This PDF file contains the front matter associated with SPIE Proceedings Volume 8430, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

In microelectronics, vacuum techniques such as turbo molecular pumps have to fulfill the demand of lowest vibrations. The standard measurement technique for this purpose is the laser Doppler vibrometer. However, vibration measurements of fast rotating objects such as vacuum pump shafts are challenging due to the laterally moving speckle pattern. In order to overcome this drawback, a novel non-incremental interferometric technique is presented for precise shape, vibration and displacement measurements of high speed rotating objects. Two inclined interference fringe systems are generated in one measurement volume. Their signal phase difference depends on the axial position and their signal frequency corresponds to the lateral velocity. Thus, simultaneous position and velocity measurements can be accomplished. However, the tilted interference fringe systems result in different speckle patterns and therefore in a low crosscorrelation coefficient of the scattering signals. Holographic methods have shown the way to overcome this problem. The scientific finding is to use different receiving angles in correspondence of the different inclination angles of the interference fringe systems in order to enhance the cross-correlation coefficient significantly. By this, to our best knowledge, worldwide unique method a standard position deviation of only 110 nm has been achieved also at high speeds over 10 m/s. Since the axial position and lateral velocity are measured simultaneously, shape and vibration measurements of rotating components can be accomplished by only one sensor. This non-incremental interferometric technique has been applied especially to vacuum pumps, rotating at 48,000 rpm. Substantial vibration evaluations of the rotating shaft have been performed.

In order to achieve high resolution quantitative imaging in digital holographic microscopy (DHM) typically microscope lenses with a high numerical aperture are applied. This results in a low depth of field (DOF) of the optical imaging system. Thus, for example, surfaces and specimens that cannot be imaged in parallel with the hologram recording device are recorded partly defocused. We explored the compensation of such defocusing effects by partial numerical propagation of the complex wave fields that are retrieved from digitally recorded off-axis holograms. The numerical propagation of small wave field parts with low pixel numbers is strongly affected by Fresnel diffraction and aliasing. Thus, the influence of these effects was quantified and used in an adapted algorithm for numerical refocusing of tilted image planes that considers the DOF of the applied optical imaging system. Results from simulations and experimental investigations show that typical numerical propagation artifacts origin from Fresnel diffraction which efficiently can be suppressed by an adequate adaptation of the numerical propagation. Data from the application of the resulting algorithm demonstrates that images planes with a tilt of up to 80 degrees to the hologram plane can be compensated.

In this paper, we demonstrate how short coherence digital holography with a pulsed fiber laser frequency comb may be used for multi-level optical sectioning. For the proof of the principle, a conic object having a size of few centimeters is used. The object shape is obtained by digitally reconstructing and processing a sequence of holograms recorded during stepwise shifting of a spherical mirror in the reference arm of the holographic set-up. First experimental results are presented.

We propose an alternative reconstructing strategy in digital color holography, based on the hologram stretching techniques. With a simple adaptive affine transformation on the digital color holograms and a correlation-matching procedure applied on their numerical reconstructions, we are able to manage the digital color reconstructions of the same object in order to obtain their perfect superimposition. We test our procedure in several experimental cases considering holograms recorded in both microscope configuration and lensless configuration. Finally we give a procedure, based on the National Television Systems Committee (NTSC) coefficients, to synthesize a single hologram that contains the information associated to the three colored numerical reconstructions. Numerical analysis and display tests are used to evaluate the effectiveness of the proposed method.

Dielectrophoretic clustering is obtained both for liquid and solid matter thanks to light shaping performed by phase only Spatial Light Modulator (SLM). We present a procedure able to perform two functions: design polymeric stable structures usable as microfluidic channels and trapping micro objects. These two tasks are combined to realize a single device. The liquid matter is Polydimethylsiloxane (PDMS) and its patterning in microstructures is developed by means of photorefractive effect in a functionalized substrate. X-cut Iron-doped Lithium Niobate (LN) crystal is used as substrate while a thin film of PDMS is spin on it. When LN, covered by PDMS, is exposed to structured laser light, a space charge field arise that is able to induce self-patterning of the PDMS liquid film. The rearrangement of PDMS is due to the dielectrophoretic effect. Light structuring is achieved by a SLM positioned in the conjugated plane of the LN crystals. PDMS devices we realized are microfluidic channels. The first step of our procedure is the computing of a suitable Computer Generated Hologram (CGH) to be displayed by the SLM. An ideal target is designed and given as input to an Iterative Fourier Transform Algorithm (IFTA) to calculate the CGH. The IFTA used has been implemented for this particular application and it's tailored to generate a continuous light intensity profile in the LN plane. Then PDMS microstructures are cured to induce solidification. Such PDMS channels are then used to trap particles floating inside. Trapping is realized exploiting again dielectrophoresis induced by photorefractive effect. LN with PDMS channel is exposed to laser light which present, now, a periodic two-dimensional intensity profile. The charge distribution due to this second exposure is able to trap particle in the previously built channels. We realize a device with high degree of flexibility avoiding the need of moulds fabrication.

Surface metrology plays an important role in the field of product development and quality assurance, not only in micro systems technology. Here, nowadays increasingly materials are used that lead to systematic deviations if measured by conventional dimensional measuring techniques. One example are polymers like SU-8 that are used on the one hand as a photoresist for structuring of micro systems, on the other hand also as the material for forming micro structures themselves. The accurate measurement of the structural dimensions like e.g. the thickness of films made from transparent materials is a challenging task for conventional optical instruments. It has to be taken into account that usually instead of the geometrical thickness d the optical thickness nd (n: refractive index) is measured. In addition to that, measurement of these structures becomes even more difficult, if they consist of several materials with different behavior regarding the applied measuring technique. In this case, also the different material parameters like absorption, dispersion, etc. have to be considered.

Combinatorial CBVD (Chemical Beam Vapor Deposition) is a thin film deposition technology which has the ability to produce multi-element thin films with large controlled composition spread gradients. If functional characterizations can be carried out systematically and rapidly on such graded films over full wafers, they enable to identify precisely the best film composition for a given application, and CBVD then easily allows for the deposition of the optimized film homogeneously on large wafers. In this article, we demonstrate the efficiency of such a process development based on the optimization of new Transparent Conductive Oxide thin films (TCO) of few % Nb doped TiO₂. We have developed a full wafer metrology instrument which maps the optical thickness and the sheet resistance with a lateral resolution below 400um. We discuss the performance of various algorithms to extract the optical thickness from the white light reflectance measurement in the case of very small thickness. The sheet resistance is measured with an array of four AFM-like conductive cantilevers, allowing accurate sheet resistance (R) measurement where the standard tungsten four probes destroy porous thin oxide films. Application of these measurements to several Nb doped TiO₂ films deposited on 4" wafer by CBVD is presented.

Nanocrystalline gas sensitive materials based on tin dioxide modified by Pd or Ru were synthesized and their interaction with CO and ammonia studied by means of in situ DC-conductivity measurements and ex situ ESR spectroscopy. Modification by Pd yields the material highly sensitive to CO in low temperature region, while Ru-modified SnO₂ is outstandingly sensitive to NH₃ at raised temperature. The materials have well detectable sensitivity to these gases on the concentration level of ambient air standards. We have detected that O₂^- and OH• radicals are the main type of spin centers in unmodified nanocrystalline tin dioxide. The modifying of tin dioxide by Pd and Ru is accompanied by formation of new spin centers in the samples: Pd⁺³ and Ru⁺³. The concentration of these paramagnetic species on the materials interacting with CO and ammonia gases decreased because of their transition to the diamagnetic state Pd⁺², Pd⁰ and Ru⁺⁴, respectively.

A critical (steady state) value of the resistivity of different organic coatings was determined by a combination of optical shearography and electrochemical impedance spectroscopy (EIS). The behavior of organic coatings, i.e., ACE premiumgray enamel, white enamel, beige enamel (spray coatings), a yellow acrylic lacquer, and a gold nail polish on a metallic alloy, i.e., a carbon steel, was investigated over a temperature range of 20-60 °C. The value of the resistivity of coatings was determined by correlating the in-plan displacement of the coating (by shearography over a temperature range of 20- 60 °C) and the value of the alternating current (A.C) impedance of the coating by EIS in 3% NaCl solution. The integrity of the coatings with respect to time was assessed by comparison the measured value of resistivity to the critical (steady state) or asymptotic value of resistivity. In other words, by shearography, measurement of coating properties could be performed independent of parameters such as UV exposure, humidity, presence of chemical species, and other parameters which may normally interfere with conventional methods of the assessing of the integrity of coatings. Therefore, one may measure the resistivity of coatings, regardless of the history of the coating, in order to assess the integrity of coatings. Also, the obtained shearography data were found to be in a reasonable trend with the data of electrochemical impedance spectroscopy (EIS) in 3%NaCl solution.

The real-time measurement of three-dimensional vibrations is currently a major interest of academic research and industrial device characterization. The most common and practical solution used so far consists of three single-point laser-Doppler vibrometers which measure vibrations of a scattering surface from three directions. The resulting three velocity vectors are transformed into a Cartesian coordinate system. This technique does also work for microstructures but has some drawbacks: (1) The surface needs to scatter light, (2) the three laser beams can generate optical crosstalk if at least two laser frequencies match within the demodulation bandwidth, and (3) the laser beams have to be separated on the surface under test to minimize optical crosstalk such that reliable measurements are possible. We present a novel optical approach, based on the direction-dependent Doppler effect, which overcomes all the drawbacks of the current technology. We have realized a demonstrator with a measurement spot of < 3.5 μm diameter that does not suffer from optical crosstalk because only one laser beam impinges the specimen surface while the light is collected from three different directions.

Micro-electro-mechanical systems are exposed to a variety of environmental stimuli, making a prediction of operational reliability difficult. Here, we investigate environmental effects on properties of piezoelectrically actuated microcantilevers, where AlN is used as actuation material. The environmental effects to be considered include thermal and humid cycling, as well as harsh electrical loading performed under normal conditions. Investigated properties are defined for the static and dynamic behavior of microcantilevers. A Twyman-Green interferometer, operating in both stroboscopic regime and time-average interferometry mode, is used as a metrology tool. The initial deflection and frequency changes of the first resonance mode of the microcantilevers are monitored during accelerated thermal aging tests, humidity tests, as well as harsh electrical loading and fatigue tests. Finally, the resonant fatigue tests accelerated by application of a high voltage are accomplished to evaluate a lifetime of microcantilevers. Monitoring the micromechanical behaviors of devices driven by AlN during the lifetime tests assists monitoring of their long-term stability. FEM calculation is used to identify critical areas of stress concentration in the cantilever structure and to further explain various failure mechanisms.

We report on the advanced optical characterizations of microfabricated solid immersion lenses with 2-μm diameter, operating at λ= 642 nm. The main feature, the spot size reduction, has been investigated by applying a focused Gaussian beam of NA = 0.9. Particular illuminating beams, e.g., Bessel-Gauss beams of the zeroth and the first order, a doughnutshape beam and its decompositions, i.e. two-half-lobes beams, have also been used to influence the shape of the immersed focal spot. Detailed optical characterizations have been conducted by measuring the amplitude and phase distributions with a high-resolution interference microscope (HRIM) in volume around the focal spot. The immersion effect of the SiO₂ solid immersion lens leads to a spot-size reduction of approximately 1.5 which agrees well with theory. Particularly shaped incident beams exhibit a comparable size reduction of the immersed spots. Such structured focal spots are of significant interest in optical trapping, lithography, and optical data storage systems.

Anomalistic behavior in diffraction responses of grating can be easily detected and can indirectly provide information about the grating parameters such as the grating period, height, duty-cycle and profile. More precisely, the absorption resonance (Wood's anomaly) which arises from the excitation of a surface plasmon polariton (SPP) in reflective sub-wavelength diffraction gratings are of interest as well as Rayleigh's anomaly which takes the form of a discontinuity in the diffraction response and which is the consequence of the excitation of a new propagating mode. In this paper we describe how these anomalies can be used as a non-destructive metrology tool to estimate the grating parameters by an IR spectral scatterometry measurement. We briefly describe the theoretical conditions for which SPP are excited. We investigate the wavelength sensitivity of Wood's anomaly in the zeroth order diffraction response to individual grating parameter variations at CO2 laser wavelengths. A numerical electromagnetic grating solver software package "Gsolver" was used for the theoretical modeling. We show that this non-destructive IR spectral scatterometry measurement based on feature extraction allows us to measure grating parameter variations with nanometer resolution. The measurement time needed to scan a 4" wafer has been shown to be of the order of a few minutes. This is much faster as compared to traditional techniques as (deconstructive) SEM inspection or white light interferometry. Furthermore, the extension of this technique to larger wafers does not impose any difficulties.

The paper is devoted to characterization of topography of micro optical elements with very high numerical aperture using digital holographic microscope. For very high numerical aperture we mean the one larger than numerical aperture of optical system conjugating the object plane with the detector plane. In this case the optical system is not capable of capturing any information about micro element areas with high numerical aperture (high shape gradients). In the paper we are presenting method that can be used for recovering high numerical aperture shape from few measurements with digital holographic microscope working in transmission and reflective configuration. We are focusing on metrology of microlenses of high numerical aperture. Within the presented method measurement of tilted object is necessary. When the element is tilted then some of optical field is coming from "new high gradient element area", when the element is tangential the area of high gradient is producing field with numerical aperture larger that numerical aperture of the measurement optical system. In our paper we therefore use data captured for tilted sample in order to reconstruct micro element topography within a region of high numerical aperture. Such data are then defocused to tilted plane and only then can be used for topography reconstruction.

Optical surface topography measuring instrument manufacturers often quote accuracies of the order of nanometres and claim that the instruments can reliably measure a range of surfaces with structures on the micro- to nanoscale. However, for many years there has been debate about the interpretation of the data from optical surface topography measuring instruments. Optical artefacts in the output data and a lack of a calibration infrastructure mean that it can be difficult to get optical instruments to agree with contact stylus instruments. In this paper, the current situation with areal surface topography measurements is discussed along with the ISO specification standards that are in draft form. An infrastructure is discussed whereby the ISO-defined metrological characteristics of optical instruments can be determined, but these characteristics do not allow the instrument to measure complex surfaces. Current research into methods for determining the transfer function of optical instruments is reviewed, which will allow the calibration of optical instruments to measure complex surfaces, at least in the case of weak scattering. The ability of some optical instruments to measure outside the spatial bandwidth limitation of the numerical aperture is presented and some general outlook for future work given.

The increasing demand of the aerospace industry for new functional materials requires appropriate methods for quality assessment. It is a new challenge nowadays to characterize materials with microstructure quickly, accurately, and nondestructively. Optical coherence tomography (OCT) is a contactless and non-destructive technique for obtaining the internal structure of turbid materials. In the past 20 years it has been continuously developed and nearly exclusively applied for biomedical imaging of tissues while OCT-based methods for non-biomedical investigation tasks, e.g. within the field of non-destructive testing for material inspection, are rarely reported. Therefore, here we demonstrate and evaluate the suitability of OCT for the assessment of aerospace materials, e.g. coatings, and glass fibre composites. A well-designed OCT system was built using a broad bandwidth light source with centre wavelength of 1550 nm. 2D galvanometer scanners and an optical delay line incorporated in the system make cross-sectional imaging available. Finally in combination with appropriate image processing, the thickness of thin films and the microstructure of materials can be determined for quality assessment.

Multi scale systems offer the opportunity to balance the conflict between execution time, measurement volume and resolution for the inspection of highly complex surface profiles. An example of such a task is the inspection of gears. At first, the coarse position and form of the specimen is registered by a sensor measuring with comparatively low resolution but a large field of view. Possible defects near to the resolution limit are indicated and new regions of interest for higher resolved measurements are identified. As prerequisite for a successful multi-scale inspection, every sampled data set, acquired in different scales and at varying positions, must be registered in one global data model. This is only possible if the extrinsic coordinate transform from the sensor's internal coordinate system to the common, global coordinate system of the inspected object and its uncertainties are known. In this paper, we present an approach for the extrinsic calibration using the example of a multi-zoom fringe projection sensor mounted on a multi-axes measurement system. Finally we show the measurement result of a gear, where several sampled patches are merged together into one point cloud with the aid of the presented calibration.

We present the use of sub-micron resolution optical coherence tomography (OCT) in quality inspection for printed electronics. The device used in the study is based on a supercontinuum light source, Michelson interferometer and high-speed spectrometer. The spectrometer in the presented spectral-domain optical coherence tomography setup (SD-OCT) is centered at 600 nm and covers a 400 nm wide spectral region ranging from 400 nm to 800 nm. Spectra were acquired at a continuous rate of 140,000 per second. The full width at half maximum of the point spread function obtained from a Parylene C sample was 0:98 m. In addition to Parylene C layers, the applicability of sub-micron SD-OCT in printed electronics was studied using PET and epoxy covered solar cell, a printed RFID antenna and a screen-printed battery electrode. A commercial SD-OCT system was used for reference measurements.

For twenty years Optical Coherence Tomography (OCT) has been interested in imaging in turbid media. Recently, conventional OCT has been extended to spectroscopic investigation (SOCT). For a full-field OCT configuration in the visible range, we show that the interference conditions are not equal in the whole field of view: the effective numerical aperture depends on the observation point. This results in a spectral shift towards higher wavelengths of the OCT spectra, leading to errors in spectroscopic analysis. We propose a general calibration method for SOCT measurements which has been tested within a protocol, to perform spatially-resolved spectroscopic identification of material by OCT. Firstly we measure the reflectivity of a plane gold sample, corresponding closely to the measurement made with a spectrometer. Then we successfully identify the reflectivity of gold in a mixed sample (silicon and gold).

Nano-level 3-D measurement is one of the key technologies for the current and future generation of production systems for semi-conductors, LCDs and nano-devices. To meet with these applications, wide range nano-level 3-D shape measurement method using combination of RGB lights has been developed. It measures the height of nano-objects using RGB lights interference color fringes. To analyze the RGB color fringes, the adaptive phase analysis method of interference fringes has been developed and achieved its efficiency. But it cannot measure the shape of edges. To meet with the difficulty, the color analysis method on xy-color plane has been introduced. The combination of the phase measurement method and the color analysis method has measured the 5 micrometer columns precisely. The evaluation shows that the method has the ability to measure the plane height at 10 nm level measuring deviation with 0,5 micrometer horizontal preciseness. For a practical application, the shape of needles for AFM has been extracted, successfully.

In the calibration process of structured light three-dimensional (3D) measurement system, the accuracy of the calibration points' image coordinates directly influences the system's measurement accuracy. Based on the analysis of errors in calibration points' image coordinates, mathematical models are built. A solution to eliminate errors in those image coordinates is proposed according to the further analysis of the models, and calibration points are designed to be circle for high-precision and steady extraction. The solution contains procedures as following: 1) A novel and real-time algorithm is proposed, which is used for the correction of the non-uniform intensity in image caused by non-uniform illumination and the camera's parameters. Taking preliminary extracted elliptical center coordinates and average gray value of the ellipses as known information, the intensity distribution of calibration images can be obtained by interpolation. Then the non-uniform intensity of calibration images is corrected in accordance with the interpolation results. 2) High frequency noise in the images is filtered. 3) At last, error of asymmetric perspective projection is also compensated based on its model. Simulation and experiment results indicate that this solution can efficiently reduce the calibration errors.

A profilometer which takes advantage of polarization states splitting technique and monochromatic light projection method as a way to overcome ambient lighting for in-situ measurement is under development [1, 2]. Because of the Savart plate which refracts two out of axis beams, the device suffers from aberrations (mostly coma and astigmatism). These aberrations affect the quality of the sinusoidal fringe pattern. In fringe projection profilometry, the unwrapped phase distribution map contains the sum of the object's shape-related phase and carrier-fringe-related phase. In order to extract the 3D shape of the object, the carrier phase has to be removed [3, 4]. An easy way to remove both the fringe carrier and the aberrations of the optical system is to measure the phases of the test object and to measure the phase of a reference plane with the same set up and to subtract both phase maps. This time consuming technique is suitable for laboratory but not for industry. We propose a method to numerically remove both the fringe carrier and the aberrations. A first reference phase of a calibration plane is evaluated knowing the position of the different elements in the set up and the orientation of the fringes. Then a fitting of the phase map by Zernike polynomials is computed [5]. As the triangulation parameters are known during the calibration, the computation of Zernike coefficients has only to be made once. The wavefront error can be adjusted by a scale factor which depends on the position of the test object.

In this contribution, the orange peel on highly polished metallic surfaces was analysed by means of a 3D interferometric microscope and also using spectroscopic ellipsometry. Firstly, the surface topography of polished metallic samples, in view to detect orange peel, was determined using a phase-shifting interferometer. This metrological 3D analysis showed that the orange peel can be seen as a periodic waviness on the surface. Then the optical properties of the investigated samples were studied via spectroscopic ellipsometry at various incident angles. These ellipsometric measurements proved that the samples have peculiar optical properties. In particular, it was found that the resulting pseudo-dielectric function in the entire range from 1.5 eV to 2.5 eV - as obtained based on the measured ellipsometric parameters - does depend on the surface topography of the samples. Based in this experimental finding, it is then immediately shown that spectroscopic ellipsometry can be applied to qualitatively describe the orange peel on highly polished metallic surfaces.

The use of optical areal surface topography measuring instruments has increased significantly over the past ten years as industry starts to embrace the use of surface structuring to affect the function of a component. This has led to a range of optical areal surface topography measuring instruments being developed and becoming available commercially. For such instruments to be used as part of quality control during production, it is essential for them to be calibrated according to international standards. The ISO 25178 suite of specification standards on areal surface texture measurement presents a series of tests that can be used to calibrate the metrological characteristics of an areal surface texture measuring instrument (both contact and optical). Calibration artefacts and test procedures have been developed that are compliant with ISO 25178. The artefacts include crossed gratings, resolution artefacts and pseudo-random surfaces. Traceability is achieved through the NPL Areal Instrument - a primary stylus-based instrument that uses laser interferometers to measure the deflection of the stylus tip. Good practice guides on areal calibration have also been drafted for stylus instruments, coherence scanning interferometers, scanning confocal microscopes and focus variation instruments.

An improvement is made to the traditional 2D integration with least squares method by introducing an iterative compensation procedure. The issue of inaccurate reconstruction due to imperfection of Southwell grid model is solved through the introduced iterative compensations. The feasibility and superiority of the proposed method are investigated with simulations. Moreover, the proposed method is compared with the integration method with radial basis functions.

This paper considers coherence scanning interferometry as a linear filtering operation that is characterised by a point spread function in the space domain or equivalently a transfer function in the frequency domain. The applicability of the theory is discussed and the effects of these functions on the measured interferograms, and their influence on the resulting surface measurements, are described. The practical characterisation of coherence scanning interferometers using a spherical reference artefact is then considered and a new method to compensate measurement errors, based on a modified inverse filter, is demonstrated.

Due to its outstanding depth resolution capabilities vertical scanning low-coherence or white-light interferometry is one of the most used optical techniques in the field of 3D micro-metrology. Unfortunately, step height structures often lead to disturbing effects known as batwings in SWLI measurement that overlay the real profile heights of a rectangular structure. As a consequence, the lateral resolution capabilities and the transfer characteristics of white-light interference microscopes are difficult to characterize. In general, the lateral resolution of such instruments is assumed to agree with the lateral resolution of a conventional light microscope for 2D imaging and the measurement process of an optical profiler is assumed to be linear similar to a microscopic imaging process. Our results show that there are significant discrepancies between the instrument transfer function of a white-light interferometer and the optical transfer function of a conventional microscope. In this paper we analyze the transfer characteristics of current white-light interferometers based on theoretical considerations, simulation studies, and experimental investigations. It turns out that under certain conditions a correct measurement of a rectangular profile is possible even if only the first order diffraction component is captured by an objective lens with a given numerical aperture. In addition to the discussion of current instruments new approaches to overcome existing limits will be introduced: In order to reduce the batwing effect we combine a Mirau white-light interferometer with a confocal illumination system. Furthermore, it is shown that proper adaption of the evaluation wavelength of the low-coherent light can improve the measurement accuracy significantly if rectangular profiles are obtained from the phase information inherent in WLI signals.

In microscopy it is customary to use a wide variety of imaging methods. Unfortunately, for most of these it is necessary to physically change the setup (filters, special objectives, etc.). We present a programmable microscope in which an integrated spatial light modulator (SLM) is incorporated in order to realize a number of otherwise physically intricate modifications. We employ a HDTV LCOS SLM (Holoeye Pluto, 1920x1080 pixel, 8 μm pixel pitch), 2 different LED illuminations in reflection and transmission, an Olympus UmPlanFl 50x objective with a NA of 0.8 and a CCD camera (SVS-Vistek eco204 1/3") with 1024x768 resolution. By the use of computer generated holograms (CGHs) we are able to recreate a number of classical phase contrast imaging techniques such as Zernike phase contrast or DIC, and modify them in unconventional ways. Additionally, the SLM enables us to compensate various kinds of aberrations. Other imaging methods like stereovision for three dimensional object reconstruction on a microscopic scale, structured illumination or confocal microscopy are also possible if the setup is extended to a state in which not only the imaging light but also the illumination light is propagated over an SLM with a CGH.

An optical configuration is realized to obtain quantitative phase-contrast maps able to characterize particles floating in a microfluidic chamber by interference microscopy. The novelty is the possibility to drive the sample and measure it thorough the same light path. That is realized by an optical setup made of two light beams coming from the same laser source. One beam provides the optical forces for driving the particle along the desired path and, at same time, it works as object beam in the digital holographic microscope (DHM). The second one acts as reference beam, allowing recording of an interference fringe pattern (i.e., the digital hologram) in an out-of-focus image plane. This work finds application in the field of micromanipulation as, the devise developed allows to operate in microfluidic chambers driving samples flowing in very small volumes. Recently, the field of optical particle micro-manipulation has had rapid growth, due to Optical Tweezers development. A particle is trapped or moved along certain trajectories according to the intensity and phase distribution of the laser beam used. Here, particles freely floating are driven by optical forces along preferential directions and then analyzed by a DHM to numerically calculate their phase-contrast signature. The improvement is that one laser source is employed for making two jobs: driving and analyze the sample. We use two slightly off-axis laser beams coming from a single laser source. The interference between them gives the possibility to record in real-time a sequence of digital holograms, while one of the beam creates the driving force. By this method, a great amount of particles can be analyzed by a real-time recording of DH movies. This allows one to examine each particle at time and characterize it. The optical configuration and the working method are illustrated. Experimental results are shown for polymeric particles and in-vitro.

The purpose of this study is development of a trapping system for nano-particles by periodically localized light and of a detecting system for the trapped state by an ellipsometoric method. Nano-particles are of interest for some different attractive properties with a bulk body in terms of their reactivity. Those attractive properties are applicable to production of an optical element and a device. For production of nano-particles, it is necessary to manipulate nano-particles and to measure the trapped state without contact in micro region. In this study, periodically localized light which is generated by the nano-periodic structure allows us to trap nano-particles. Evaluation of trapping can be accomplished by using a rotating-analyzer ellipsometer for comparing the ellipsometrical parameter before and after trapping. In confirmation of affectivity ellipsometrical method, we obtained that the trapped state associated with varying a shape of the nanoperiodic structure depends on polarization properties. The trapping light intensity also was found to depend on trapping volume of the nano-particles. From experimental results, the nano-particles can be trapped by the periodically localized light. And the trapping volume was found to increase with increasing in trapping light intensity. Hence, this system achieved trapping and deducing nano-particles.

Fiber-top and ferrule-top cantilevers (FTC) are a new generation of all optical, monolithic, self-aligned microdevices. They are obtained by carving a cantilever on the cleaved end of an optical fiber (fiber-top) or on a ferrule terminated fiber (ferrule-top). FTCs rely on Fabry-Perot interferometry to measure the deflection of the cantilever with subnanometer deflection sensitivity. FTCs specially developed for scanning probe microscopy are equipped with a sharp tip that has the dual function of probing the topography and collecting/emitting light. We perform the scanning probe microscopy using these probes in air, liquid and at low temperature (12°K). The light emission/collection functionality of FTC probes also allows one to combine scanning near field optical microscopy (SNOM) and optical transmission microscopy with contact and non-contact mode atomic force microscopy (AFM). This makes FTCs ideal for AFM+SNOM on soft samples, polymers and biological specimen, where bent fiber probes and tuning fork based systems would not be recommended because of the high stiffness of those probes. We demonstrate here the capability of fiber-top cantilevers to measure deflection and collect near field optical signal, and also the capability of ferrule-top cantilevers for simultaneous optical transmission microscopy and topography of SNOM gratings. Thanks to their unique features, FTCs also open up possibilities for UV nanolithography and on-demand optical excitation at nanoscale.

The cleanliness of steel is described by the amount, size, composition, morphology, and distribution of nonmetallic inclusions (NMIs). These nonmetals are present because of natural physical-chemical effects, and because during continuous casting steel is accidentally contaminated with slag, refractories, and materials from casting moulds. NMIs influence the properties of steel. Therefore, in this paper, a combined milling and image processing system is proposed that mills and scans slices of steel samples to retrieve volumetric information about NMIs. The system is capable of scanning steel samples of 300 × 100 × 90mm³ in size at spatial resolutions of either 3, 5, 10, or 20μm and a volumetric resolution of 10μm within a few hours. After each milling operation the steel surface is captured by a moving large-area CCD image sensor. The optical system further consists of a distortion-free macro lens and diffuse coaxial lighting for brightfield illumination. Additional results using dome lighting are also presented. The interaction of an NMI with the milling cutter results in non-homogeneous NMI reflectances which carry information about the NMI's mass density and chemical compound. Although the steel surface is highly reflective, the milling cutter creates a periodic pattern of moldings which is accentuated by patterns of shadow and light. An adaptive wedge filter in the Fourier space dampens those artifacts. NMIs are binarized separately in every image by local thresholding. In order to reduce segmentation artifacts neighboring slices in the volumetric stack of images are filtered using morphological operators. A statistical analysis of the segmentation results estimates the macro cleanliness. Furthermore an interactive 3D visualization enables the exploration of NMIs and their distribution within the sample. Different viewing, filtering and sorting capabilities are implemented, like ordering NMIs with regard to their shape factor. It is expected that the study of these attributes will lead to information about the composition and formation of NMIs.

Fast figuring of large optical components is well known as a highly challenging manufacturing issue. Different manufacturing technologies including: magnetorheological finishing, loose abrasive polishing, ion beam figuring are presently employed. Yet, these technologies are slow and lead to expensive optics. This explains why plasma-based processes operating at atmospheric pressure have been researched as a cost effective means for figure correction of metre scale optical surfaces. In this paper, fast figure correction of a large optical surface is reported using the Reactive Atom Plasma (RAP) process. Achievements are shown following the scaling-up of the RAP figuring process to a 400 mm diameter area of a substrate made of Corning ULE®. The pre-processing spherical surface is characterized by a 3 metres radius of curvature, 2.3 μm PVr (373nm RMS), and 1.2 nm S_q nanometre roughness. The nanometre scale correction figuring system used for this research work is named the HELIOS 1200, and it is equipped with a unique plasma torch which is driven by a dedicated tool path algorithm. Topography map measurements were carried out using a vertical work station instrumented by a Zygo DynaFiz interferometer. Figuring results, together with the processing times, convergence levels and number of iterations, are reported. The results illustrate the significant potential and advantage of plasma processing for figuring correction of large silicon based optical components.

Lithium fluoride (LiF) crystal is a very promising candidate as nanometer resolution EUV and soft X-ray detector. Compared with other EUV and soft X-ray detectors, charge coupled device and photographic films, LiF crystal has high resolution, large field of view and wide dynamic range. In this paper, using LiF crystal as EUV detector and a Schwarzschild objective (SO) working at 13.5nm as projection optics, mesh images with 4.2 μm, 1.2 μm and 800 nm line width and pinhole patterns with ~1.5μm diameter are acquired in projection imaging mode and direct writing mode, respectively. Fluorescence intensity profiles of images show that the resolution of mesh image is 900 nm, and the one of pinhole image is 800 nm. In the experiments, a spherical condense mirror based on normal incidence type is used to eliminate the damage and contamination on the masks (mesh and pinhole) caused by the laser plasma, and the energy density is not decreased compared with that the masks are close to the plasma. The development of the SO, the alignment of the objective and the imaging experiments are also reported.

Medium thickness transparent layers are becoming increasingly important in various fields of materials science such as in micro-electronics, nanotechnologies, polymer science, biomaterials and chemistry. Such layers vary from simple, transparent layers to those that are much more complex, containing heterogeneous materials and very rough interfaces and requiring new types of characterization techniques. In this paper we present the application of white light scanning interferometry to the structural tomography of such layers. Due to the complexity of the fringe signals along the optical axis, we have developed 2D signal processing techniques of the XZ images to improve the robustness to noise. Knowing that the measurements are prone to artifacts we have also developed a cautious approach to the extraction of pertinent information. Thus, using a manual point Z-scan investigation in an XY image, initial information of the quality of the fringe signals and the appropriate signal processing necessary can be obtained and provide initial structural information. Then, optimized image processing can be performed on the XZ images to provide tomographic cross sections of the layer. Applications of the technique are given on transparent and insulating layers used in electronics and micro-electronics, layers of hydroxyapatite (a biomaterial) and colloidal layers.

A novel method for measuring roughness and reflectance of very smooth surfaces has been presented in the paper. It is based on the measurement of the Total Integrated Scatter (TIS) parameter using a flat photodiode integrator rather than a conventional optical sphere or hemisphere. By that means, one can obtain much less expensive and smaller instruments than the traditional ones that could find their application for surface control purposes in the production area of a wider range of companies. Unfortunately, a decrease of the integrator dimensions could reduce its spatial frequency bandwidth causing measurement errors. Additional errors can occur because of the integrator flatness. Therefore, an analysis of the influence of those factors has been performed. Using the results of the Rayleigh-Rice vector perturbation theory, dependences showing the influence of the range-of-acceptance angle on the TIS value measured have been shown. For the case when very smooth surfaces (e.g. silicon wafers, optical mirrors, precision metal elements) are investigated, the lower limit of the angle range is particularly critical and should be carefully selected. On the other hand, the upper limit can be even smaller than 20-30° which makes it possible to find a compromise while designing the measuring unit. Assuming such a limit, the influence of the integrator flatness is proved to be irrelevant. In the paper, results of measurements of some parameters valuable for the analysis are presented as well as preliminary results of sample measurements in a tentative system. The results obtained confirm the validity of further investigations in this research area. A precise unit for investigating functional properties of the method is under development, and it is planned that the measurement results derived from this unit are to be compared with results of different measurements conducted by means the Ulbricht sphere instruments and by other methods.

The aim of the paper is to discuss a non-invasive method for a glass fibre diameter characterization. The method involves scattering of low-coherent light in the vicinity of a primary rainbow. Theoretical considerations include discussion on complex as well as approximate models of the rainbow. A simple inverse model based on the Airy theory of rainbow is used to characterize a glass fibre diameter. The empirical analysis is mainly devoted to confirm the theoretical predictions and present some achievements in the formation and processing of the Airy rainbow with the use of high-power light emitting diode (LED).

LED based infrared scanning white light interferometry (IR-SWLI) permits non-destructive imaging of embedded MEMS structures. We built an IR-SWLI instrument featuring a custom-built IR-range LED-based light source, capable of stroboscopic use. The source combines multiple separately controllable LEDs with different wavelengths into a collimated homogenous beam offering an adjustable spectrum. We employ software-based image stitching to form millimeter-size 3D images from multiple high magnification scans. These images delineate three layers in a MEMS cavity covered by silicon and reveal a micron-size inlet inside the channel.

We report on building a broadband LED light source for stroboscopic white light interferometry. We chose phosphor types, mass ratios, and encapsulant, to tailor the necessary emission spectrum. Based on known emission spectra, we mixed combinations of blue, cyan, yellow, and red down-conversion phosphors. The phosphor composite was excited with a modified UV LED (365 nm). UV provides primary excitation of blue phosphor BAM (BaMgAl10O17:Eu). The emission (≈ 450 nm) of the blue phosphor provides secondary excitation of longer wavelength phosphors (YAG (yttrium aluminum garnite), strontium-barium silicate, and sulfoselenide). The effective spectrum's FWHM was 244±1.5 nm; spectral drop was 14%. The pulse width was 2.2 μs when the LED was driven with 14 A. We used the source for static MEMS measurements in a SWLI system. The obtained SWLI interferogram features 883 nm FWHM and low side lobes.

Three different types of white light emitting diodes (LEDs) and three types of single color LEDs were tested as light sources for stroboscopic scanning white light interferometry (SSWLI) for dynamic (MEMS) characterization. Short, intense, light pulses and low duty cycle (< 10%) are required to freeze the motion of an oscillating sample. A custom designed LED driver was built utilizing a Metal-Core Printed Circuit Board. At the core of the circuit is a CMOS high speed high current gate driver (IXDD415SI). The LED pulser is compact (50×110 mm²), has good thermal resistivity (0.45 °C/W), wide bandwidth (~DC-10 MHz), and can drive single LEDs at 5A peak current (0.7% duty cycle at 1 MHz). The shortest measured electrical pulses were 6.2 ± 0.1 ns FDHM. The minimum measured Full Duration at Half Maximum (FDHM) of the optical pulse was 8.4 ± 0.1 ns using nonphosphor white LED and 32.1 ± 0.1 ns using white phosphor-converted LED (0.7 % duty cycle at 1 MHz in both cases). The minimum optical pulse FDHM for a single color blue/green LED was 6.4 ± 0.1 ns. The maximum intensity of these pulses was 630 ± 40 μW and 540 ± 30 μW, respectively. All types of white LEDs could be used for stroboscopic SWLI measurements at frequencies up to 2 MHz. For higher frequencies, non-phosphor white LEDs must be used together with a cyan LED to avoid ringing in the SWLI interferogram.

Optical microscope is a well known instrument with many applications in biomedical imaging and precise measurements. Nowadays a lot of modalities arose, which utilize combination of a microscope arrangement with other optical techniques, such as holography or low-coherence interferometry. The most important features of these modalities are related to the diffraction or coherence effects due to such combination, rather than to exact ways of lens aberrations correction. Therefore for analysis and understanding of these effects a theoretical model is necessary, which would be rigorous enough to take into account the diffraction and coherence effects and in the same time simple enough to allow clear physical interpretation of the observed effects. In this paper we propose such a model of volumetric samples imaging in a microscope, that utilizes theory of two-dimensional image formation and analysis of volumetric sample via an "effective" two-dimensional field. Applicability of the proposed model to analysis of volumetric samples imaging is shown by the example of a full-field microscope by Köhler illumination.

A simple method for measuring bilayer system refractive indexes and thicknesses in the low absorbing part of spectra is demonstrated. The method is based on application of Savitzky - Golay smoothing filters and interference fringe separation in the reflected or transmitted spectra of the bilayer system. The refractive indexes and thicknesses are extracted from the wavelengths corresponding to extreme points in the spectrum. Due to the fact that wavelength difference of extreme points in the analyzed spectrum is defined by the product of both, the layer thickness and refractive index, one must generate an appropriate initial guess of these parameters. For refractive index approximation two different methods have been used - point by point and Sellmeier dispersion relation. The final optimization procedure is based on a priori assumption that the thickness calculated from permutations of all extreme points in the spectrum should be the same. Thus the optimal penalty parameter for finding the solution is the standard deviation of calculated thicknesses. In order to demonstrate the effectiveness of this simple method, results of thin organic film thicknesses and refractive indexes are presented.

One of considerable sources of displacement measurement uncertainty in nanometrology systems such as multidimensional interferometric positioning for local probe microscopy is the influence of amplitude and especially frequency noise of a laser source which powers the interferometers. We investigated the noise properties of several laser sources suitable for interferometry for micro- and nano-CMMs (coordinate measurement machines) and compared the results with the aim to find the best option. The influences of amplitude and frequency fluctuations were compared together with the noise and uncertainty contributions of other components of the whole measuring system. Frequency noise of investigated laser sources was measured by two approaches - at first with the help of frequency discriminator (Fabry-Perot resonator) converting the frequency (phase) noise into amplitude one and then directly through the measurement of displacement noise at the output of the interferometer fringe detection and position evaluation. Both frequency noise measurements and amplitude noise measurements were done simultaneously through fast and high dynamic range synchronous sampling to have the possibility to separate the frequency noise and to compare the recorded results.

In this paper a MEMS based micro-SPM head array is proposed to enhance the performance of the currently available nano-measuring machines and effectively reduce the measurement time for large specimen. It consists of 1 × N ( N = 7 in our case) micro-SPM heads/units, realized in one chip by MEMS technique. And it can be easily extended to a micro- SPM head matrix. The main part of the micro-SPM head is the MEMS-positioning stage, which is realized on the basis of an electrostatic lateral comb-drive actuator. In order to take the advantage of the high lateral resolution of conventional cantilevers, a flexible cantilever gripper was designed to be integrated into the MEMS-positioning stage within the SPM head. Conventional cantilevers can be mechanically mounted onto the MEMS-positioning stage or dismantled from the MEMS-positioning stage after the tip is worn out. In this way, the well-designed and calibrated MEMS-positioning stage can be repeatedly and efficiently utilized. The structure design and simulation of mechanical and electrical performances of the mico-SPM head will be detailed in this paper. First experimental results proved the feasibility of the cantilever gripper design.

Digital holographic microscopy is a technique which enables real time monitoring of fast phenomena by using high speed sensors of video cameras. Using this advantage, we obtain holographic images of flow in microcavities, employing a CMOS video camera sensor with acquisition rate of 10 000fps. The corresponding reconstructed 3D image for different flow conditions is obtained from a single hologram using simulations based on the Fresnel approximation. We develop an automated image processing procedure in order to obtain quantitative information about the dynamic contact angle evolution, the shape and velocity of an approximately 300μm wide portion from the water-air meniscus interface in different microscopic cavity geometries.

Particle Image Velocimetry (PIV) is a non-invasive, full-field optical measurement technique that has become a dominant tool for velocity measurement of fluids and gases at both macro (traditional PIV) and micro (microPIV) scales. In PIV experiments, the fluid under the investigation is seeded with tracer particles, which are shining under an excitation by a properly tuned light source. The idea behind the method is to precisely register the position of corresponding particles in two shifted instances of time and then using these records calculating particle displacements, i.e. flow velocity. In most PIV experimental setups, illumination is performed using dual cavity pulse lasers, whose outputs reach several hundreds mJ at short pulse lengths (tens of nano-seconds). Unfortunately, such laser systems are very expensive and bulky. In this work, we investigate a possibility to replace the laser illumination with a high power LED illumination, aiming towards the development of the cost effective and portable microPIV systems. We have developed an electronic circuit, which drives LEDs with a high current over short time duration. The driver circuit is triggered by an internal electronics of the CCD camera, and is able to produce single or double current pulses per camera trigger. Besides, the circuit also allows i) flexible adjustment of the pulse duration (from 1 μs up to tens of msec), ii) the time delay within pulse pairs, which is crucial for double-frame mode, and iii) time delay between the trigger signal and current pulses. We present experimental results of flow velocity measurements obtained using the microPIV system and the developed illumination setup. We have investigated the flow of water, which was seeded with the spherical-polystyrene-fluorescent particles, inside rectangular microchannels. For illumination, a LumiLED LED with a peak wavelength at 470 nm was used at the double-illumination mode, where current pulses of up to 10 A at duration of 5 μs were achieved.

In this paper we have explained a new method for measuring the cantilever displacement using both reflective and interferometric properties of the cantilever. In our method, a Laser light is shone on the cantilever, and the reflected pattern is monitored by a commercially available CCD. Due to the micrometer dimensions of the cantilever which was smaller than the spot size of the laser, the laser beam would be reflected by both substrate and the cantilever's surface, and this will produce an interference pattern on the screen. In this configuration, a displacement in the cantilever will reflect the light in a different angle and also changes the optical path difference between the reflected light from the cantilever and substrate. The overall result of these two effects would be a total displacement of the pattern, which could be simply measured using a CCD. Finally, by taking both effects into consideration,, the cantilever's displacement could be measured. For testing this technique different cantilevers were fabricated and were electrostatically actuated. In this method, displacements as small as 10nm were possible to measure.