show abstract
There is a long list of new ground-based optical telescopes being considered around the world. While many are
conventional Cassegrain and Ritchey-Chretien designs, some are from a family of 3-mirror offset field (but still
obscured) optical forms that trace back to designs developed in the 1970s. The nodal theory of aberrations, developed in
the late 1970s, provides valuable insights into the response of these systems to alignment errors and provides simple,
linear solutions to real-time or at-assembly alignment algorithms. The application of nodal aberration techniques to the
alignment of two and three mirror astronomical telescopes will be presented.
The research on electric method for testing co-phasing error
Show abstract
The primary mirror's aperture limits the telescope's resolution. A segmented primary mirror is adopted to improve the
resolution. Since the primary mirror with large diameter is segmented, the segmented mirrors must be co-phased to
ensure the imaging quality. Optical method and electrics method can be used to test the co-phasing error between the two
adjacent segment mirrors. However the optical system of telescope will be complicated by attaching an optical cophasing
test system, and some unstable factors will be introduced. In this paper, an electrics co-phasing testing method
was discussed. Capacitance micrometer technology was used in this method, and relevant experiments have been carried
out. And the result of these experiments indicated that the method described in this paper is feasible.
Imaging analysis of optical sparse aperture systems with multiple-array configuration designs
Show abstract
Based on the traditional array configuration, a novel array configuration design, named the multiple-array sparse aperture system, is proposed, and three kinds of configuration models, including the multiple-annulus, the multiple-Golay6 and the multiple-Tri-arm, have been investigated. The imaging performances of the different multiple-array configurations are compared according to their modulation transfer functions (MTFs). Then the optical experiments with the multiple-array configurations have been fulfilled with the specific system parameters. The MTFs and the direct imaging results of the multiple-array sparse aperture systems are obtained, and then the image restoration of the direct output is performed by measuring the corresponding point spread functions (PSFs) and by using the Weiner filter. The experimental results show that the characteristic of the MTFs of the multiple-array configurations and the corresponding imaging performance are in accordance with the numerical simulation. And it is demonstrated that the multiple Tri-arm array configuration among the three kinds of multiple-array configuration models can produce higher resolution and larger correlation coefficient after the restoration. The results illustrate the possible way to construct very larger array configuration of optical sparse aperture systems by combining multiple copies of the simple array.
Head-Mounted Display Design
Beyond the desktop: emerging technologies for supporting collaborative teams in virtual environments
Show abstract
The emergence of several trends, including the increased availability of wireless networks, miniaturization of electronics
and sensing technologies, and novel input and output devices, is creating a demand for integrated, fulltime displays for
use across a wide range of applications, including collaborative environments. In this paper, we present and discuss
emerging visualization methods we are developing particularly as they relate to deployable displays and displays worn
on the body to support mobile users, as well as optical imaging technology that may be coupled to 3D visualization in
the context of medical training and guided surgery.
Design of hybrid refractive-diffractive objective lens of head-mounted projective displays
Show abstract
Based on the requirements of the modern head-mounted display on the image quality, distortion, size and weight, we
design a diffractive-refractive objective lens for the head-mounted projective display with the field of view of 50 degree,
exit pupil diameter of 10mm, effective focal length of 20mm and 1.3 inch micro-display. It is shown that the designed
optical system, comparing with the traditional ones, has smaller size, lighter weight and compacter structure with better
aberrations performance. With the other unique properties such as the ability of allowing correct occlusion of real and
virtual objects in augmented environments, the depth perception of the objects in real scene, independent viewpoints and
no crosstalk in multi-user environments, the designed system has a potential applications in collaborative environments,
wearable computers and visualization training.
Research-oriented teaching in optical design course and its function in education
Show abstract
The principles and operation plans of research-oriented teaching in the course of computer aided optical design are
presented, especially the mode of research in practice course. This program includes contract definition phase, project
organization and execution, post project evaluation and discussion. Modes of academic organization are used in the
practice course of computer aided optical design. In this course the students complete their design projects in research
teams by autonomous group approach and cooperative exploration. In this research process they experience the
interpersonal relationship in modern society, the importance of cooperation in team, the functions of each individual, the
relationships between team members, the competition and cooperation in one academic group and with other groups, and
know themselves objectively. In the design practice the knowledge of many academic fields is applied including applied
optics, computer programming, engineering software and etc. The characteristic of interdisciplinary is very useful for
academic research and makes the students be ready for innovation by integrating the knowledge of interdisciplinary
field. As shown by the practice that this teaching mode has taken very important part in bringing up the abilities of
engineering, cooperation, digesting the knowledge at a high level and problem analyzing and solving.
Compact Optics
Optical design, fabrication, and evaluation of optical systems using free-shaped prism
Show abstract
Free-shaped optical systems can highly correct aberrations by reflecting light at multiple aspherical surfaces inside a
prism and can realize more-compact, higher-performance optical systems than is normally achievable. We have
exploited these features at Olympus to construct optics for display systems and image-capturing modules in mobile
phone cameras. In the course of their development, we improved the accuracy of the finished form of free-shaped prisms
by establishing a design methodology for free-shaped optical systems and developing high-precision fabrication and
measurement techniques. In this paper, we describe the structure and characteristics of an optical system for an image-capturing
module, as well as evaluation results of a prototype that we fabricated.
Design of an objective lens for optical disc systems employing a blue laser by scalar diffraction simulation
Show abstract
We have designed a compatible objective lens for HD DVD/DVD/CD drives utilizing a multiple diffractive
structure. In this case, if priority has been given to a high HD DVD diffraction efficiency, the CD diffraction
efficiency is reduced. Therefore, plenty of noise light is generated at the entrance pupil diameter of a CD
inner area which may cause a false signal in the focus error (FE) signal during CD playback. Furthermore, the
quality of the spot and the side-lobe intensity gets worse due to the light at the entrance pupil diameter of a CD
outer area, and hence, may cause recording and playback problems. To solve these problems, we improved the
objective lens applying a scalar diffraction simulation. We separated the position of the false signal far away
from the regular signal in the FE signal, and suppress the amplitude of the false signal much smaller than the
regular signal in FE signal during CD playback to achieve the reliable focus servo. In addition, we managed to
improve the spot and the side-lobe quality to a practical level during CD playback with providing an aperture
filtering function on the objective lens.
Study on mathematical modeling for optical pickup virtual analyzer
Show abstract
Optical pickup is an optical apparatus to record and/or reproduce information from an optical disc. It is a kind of
large aperture optical system of diffraction limited. As a product of mass production, its accuracy is guaranteed by
reasonable balance among fabricating and assembling tolerances of optical, mechanical and optoelectronic elements.
One method employed is conduct sensitivity analyses to identify tolerances for each element, which usually limits the
manufacturability and cost of optical pickup.
In this paper, the method of optical pickup virtual analyzer is proposed to improve the manufacturability. The
mathematical modeling used for virtual analyzer is established based on the system image quality and laser spot
characteristics on photo detector. First, a three-dimensional virtual optical pickup model is established, in which the
characteristics and fabricating and assembling errors of each optical element (beam splitter, mirror, collimator and
objective ), optoelectronic element (laser diode and photo diode)and mechanical support element are described. The
optical disk is represented as a reflective surface. The photo diode integrated circuit could work virtually so that it could
receive the laser spot reflected from the optical disk. The photosensitive division on it would differentiate the laser spot
on it and give the signals according to requirements of the real analyzer. The virtual analyzer can help combine suitable
elements of looser tolerance for optical pickup assembling and improve the manufacturability efficiently. The
mathematical model is developed using the Macro-PLUS language and a CD/DVD optical pickup virtual analyzer is
successfully optimized with the model.
Interferometry in Optical Testing
New low-cost metrology system for mass production
Show abstract
The mass production optic industry in many Asian countries frequently employs human inspection lines to assess the
yield of their volume-produced optic components. The testing of shape and radius for the quality assessment of such
lenses or prismatic elements of average accuracy specification is traditionally performed by using Fizeau
interferometers for visual inspection. This method typically does not allow the documentation and/or printing of
inspection reports due to the lack of cost-intensive computer and printer periphery. Increasing accuracy as well as the
rising importance of quality assessment in mass production requires the elimination of human error as well as the
documentation and statistical analysis of the inspection results. FISBA OPTIK developed the μPhase(R) smartgage, a
new stand-alone metrology system to address exactly this need. This instrument meets the major demands of the mass
production for touch-of-a-button inspection, reliable pass/fail analysis, storage of measurement results and low
investment costs. The compact unit is designed with the potential to replace visual human-inspection instruments for
large-volume testing of relative shape accuracy and radius of curvature. The novel, small-footprint instrument is a
stand-alone system with a fully integrated computing and display unit, sample alignment stage, touch-screen operation
and optional connectivity for data export. This instrument offers simple, fast, reliable and vibration-insensitive
measurement of shape deviation on flat and spherical optical components as well as relative radius of curvature. We
present the measurement principle, the method of use and application, the measurement data presentation and data
export capabilities. Application areas for the μPhase(R) smartgage include testing of digital camera lenses, cell phone
camera lenses, general purpose spherical lenses and flats of diameters up to one inch.
A compact, high-speed, desktop turnkey measurement system for the characterization of the surface topography of spherical, aspherical, and toroidal surfaces
Show abstract
This paper describes a desktop, turnkey metrology system tailored for the measurement of the surface topography of
small optical components such as contact and intraocular lenses and molds. The system incorporates a wavefront sensor
that provides interferometric accuracy while being relatively insensitive to vibration. Highly accurate measurement of
the radius of curvature (typically better than .02%, 2 micrometers on a 10 mm radius part) is obtained using a patented
data reduction system. The system also measures toroidal and aspherical systems and can be readily adapted to the
measurement of longer radius parts. The system is capable of measuring surface topography in less than 10 seconds
after part placement and is usually operated by unskilled personnel. Full three-dimensional topography is reported
including peak-to-valley and root-mean-square surface departure, and Zernike polynomials. This paper provides an
overview of the optical configuration and software algorithms that enable the highly precise capability of the device.
Mach-Zehnder optical interferometric polarimeter using two reference beams with different heterodyne frequency
Show abstract
Optical heterodyne interferometry has been widely used in precision measurements. In this paper, we develop a modified
Mach-Zehnder interferometer for measurement of light polarization state in real time by using two heterodyne frequency
reference beams. Two collinear linearly polarized reference beams with different frequency, ωp and ωs, interfere simultaneously with the measured beam with frequency ω0. The polarization directions of the two reference beams are perpendicular to each other. The light intensity of the interference fringe is monitored by a photodetector. The heterodyne signals, ωp and ωs - ω0, give the amplitudes and the phase difference of the orthogonal polarization components of the measured beam projected to the polarization directions of the reference beams. We analyze the beat frequency signals by Fourier and inverse Fourier transform and realize accurate measurement of polarization state experimentally.
New interferometric algorithm for the measurement of phasing errors in spherical segmented-mirrors system
Show abstract
In segmented-mirror telescopes, wave-front discontinuities caused by segment misalignment are a major problem
because they severely degrade optical performance. So for segmented-mirror system, it's necessary to exactly acquire
position and gesture of each mirror. In this paper, Hough transform is used to obtain the edge of each segmented mirror,
and then each separated segmented can be solely processed. And a new method to calculate tilt, tip and piston of
spherical segmented mirror is given. This algorithm is based on the character of acclivitous spherical mirror which turns
around any axis in different position and different angle, so it is useful to obtain each spherical segmented mirror's
position and gesture. A mount which is allowed to do the segmented mirrors' tilt, tip and piston movement is designed.
With the FISBA phase shifting interferometer the phase of whole system can be obtained, and in the method proposed in
this paper tilt, tip and piston can be calculated to calibrate the spherical segmented-mirror system.
Inhomogeneous radial shearing technique
Show abstract
The proposed method in this paper, in which wave front is sheared in radial direction, is independent on type of
aberration so it can determine type of aberration as well as its coefficients. Its simple arrangement, high precision and
wide range of application makes it distinct.
Testing for Aspheric Surfaces
Study on testing larger asphericity in non-null interferometer
Show abstract
Optical systems benefit from the use of aspheric surfaces because aspherics provide additional degrees of freedom for
aberration control, yielding higher performance while reducing system weight and complexity. But optical designers
always avoid to use aspheres with larger asphericity in optical systems mainly for the reason that the test of the steep
aspherics requires extraordinary skill of the experimenter and the technical means to reduce the asphericity of the
wavefronts that detected by the digital camera. Even though null optics can be adopted to compensate the asphericity of
the test wavefront, they are not suitable for many cases. Each aspheric surface requires a unique null optics, which
greatly increases a project's complexity, cost and time delay. In this paper, a type of novel lens with large longitude
aberration and simple structure is proposed to reduce the asphericity of the wavefronts. The characteristic and the design
process of the simple lens are discussed in detail. A comparison between the simple lens and the aplanat with different
focus setting is given. Computer simulation shows the simple lens has much more power in reducing asphericity.
System optimization of radial shearing interferometer for aspheric testing
Show abstract
The large slope of the aspheric departure presents great difficulty for optical testing researchers to test aspheric surfaces
and wavefronts. The instrument dynamic range of traditional interferometers does not support the high number of fringes
due to the steep slopes commonly found in aspherics. The radial shearing interferometer, which can greatly reduce the
slope of the aspheric wavefront under test, is always adopted to test aspherics. In this paper, the two evaluating
parameters of a radial shearing interferometer, the wavefront slope tolerance and the wave phase sensitivity, are
proposed. The effective radial shear plays important role in reduction of the wavefront slope and that of the wave phase
sensitivity. How the two parameters effect the radial shearing interferometer is discussed in detail. Computer simulation
shows that by properly choosing the effective radial shear, the radial shearing interferometer can obtain the best
performance when testing an arbitrary aspheric wavefront. This research is of greatly importance to the design of the
radial shearing interferometer for aspheric testing.
Novel System Design
Optics for digital photography
Show abstract
The role of optics in digital photography is in certain aspects quite different from that in conventional (silver-halide)
photography. We first give an overview on the different classes of the digital still camera market. In order to judge the
role of optics, one has to look on the different members of the transmission chain and their influence on image quality.
These are mainly:
(1) the optoelectronic image sensor with his modulation transfer function (MTF) and
the particular situation of sensor cross-talk (aliasing), which will be interpreted as
spatial frequency depending additive noise. A quantitative measure for this will be
given.
(2) the optical low pass filter with his own MTF which is intended to minimize the
cross-talk (aliasing).
(3) the optical system which has to be in a well balanced equilibrium concerning
image quality with these components.
Besides MTF-considerations the generation of colour has significant influence on image quality. Here the appearance of
colour fringes is most disturbing and is due to different reasons.
First of all the widely used (RGB) Bayer mosaic filter gives rise to colour aliasing because of the enlarged pixel pitch in
the RGB-channels. Secondly the missing colour pixels in each channel must be interpolated from the corresponding
neighbours who also introduce colour artefacts. Last but not least the optical system may contribute to colour fringes if
the lateral chromatic aberrations are not corrected to a high degree.
Compact hyperspectral imaging system with a convex grating
Show abstract
A hyperspectral imaging system composed of a fore-optic and an imaging spectroscope is
designed and presented. The fore-optic is a three-mirror anastigmatic telescope with a 360mm
focal length to match the FPA with 1024×1024 pixels. The imaging spectroscope is based on a
modified Offner 1× relay with a holographic convex grating in the place of the secondary mirror.
The hyperspectral imaging system is designed for the visible-near infrared (VNIR) band with 5nm
spectral and 18m ground spatial resolution from the altitude of 500km. Its many attractive features
such as fast speed (F/2.5), large flat field, wide spectral range, low distortion, and compactness
made it ideally suited for spaceborne remote sensing.
Design of a lens system within mobile terminal
Show abstract
As the development of technology of liquid crystal monitors, mobile communication terminal products with cameras
integrally installed in have become more popular with consumers. These cameras must satisfy some requirements, for
example, the lens system must have a sufficient resolution and a size larger than the actual size of a sensor in
consideration of an assembly tolerance. In this paper, we provide a lens system with a high performance and compact
structure, which comprises a small number of lenses and is installed in a mobile communication terminal. In the system,
both the first and the second lenses have positive powers, and the third lens has a negative power, respectively. One of
the these lenses has at least one aspherical surface, and a perforated iris is located between the first lens and the second
lens. All the material for the lenses is plastic. The lens system is compact and its field angle is larger than 60 degree.
Moreover, the system consists of an infrared filter separated from the third lens by a designated distance for filtering
infrared wavelengths incident onto the optical system so as to protect an image plane from the infrared wavelengths.
Singlet mega-pixel resolution lens
Show abstract
There always exist some new challenges for lens designers to keep their old-line technology update. To minimize lens
volume is one of the most notified examples. In this paper we designed a single thick lens, constructed by using one
oblique (reflective) surface, apart from two conventional refractive surfaces, to bend the optical path of the optical
system to achieve this goal. Detail design procedure, including system layout and lens performance diagrams, will be
presented.
Following the first order layout, we applied aspherical form to the two refractive surfaces in order to correct the spherical
aberration up to an acceptable condition. Then, the reduced aberrations such as coma, astigmatism, field curvature and
distortion can easily be corrected with some calculations related to spherical aberration as shown in the publication of H.
H. Hopkins (1950). Plastic material is used in the design, because the aspherical surfaces can then be manufactured in a
more cost effective way. The final specification of the design is: EFL is 4.6 mm, the F number is 2.8, the over all
thickness of lens is 3.6 mm, its MTF is 0.3 at 227 lp/mm in center field and chief ray angle is less than 15 degrees. Lens
data as well as optical performance curves are also presented in the paper. In conclusion we have successfully finished a
mega-pixel resolution lens design and its overall thickness is compatible with the state of the art.
Wavefront Sensing and Coding
High-resolution imaging of phase-distorted extended object using SPGD algorithm and deformable mirror
Show abstract
The conventional adaptive optics (AO) technique based on phase conjugate principle requires the information about a
reference wave front that corresponds to the undistorted image when it is applied to extended source image correction.
The AO technique based on the image function appears more promising than the conventional AO for this application.
The success of this technique depends on an appropriate image quality criterion and a suitable control algorithm. We
tried to find a convenient image performance metric not from additional optics elements, but only from the distorted
image which is a gray level image. Simulation results showed the variance function of gray level presents more potential
than other ways, such as ways based on the information about the gray level gradient of each pixel. Based on SPGD
algorithm, an AO system was simulated with a 61-element deformable mirror and the above resultant image quality
criterion. The correction capability of the AO system was investigated through different images and different level
aberrations. Numerical simulation results verified the performance metric we used is effective. The system can correct
different level disturbed images successfully when parameters of the algorithm were appropriate for static distorted
wave-fronts.
Wavefront sensing
Show abstract
The development of new technology in optical systems has provided the
possibility of measure intensity and establishes the wavefront. This idea is based in the
fact that wavefront and its intensity are related in the mathematical expression
irradiance transport equation, which is a partial differential equation. The solution for
this kind expression was done in the middle of 1700 by mathematicians like Bernoulli,
Euler, d'Alambert, Laplace, Legendre, Fourier and others, all of them using numerical
techniques to solve these expressions.
The use of optical system i.e. astronomical systems, that can change their
properties adding, removing or altering optical elements is basic when the information
can be a collimated or focused beam reach in best condition, using the wavefront have
been the best way to do this. With this condition is necessary to develop different ways
to establish and measure the wavefront who travels thorough optical system.
To do this will be use the irradiance transport equation. Our treatment is to
solved the irradiance transport equation who describe the intensity variation in a beam
with irradiance I, when it propagates a long the z-axis of optical system. More over,
using a Hartman screen test we expect module the wavefront, measuring the distribution
of intensity at two planes along the z-axis, and finally give the real wavefront.
Wavefront error correction with stochastic parallel gradient descent algorithm
Show abstract
A novel type of adaptive optical system based on direct optimization of system performance metric is studied. The
optimization method is based on stochastic parallel gradient descent (SPGD) algorithm. Theoretical analysis, computer
simulations, and experimental results under point source and extended source conditions are presented.
Design of objective lenses to extend the depth of field based on wavefront coding
Show abstract
Wavefront coding extended the depth of field to a great extent with simpler structure compared to confocal microscope.
With cubic phase mask (CPM) employed in the STOP of the objective lens, blurred images will be obtained in charge
coupled device (CCD), which will be restored to sharp images by Wiener filter. We proposed that one CPM is used in
one microscope although there are different objective lenses with different power indices. The microscope proposed here
is the wavefront coding one when the CPM is used in the STOP; while it is the traditional one when a plane plate is used
in the STOP. Firstly, make the STOP in the last surface of the lens, and then add a plane plate at the STOP with the same
material and the same center thickness of the CPM. Traditional objective lenses are designed, based on which wavefront
coding system will be designed with the plane plate replaced by a CPM. Secondly, the parameters of CPMs in different
objective lenses are optimized to certain ranges based on metric function of stability of modulation transfer function
(MTF). The optimal parameter is chosen from these ranges. A set of objective lenses is designed as an example with one
CPM. The simulation results shows that the depth of field of 4X, 10X, 40X, 60X and 100X objective lenses with the
same CPM can reach to 400um, 40um, 24um, 16um and 2um respectively, which is much larger than 55.5um, 8.5um,
1um, 0.4um and 0.19um of the traditional ones.
Strehl ratio analysis for the wavefront coding system
Show abstract
Strehl ratio is an important aspect in evaluating the performance of the optical imaging system. Even in wavefront
coding imaging systems, Strehl ratio also plays an important role. It can be used to evaluate the sensitivity of phase
masks to aberrations, and it can also be added as the penalty in the optimization of phase mask parameters to make sure
that the noise gain of the intermediate image recovery is not too large. However the conventional Strehl ratio analyses
are only suitable for the optical system with a small amount of aberration, while the wavefront coding imaging system is
an optical system with a large aberration, the most of which are the characteristic aberrations introduced by the phase
plate. In this paper, the approximate expressions of Strehl ratio are derived for the wavefront coding system with phase
plates of free order and free type. These expressions show a good coincidence with the numerical ones. Based on these
expressions, the impact of the phase mask's order can be analyzed. Besides, the sensitivity of Strehl ratio to all kinds of
aberrations can also be analyzed for the wavefront coding system with phase plates. Phase plates of different types are
shown to be sensitive to aberrations of different types, and the impact of the aberration order can also taken into account.
At last, some advice is given for taking Strehl ratio as one of the performance aspects while choosing phase plates.
Optical Measurement
A generalized temporal phase unwrapping algorithm
Show abstract
A generalized temporal phase unwrapping (GTPU) algorithm is proposed for absolute phase measurement of object
surfaces with complex topography. Comparing with the classical TPU algorithms, GTPU shows more robust and has
better noise immunity and less computational complexity. According to the type of fringe sequence used, the current
TPU algorithms proposed by Huntley can be divided into three categories: linear sequence, exponential sequence and
reversed exponential sequence. The two types of exponential sequences make use of the fact that the relation between the
phase and the number of projected fringes is linear, resulting in a reduction of total number of acquired images compared
to linear sequence illumination. Error analysis for the different TPU methods were done firstly, that reveals the problems
existed in theses phase unwrapping methods, for example the limitation imposed on the fringe sequence, noise immunity
and computational efficiency. In order to overcome these drawbacks, we present a generalized TPU algorithm in this
paper. The GTPU can eliminate the limitation on fringe sequence, so that an arbitrary fringe sequence will be used to
encode the object surface, leading to a flexible method for phase reconstruction. Computer simulations and experiment
results have been also proved that the GTPU has better performance on noise control and computational efficiency.
Simultaneous defect inspection on the surface and in the interior of bare wafers using a simple knife-edge test
Show abstract
This paper proposes a new, simple, high-speed wafer-inspection method using a knife-edge approach. This method
basically corresponds to a bright-field microscope except the light reflected from the wafer surface is partially cut by a
knife-edge, which increases edge contrast in the cutting direction. In addition, the knife-edge test does not depend on the
light wavelength and thus the light can have any wavelength as far as it is reflected by the wafer surface. Therefore, the
knife-edge test, which uses visible light, can be employed simultaneously with a looking through inspection technique,
which uses infra-red, with a single white-light source. The knife-edge method in tandem with a looking through
inspection is implemented at a laboratory level and preliminary experimental results demonstrating edge enhancement
are presented.
Research of light reflex surface defects detection technology
Show abstract
The surface defects (indentations, humps, scores) of semiconductor wafers are the major factor to affect the performance
of the semiconductor devices. Moreover, these defects make the manufacturing process difficult or yield of the
semiconductor devices decrease. Consequently, it is necessary to do an on-line wafers detection in the benefit of the
performance and yield of the devices. Thus, developing a way suited for practical detection is the urgent affair faced to
people. The optical methods are the most suited ways for surface defects detection because of their non-contact
operation. We discuss a relatively unknown method of the light reflex surface defects detection technology (Makyoh (or
magic-mirror) topography (MT)). The optical system that we designed achieves the detection mode of the parallel light
vertical incidence for the first time. It corrects the deviation between the tradition light path and arithmetic, promotes the
detection precision. A lot of experiments based on this optical system are taken to get the difference between the
detection modes of vertical incidence and the oblique incidence. The experiments prove that the vertical incidence mode
excels the oblique incidence mode. The MT images are also analyzed and disposed. The quantitative measurement can
be realized by digital image processing technology.
Optical System Analysis and Optimization
Optimization of sampled imaging system with baseband response squeeze model
Show abstract
When evaluating or designing a sampled imager, a comprehensive analysis is necessary and a trade-off among optics,
photoelectric detector and display technique is inevitable. A new method for sampled imaging system evaluation and
optimization is developed in this paper. By extension of MTF in sampled imaging system, inseparable parameters of a
detector are taken into account and relations among optics, detector and display are revealed. To measure the artifacts
of sampling, the Baseband Response Squeeze model, which will impose a penalty for undersampling, is clarified.
Taken the squeezed baseband response and its cutoff frequency for favorable criterion, the method is competent not
only for evaluating but also for optimizing sampled imaging system oriented either to single task or to multi-task. The
method is applied to optimize a typical sampled imaging system. a sensitivity analysis of various detector parameters is
performed and the resulted guidelines are given.
Development in local and global optimization methods
Quanxin Ding,
Hua Liu
Show abstract
Advanced local and global optimization methods are studied systematically in a great level. Local and global
optimization applied in optical system started back in last century, coming true various domain, especially in optical
design and testing, of success. The three main elements of optimization, that is Model Parameterization, Optimization
Algorithm and Merit Function, base on this, the relationship among them and their reciprocity is defined and analyzed in
detail.
Analysis of infrared radiation from optical window with graded temperature distribution
Show abstract
When the outside temperature rapidly changes, there is graded temperature distribution at optical window in infrared
detection systems and the detection sensitivity will be affected. It is necessary to analyze the response of detector
according to the temperature distribution. In this paper the graded temperature distribution is described in optical system
parameters as environment data, the radial graded temperature function using orthogonal polynomial method is created,
and the temperature of any position at optical window can be calculated easily. Based on the principles of blackbody
radiation, the sampling plans of wavelength and thermal radiation source surface are presented. Having imaged each
surface at object space or image space, the common entrance for infrared radiation from the window is found and named
as thermal pupil, then sampling at the entrance to create millions of rays. These rays are traced through the system with
energy and the power spectral density is calculated. Taken an infrared optical system as an example, the radiation of its
optical window with temperature of 30°C and 55°C±5°C is analyzed. As shown by the example that the radial
temperature gradient will lead to nonhomogeneous noise at the image.
Using Monte-Carlo method for evaluating the imaging through a disturbed medium with random distribution
Show abstract
The image is blurred and shaken when the object through a flow with random refractive index distribution. As the
response time of the image detector is far longer than that of the random disturbance, what the detector actually detects
is an integral picture within the response time. Therefore, researches on the mean image quality within the detector's
response time are great helpful to image recovering and correction.In this paper, Monte Carlo method is used to
simulate the time-related random fluctuation of the inhomogeneous medium, which can be treated statistically.
According to the mean value and variance of the refractive index at each position within the random medium during
detector's response time, many sample refractive distributions are generated to describe the disturbance with time. And
then, ray trace through the generated medium with different refractive index distribution is made, and the spot diagram
at each sample medium is summed up as the final result. Finally, taking the flowing liquid as an example, we obtained
the spot diagram through a medium with disturbance, and made a comparison with that through a medium with the
mean refractive distribution.
Comparison of ray-tracing methods in self-adaptive grid for inhomogeneous medium
Show abstract
The difficulty of tracing rays through the random index medium, like atmosphere, or flowing liquid, lies on how to fast
obtain the refractive index and gradient values of each location along the ray trajectory in space. Recently, the method of
"self-adapting grid" has been developed to efficiently describe such a medium. There are several available numerical
techniques for tracing rays through inhomogeneous medium, such as Taylor method and 3rd order Runge-Kutta method,
the combinations of the self-adapting grid with different ray tracing techniques result in different accuracy and require
different computational effort. In this paper, according to the fundamentals of numerical computation, the derivation of
4th order Runge-Kutta method is presented. For the convenience of comparison, the ray trace through a regular gradient
medium (GRIN) has also been made by these methods, and the results are compared with that from other commercial
lens design codes. The results show that the 4th order Runge-Kutta method has the highest accuracy for the same step
size, but it consumes the longest time. When the ray trace step is relatively large, i. e., one fifth of the GRIN rod size, the
4th Runge-Kutta method is much more accurate than the 3rd method, however, there's few difference of the accuracy
when ray trace with a small step size. Therefore, the 3rd order Runge-Kutta method is the optimum choice for ray tracing
in self-adapting grid when comprehensively considering the accuracy and computational efforts.
Optical Testing and System Alignment
Electrically calibrated pyroelectric detector for high-accuracy calibration of UV radiation
Show abstract
A pyroelectric detector with special structure was developed for calibration of UV radiation. A new relaxor-based
ferroelectric single crystal with high pyroelectric coefficient was selected as the detector material. The detector is free of
substrate and a black coating film was deposited on the surface of the sensitive area. The reflectance of the coating film
is less than 1% in the spectral range 200nm to 400nm, and its sheet resistance is near 100 Ohm. Both the UV radiation
absorption and the electrically heating in the coating film can result in temperature change. Accordingly, the film can
work both as optical absorber and electric heater. By this means, the measurement of UV radiation power can be
converted to the measurement of electrical power. The direction of the heat flow is same in both cases, but the
mechanism of heat transport has tiny differences. A finite element model was set up by ANSYS software to simulate the
thermal diffusivity. The factors which may bring errors to the optical-electrical equivalence were measured and analyzed
in detail. The detectors were used to establish UV electrically calibrated system with uncertainty less than 4% in the
spectral range from 200nm to 400nm at room temperature.
Novel method based on DDE technology for computer-aided alignment
Show abstract
A new method based on Dynamic Data Exchange (DDE) technology for computer-aided alignment is put forward in this
paper. It is adopted to realize the automatic data transferring between Matlab and Zemax optical software. Based on the
analysis of CAA and its procedure, a self-made program is developed to perform all the CAA steps under Matlab
environment. Flow process of this program is shown in this paper. A Gregorian system is adopted as an example to verify
the feasibility of the program. Comparisons of the image quality between the misaligned system and the post-aligned
system are presented. Results show that this program is very effective.
Research on measurement of lens centering errors based on image processing
Show abstract
To combine modern sensor technology with digital image processing, a real-time measurement system of lens centering
errors is designed based on CCD sensor. Following transmission principle as well as reflection principle, a scheme that
applies two orthogonal light sources to the measurement system is put forward with the combination of cross and double
slit reticles. The experimental result shows that the standard deviation of centering errors is up to 0.0019mm, the limit
errors is ±0.0057mm. It is proved that the measurement system is of good reliability and practicability for measurement
of centering errors. In addition, the designed system is suitable for multi-parameter measurement, including focal length,
intercept and curvature radius, etc.
Poster Session
Optical design of a synthetic aperture ladar antenna system
Show abstract
The spatial resolution of a conventional imaging LADAR system is constrained by the diffraction limit of the telescope
aperture. The purpose of this work is to investigate Synthetic Aperture Imaging LADAR (SAIL), which employs
aperture synthesis with coherent laser radar to overcome the diffraction limit and achieve fine-resolution, long range,
two-dimensional imaging with modest aperture diameters. According to the demands of the Synthetic Aperture LADAR
(SAL), the key techniques are analyzed briefly. The preliminary design of the optical antenna is also introduced in this
paper. We investigate the design method and relevant problems of efficient optical antenna that are required in SAL. The
design is pursued on the basis of the same method as is used at microwave frequency. The method is based on numerical
analysis and the error values obtained by present manufacturing technology. According to the requirement to SAL with
the trial of little size, light mass, low cost and high image quality, the result by ZEMAX will result.
Design of a wide field of view infrared scene projector
Show abstract
In order to make the projected scene cover the seeker's field-of-view promptly the conventional projection optical
systems used for hardware-in-the-loop simulation test usually depend on the 5 axes flight-motion-simulator. Those
flight-motion-simulator tables are controlled via servomechanisms. The servomechanism needs many axis position
transducers and many electromechanical devices. The structure and controlling procedure of the system are complicated.
It is hard to avoid the mechanical motion and controlling errors absolutely. The target image jitter will be induced by the
vibration of mechanical platform, and the frequency response is limited by the structural performance. To overcome
these defects a new infrared image simulating projection system for hardware-in-the-loop simulation test is presented in
this paper. The system in this paper consists of multiple lenses joined side by side on a sphere surface. Each single lens
uses one IR image generator or resistor array etc. Every IR image generator displays special IR image controlled by the
scene simulation computer. The scene computer distributes to every IR image generator the needed image. So the scene
detected by the missile seeker is integrated and uninterrupted. The entrance pupil of the seeker lies in the centre of the
sphere. Almost semi-sphere range scene can be achieved by the projection system, and the total field of view can be
extended by increasing the number of the lenses. However, the luminance uniformity in the field-of-view will be
influenced by the joint between the lenses. The method of controlling the luminance uniformity of field-of-view is
studied in this paper. The needed luminous exitance of each resist array is analyzed. The experiment shows that the new
method is applicable for the hardware-in-the-loop simulation test.
Improved first Rayleigh Sommerfeld method for investigating microlens array with long focal depth and small f-number
Show abstract
In recent years, with the developments of the micro-photolithography, micro-optical elements
with small characteristic size and highly refinement are available. These micro-optical
elements with a sub-wavelength structure can realize multi-function, such as a microlens array
with a long focal depth and high transverse resolution, and it has been extensively studied
owing to its potential applications. With the decrease of the characteristic size of faster
focusing microlens array, the scattering or coupling effect of the light waves becomes much
stronger. Therefore, rigorous Maxwell's electromagnetic theory should be adopted to analyze
the focusing performance along both the longitudinal and transverse directions of faster
focusing microlens array. However, rigorous numerical methods cost a lot of computing
times and memories. Thus, it is impossible to perform optimal design of the faster focusing
microlens array by rigorous methods. A simpler and faster, even somewhat less accuracy,
design approach is needed. Various approximate scalar methods have been developed under
some assumptions and approximations, which are inadequate, especially, in the analysis of
various microlens with small f-number less than f/1.0 and small feature size. In this
presentation, an improved First Rayleigh Sommerfeld Method (IRSM1) is applied to analyze
the focusing performance of dual- and tri- cylindrical microlens arrays with long focal-depth
and small f-number for the TE polarization. The real extended focal depth, the diffraction
efficiency, the spot size, and the real position of the focal plane of the microlens array with
different f-numbers and preset extended focal depths are calculated by the IRSM1, rigorous
boundary element method (BEM) and original Rayleigh Sommerfeld method (ORSM1),
respectively. The accuracies of the IRSM1 and the ORSM1 are evaluated along the
longitudinal direction. The results indicate that the IRSM1 can be used for analyzing the cylindrical microlens array with long focal depth and small f-number, but the ORSM1 is fully
failure for those microlens arrays with small f-number. This investigation can provide valuable
information for optical engineers and might be used for further guiding the designs of the
micro-optical elements for realizing longitudinal optical field modulation.
Algorithm realization of median filter in multiple environments testing conditions for low-level-light sight devices measurement system
Show abstract
Low-level-light (LLL) sight devices measurement technologies based on multiple environments testing conditions
are always concerned by military equipments manufacturers. Because vibration, shooting, shock, drop and high
low-temperature environment, etc. are under loaded function, the machinery, optics structure and electric
performance parameter change to make LLL sight instrument, causing the LLL sight instrument can't be worked
and used normally while taking aim. We have designed the measure and test system of LLL sight instruments
under multiple environmental experimental conditions, provided and made up the operation principle of the
detection system by CCD. Have analyzed the image of LLL sight devices, have brought forward algorithm of
median filter, and have already confirmed its accurate number value. Have combined actual project application, the
measure precision which is less than 0.05 mil. And the measure range which is greater than 40 mil. It can meet the
project requirements.
Multi-alkali photocathode thermal performance analysis of image intensifier based on low-high temperature environment testing conditions
Show abstract
Low-level-light (LLL) weapon sight measurement technologies based on Low-high temperature environments testing
conditions are always concerned by military equipments manufacturers. Because low-high temperature environment, etc.
are under loaded function, the electric performance parameter change to make LLL weapon sight, causing the LLL
weapon sight can't be worked and used normally while taking aim. Generally believed that many photocathode is n-type
and p-type doping of the inner surface layer comprising more photocathode not light sensitive, but also sensitive to
temperature. To image intensifier is non-working state at the temperature 70°C ±2°C test boxes and thermostats time
one hour, five minutes to image intensifier into -50°C±2°C Test Box temperature one hour, then five minutes again
placed 70°C ±2°C high temperature test box for three cycle question image intensifier restore normal temperature
after the test. The experiments show that, when the temperature rises, the heat semiconductor photocathode current
density, thermal current rise in the temperature range 0 to 70°C, 4°C temperature is increased, almost twice its
current heat. Of course, image intensifier imported the equivalent background illumination will also increase, resulting in
night vision systems observed at the scene image contrast and differential rates were lowered, target detection system
performance last night caused the decline. A study of the reasons is the photo-cathode materials and fabrication of
thermal electron emission standards restricting the ability.
Influence of temperature on fractal dimension of dynamic scattered light intensity signal of ultrafine particles
Show abstract
The fluctuation of the dynamic scattered light of particles was characterized with fractal dimensions, and the influence of
temperature on the fractal dimension was discussed. In the experiments, the fractal dimensions of dynamic scattered light
intensity signal of particles with the diameter of 60nm, 90nm, 200nm, 300nm and 450nm, were obtained under the
temperatures of 18°C, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C. The experimental results shown the monotony relationship
between fractal dimension of scattered light intensity signal of particles and the temperature in the particle system, which
indicate that the fractal dimension of scattered light signal correlate well not only with the particle size but also the
temperature of the suspension. Under the condition of constant temperature in the cuvette, the smaller the particles, the
larger their fractal dimensions. For the same particle system, the higher the temperature, the larger the fractal dimensions
of dynamic scattered light. By using two-dimensional interpolation surface chart of fractal dimensions, the polydisperse
particle system were measured.
Effect of radius mismatch on performance of segmented telescopic systems
Show abstract
There exist great interests in using segmented mirrors instead of monoliphic primary mirror to build large aperture
telescopes. The use of segmented mirrors reduces the difficulties in fabrication, transportation and replication as well as
decreases the impact of gravity. In the meanwhile, one of the grand challenges in this approach lies in matching the
individual mirrors to yield the form of a continuous surface. The erroneous differences between the global radii of
curvature (GROC) of the segmented mirrors have significant influence on image quality. In this paper, we present a
model of segmented systems and an analysis technique which reveals the effect of these errors on the image quality. Our
analytical results show that the GROC differences have great influence on image quality and the impact remains high
despite of using active optics to compensate these errors. The local radii of curvature of individual mirror segment
should be used to correct these errors. We propose a new approach to generate compensators that controls the local
radius of curvature of each segment efficiently. Finally, through simulation results, we demonstrate that the new
compensators can dramatically reduce the effect of radius mismatch.
Extrapolation method to extend the dynamic range of the Shack-Hartmann wave-front sensor
Show abstract
The maximum tolerable spot displacement of the Shack-Hartmann wave-front sensor is called dynamic range, and it is
limited by the f-number of the micro-lens. It is well known that there is a trade-off between the sensitivity and the
dynamic range, if the f-number is relatively short, a high dynamic range is achieved, but the corresponding sensitivity is
degraded and vice versa. Extrapolation method could overcome the trade-off; since the extrapolation method is a simple
algorithm that does not change the measurement configuration, there is no requirement for extra hardware, multiple
measurements, or complicated algorithms. In this paper, we not only present the theory but also actually implement
measurement of a highly aerated wave-front.
Application of a white-light interferometric measuring system as co-phasing the segmented primary mirrors of the high-aperture telescope
Show abstract
For the optical system of the telescope, with the increase in telescope size, the manufacture of monolithic primary
becomes increasingly difficult. Instead, the use of segmented mirrors, where many individual mirrors (the segments)
work together to provide an image quality and an aperture equivalent to that of a large monolithic mirror, is considered a
more appropriate strategy. But with the introduction of the large telescope mirror comprised of many individual
segments, the problem of insuring a smooth continuous mirror surface (co-phased mirrors) becomes critical. One of the
main problems is the measurement of the vertical displacement between the individual segments (piston error), for such
mirrors, the segment vertical misalignment (piston error) between the segments must be reduced to a small fraction of
the wavelength (<100nm) of the incoming light. The measurements become especially complicated when the piston error
is in order of wavelength fractions. To meet the performance capabilities, a novel method for phasing the segmented
mirrors optics system is described. The phasing method is based on a high-aperture Michelson interferometer. The use of
an interferometric technique allows the measuring of segment misalignment during the daytime with high accuracy,
which is a major design guideline. The innovation introduced in the optical design of the interferometer is the
simultaneous use of monochromatic light and multiwavelength combination white-light source in a direct method for
improving the central fringe identification in the white-light interferometric phasing system. With theoretic analysis, we
find that this multiwavelength combination technique can greatly increase the visibility difference between the central
fringe and its adjacent side fringes, and thus it offers an increased signal resolution. So make the central fringe
identification become easier, and enhance the measure precision of the segment phasing error. Consequently, it is
suitable for high-precision measurement purpose and application in the segment piston error phasing system. The
description about the expected interferograms and the feasibility of the phasing method are presented here.
Method for calculating the center position of collimated laser beam spots
Show abstract
It is a key problem of measuring warp making use of collimated laser how to accurately calculate laser beam's center. A new
method, named double geometrical center method, is put forward. In this method, plane wave perpendicularly irradiates an aperture stop,
and a charge couple device (CCD) is employed to receive diffraction-beam spots, then the geometrical centers of the first and second
diffraction-beam spots are working-out respectively, and their mean value is regarded as the center of datum beam. In face of such
adverse instances as intensity fluctuations of the laser beam spots, part of the image being saturated, this method can still work well.
What's more, this method can detect whether an unacceptable error is exits in the courses of image receiving, processing and calculating.
Experimental results indicate this method can remarkably improve the measurement accuracy.
Particle size measurement system of the aerosol time-of-flight mass spectrometer optimization study
Show abstract
In this paper, Aerosol time-of-flight mass spectrometer optical particle size measurement system
optimization and influencing factors are studied. Optimized the distance between nozzle and the
skimmer, using a shorter wavelength light source measurement, Aerosol particle size measurement
from the previous limit of 260 nm to 120 nm. Study found that the particles scattered light intensity is
connected with light intensity and wavelength of the light source. particle size measurements using
shorter laser wavelengths or greater energy, which can measure smaller size diameter within certain
range. combining particle beam focusing aerodynamic lens system device, the particle size of air the
time-resolved measurement of 256 / min, Measurement of time-resolved mass spectrometry to 170 /
min, MS hit rate of 64.5%.
Dark point algorithm: a new method to test periodic structures of optical instruments
Show abstract
Periodic structures are of great importance in optical instruments. Actually, the periodic structures in
optical instruments are not perfect and this may result in the negative effect on the function of the
instruments. It is necessary for us to study the specification of periodic structures. In this paper, a new
meaningful parameter, named the total of dark points, is defined based on the characteristic of the
overlay of the images of two repeating elements in a periodic structure. Furthermore, a new method
with high measure accuracy, named dark point algorithm, is introduced to test the periodic structures.
Some testing examples and testing results using dark point algorithm are provided as well. Quantitative
description of the quality of periodic structures can be made taking this new method, and it can help to
analyze the differences between the structures and their designs. The new method can also be easily
realized in many physics processes and with some equipment, it can indeed be used in large scale
production and bring economic value to us.
Spherical aberration correction of Gaussian beam
Show abstract
The relationship between the Strehl ratio and the standard deviation of the wave front aberration of a Gaussian beam is
derived from the diffraction integral in the presence of aberrations. Let it be required to develop the spherical aberration
of a Gaussian beam into an aberration polynomial. For the maximum value of the Strehl ratio, a set of linear equations is
obtained. The optimum configuration of the balanced spherical aberration is obtained from the solution of this set of
linear equations. The coefficients of the spherical aberration of a Gaussian beam for the optimum design are illustrated in
terms of tables. A comparison is made between the Strehl ratio of the corrected spherical aberration of the Gaussian
beam using the optimum design of the uniform beam for the minimum RMS wave front aberration and those for the
minimum P-V wave front aberration. The Strehl ratio of the configuration using the optimum design of the uniform
beam changes slightly. It turns out that the spherical aberration of the Gaussian beam can be balanced with the optimum
configuration of the uniform beam. Finally, the correction of the spherical aberration of the Gaussian beam is illustrated
with an example.
Measurement of self-organization pattern in dielectric barrier discharge by a special photoelectronic detection system
Show abstract
The non-intrusive optical emission spectroscopy is used to measure the vibrational temperature and the electron density
in white-eye pattern in dielectric barrier discharge (DBD) in air. The electron density is investigated by stark broadening
of spectral line profile, and the molecule vibrational temperature is calculated by analyzing the intensity ratio of lines in
the second positive system (SPS) of N2 (C3 ∏u
−B3∏g). The results show that the vibrational temperature and electron
density of the spot in white-eye pattern is slightly different from that of the background in white-eye pattern. It indicates
that both the spot discharge and the background discharge are microdischarges.
Study on the photo-electrical characteristics of different patterns in dielectric barrier discharge by using photoelectricity method
Show abstract
A dielectric barrier discharge apparatus with two liquid electrodes and a photoelectric detection system are specially
designed to study the photo-electrical characteristic of different patterns. A series of filamentary patterns, in which the
filaments can be fixed for a long time, have been generated from filaments moving stochastically by increasing applied
voltage. It follows the sequence of square pattern, square superlattice pattern and hexagon pattern. The studies of optical
and electrical characteristics, including discharge current, light signals, the voltage drop across discharge gap, transported
charges, and Lissajous figures of these different patterns are realized by the photo-electrical detection method. From the
light signals and waveforms of current, it is found that the square pattern has two discharge pulses, the square
superlattice has three and the hexagon has several pulses in each half cycle of the applied voltage. The voltage drop
across discharge gap and transported charges increase with the increasing of applied voltage. The dissipated power
obtained by the charge-voltage Lissajous figures also increases with the increasing of applied voltage.
Improvement in design of panoramic annular lens using cemented lenses
Show abstract
A new method using cemented lenses to improve the design of Panoramic Annular Lens (PAL) is introduced. This
structure can help to realize the design of PAL optical system with long focal length, which can help to see much further
than the ones with short focal lengths. It can also keep the volume of the system moderate. The chromatic aberration of
PAL is investigated theoretically. Method of selecting proper cemented glasses of PAL is also discussed. A doublet PAL
and its relay optics with a total effective focal length of 10.3mm are realized.
Simulation of the phase-shift and anti-vibration in wavefront time-domain algorithm
Show abstract
The wavefront time-domain detection algorithm is a simple, practical and low-cost interferometry method, which can be
adapted to all kinds of outside noise and achieve high accuracy in interferometric measurement on optical components
and systems. For further understanding the wavefront time-domain measurement of anti-jamming capability and
accuracy of interferometry, the simulation is presented of time-domain sampling frequency of interferograms, external
vibration frequency and amplitude, and harmonic effect, etc. in this paper. This algorithm makes the measurement
controlled by means of using the environment vibration and air turbulence as phase shifters, simply with assistance of
active phase shifting. Acquiring adequate interferograms to calculate the phase value of each point, we can obtain the
stable wave surface wiping off random vibration and air turbulence by the unwrapping and average calculation. In this
process, by changing the time-domain sampling frequency, external vibration frequency and amplitude in the simulation,
the relationships among them can be obtained. The appropriate sampling frequency could be chosen according to the
conditions of actual measurement to ensure the accuracy and stability of measurement. According to statistical analysis,
this algorithm enhance its ability of anti-jamming, and improve the adaptability and especially for the real-time detection
of large aperture mirror.
Athermalization for infrared dual field-of-view optical system
Show abstract
With the principle of mechanical passive athermalization, a method of making the dual field-of-view (DFOV) switching
zoom system for passive athermalization is presented. The long effective focal length (EFL) and short EFL have the
same focus shift values of temperature by optical material combination of switching groups. So the long EFL and short
EFL of this system achieve the best temperature compensation simultaneously by moving the compensated lens with the
same distance, and the system has the best images and parfocality in a large working temperature.
A DFOV switching zoom system is designed. It has a relative aperture of f/4.0, 100% cold shield efficiency, the EFL of
180mm/60mm at 3.7-4.8μm. The movement of compensated lens can be achieved with four layers of aluminum/titanium
materials. Compared with the MTF of a normal switching zoom system without athermalization, this system needn't
move the compensated lens repeatedly to obtain the best images from -30°C to 70°C and enhances the performance of
target tracking and recognition.
Comparison of signals under top-hat and Gaussian beam excitations in surface thermal lens technique
Show abstract
A theoretical model for the surface thermal lens (STL) signal with modulated top-hat and Gaussian beam excitations is
developed. For an optical coating sample, distributions of the temperature and surface deformation in both transient and
quasi-steady states are deduced, and the STL amplitudes, corresponding to the alternating current (AC) deformation and
direct current (DC) deformation, respectively, are defined. Numerical simulations and comparison results for the
temperature and deformation demonstrate that there exist large differences in radial distributions between the AC and
DC cases especially in the high modulation frequency range. The pulsed or AC STL amplitude under the top-hat beam
excitation is approximately two times of that under the Gaussian beam excitation at the optimum detection distance in
the high frequency, and correspondingly, the DC STL amplitude in quasi-steady state with top-hat beam excitation is
only ~1.1 times of that with Gaussian beam excitation at the optimum detection distance. Influences of the heating-beam
radius and modulation frequency on the STL amplitudes are also presented and compared. The application of the STL
technique to the deformation measurement of an optical component is discussed.
Microscope auto-focusing system with the self-adaptive mountain-climbing search method based on PC control
Show abstract
A microscope auto-focusing system using the self-adaptive mountain-climbing search (SAMCS) method is introduced
based on personal computer (PC) control. It mainly consists of four parts: the microscope, the digital camera to get the
video images, the mechanical part of step motor and the computer to control the focusing process. The precision of the
auto-focusing system is to some extent improved through high-resolution color images acquired by the digital camera as
well as high subdivision of the step motor drive. An improved searching method--the SAMCS method is presented here.
It can effectively improve the searching efficiency while guaranteeing the precision of the auto-focusing system. Based
on the normal mountain-climbing search (MCS) algorithm, the SAMCS method takes full consideration of omnidistance
concept and local extreme point influences. Thereby it can adaptively adjust the searching range according to different
environmental conditions, and has quite good robustness. This feature mainly has two advantages. First, this method is
much more exact than the normal mountain-climbing, which can not avoid local fluctuations. Second, it is much faster
than the method of only using omnidistance searching to avoid local fluctuations. At the same time, we also take
evaluation function and region selection into consideration to reach a faster and more accurate focusing result. And the
experimental result demonstrates a good efficiency and accuracy.
Modulation transfer function measurement of charge-coupled devices using frequency-variable fringe patterns
Show abstract
Although there are various methods to measure the modulation transfer function (MTF) of charge-coupled devices
(CCD), the interferometric fringe pattern method has advantages over others, such as canted slit sources, bar targets,
knife-edge, laser-speckle patterns, random noise pattern, etc. Our interferometric method is relatively simple and
versatile: It requires no critical optics and no focusing or precision alignment, the entry array is tested, the contrast ratio
of the test pattern is high enough, the spatial frequency of the fringe pattern can vary continuously.
Our method generates the formation of a sinusoidal intensity fringe pattern by the interference of two monochromatic
plane waves, and straightforward projects it onto the CCD array under test. The construction of the experimental device
is based on the Fresnel Double-Mirror structure. A 2.5 mw He-Ne laser with the wavelength of 632.8 nm is used as the
light source, the laser beam is spatially filtered by a 10 μm pinhole and expanded to a diameter of 30 mm, and the
resulting wave front is divided by two mirrors, which incline to each other at a small angle, and interfered. One of the
mirrors is rotatable to vary the frequency of the pattern. The CCD array is mounted on a stage, which is also rotatable to
make that the CCD array takes different angle with the fringe pattern direction, to receive the patterns.
With the method we provided, the spatial frequency can be extended to some 2 times the Nyquist frequency of the CCD
array to study the aliasing effect. In the Cartesian coordinates, the x- and y- axis MTFs (at angle 0° and 90°) of the CCD
array were measured, the other three MTFs (at angle 26.56°, 45° and 63.44°), which nobody has done before, were also
tested offering a more comprehensive characterization of the CCD array.
Analysis of resolution criterion and aberrations for Fizeau interferometer
Show abstract
The quest for higher angular resolution in astronomy will inevitably require the telescope with large aperture. However,
the primary mirror diameter is limited by the fabrication problems, and the cost of monolithic optics increases faster than
diameter squared. The Fizeau interferometer imaging system represents a promising new technology to overcome the
above-mentioned problems. The sub-apertures of the system are phased together to synthesize an imaging system that
has a large effective aperture than any of the independent sub-apertures. Due to discontinuation of pupil plane, the lost of
circular symmetry and the increase of secondary peak indicate that the standard Rayleigh resolution criterion for the
single-aperture system is not appropriate for the Fizeau interferometer imaging system. On the other hand, in order to
obtain diffraction-limited performance, the sub-apertures of the system must be coherently phased together to much less
than the wavelength of light, so the optical aberrations of sub-apertures can rapidly degrade system performance. The
purpose of this paper is to analyze the resolution performance and the effect of aberrations for a Fizeau interferometer
imaging system that consists of four identical sub-apertures. The resolution based on the threshold and contracted with
directional property is deduced. The relationship between the system's Strehl ratio and the sub-apertures' aberrations is
given with the exponential approximation, which implies that Strehl ratio contacts not only with each sub-aperture's
aberrations, but also with the interference between sub-aperture's aberrations.
Observation of aerosol with a compact lidar over Hefei, China
Show abstract
A portable compact lidar system was presented in this paper. The measurement results of lidar were compared with
the result measured by visibility sensor of vaisala and reliable and Aethalomete of Magee, so the reliable of the lidar
system was tested. The experimental results show good agreement. With the changing lidar ratios, the extinction
coefficient of aerosols in Hefei was derived.
The effect of beam incident angles on cube corner retro-reflector measurement accuracy
Show abstract
The working principle and optical characteristic of cube corner retro-reflector (CCR) using in laser tracking system (LTS)
are analyzed. A novel approach has been proposed to determine the effective reflection area of CCR with an arbitrary
beam incidence angle. The optical model of CCR under the limitation of maximum incident angle and available
reflection area is developed based on rays tracing algorithm. Finally, the relationship between CCR measuring accuracy
and beam incident angle is established. Theoretical analysis and experimental results have demonstrated that the CCR
measuring accuracy reduces as the incident angle increases, the CCR measuring error is largest when the maximal
incident angle is reached. The maximal incident angle at which LTS can still work well is ±35°. The measuring accuracy
of a CCR can maintain the manufacturer specifications of LTS only when the incident angle is within ±20°.
The optimal design of TIR lens for improving LED illumination uniformity and efficiency
Show abstract
With the development of LED technology, LED will potentially replace the traditional light source for its cost and size
advantages, especially in the micro-projection system. And since the illumination uniformity and efficiency on spatial
light modulators (SLM) are two important factors in evaluating the performance of micro-projection system, tapered
light pipe (TLP) and square compound parabolic concentrator (SCPC) are often used as beam shaper in LED-based
micro projection system to provide SLM with uniform and efficient illumination. In this paper, in order to overcome the
disadvantage of insufficient compactness induced by the working length of TLP or SCPC for the illumination system, a
total internal reflection (TIR) lens with rotated and faceted structure is designed with an optimization method to couple
and transfer most of the light emitted from LED into a rectangular target plane (RTP) representing SLM. The TIR lens
has six surfaces controlled by 17 dimensional parameters and is designed by optimization of dimensional parameters
with generic algorithms. In order to provide RTP in fixed position with satisfied illumination uniformity and efficiency,
the illumination uniformity and efficiency on RTP are taken into account in the merit function for the optimization
process. In Tracepro program, the simulation result of the LED illumination system with the optimized TIR lens shows
that the illumination efficiency and uniformity has respectively achieved to 61.9%, 76% with considering the limitation
angle of light (15°).
Design of double refractive pattern recognition system for optical low pass filter
Show abstract
Photo-electronic imaging system is a discrete imaging system, according to Nyquist sampling theorem, if the maximum
spatial frequency is higher than Nyquist frequency, there is aliasing, and Morie fringe appears on image. The quality of
image is receded and the trueness of color depressed. An optical low pass filter (OLPF) used in front of photo-electronic
imaging sensor, can effectively limit the frequency spectrum width and critically satisfy Nyquist sampling condition.
Thereby, the aliasing will be eliminated and the quality of the image will be improved. This paper analyzes the
characteristics of frequency response of the OLPF and designs a novel system to measure the optical characteristic of the
OLPF. According to the characteristic of birefringent crystal, a light spot will be separated by the OLPF into several light
spots which will be processed by the computer. For the size of light point determined the limit of measurement accuracy
of OLPF's thickness, laser source, which can obtain light point with 2um diameter is used here as a target light point.
Magnified lens are used to improve the precision of the system. Other system used long working distance (WD)
microscope objective. Instead, this novel system uses the standard 100x optical microscope objective (WD<0.2mm) as
magnifying system. In this way, the cost of the system will be reduced in a great deal. The software of the system is also
very powerful, in addition to the basic function image caption and scanning, it can automatically detect the number of
light spots, distance and angles between light spots. The system can accurately measure the distance of point light at a
high resolution of 0.1um, and the measurable thickness of OLPF is from 0.5 to 5mm.
A subpixel localization method based on edge diffraction
Show abstract
The subpixel localization is an important factor to determinate measurement accuracy in using CCD vision measurement
system for measuring the size of precision part. For investigating the reason of the image edge's gray-scale distribution
and the edge subpixel localization calculation method of the precision part vision measurement, the influence of diffraction
on the edge gray-scale distribution of the precision part's CCD image has been studied with the theory of Fresnel straight
edge diffraction and the experiment, the theoretical analysis and experiment results have confirmed that the main influence
factors on the edge gray-scale distribution of the precision part's CCD image were the edge diffraction and imaging
parameters. An empirical formula of subpixel localization for precision part's CCD vision measurement has been given,
and its rationality and practicality have been certified by the vision measurement experiment on the standard measuring
gauges.
Evaluation of the sphericity measurement uncertainty for the fiber point diffraction interferometer
Show abstract
Due to the imperfectness of the reference wavefront produced by standard lens, the spherical figure measurement
precision of the traditional interferometer is limited. The fiber point diffraction interferometer (FPDI) provides a method
to produce the nearly perfect reference wavefront for the spherical figure measurement. The diverging wavefront
diffracting from the fiber tip can serve as an ideal reference for the concave spherical surface measurement. However, it
can not serve for the convex surface measurement until an auxiliary positive lens is introduced. This paper presents the
different FPDI configurations for the concave and convex spherical surface measurement. The measurement uncertainty
of the FPDI comes from the following factors: the spherical figure error of the reference wavefront diffracting from the
fiber tips; the flatness of the fiber tips; the phase shifting error of PZT; the tilting error introduced by adjustment during
measurement; the environmental influences such as temperature, vibration, and air turbulence. In all of these factors, the
flatness of the fiber tips mostly affects the measurement uncertainty. The estimation of the expanded uncertainty is about
λ/95 for the concave and λ/40 (λ=532nm) for the convex spherical figure measurement by FPDI.
A new method of evaluating counting efficiency based on signal amplitude response function
Show abstract
In order to accurately measure counting efficiency of laser airborne particle counter, the characteristics and shortages of
the signal amplitude response functions of domestic instruments were analyzed firstly. Then the design of performance
optimization for optical sensors was developed through using sheath air inlets to replace the original inlets, which can
cause the signal amplitude response functions to be described by the normal distribution. Base on these, a new method
for calculating counting efficiency was presented. Through analyzing the relation between signal amplitude response
function and coordinate origin, the counting efficiency for mono-disperse particles can be confirmed. If the signal
amplitude response function intersected with the coordinate axis, fitting the incomplete curve into the complete curve
using non-linear Least Square Method, then the counting efficiency can be defined as the ratio of the included area of the
incomplete curve to the complete curve. If the whole signal amplitude response function totally diverged from the
coordinate origin, it proved that the counting efficiency of mono-disperse particles was up to 100%. The theory and
experiments prove that this method is simple, useful and practical. It also offers the clear guidance direction for
appraising performance of the instrument.
Research on design of optimum phase mask for wave-front coded imaging system
Show abstract
Wave-front coding is a system level design method which can be used to extend the depth of field of an incoherent
optical system. By attaching a phase mask to the aperture, the optical transfer function can not only be made insensitive
to misfocus, but also can avoid the isolated zeros caused by defocus. With this modified optical transfer function, a
purposely blurred image can be obtained and its corresponding clear one with large depth of focus can be generated
through digital processing techniques, such as direct inverse filtering, wiener filtering and maximum entropy restoration
and so on. This is why the wave-front coded imaging system is called optical/digital hybrid imaging system as well.
The most important part of the system design lies in the design of phase masks. So far, many kinds of phase masks have
been suggested; among all those types, two are classical: cubic-phase-mask and logarithmic-phase-mask. However,
whether an optimum phase mask exists or not is still a question that is not answered yet. This paper focuses on this
question and tries to find one answer. In this paper, considering several critical factors and with the help of a simulation
program developed by ourselves, we make a comparison among the performance of different phase masks and finally
propose a prototype phase mask whose performance is acceptable in several aspects.
Preliminary analysis and experiment of thermal influence on a large-aperture mirror
Show abstract
Thermal distortion of the optical elements can greatly reduce the high resolution of the space-borne camera. The
general thermal effect on mirror is analyzed and the optical aberration of the optical surface resulting from 3 kinds of
thermal gradient is discussed. The thermal distortion simulating experiment of a large aperture flat mirror is designed and
the optical aberration is tested on 18" ZYGO with the different axial thermal disturb. The testing results conclude that the
small thermal gradient can greatly affect the wave-front, the aberration of this large aperture flat mirror can be used to
simulate the thermal distortion on space, and MTF is also reduced greatly when this large aperture flat mirror is used in
the real space-borne camera under the same thermal environment. In order to correct the thermal distortion and keep the
high resolution, the 37-units adaptive optics correction close loop experiment is designed and installed in the above
camera. The correction results show that MTF of the testing camera will not reduced greatly under the large thermal
distortion. So employing adaptive optics on a high resolution space camera is the necessary and the valid method to
correct
Research of the grid computing system applied in optical simulation
Wei-wei Jin,
Yu-dong Wang,
Qiangsheng Liu,
et al.
Show abstract
A grid computing in the field of optics is presented in this paper. Firstly, the basic principles and research background of
grid computing are outlined in this paper, along with the overview of its applications and the development status quo.
The paper also discusses several typical tasks scheduling algorithms. Secondly, it focuses on describing a task scheduling
of grid computing applied in optical computation. The paper gives details about the task scheduling system, including the
task partition, granularity selection and tasks allocation, especially the structure of the system. In addition, some details
of communication on grid computing are also illustrated. In this system, the "makespan" and "load balancing" are
comprehensively considered. Finally, we build a grid model to test the task scheduling strategy, and the results are
analyzed in detail. Compared to one isolated computer, a grid comprised of one server and four processors can shorten
the "makespan" to 1/4. At the same time, the experimental results of the simulation also illustrate that the proposed
scheduling system is able to balance loads of all processors. In short, the system performs scheduling well in the grid
environment.
Application of MATLAB in optical alignment
Show abstract
The article has mainly introduced a new method in the process of adjusting the average windward area measuring system
of cannonball fragment with the aid of MATLAB. The method can not only analyze the amount of deviation qualitatively
but also quantitatively, comparing with the traditional method which just can be used for qualitative analyzing. When the
measuring system works, four optical axes of CCD cameras should aim at the center point of the universal platform
strictly with different object distances and image distances. In the process of assembling and debugging the system,
analyzing the image acquired with MATLAB to get the amount of deviation which can be used as gist.
The wavefront aberration analysis and testing accuracy evaluation for the large aberration aspheric system based on the best fit sphere
Show abstract
In the measurement of aspheric surfaces, the vertex sphere and the best fit sphere are often used as reference sphere to
calculate the non-null compensation deviation. In traditional interferometry, the detected wavefront is equal to twice of
the deviation; but it is true only in the null condition or with a certain tolerance in the near null condition. In the non-null
condition, when reference spherical wavefront (the best fit sphere in this paper) incidences to the aspheric surface, the
rays will not return in the same path but deviate certain angles which cause normal longitudinal aberration. If the normal
longitudinal aberration is small enough, for example, much smaller than one wavelength, the wavefront aberration can be
equalized to twice of the deviation between the aspheric surface and the reference sphere. However, if the normal
longitudinal aberration can not be negligible, the wavefront aberration should not be equalized to twice of the deviation.
In this paper, the distribution of the deviation between the aspheric surface and the reference sphere is modeled, and the
relationship between the wavefront aberration and the normal longitudinal aberration is discussed. Two paraboloids, one
with small asphericity and the other large, are analyzed respectively to compare the different result when whether
considering the influence of the normal longitudinal aberration. Computer simulation is also carried out in optical tracing
software.
A robust and efficient point matching method for stereovision measurement using dynamic programming
Show abstract
Many vision tasks such as 3D measurement, scene reconstruction, object recognition, etc., rely on feature
correspondence among images. This paper presents a novel binocular method taking full account of the causes of
matching ambiguities. On the basis of rectification which increases the distribution similarity of the points from the two
images, the dynamic programming technique is used to search for an optimal path with the matching fashions of the
most appropriate correspondences along each scan line as its nodes, which makes a global minimization of the
summation of all the intra- and inter-scan line disparity gradients. This method was applied to the 3D surface
measurement for an inflatable parabolic reflector with satisfactory results despite the significantly different viewpoints
and occlusion that indicates the robustness, efficiency and application feasibility in real-time measurement field of this
method.
Highly precise nonlinear error calibrating system based on Fabry-Perot interferometer
Jichi Ma,
Yan Li,
Chunyong Yin
Show abstract
Nanometer measurement has become more and more important in the development of metrology, material science,
microelectronics and biology. Heterodyne Fabry-Perot interferometer can be used in the nonlinear error calibration with
an accuracy of nanometer and sub-nanometer order. We can get very high resolution by using heterodyne Fabry-Perot
interferometer frequency locking technique in theory. However, the measure uncertainty and the stability of results are
worse than the expectation's. In this paper, in order to solve the problems of air refrective index change and temperature
excursion, we designed the vacuum system that adjusts the interference light path and built it based on NIM's heterodyne
Fabry-Perot interferometer. The key in our design is to reduce the thermic balance time and to ensure reliable
hermetization of movable components. The influnce of the change of air refractive index to the measured precision was
studied, and the approximate formula of vacuum degree that the system requires was concluded. It has been proved in
the experiment that the system works steadily. The system's ability of anti-jamming has been improved, and the demand
of the measure surroundings has been lowered. Comparing with capacitance displacement measurement instrument, we
conclude that the nonlinear degree of this system in the range of 0.35um, which is longer than half of the wavelength of
the laser, is better than 3.9nm.
Experimental study on Zeeman-birefringence dual-frequency laser interferometer with mid-frequency difference
Show abstract
With the development of mechanical engineering, the moving velocity of the machine centers and the CMMs are
increased to 1000 mm/s. However, at the present time the measurement speed of the commercial heterodyne
interferometer can not meet the requirement. The key element of heterodyne interferometer is a dual frequency laser,
which produces two lights with different frequency, whose wavelength is used as basic scale for length measurement.
The frequency difference of the dual frequency laser is the primary factor which constrains the measurement speed. A
new pressure birefringence dual frequency laser was put forward to be the light source of interferometer. Magnetic field
was applied on this laser to eliminate frequency difference lock-in, and therefore dual frequency laser with adjustable
frequency ranging from 3 MHz to 40 MHz can be obtained, which is called mid-frequency difference. Using the new
laser referred above as the light source, the dual frequency laser interferometer system is constructed. Taking the HP
5528A dual frequency laser interferometer as measuring basis, this dissertation has measured a displacement of 10 mm
rang in low speed by experimental system. The standard uncertainty of measurement is less than 0.1 μm, and the linearity
is less than 0.002%. Through the measure experiment it is proved that this high speed measurement system is feasible
and the system we designed for the new light source is correct. It offers a new way to improve the measurement velocity
of dual frequency interferometer system.
Measurement of target deformation under laser shock with optical beam shading technique
Show abstract
A new sensor based on optical beam shading technique for the investigation of mechanical effects during laser-metal
interaction is developed. This sensor is applied to detect the laser-induced plasma explosive impact and deformation
process during the explosion when a Q-switched laser is focused on a metal. The experimental results indicate that
elastic deformation and plastic deformation associated with the event induced by laser plasma the same time. This
technique has the advantages of high-frequency response, simple structure, and nondestructive examination.
CCD-based on-line thickness measurement system for calender
Show abstract
An on-line calender thickness measurement system based on linear CCD is proposed. In this system, an optical
projection method based on collimated light and CCD is used to realize the thickness measurement for sheet product. To
test the accurate position of the edge of the sheet projection, a quadratic differentiating circuit and an accurate pulse
width measurement method based on programmable counter array are used to deal with the CCD signals, which make
the resolution up to 0.5μm for a linear CCD with 14 μm image sensing element size. Based on microcontroller, the
integrated CCD sensor module and 2-D coordinate data acquisition module are developed to record the values of
thickness and position coordinates. A distributed automatic data acquisition and control system is established by using
the USB and RS485 serial bus to connect the host computer and measuring modules. In addition, to eliminate the factors
that influence the on-line measurement accuracy, such as the roundness tolerance of roller, the irregularities of guide rail,
an error compensation method based on multilayer feedforward neural network is used. The in situ experiments show
that the on-line measurement standard deviation is 10μm within the measuring range of 10 mm.
A digital optical autocollimation method for measuring 2D small angle
Show abstract
A recognizing and sub-pixel locating algorithm of a crosshair image and a calibrating method of the setup are studied. A
sub-pixel locating accuracy and 2" within the full range are achieved. The crosshair captured with a CCD camera was
processed and calculated by a computer. The gray values of each cross section of each line were fitted to Gaussian curve
with the least squares method, the central points of the curves were fitted to a line with the same method, the
intersections of two pair of lines were obtained and 2D displacement in pixels was figured out. With the precision stage
and HP5528A dual-frequency laser interferometer, the setup within the full range was calibrated with piecewise linear
interpolation method. Eye fatigue and errors by eye sighting and reading are eliminated and measuring efficiency is
raised greatly. It is suitable for NC machine stage precision measurement and stage error automatic compensation.
A specially designed optical system for measurement of the characteristic of square super-lattice pattern in DBD
Show abstract
In this work, a special designed optical system is used to measure the characteristic of square super-lattice pattern in
DBD system. A dielectric barrier discharge system with two liquid electrodes is used, which has a lot of advantages and
convenience to the experiment. A square super-lattice pattern is observed in the system at appropriate experimental
parameters. The patterns follow as random filaments, square pattern, quasi-super-lattice pattern, square super-lattice
pattern, stripe pattern and hexagonal pattern when the applied voltage increases. The influence of the gas pressure p, the
gas gap width d, and the pd value (the product of gas pressure p and the gas gap width d) on the square super-lattice
pattern are investigated. There are some changes of the pattern scenario when the experimental parameters changes. It is
found that the voltage of the square super-lattice pattern increases slightly as d increases. In addition, it is found that the
voltage of the square super-lattice pattern decreases as the gas pressure decreases. The square super-lattice pattern can be
observed stable and regular at atmosphere pressure when 1.36mm < d < 2.2mm, and the gas pressure is reduced less than
atmosphere pressure to obtain the square super-lattice pattern if d >2.2mm.
An optical method of online measurement for the thickness of thin films
Show abstract
This paper introduced an optical method for measuring the thickness of solid thin films. This method is of high
measuring speed, noncontact and online work. An experimental system has been constructed for on-line
measurement of the thickness of thin film. The experimental results show that the measuring error is lower than 10%
in the range of 10~100μm , which fit the production need.
Research on field correctors of the infrared space optical remote sensor
Show abstract
In order to enlarge the effective field, field correctors were introduced into the R-C system. In this paper, discussed the
relationship among the field corrector, focal ratio of the primary mirror and the vertex back focus. Five sets of correctors
were designed for various Fp of the primary mirror of the RC systems: Fp/1.1, Fp/1.5, Fp/1.8, Fp/2, and Fp/2.5. The
results indicate that the decrease of the focal ratio of the primary increases the difficulty of the field correctors' design.
Key techniques in an absolute measurement method of spherical lens
Show abstract
An absolute measurement method of spherical lens with Fiber Point Diffraction Interferometer (FPDI) was developed.
To achieve a high accuracy, several key techniques are discussed such as: short coherence length laser, interferogram
collecting, experiment set up, and reconstruction of wave front. Through these techniques an experiment system has been
built. The 5-step phase shifting interferograms are collected. The wave front is fitted by Zernike polynomials and
reconstructed. The repeated measurement result has a good performance compared to a Zygo GPI interferometer.
Research on color encoding structured light 3D measurement technology
Show abstract
A novel system based on color-encoded structured light for 3D shape measurement is presented in this paper; only one
image is needed to be captured by the camera, so it has some advantages such as high resolution, rapid measurement.
The relationship between color and height is established through color coding, the height of object can be calculated by
decoding. According to the measurement principle, the calibration technique of the system is designed. The color stripe
encoded pattern with 6 colors, they are three primary colors: red, green, blue and their contrary colors: yellow, magenta
and cyan. There are two important characters that the combination of three color stripe order is unique and any two of
adjoining color stripes are different. An effective stripe thinning method is put forward. Finally, experiment system is set
up, and experiments of measurement cuboids are performed.
Simulation of atmospheric turbulence layers with phase screens by JAVA
Show abstract
In multiconjugate Adaptive Optics (MCAO), the phase screens are used to simulate atmospheric turbulence layers to
study the optimal turbulence delamination and the determination of layer boundary position. In this paper, the method of
power spectrum inversion and sub-harmonic compensation were used to simulate atmospheric turbulence layers and
results can be shown by grey map. The simulation results showed that, with the increase of turbulence layers, the RMS
of adaptive system decreased, but the amplitude diminished. So the atmospheric turbulence can be split into 2-3 layers
and be modeled by phase screens. Otherwise, a small simulation atmospheric turbulence delamination system was
realized by JAVA.
A novel method of lens initial structure selection: study on structures-aperture relationship of finite image distance achromatic spherical microscope objective with larger numerical aperture
Show abstract
A number of finite image distance achromatic spherical microscope objectives with larger numerical
aperture are collected. And the lens system structures are analyzed statistically based on optical design
experience. Then a quantitative formula of the relationship between system structure and deflection angle
on finite image distance achromatic spherical microscope objective, whose deflection angle is up to 0.3, is
proposed. A optical systems for microstructure inspection is obtained on the basis of the fruit. The high
resolution system with simple structure is achieved. Accordingly the efficiency of initial structure selection
study on achromatic microscope objective (deflection angle up to 0.3) is validated.
Design of an FT-NIR spectrometer for online quality analysis of traditional Chinese medicine manufacturing process
Show abstract
As a fast, non-destructive analysis method, Fourier transform (FT) near-infrared (NIR) spectroscopy is very suitable and
effective for online quality analysis of traditional Chinese medicine (TCM) manufacturing process. In this thesis, the
theoretics of FT-NIRS was analyzed and an FT-NIR spectrometer with 4 cm-1 resolution in the 12500-5000 cm-1
frequency range was designed. The spectrometer was based on a Michelson interferometer with Bromine tungsten lamp
as the NIR light source and InGaAs detector to collect the interference signal. Each element was designed and chosen to
provide maximum sensitivity in the NIR spectral region. A fiber-optic flow cell system was used to realize online
analysis of traditional Chinese medicine. The performance of the spectrometer was evaluated and the feasibility of using
FT-NIR spectrometer to get absorption spectra of traditional Chinese medicine was demonstrated.
A high-accuracy dual-channel method of measurement on visible light transmittance of telescope system
Show abstract
The Optical capability of visible light transmittance is studied on this paper. The system is based on the
principle of cross-correlation detection, and measure the transmittance of visible light Optical system
though the way of dual-channels, compare to the previous way, eliminate the error of measuring many
times, and restrain the noise signal more effectively. Moreover, the whole system can work on the
conditions of light field. And monitoring and dealing with the result in real-time. The testing accuracy
reaches 1%.
Study of CAD-based laser guiding measurement technology
Show abstract
The laser Guiding Measurement Robot (LGMR) technology is based on the measurement method "laser beam moving,
Spherical Mounted Retro-reflector (SMR) tracking", which uses CAD model to control the position and attitude signals
of measuring laser beam that guides the robot carrying SMR to the required position to complete the measurement of the
objects together with a laser tracker. It is a key technology to be studied deeply how the CAD model is converted into the
signals, which can make laser beam scan and guide the device with SMR to move to the required position. This paper
describes the research work to the development of an optical guidance system for CMM with SMR by use of the CAD
model of a completed object. The working principle and structure of LGMR are presented firstly. Then the method
converting the CAD model to signals is studied successfully. Next, the guidance system employs the signals to make
laser beam point to the required position and guide the CMM with SMR to the position at the same time. Finally, the
experiment is carried out to prove the correctness of the methodology. The results show the maximum error of the
measured curve is 0.12mm.
Specular surface measurement by using a moving diffusive structured light source
Show abstract
This paper presents a novel technique for measuring the three-dimensional shapes of specular surfaces. Differing from
the conventional techniques, the diffusive light source in our technique can be moved vertically to two different
positions, and at each position the phase distribution of the deformed fringe pattern is measured, so that the orientation of
incident light for each pixel is tracked through the corresponding phases. The 3-D coordinates of points on the specular
surface are further determined. In so doing, the restrictions and limitations of the existing techniques in computational
complexities, phase ambiguities and error accumulations are eliminated. The validity of this technique is demonstrated
by experimental results.
Infrared telephoto lens design of hybrid optoelectronic joint transform correlator
Show abstract
Hybrid optoelectronic joint transform correlator is very useful for target detection and recognition in military and
industry field. Nowadays, there are two kinds of usual detectors: one is visible detector which is sensitive to the diffusion
of target; the other is infrared detector which is sensitive to the radiation of target. The performance of these two
detectors both depend on their working conditions.
Designing perfect optical system is the first step to target detection. While the merit of infrared optical system is it can
not only detect great distance but also detect the target in the turbid air or smoke, flog and snow no matter at day or night.
So it is much more appropriate to be applied in cluttered and formidable conditions and it can enhance target recognition
ratio.
In this paper, the infrared detector we adopted is infrared focal plane arrays with working waveband 8-12μm. Its
resolving power is 30 lp /mm. For the infrared optical system, the effective focal length, relative aperture and the field of
view should be large enough to ensure the long distance and large field of view target can be detected. In hybrid
optoelectronic joint transform correlator, the high performance of infrared telephoto lenses is required. Here, we
designed infrared telephoto lenses composed of three lenses. Its structure is simple but its performance is very good. It
has met the requirement of target detection. Thus we can get the longer detection distance and higher recognition
accuracy.
Information entropy characteristic of the light scattering signal amplitude distribution of aerosols
Show abstract
The light scattering signal amplitude distribution of aerosols, which was measured by the single particle counting
technique, was applied to calculate aerosol mass concentration using an inversion algorithm. Therefore, how to
accurately extract the information of the signal amplitude distribution is a crucial problem for aerosol mass concentration
inversion. In view of mass concentration inversion accuracy and stability are related to information extraction methods,
the linear and non-linear segmentation methods were presented. Experimental results indicate the information entropy of
the signal amplitude distribution obtained by the non-linear segmentation method is clearly larger in the same number of
signal subsets, and when inversion accuracy achieves stability, the ratio of information entropy to the number of signal
subsets is also larger than that of the linear segmentation method, leading to rapid stability of inversion accuracy. The
study of the information entropy characteristic of the signal amplitude distribution of aerosol provides theoretical
guidance for the circuit design of an optical particle counter.
Optical measurement of discharge pattern in dielectric barrier discharge system
Show abstract
A honeycomb hexagonal pattern is observed in a dielectric barrier discharge system, which bifurcates from a square
pattern. As the filaments composing the pattern emit visible light, an optical system is specially designed to study the
spatiotemporal dynamics of the honeycomb hexagonal pattern. The light emitted from pattern, one honeycomb-like cell,
filaments in a line of a cell, and a single filament are detected, respectively. The measurement on spatiotemporal
correlation between two different individual filaments is also performed. It is found that the honeycomb hexagonal
patternis an interleaving of three hexagonal sublattices discharging harmonically and subharmonically. It is found
experimentally that the discharge current signals have three pulses in each half cycle of the driven voltage. Its
characteristics are also investigated by measuring FWHMs and peak voltages of the three discharge pulses, as well as the
time intervals between peaks of different pulses, respectively.
Michelson interferometer in a 2D photonic crystal utilizing self-collimation effect
Show abstract
A Michelson interferometer (MI) constructed in a two-dimensional photonic crystal (2D PhC) utilizing self-collimation
effect is proposed and investigated theoretically. The 2D PhC consists of a square lattice of air holes in silicon. It has
square-shaped equal frequency contours (EFCs) in the frequency range of 0.26-0.275c/a for TE modes. The MI proposed
consists of two PhC mirrors and one defect-row splitter. Light propagates between them employing self-collimation
effect. The two interferometer branches have different path lengths L1 and L2. The FDTD calculation results show that
the transmission spectrum from 0.26c/a to 0.275c/a at the MI output port is comb-shaped. The transmission peaks have a
uniform spacing. Moreover, the peaks shift to the lower frequencies and the peak spacing decreases when the difference
between L1 and L2 is increased. For the operating wavelength around 1550nm, the dimensions of this MI are only tens of
microns. So this PhC Michelson interferometer may be applied in future photonic integrated circuits.
Optical fiber method for measuring small plane flatness error
Show abstract
A non-contact flatness error of small plane measurement method based on reflective optical fiber displacement sensor is
presented. Using the model of single optical fiber, the light from laser source is modulated by the modulator. The
modulated light passes through a circulator to an optical switch to realize the Time Division Multiplex (TMD) of optical
fiber sensing array. The reflective light passes through the circulator to a common detector and process circuit. This
configuration avoids the problem of parameter disagreement of multi-processing circuits, improves the measurement
efficiency and cuts down the cost. The intensity fluctuation of the reference light is adopted to rectify the effects of the
power variation of laser source, so as to improve stability of the system. The experiment results show that the measurand
flatness error is consistent with the measurement result of Three Coordinates Measuring Machine (CMM). The
architecture of the system is simple that it can be used in flatness error measurement of mechanical parts of different
shapes by changing the number and layout of the optical fiber sensing array flexibly.
Area testing study of arbitrary shape plane object based on CCD matrix
Show abstract
In the industrial production, it is frequently needed to test the area of the irregular shape plane object. In this paper
optical method is used to perform non-contact area measurement of random shape plane object testing and matrix
CCD-computer system is combined to realize real time automatic measurement. In this paper principle and method for
area measurement of arbitrary shape plane object using matrix CCD-microlens-compute system is present. Testing
device is designed from the hardware and the software. At last the factors affecting on the accuracy are analyzed. By
experiment, it is proved that this method processes fast speed, high accuracy and strong adaptability. The system makes
on-line testing possible and may be applied in the modern industrial testing conveniently.
Equipment for 2D profile measuring of aspheric microscope condenser in mass production
Show abstract
This paper deals with the measurement of aspherics on surfaces of microscope condenser in mass production. The
aspheric surface in microscope condenser is a kind of optical surface working under very large numerical aperture and
small field of view. To fulfill Kohler illumination for the microscope condenser, the aspheric surface must be fabricated
as well as designed capable of projecting an image of the source, large enough to fill the sub stage condenser of the
microscope. For larger numerical aperture condenser fabrication, it is crucial to guarantee a reasonable aspheric profile
for spherical aberration compensation and even illumination.
Here we established the equipment for microscope condenser aspheric profile measuring in mass production. The
industry microscope is reconstructed to image the profile, with LED panel light source for even backlighting. The profile,
captured with a high resolution CCD, is processed. It can be compared with theoretic aspheric profile directly or
interpolated with a predefined polynomial. In this method, supports for aspheric lens fabrication and measurement are
designed and employed on the industry microscope. It guaranteed that a table of points can accurately describe the
profile of the aspheric surface, introducing less assembling error. Measurement with this method has proved satisfactory
for certain high aperture microscope condenser at low cost. For systems requiring still higher accuracy, the CCD
resolution may have to be increased and interpolation method optimized accordingly but the online aspheric testing
equipment with proper supports could surely improve the accuracy of aspheric surface fabrication at low cost.
A novel optical tweezers system
Show abstract
Optical tweezers, first developed by Askin et al, is an increasingly important technique for trapping and moving matter
at length scale ranging from nanometers to millimeters. In recent years, the improvement of tweezers apparatus
emphasizes two aspects: one is to make the traps more practical and the other is to manipulate micro-particles more
conveniently.
The article brought forward one kind of novel implement which can provide optical traps of arbitrarily forms and can
control the traps at will. The optical tweezers is based on real-time computer generated holography. The paper described
the implementation of the technique in detail and gave experimental results.
The system is a dynamic holographic optical tweezers based on a computer controlled TFT-LCD. By using FFT, we can
make desired types of traps which can be draw up with mouse on computer displayer into dynamic holograms. The
hologram reconstruction is based on TFT-LCD. While laser illuminates on TFT-LCD and passes through the next
optical system, we get the traps we need and it can be controlled freely.
The tweezers system can form multi-traps, hollow traps, and many other forms of traps. It is more convenient and rapid
to control the trap's position in our tweezers system, and the cost of the system is reduced. This provides new means for
the development of optical tweezers.
Optical design of free-form bicycle lamp
Show abstract
Bicycle lamp used for road lighting is becoming popular now. However, few people have realized its potential market
and correlative researches are far from enough. Generally speaking, researches on bicycle lamps are mostly focused on
how to design a reflector which will collect light energy more efficiently and can transfer it to certain areas forward
when the light source is determinated. In traditional angle of view, the reflector is usually a paraboloid or ellipsoid.
However, both of them can not meet the requirement in practice most of the cases. Therefore, free form reflectors (FFRs)
instead are widely used. In this paper, a new approach to design FFR which is convenient and rapid is presented. To do
computer-aided simulation, certain light source should be selected first. Usually, light sources that behavior like a
Lambertian emitter are modeled. To examine the correctness of this approach, a bicycle lamp is designed according to
this approach to see if it can meet the requirements of the Germany standard which will be introduced in the text later.
The standard requires specific illuminance values for particular points at the test screen with a distance of 10m from the
source. The simulation results is exciting and can meet all the requirement. For example, 10lx is expected at the point (0,
0) while the obtained value is 10.42lx, under the conditions that the total luminous flux of the light source is 42lm and
the reflectivity of FFR is 0.8. This method has certain universal significance and can provide references for the design of
other illumination systems.
Research and design of an optical system of biochemical analyzer based on the narrow-band pass filter
Show abstract
Biochemical analyzer is one of the important instruments in the clinical diagnosis, and its optical system is the important
component. The operation of this optical system can be regard as three parts. The first is transforms the duplicate colored
light as the monochromatic light. The second is transforms the light signal of the monochromatic, which have the
information of the measured sample, as the electric signal by use the photoelectric detector. And the last is to send the
signal to data processing system by use the control system. Generally, there are three types monochromators: prism,
optical grating and narrow-band pass filter. Thereinto, the narrow-band pass filter were widely used in the semi-auto
biochemical analyzer. Through analysed the principle of biochemical analyzer base on the narrow-band pass filter, we
known that the optical has three features. The first is the optical path of the optical system is a non- imaging system. The
second, this system is wide spectrum region that contain visible light and ultraviolet spectrum. The third, this is a little
aperture and little field monochromatic light system. Therefore, design idea of this optical system is: (1) luminous energy
in the system less transmission loss; (2) detector coupled to the luminous energy efficient; mainly correct spherical
aberration. Practice showed the point of Image quality evaluation: (1) dispersion circle diameter equal the receiving
device pixel effective width of 125%, and the energy distribution should point target of 80% of energy into the receiving
device pixel width of the effective diameter in this dispersion circle; (2) With MTF evaluation, the requirements in 20lp/
mm spatial frequency, the MTF values should not be lower than 0.6. The optical system should be fit in with ultraviolet
and visible light width spectrum, and the detector image plane can but suited the majority visible light spectrum when by
defocus optimization, and the image plane of violet and ultraviolet excursion quite large. Traditional biochemical
analyzer optical design not fully consider this point, the authors introduce a effective image plane compensation measure
innovatively, it greatly increased the reception efficiency of the violet and ultraviolet.
The influence of high-order dispersion on femesecond solitons
Show abstract
In the nonlinear optical fiber, soliton is a pulse envelop that formed under the balance of group velocity
dispersion(GVD) and self-phase modulation(SPM). It has the transmission characteristic that the pulse shape and
amplitude are steady. The GVD causes the pulse stretch, but the SPM induces the high frequency elements to
accumulate step by step, and the soliton pulse change steep. The two kind of opposition factors unit in together,
mutually balances can maintain the pulse shape stabilization invariable.
Along with the soliton research, it extends from picosecond (ps) to femesecond (fs). High order dispersion, in
particular the third order dispersion (TOD) influences the soliton transmission very large. The high order
dispersion is studied by the split step Fourier method (SSFM) numerical analysis the modified high order
nonlinear Schrödinger equation(HNLSE). The results indicate that the TOD and the fourth order dispersion(FOD)
can all affect the quality of the telecommunication. And the TOD plays the main role. It causes the pulse bottom
vibration in one side, causes the pulse to stretch and to form vibration belt. The FOD causes the soliton bottom
vibration in two sides, it causes the pulse stretch and the spectrum appears side lobe.
Distributed optical fiber sensor for multi-point temperature measurement
Show abstract
The distributed optical fiber temperature sensor is set up by using the technique of optic
time-domain reflection (OTDR) to get temperature information, and the way of getting the mean
by the accumulating time-domain signal to improve the ratio of signal to noise. Base on the
theory of Optical Time Domain Reflectometer, Raman scattering distributed optical fiber system
for Multi-point temperature measurement is established. A new demodulation method is proposed,
that is circulation demodulation method. The OTDR temperature curve of the next point to be
measured is demodulated by the current OTDR temperature curve. The experiment validated that
the theoretical analysis is correct, and the system can inhibit the calculation of temperature noise
and prevent Rayleigh back scattering light from harassing anti-Stokes back scattering light. The
spatial resolving power is less than 3m, the temperature resolving power is about ±3°C, and time
resolving power is not more than 3min.
Error analysis for integrating sphere of color measuring system
Show abstract
Integrating sphere has been widely used in the photoelectric integrating color measurement. Ordinarily,
the measurement caliber of integrating sphere is smaller than the diameter of incidence beam, and
some of the incidence beam irradiate on the inner surface of integrating sphere directly. It introduces
error into the color measurement. The paper establishes the mathematics model of the error introduced
by integrating sphere in color measurement, and has found the way to revise the error. The result
indicates that this method can revise the error which is carried by the mismatch between the
measurement caliber of integrating sphere and the diameter of incidence beam effectively.
Analytical method of genetic algorithm in fiber grating sensing system with transverse uniform stress
Show abstract
Based on the basic theory of Genetic Algorithm and fiber Bragg grating sensing with transverse uniform press, an analytical method of Genetic Algorithm in quasi-static fiber grating sensing system with transverse uniform press is proposed and the relevant mathematical model is established. The objective function related with Genetic Algorithm is also established. The effect of population size, generations, crossover ratio and mutation ratio to Genetic Algorithm is studied, and the optimization parameters of Genetic Algorithm are given. Meanwhile, the relevant experimental system is constructed, and the related simulation and experiments are finished. The simulation and experiments show that the analytical method proposed can be applied to quasi-static fiber grating sensing system with transverse uniform press, and the accuracy can achieve to 0.91%.
Technology of wavelength tuning based on refractive optical lever and its application in optical spectrum analysers
Show abstract
With the development of DWDM, optical analysers which are portable and can be applied to DWDM project site, are in
great demand. This paper describes a novel method for wavelength fine-selection. This new method employs a refractive
optical lever system, the structure of which is simple. It also has low cost and enough feasibility. This is a significant
improvement not only on the wavelength discrimination capability of optical spectrum analysers for demanding DWDM
test applications, but also on technology of frequency stabilization of lasers. We firstly demonstrate the refractive optical
lever principle of a wedge prisms and the amplification factors for wedge prisms with different wedge angles. Secondly,
the feasible experiment is done, the aim of which is improving the wavelength selecting accuracy of the optical spectrum
analyser.
Scene simulation optics in testing of dual-field angle infrared imagers
Show abstract
The paper outlines a simulation system based on the IR liquid crystal light valve (LCLV) and describes the design of the
optical systems for simulator including the variable magnification lens and the projection optics. The simulator is used in
testing of an infrared imaging system, which has two field angles of 6° and 8°. The variable magnification lens between
the LCD panel and the LCLV produce a visible image at varying magnifications on the LCLV. The projection optics
collimates the infrared image which is inverted by the LCLV to generate an infrared scene in the 8~12μm waveband. The
varying image size meets the need of the test IR imaging system, which field angle varies. The projection optics is
designed for a constant field angle and constant entrance pupil. Thus the IR image always fills the entrance aperture and
FOV of the test optical system. A long working distance and sufficient exit pupil distance of the projection optical
system ensure the mechanical and the optical assembly, and match the simulator exit pupil to the imagery system
entrance pupil. The Modulation Transfer Function (MTF) and spot diagram show the perfect image quality of the
projection optics.
Design of infrared zoom system with rotating lens group
Show abstract
In surveillance applications there is a need for infrared zoom systems which give two fields of view. For such
systems long operation range is the most critical parameter which is bound up with focal length and transmittance of
systems. In this paper the design of an infrared zoom system with rotating lens group is described. Different from the
conventional axially moving zoom systems, this system is based on a rotating mechanism consisting of two
separated lenses. The system achieves dual FOVs due to different magnifications. In narrow field of view mode, the
system has long focal length and higher transmittance because the rotating lens group is outside the optical path.
The final design is an infrared zoom system operating in 3μm~5μm, with a F number of 4.0, EFL of 250mm/62.5mm.
This paper contains the calculation of first-order parameter, the optimum design of rotating motion, the analysis of
aberrations, MTF, and Narcissus, This designed system has diffraction limited image quality of in both FOVs.
Research on a system and method of automated whole-field measurement of optical glass stress
Show abstract
On the basis of the principle of single quarter wave plate method, a model of automatic whole-field measuring optical
glass stress is presented, which is called "4+1steps phase shifting method" including the model for the isoclinic
parameter and the stress birefringence. According to this model, an automatic whole-field measuring system is
established. The correctness of the model was testified by numeric emulation experiments under the preset conditions of
isoclinic angle and stress birefringence. Practical measurement obtained a result coincident with the actual distribution of
the isoclinic angle and the birefringence. The automatic whole-field measuring model and system can achieve the whole
process intelligently and automatically, and dispose the disadvantages of tradition method about interpreting the stress
level by subjective judging birefringence of some selected spots.
A prototype system for high precision 3D measurement based on grating method
Show abstract
In this paper a 3D shape measurement system based on the grating method was developed. The system consists of two
CCD cameras and a DLP projector. The multi-frequency heterodyne principle was presented to overcome the
unwrapping problem of phase functions, and a phase-to-coordinates conversion algorithm was proposed to reconstruct
the 3D geometry from the unwrapped phase map. To demonstrate the performance of this 3D measurement system, a
face model was measured, and the reconstructed 3D geometric surface is very smooth with details. Additionally, a ladder
with one step was measured. The result shows the system can measure the discontinuous object and get high
measurement precision.
A novel ellipsometer for measuring thickness of oxide layer on the surface of silicon sphere
Show abstract
The Avogadro constant NA is used as one of the several possible routes to redefinition of the kilogram in metrology
today. Usually in order to accurately determine NA, the volume of a perfect single crystal silicon sphere of nearly 1 kg
mass should be measured with a high relative uncertainty, i.e. about 1×10-8. However, the oxide layer grown on the
surface of the silicon sphere causes a remarkable systematic difference between the measured and real diameters. A novel
ellipsometer has been developed to determine the thickness of the oxide layer accurately and automatically. The
arrangement of this instrument is suitable for measuring the layer on the sphere surface. What's more, the measuring is
faster by optimizing the parameters and developing the algorithm of calculating the thickness and refractive index of the
oxide layer. The preliminary simulation result has present. Thus, the uncertainty of the diameter measurement caused by
the oxide layer can be observably reduced. And the further improving of this ellipsometer is discussed in the end.
Simulation of multi-reentrant two-mirror ring cavity lasers
Show abstract
This paper utilizes optical design software ZEMAX to simulate the ring cavity structure. Use two plan-concave lenses to
form the cavity structure with one gain medium located off the optical axis. These simulation results are in line with the
experiment results. The results, taking the effect of the gain medium into account, are far more accurate than that
generated by Beam4. These results help the researchers to have better understanding on the behavior of this type of ring
cavity lasers.