Several small-field catadioptric optical designs have been developed over the last decade to meet the demanding needs from lithographers. Design solutions that use a multi-function component can provide nearly perfect wavefront correction for optical systems with broad bandwidth sources, such as free running (un-narrowed) excimer lasers operating at wavelengths below 300 nm, with limited choices of optical materials with high transmission at these wavelengths. From these catadioptric design forms, variations have been developed to accommodate changes in wavelength, increases in the numerical aperture and conversion of the imaging medium from nitrogen to ultra-high purity water and other high index fluids for immersion lithography applications. Some designs also address the need for increased working distance. This paper will discuss the use of multi-function components, the evolution of several design forms, the optical materials required, their benefits for specific applications, and the challenges they have created.

The merit function space of mirror systems for EUV lithography is studied. Local minima situated in a multidimensional merit function space are connected via links that contain saddle points and form a network. In this work we present the first networks for EUV lithographic objectives and discuss how these networks change when control parameters, such as aperture and field are varied and constraints are used to limit the variation domain of the variables. A good solution in a network obtained with a limited number of variables has been locally optimized with all variables to meet practical requirements.

This paper describes how genetic programming was used as an automated invention machine to synthesize both the topology and numerical parameters for seven previously patented optical lens systems, including one aspherical system and one issued in the 21st-century. Two of the evolved optical lens systems infringe the claims of the patents and the others are novel solutions that satisfy the design goals stated in the patent. The automatic synthesis was done "from scratch"--that is, without starting from a pre-existing good design and without pre-specifying the number of lenses, the topological layout of the lenses, or the numerical parameters of the lenses. Genetic programming is a form of evolutionary computation used to automatically solve problems. It starts from a high-level statement of what needs to be done and progressively breeds a population of candidate individuals over many generations using the principle of Darwinian natural selection and genetic recombination. The paper describes how genetic programming created eyepieces that duplicated the functionality of seven previously patented lens systems. The seven designs were created in a substantially similar and routine way, suggesting that the use of genetic programming in the automated design of both the topology and numerical parameters for optical lens systems may have widespread utility.

It is well known that a fish-eye lens produces a circular image of the scene with a particular distortion profile. When using a fish-eye lens with a standard sensor (e.g. 1/3", 1/4",.), only a part of the rectangular detector area is used, leaving many pixels unused. We proposed a new approach to get enhanced resolution for panoramic imaging. In this paper, various arrangements of innovative 180-degree anamorphic wide-angle lens design are considered. Their performances as well as lens manufacturability are also discussed. The concept of the design is to use anamorphic optics to produce elliptical image that maximize pixel resolution in both axis. Furthermore, a non-linear distortion profile is also introduced to enhance spatial resolution for specific field angle. Typical applications such as panoramic photography, video conferencing, and homeland/transportation security are also presented.

A historical collection of Corning Tropel optical systems was analyzed with the primary goal of organizing and archiving the designs in a searchable computer database. The analysis of these systems was two-fold: the system data and documented design procedure were examined from both a technical as well as a historical viewpoint. Items of historical interest included letters and handwritten comments from various well-known designers, computer print outs from early lens design programs, and aberration plots and pictures of the system drawn painstakingly by hand. The technical analysis involved entering the system data into a modern day computer analysis package (CODE V) and comparing the performance (in the form of MTFs, field and distortion curves, etc.) with the original performance claimed by each system. One of the most significant findings was the ability to consistently replace obsolete glasses with current glasses, without sacrificing performance. In some cases, it was even possible to reoptimize the system and improve the performance.

Lenticular lens arrays are widely used in the printed display industry and in specialized applications of electronic displays. In general, lenticular arrays can create from interlaced printed images such visual effects as 3-D, animation, flips, morph, zoom, or various combinations. The use of these typically cylindrical lens arrays for this purpose began in the late 1920's. The lenses comprise a front surface having a spherical crosssection and a flat rear surface upon where the material to be displayed is proximately located. The principal limitation to the resultant image quality for current technology lenticular lenses is spherical aberration. This limitation causes the lenticular lens arrays to be generally thick (0.5 mm) and not easily wrapped around such items as cans or bottles. The objectives of this research effort were to develop a realistic analytical model, to significantly improve the image quality, to develop the tooling necessary to fabricate lenticular lens array extrusion cylinders, and to develop enhanced fabrication technology for the extrusion cylinder. It was determined that the most viable cross-sectional shape for the lenticular lenses is elliptical. This shape dramatically improves the image quality. The relationship between the lens radius, conic constant, material refractive index, and thickness will be discussed. A significant challenge was to fabricate a diamond-cutting tool having the proper elliptical shape. Both true elliptical and pseudo-elliptical diamond tools were designed and fabricated. The plastic sheets extruded can be quite thin (< 0.25 mm) and, consequently, can be wrapped around cans and the like. Fabrication of the lenticular engraved extrusion cylinder required remarkable development considering the large physical size and weight of the cylinder, and the tight mechanical tolerances associated with the lenticular lens molds cut into the cylinder's surface. The development of the cutting tool and the lenticular engraved extrusion cylinder will be presented in addition to an illustrative comparison of current lenticular technology and the new technology. Three U.S. patents have been issued as a consequence of this research effort.

We report on our work on producing liquid crystal switchable modal lenses and their use in a compound lens system in order to produce variable focus/zoom lenses. We describe work on producing a high power lens, and present theoretical work on off-axis phase modulation in a liquid crystal lens which is important in order to be able to carry out a complete optical design of a liquid crystal lens.

This paper presents the optical design and experimental demonstration of a compact, foveated, wide field-of-view (FOV) imaging system using two lenses and a liquid crystal spatial light modulator (SLM). The FOV of this simple doublet system is dramatically improved by the SLM, which can be programmed to correct all the geometrical aberrations at any particular field angle. The SLM creates a variation in the image quality across the entire FOV, with a diffraction-limited performance at the field angle of interest (similar to the foveated human vision). The region of interest can be changed dynamically, such that any area within the FOV of the system can be highly resolved within milliseconds. The wide FOV, compactness, and absence of moving parts make this system a good candidate for tracking and surveillance applications. We designed an f/7.7 system, with a 60° full FOV, and a 27 mm effective focal length. Only two lenses and a beam splitter cube were used along with a reflective SLM. The theoretical wavefront aberration coefficients were used to program the SLM, which was placed in the pupil plane of the system. A prototype was built and the system was experimentally demonstrated using monochromatic light and a CCD camera.

Optical diagnostics are currently being designed to analyze high-energy density physics experiments at the National Ignition Facility (NIF). Two independent line-imaging Velocity Interferometer System for Any Reflector (VISAR) interferometers have been fielded to measure shock velocities, breakout times, and emission of targets having sizes of 1-5 mm. An 8-inch-diameter, fused silica triplet lens collects light at f/3 inside the 30-foot-diameter NIF vacuum chamber. VISAR recordings use a 659.5-nm probe laser. By adding a specially coated beam splitter to the interferometer table, light at wavelengths from 540 to 645 nm is spilt into a thermal-imaging diagnostic. Because fused silica lenses are used in the first triplet relay, the intermediate image planes for different wavelengths separate by considerable distances. A corrector lens on the interferometer table reunites these separated wavelength planes to provide a good image. Thermal imaging collects light at f/5 from a 2-mm object placed at Target Chamber Center (TCC). Streak cameras perform VISAR and thermal-imaging recording. All optical lenses are on kinematic mounts so that pointing accuracy of the optical axis may be checked. Counter-propagating laser beams (orange and red) are used to align both diagnostics. The red alignment laser is selected to be at the 50 percent reflection point of the beam splitter. This alignment laser is introduced at the recording streak cameras for both diagnostics and passes through this special beam splitter on its way into the NIF vacuum chamber.

Freeform Optical surfaces are defined as any non-rotationally symmetric surface or a symmetric surface that is rotated about any axis that is not its axis of symmetry. These surfaces offer added degrees of freedom that can lead to lower wavefront error and smaller system size as compared to rotationally symmetric surfaces. Unfortunately, freeform optics are viewed by many designers as more difficult and expensive to manufacture than rotationally symmetric optical surfaces. For some freeform surfaces this is true, but a designer has little or no feedback to quantify the degree of difficulty for manufacturing a surface. This paper describes a joint effort by Optical Research Associates (ORA) and the Precision Engineering Center (PEC) at North Carolina State University to integrate metrics related to the cost and difficulty of manufacturing a surface into the merit function that is used during the design of an optical system using Code V. By incorporating such information into the merit function, it is possible to balance optical performance and manufacturability early in the design process.

The incorporation of aspheric lenses in complex lens system can provide significant image quality improvement, reduction of the number of lens elements, smaller size, and lower weight. Recently, it has become practical to manufacture aspheric glass lenses using diamond-grinding methods. The evolution of the manufacturing technology is discussed for a specific aspheric glass lens. When a prototype all-glass lens system (80 mm efl, F/2.5) was fabricated and tested, it was observed that the image quality was significantly less than was predicted by the optical design software. The cause of the degradation was identified as the large aspheric element in the lens. Identification was possible by precision mapping of the spatial coordinates of the lens surface and then transforming this data into an appropriate optical surface defined by derived grid sag data. The resulting optical analysis yielded a modeled image consistent with that observed when testing the prototype lens system in the laboratory. This insight into a localized slope-error problem allowed improvements in the fabrication process to be implemented. The second fabrication attempt, the resulting aspheric lens provided remarkable improvement in the observed image quality, although still falling somewhat short of the desired image quality goal. In parallel with the fabrication enhancement effort, optical modeling of the surface was undertaken to determine how much surface error and error types were allowable to achieve the desired image quality goal. With this knowledge, final improvements were made to the fabrication process. The third prototype lens achieved the goal of optical performance. Rapid development of the aspheric glass lens was made possible by the interactive relationship between the optical designer, diamond-grinding personnel, and the metrology personnel. With rare exceptions, the subsequent production lenses were optical acceptable and afforded reasonable manufacturing costs.

New technologies for the fabrication of aspheres have increased opportunities for using aspheres in a wider range of optical systems. If manufacturability is considered early in the optical design process, the short and long term costs of the aspheric surface can be greatly reduced without sacrificing performance. The optical designer must learn how to select optimum materials for aspheres. Using non-staining glasses, higher index glass types, and softer glass types can help reduce production costs. If the optical designer understands what range of aspheric surfaces can be manufactured, they can constrain the aspheric surface during optimization. The steepness of the aspheric departure (the slope of the aspheric departure) often has a larger impact on manufacturing difficulty than the amplitude of the asphere or the steepness of the base radius. Tolerancing can increase the difficulty without measurably improving optical performance. Finally, the asphere can be designed for ease of metrology. Understanding the options that are available for aspheric metrology will allow the engineer to control tooling and fixturing that is required for testing.

We here report on the modeling and characterization of adaptive microlenses. We first address device simulation with the theoretical treatment of its characterization. A follow-up paper addresses the experimental results of the focal length measurements using a simple Z-scan method. In addition, the sources of error and ways to overcome them are discussed. Previously, an adjustable electro-optic microlens with concentric electrodes was presented. The electrostatic potential was found by numerically solving Laplace's equation where the surface charge method was incorporated. The refractive index distribution within the lens aperture and the effective light path modulation was found by integration over the entire substrate thickness. We have used finite element analysis to characterize the electrostatic field distribution within the lens aperture. Unlike the previous theoretical treatment, we implement the beam propagation method to calculate the total phase delay. This will allow for accurately modeling the phase based on the optical field profile, medium inhomogeneties, and scattering and depolarization effects. Furthermore, we represent the theoretical basis for characterizing such types of lenses, and microlenses in general. In this method, we implement Fresnel diffraction and a simple Z-scan method. This technique allows for finding the lens focal length, and its sign, and study aberration effects as well.

In the second paper of two papers that address the modeling and characterization of adaptive microlenses, we report the theoretical basis for characterization of such lenses based on the z-scan method. In addition we compare the experimental measurement results with the simulated results obtained using Finite Element Analysis (FEA) utilizing FEMLABTM in the first paper. Some of the method advantages and limitations will be briefly addressed.

In this paper we present the fabrication of optical mode field adaptors for fiber optical communications devices in combination with a new method for spot size measurement for single mode optical components. At the end of standard single mode fibers we have manufactured reproducible mode field transformers with diameters from 5 μm to 90 μm. Additionally, we present a new planar optical field characterization method. BPM simulations are performed to predict the spot sizes at different fiber end diameters. Based on the measurement of a singlemode fiber in accordance with ITU Recommendation G.652 the efficiency is demonstrated and discussed.

Hybrid refractive-diffractive optics are widely used in infrared systems, but their performance is limited by reduced diffraction efficiency away from the design wavelength. Two techniques are currently being investigated to improve broadband efficiency; dual-layer blaze structures and blazed-binary optics. This paper discusses the design of dual-layer blaze structures in detail, and presents some athermalised lenses which benefit from this approach. A brief summary of using blazed-binary structures to improve efficiency is presented.

Improvement in the fabrication of large solid-state focal plane array photonic sensors has emphasized the need for telescopes with flat and wide angular fields of high resolution and with large spectral passbands. To increase the angular field of Cassegrain-like telescopes, various designs of correctors have been incorporated in the optical train. This paper compares specific designs based on the Dall-Kirkham format of prolate ellipsoid primary and spherical secondary mirrors, in which excellent correction is achieved over a significant field angle. The attraction of the Dall-Kirkham format is the relative ease of fabrication to a very high accuracy by simple null tests of the concave prolate-ellipsoid primary by specific separation of light source and knife-edge, and of the convex secondary by interference-matching with a previously null-tested concave spherical master. Null tests of the more common Ritchie-Chretien design require the additional fabrication of two "Hindle spheres" or other auxiliary optics such as holograms for testing of the hyperboloidal primary and for the hyperboloidal secondary. If the Dall-Kirkham format is modified to include variants in which the "Cassegrain" image is imperfect or even afocal, it is possible to design simple corrector relays with exceptional final imaging characteristics. Examples are presented that provide distortionless, diffraction-limited, flat-field imaging over usefully wide fields and large passbands at speeds of f/5 - f/4, and having an unusually compact layout.

The Terrestrial Planet Finder-Coronagraph (TPF-C) is a NASA exploration mission to directly detect and characterize terrestrial exoplanets at visible wavelengths. The TPF-C observatory must be able to distinguish a planet that is more than 10 orders of magnitude fainter than its parent star at a separation of 75 milli-arc-seconds (mas). Coronagraphic detection requires a large aperture telescope to resolve the exoplanet from its star, and extreme stability during detection and characterization observations. This paper discusses the requirements and trade studies leading to the current baseline optical design for the TPF-C telescope. The current baseline design is summarized and its prescription is presented.

A baseline design for NASA's Terrestrial Planet Finder Coronagraph (TPFC) starlight suppression system (SSS) is described. The design is based on a 8x3.5m elliptical aperture telescope leading to terrestrial planet detection at a minimum angle of ~4λ/D. The design accommodates classical Lyot coronagraph as well as shaped pupil approaches and includes separate optical paths for two polarizations each with its own deformable mirror control. Critical design challenges and trades are described.

The High Resolution Imaging Science Experiment (HiRISE) camera will be launched in August 2005 onboard NASA's Mars Reconnaissance Orbiter (MRO) spacecraft. HiRISE supports the MRO Mission objectives through targeted imaging of nadir and off-nadir sites with high resolution and high signal to noise ratio [a]. The camera employs a 50 cm, f/24 all-reflective optical system and a time delay and integration (TDI) detector assembly to map the surface of Mars from an orbital altitude of ~ 300 km. The ground resolution of HiRISE will be < 1 meter with a broadband red channel that can image a 6 x 12 km region of Mars into a 20K x 40K pixel image. HiRISE will image the surface of Mars at three different color bands from 0.4 to 1.0 micrometers. In this paper the HiRISE mission and its camera optical design will be presented. Alignment and assembly techniques and test results will show that the HiRISE telescope's on-orbit wave front requirement of < 0.071 wave RMS (@633nm) will be met . The HiRISE cross track field is 1.14 degrees with IFOV 1.0 μ-radians.

The Optical Navigation Camera (ONC) is part of NASA's Mars Reconnaissance Orbiter (MRO) scheduled for an August 2005 launch. The design is a 500 mm focal length, F/8.3 Ritchey-Chretien with a refractive field corrector. Prior to flight, the off-axis performance of the ONC was measured at visible wavelengths in the off-axis scatter facility at the Space Dynamics Laboratory (SDL). This unique facility is designed to minimize scatter from the test setup to prevent data corruption. Testing was conducted in a clean room environment, and the results indicate that no detectable contamination of the optics occurred during testing. Measurements were taken in two time frames to correct an unanticipated stray light path, which occurred just outside of the sensor's field-of-view. The source of the offending path was identified as scatter from the edges of the field corrector lenses. Specifically, scatter from the interface between the flat ground glass and polished surfaces resulted in significant "humps" in the off-axis response centered at ± 1.5°. Retesting showed the removal of the humps, and an overall satisfactory performance of the ONC. The troubleshooting, correction, and lessons learned regarding the above stray light path was reported on in an earlier paper. This paper discusses the measurement process, results, and a comparison to a software prediction and other planetary sensors. The measurement validated the final stray light design and complemented the software analysis.

Rayleigh scaling equations for resolution and the control of computer chip critical dimensions (CD) within a finite depth of focus (DOF) have always indicated that resolution is better improved by reductions in wavelength of exposure light rather than by increasing the numerical aperture (NA) of the projection optics, particularly as it approaches the physical limit in air of 1.0. However, liquid immersion of the image increases the physical NA limits and presents new optical design challenges, while postponing the necessity for drastic reductions in the wavelength.

Lateral intensity fluctuations of laser beams can be removed by spatial frequency filtering using a pinhole. Beams with a high divergence have a very small and narrow focus, therefore the pinhole must be both very small and thin. Conventional pinholes, based on absorption or reflection of the unwanted parts of the beam, have several limitations in this case. Their disadvantages can be overcome by a new kind of pinholes that are based on microstructures. They are characterized by a higher laser damage threshold, only limited by the bulk material, and a constant visibility of the beam, making the adjustment process of the pinhole a lot easier. The microstructures can be circular, binary gratings working mainly in a diffractive way, as we described earlier. This paper will summarize and update the results for this diffractive, dielectric pinholes and introduce a new idea of using cone-like structures, working mainly in a refractive way. We present the design, fabrication and characterization of pinholes, realized with both of these new concepts and we asses their performance and their limitations.

The ability of commercial optical design software to ray trace through uni-axial birefrigent materials at any Field Of View (FOV) plus the capability of the optimization routines to select exact birefrigent materials that achromatize compound wave-plates make the software useful for the design of wide FOV multi-element achromatic retarders and analysis of their performance. In this paper I will describe some of the properties that govern retarders made of uni-axial birefrigent materiais, discuss some tips for building the merit function and show results of the various half wave-plate types designed and their performance.

The design of the hybrid athermal CCD camera includes optical and mechanical considerations for minimizing the thermal defocus of the camera. In order to check the thermal characteristic of the athermal CCD camera, a special test was conducted. The CCD camera, its optical and mechanical design, the test setup, and the test results are described.

A novel method for the fabrication of continuous micro-optical components is presented in this paper. It employs a computer controlled spatial-light-modulator (SLM) as a switchable projection mask and silver-halide sensitized gelatin (SHSG) as recording material. By etching SHSG with enzyme solution, the micro-optical components with relief modulation can be generated through special processing procedures. The principles of digital SLM-based lithography and enzyme etching SHSG are discussed in detail, and microlens arrays, micro axicon-lens arrays and gratings with good profile were achieved. This method is simple, cheap and the aberration in processing procedures can be in-situ corrected in the step of designing mask, so it is a practical method to fabricate continuous profile for low-volume production.

We obtained novel analytic expressions which permit us to realize the optical design of any thick lens, this analysis include both first and exact order design. We employ the conic constant of the first surface to correct the marginal spherical aberration. We analyzed both finite and infinite conjugates cases. Examples done with our methodology also show good agreement with commercial optical design programs.