No abstract available.

Loss in optical fiber coupling efficiency and transmission are computed for a telecommunication optical circulator. Optical performance degradation is due to thermally induced optical errors in the two beam splitter cubes. The computation of the optical errors is discussed for two materials and the effects illustrated. Bulk volumetric absorption of the incident laser radiation from the input optical fiber and surface absorption via the coatings on the beam splitter interface generate temperature gradients. Loss in optical fiber coupling efficiency is produced by wavefront error caused by thermal expansion effects, and refractive index changes with temperature and stress. Transmission loss in the optical circulator is caused by polarization errors generated by the effects of stress birefringence. The optical errors were computed using temperatures generated from a Thermal Desktop model and displacements and stresses generated by a MSC/Nastran finite element model. The optical errors were imposed upon a Code V optical model to compute loss in fiber coupling efficiency and transmission in the optical circulator.

With the development of free space interconnection and optical computing different optics for these approaches have been designed, which are usually difficult to realize with conventional optical systems. The concept of an electrooptical interface based on the Photonic Mixer Device (PMD), which detects and mixes and optical signal simultaneously, has been proposed in previous publications. An array of vertical cavity surface-emitting lasers (VCSELs) is driven by input signals from different channels. The optical signals are then transformed by a lens system and a diffractive optical element (DOE) to a PMD array for processing and multiplexing. In this paper the DOE to realize the optical transformation in the electrooptical interface is presented. The DOE is composed an array of small segments, which correspond to the VCSELs with a pitch of about 250micrometers . The phase functions of the DOE are designed separately for each VCSEL to generate a shifted uniform distribution on the PMD-array. For compactness the segments on the edge work at a large diffraction angle, which leads to an equivalent quasi-constant phase gradient added to them and results in high frequency structure. Therefore, for simplification of the production of the DOE, a prism is combined with the DOE to generate the desired optical transformation. The optical transformation is investigated with the simulation tool ZEMAX. The simulation results show that the DOE with the designed phase function works well for the PMD based optical interface, and it is possible to realize a parallel multi- channel electrooptical interface for code division multiplex access (CDMA) communications.

Graphical methods have been used in Engineering and Physics to speed up long numerical calculations often done by hand. Many of these methods have become obsolete with the increasing speed of digital computers. Charts for the selection of glasses for thin achromatic doublets with reduced secondary spectrum are among the graphs still in use probably because of the sizable number of possible combinations. With any of the most popular, present day, PC's all the possible combinations of all the glasses in the Schott Glass Catalog, taken a pair of glasses at a time secondary spectrum can be computed, sorted in increasing value and displayed on the monitor screen as a table in about 30 seconds. The number of acceptable solutions on the bases of magnitude of secondary spectrum only may still be huge. Further calculations of aberrations for specific cases will help reduce drastically the number of acceptable solutions. Beyond that, it will be left to the user to consider other parameters generally listed in glass catalogs data sheets to finally come out with one solution.

A new method to measure the straightness of a moving table by using a laser beams is proposed. The straightness of a moving table consists of three rotation angle errors and two parallel displacement errors. The former error components are measured by two sets of parallel mirrors and the latter by a corner-cube mirror.

Optimum performance of a scanning photolithography tool is highly dependent upon the characteristics of its installation support system. Since the quality of the imaging product relies on precise control of the imaging process, vibration management is critical . Stiffness, mass, and inherent damping of the overall support system are the primary factors in determining whether the equipment is able to provide good process control under varied operating conditions. Current generation lithography scanners employ internal reaction forces to ultimately stabilize their optical exposure systems. These reaction forces are generated in order to counteract dynamic acceleration forces resulting from stages, wafer loaders and other devices and can transmit relatively large dynamic loads into the support system. In addition to withstanding the static weight of the tool, the support system must also resist these dynamic loads. Although there are several techniques for establishing the integrity of a support system, this paper will discuss a method for gauging how a system reacts dynamically to the loads generated by a scanning lithography tool. By computing the transfer function of acceleration divided by force, a dynamic measurement term called accelerance is used to quantify the integrity of the pedestal support system on which the tool resides.

Future space and ground telescopes will have apertures that are increasingly larger in size. The primary mirrors for these telescopes will be so large that they cannot be fabricated, transported, and/or launched as a single entity. One solution is to build a large mirror out of smaller segments. The biggest challenge in fabricating segmented mirrors is matching the individual pieces so they form a single, continuous surface. This requirement means that the radii of curvature must all match. We present a technique for matching the relative radii of curvature for segmented mirrors, and we include an error analysis of this method.

No abstract available.

By using a binary phase grating, a lens centering system is constructed. In our system, the lens under alignment is mounted on a suitable mechanical axis that can be a spindle of precision lathe. A binary phase grating is used as a beam splitter. Laser beam after passing through the grating only ±1 orders are kept unstop, reflected back by lens surface, recombined by the same grating, and very good contrast interference fringes can be attained. When the lens together with the spindle is rotated, the interference fringes remain motionless only when the lens rotates around its axis of symmetry. If the lens rotates around an axis of asymmetry, the fringes will move. A CCD camera is used to monitor the fringes and transversal error less than a micrometer can be achieved. The interference fringes are very insensitive to vibration and environment. I the paper the theory are presented and the experimental results are given.

This paper concerns the light-absorptive coating intended for reduction of stray sunlight in the satellite-borne optical instrumentation and particle-analyzing apparatus operating in open space under intensive solar illumination. Through the inner surfaces are the passive elements in optical instruments, nonetheless the condition and reflectivity of their surfaces can have noticeable effect on the signal-to-noise ratio of their detectors. In order to reduce an influence of the stray light on sensitivity of devices, the reflectivities of inner surfaces are strived to keep minimum in those wavelengths ranges, where the detectors spectral responses are high. We measured reflectivities of several types of traditional light-absorptive coating and also tested our own approach to development of low reflectivity materials. The reflectivities were measured in visible and near-infrared wavelengths ranges (400 to 927 nm), as well as at the hydrogen Lyman-α line (121.6 nm), the most intensive line of the solar UV radiation. Also, the values of the solar absorptance α_s and the emissivity ε were measured. They made it possible to classify the investigated coating with their respects to a possible use in converters of solar radiation into the heat. Conclusions are given on application of diverse coatings depending on the instrument's detector type, operational wavelengths range, and operating conditions.

This paper describes the Rubicon^tm actuator, discusses its test data and derives from the data the actuator's accuracy function based upon the observed accuracy of long and short stroke motion commands. The accuracy is described in terms of the rms positioning error (in nanometers) for moves of a given size, regardless of position in the stroke.

In Free Gyroscopic Stabilized Seekers, the Primary Mirror has the multiple functions of a magnetic rotor, the primary rotating mass and the primary reflector for the optical train. The introduction of rare-earth magnetic alloys to this class of seeker has provided increased flexibility in materials selection, opto-mechanical design and cost of manufacture. Along with superior magnetic properties, the rare-earth alloy Neodymium-Iron-Boron (NdFeB) comes with the undesirable properties of anisotropic CTE, high susceptibility to corrosion and manufacturing challenges. This paper discusses the opto-mechanical design, structural and optical modeling and analysis of a primary mirror assembly utilizing an NdFeB insert with centrifugal, linear acceleration and thermal loading as well as the optical test results, qualification testing of long-term figure stability and validation of the mechanical/magnetic/optical design model.

Low-cost CCD-based cameras offer several cost and performance advantages for remote sensing applications. The optomechanical design of such cameras is inherently simple because zoom, gain and yaw corrections can be performed electronically, thereby, requiring no moving parts or mechanisms. This paper presents the optomechanical design and the results of structural and thermal analyses for a low-cost camera consisting of only three major parts: lens, electronics and camera housing. This camera uses a wide field of view lens with a fast f-number to acquire high- resolution images under various day and night time illumination scenarios. Passive athermal design of the lens maintains a high value of the MTF over a temperature range of 110°C. Selection of the materials and adhesives used in this camera is dictated by a lifetime requirement of over 30 years under adverse environmental conditions. Structural and thermal modeling results confirm the survivability and performance of this camera under various shock, vibration and thermal loads.

The optomechanical design of the Wide Field of View Imaging Spectrometer (WFIS) is presented. Developed under NASA's Instrument Incubator Program, the Incubator WFIS is a hyperspectral-imaging spectrometer covering a 120° x .015° field of view over a 360 nm to 1000 nm spectral range. The Incubator's mission is to demonstrate, via flight aboard NASA's DC-8 Research Aircraft, new technology for earth science. The Incubator WFIS is designed specifically for observing the earth and earth's atmosphere for chemistry and aerosol studies. The optomechanical design couples an off-axis F/3 Schwarzchild telescope to a three element Offner Spectrometer using two unique anamorphic/aspheric field elements. The complete sensor, including a CCD detector and electronics, occupies a volume of approximately cubic shape measuring 25 cm on an edge. An off-axis optical system such as the incubator WFIS requires a multidisciplinary design approach. This paper emphasized the importance that systems approach plays in optomechanical design. This is typified by the trades performed to establish the optimum design alternative for the optical metering structure to achieve the 0.010 nm wavelength stability (with a .005 nm goal) needed for the science mission.

A method of minimizing the optical distortion from gravity sag on a suspended large autocollimating flat mirror has been devised. This method consists of an inverted nine- point Hindle-Mount. A conventional Hindle-mount is located underneath a sky-viewing mirror and is primarily under compression loads from the weight of the mirror. It is not suitable for the situation where the mirror is viewing the ground, since a mirror would tend to fall out of the mount when in an inverted position. The inverted Hindle-Mount design consists of bonded joints on the backside of the mirror that allow the mirror to be held or suspended above an object to be viewed. This ability is useful in optical setups such a s a calibration test where a flat mirror is located above a telescope so that the telescope may view a known optic.

The Ultra-Precision Linear Actuator presented in this paper was developed for the Next Generation Space Telescopes' (NGST) primary mirror surface figure control. The development was a joint effort between Alson E. Hatheway, Inc (AEH) and Moog, Schaeffer Magnetics Division (SMD). The goal of this project was to demonstrate an extremely light weight, relatively high stiffness actuator capable of operating uniformly well over the range of 20°K to 300°K and achieving diffraction-limited performance (±10 nm) in the optical band for weeks at a time, while consuming no electrical power and dissipating no heat. The essence of the design challenge was to develop a lightweight, high stiffness, low power, thermally stable linear positioning mechanism. Actuation systems with resolutions comparable to that of this design normally are operated in a closed-loop control system to compensate for any non-linearities and hysteresis inherent in their enabling technologies, such as piezoelectric and magnetostrictive transducers. These technologies require continuous application of power and therefore are not low power consumption devices. The development challenge was met through the use of Alson E. Hatheway's (AEH) patented Rubicon^tm elastic transducer which consists of two elastic elements; a soft spring and a stiff flexural member. Deflection of the soft spring applies a force input to the stiff flexure, which responds with a proportionally reduced output deflection. To maintain linearity, the displacements, and hence the stresses, developed in both elastic members are kept well below the elastic yield strength of the material. The AEH transducer is inherently linear and hysteresis free.

According to the requirement of the Lower Latitude Meridian Circle (LLMC) that the instrument can still determine absolutely the position of a celestial body after a scientific CCD is attached to it, a new control plan is presented in this paper. The plan includes two parts. One is that the CCD camera is driven to track the stellar image in the horizontal direction when observed in the meridian direction. The other is that the CCD camera still moves in the horizontal, while the tube of the instrument moves in the vertical direction when observed in the prime vertical direction. In order to accomplish the plan we have developed a control system that includes three main parts: a personal computer (PC), a single chip microcontroller system for CCD driving scan and a vertical angle control system. The first to parts are described in the paper. The PC sends all kinds of instructions and data to the microcontroller via an output interface board. The control software in the PC is written in C++, and the one in the microcontroller is written in ASM. Two simplified program flow charts are presented. We also discuss the CCD tracking error caused by the control system, and propose a corresponding way to solve the problem.

Two data acquisition systems of the Lower Latitude Meridian Circle (LLMC) are described in this paper, of which one is based on a video CCD and the other is based ona scientific CCD. To determine the position of a celestial body absolutely and precisely, the LLMC is equipped with several precision measurement devices such as one precision clock, nine Reticon linear photodiode arrays, one video CCD, one scientific CCD, one rotary inductive synchronizer, and one grating linear displacement transducer. To control these devices properly and collect data from these devices orderly during observations, two data acquisition and control systems are developed. The one based on a video CCD is used to test the instrumental precision of the LLMC. The other based on a scientific CCD is used for normal observations, and is composed of three subsystems. We will illustrate the functions of the measurement devices in the two systems, discuss the methods of data acquisition, and present our thoughts about software programming in the paper.

A new control system of the azimuth transmission mechanism used in the Lower Latitude Meridian Circle (LLMC) is described in this paper. Because the original azimuth transmission mechanism causes too much vibration during the transposition of the horizontal axis of the instrument, we decided to modify the original system by two ways. One is to modify the lift mechanism and the azimuth transmission mechanism. The other is to replace the original stepper motors with a new type of stepper motor. According to the requirement of the new motor and its sine subdivided microstep driver, the original control system has been modified. The new system has an expansion output board and a new control program compared with the original one. The hardware architecture of the new system is described. The program in the single chip microcontroller is written in ASM, which is composed of 10 subroutines. The program in a host PC is written in C++. The methods using in controlling motors and skills in designing these programs are discussed. Two sketch flow charts of the control program are presented in the paper. Modification of the lift mechanism is also introduced. All this works make the vibration very slight.

A control system of the vertical angle transmission used in the Lower Latitude Meridian Circle (LLMC) is described in this paper. The transmission system can change the zenith distance of the tube quickly and precisely. It works in three modes: fast motion, slow motion and lock mode. The fast motion mode and the slow motion mode are that the tube of the instrument is driven by a fast motion stepper motor and a slow motion one separately. The lock mode is running for lock mechanism that is driven by a lock stepper motor. These three motors are controlled together by a single chip microcontroller, which is controlled in turn by a host personal computer. The slow motion mechanism and its rotational step angle are fully discussed because the mechanism is not used before. Then the hardware structure of this control system based on a microcontroller is described. Control process of the system is introduced during a normal observation, which is divided into eleven steps. All the steps are programmed in our control software in C++ and/or in ASM. The C++ control program is set up in the host PC, while the ASM control program is in the microcontroller system. Structures and functions of these r\programs are presented. Some details and skills for programming are discussed in the paper too.

A strategy for optimizing both the on-axis and the off-axis performance of coherently (directly) coupled visual instruments is presented. The strategy draws on the recently published body of data regarding the influence of various individual Seidel aberration and aberration combinations on subjective contrast sensitivity and resolution tasks, as well as studies on the correlation between subjective image quality and objective instrumental figures of merit. An MTF-based metric allows both optimization and tolerancing to be performed in a coherent manner that is based on experimental results of the effects of aberrations.

ITT Industries has developed a precision optical adjustment mechanism capable of ultra-precision adjustment in microradian increments. The success of the Mono-Ball mechanism is its ability to maintain registration after sustaining harsh vibration and thermal environments. This technical paper will detail the Mono-Ball mechanism's opto- mechanical configuration. Supporting test data demonstrates the device's performance in thermal and vibration environments. This lightweight mechanism was developed for use in spaceflight earth weather observing instruments. However, the Mono-Ball mechanism may be used in numerous optical applications that require ultra-precision adjustment. Although the Mono-Ball mechanism is patent pending, this paper presents an overview of the engineering principals utilized in precision mechanisms that the reader may be able to utilize in his or her design project.

This technical paper describes an adjustment mechanism capable of producing microradian resolution rotational motion of an optical element. The mechanism rotates an optical element about two orthogonal axes utilizing flexure beam elements. The flexures facilitate frictionless rotation about the center of the optical element, in roll and tilt over a 1.5 degree range. The optical element is retained in an athermal mount to minimize distortion. The mechanism is constructed entirely of titanium. Integral to the mechanism is adjustment actuators to provide position adjustment of the optical element. Locking actuators retain the mechanism's final adjusted positions when exposed to severe vibration and thermal environments. The mechanism configuration may be scaled in size appropriate to the optical component requiring mounting. Although the flexure mechanism is patent pending, this paper presents an overview of the engineering principles utilized in precision mechanisms that the reader may be able to utilize in his or her design project.

Ever since the gradient index (GRIN) materials came into existence, there have been continuous efforts by various research groups in the world to improve these materials and explore their potential for designing high-performance and compact optical systems. Recently, with the advent of a commercial gradient index glass such as GRADIUM by LightPath Technologies Inc., Arizona, USA, there has been an increased interest among optical engineers to use these materials for developing realizable GRIN systems. We have previously reported the use of GRADIUM in image intensifier tube based night vision systems such as passive night vision goggles for patrolling and passive night sights for drivers of armored vehicles. These applications generally use systems with unit magnification and large field of view. Derivatives of Double-Gauss configuration are best suited for the front-end objective lens of such systems. In this paper, we discuss the use of GRADIUM in night vision systems for long-range target recognition under low-level of illumination. These applications use image intensifier night vision systems for long-range target recognition under low-level of illumination. These applications use image intensifier night vision telescopes having certain desired magnifications. The front-end objectives used for such telescopes should have large focal lengths and high apertures generally in the range of 80mm to 140mm for meeting the range specifications for target recognition. Petzval type of configuration is typically used for realizing such large-aperture and low f-number objectives with high contrast at lower frequencies throughout the image field. Use of conventional glass elements in such systems often limits the off-axis performance. We demonstrate, in this paper, the potential of GRADIUM in improving the overall performance of a pair of conventional Petzval objectives used in night vision devices for long range observations.

Present paper considers a technique of diffraction element microminiaturization in the process of optical data recording onto photothermoplastic films (PTPFs) by using the photothermoplastic recording (PTPR) equipment adapted for outer space. It has been found that the application of surface- active substances (SAS) onto the free surface of PTPF facilitates the appearance and evolution of microdiffraction optical systems (whose period doesn't exceed 1 micrometers ) on the profile of basic diffraction elements (with a period <5 μm). Miniature dimensions of microdiffraction elements provide high resolution without loss in diffraction efficiency, as the dimensions, shape (depth) of a diffraction element actually depend not only on the thickness of the visualizing layer but also on SAS properties, namely on the dielectric and physical- chemical properties and, particularly, on the ability of SAS to influence onto the surface tension. The shift in the flow point of the visualizing layer material provides the increase both in the diffraction efficiency and resolution at the expense of discretization of the surface diffraction elements into 2,4,6,... microdiffraction elements.

Different wavefront description possibilities are today available to the optical designer, usually in the form of polynomial fitting (seidel, Zernike, monomials...). This kind of representations have the general drawback of being based merely in the geometrical shape of the wavefront considered, calculated as a distribution of optical path differences, without taking into account the energetic distribution present in the wavefront. As a consequence, optimization of optical systems is carried on based only on geometrical criterions, while applications tend to rely more on energetic properties of the wavefront (detection on CCD arrays or photodiodes, image formation, etc.). In this paper we are proposing a new type of wavefront descriptor which includes its energetic distribution. The description is based on classical ray tracing procedures, in such a way that in each surface normal to the axis of the optical system, information on the position (z,y) and the director cosines (w.v) of the ray are known, together with the energy flux assigned to each ray (F). This allows obtaining the energetic distribution in any plane in the optical system together with the classical wavefront description based in OPD calculations, allowing to obtain complementary wavefront information. This complementary wavefront description has been applied to some simple optical systems (a large diameter cemented achromatic doublet, and a Cookes' triplet) showing how even in these very simple case the differences in the energetic distribution and the geometrical shape at the exit pupil plane are relevant. Such a fact is demonstrated by least- squares fitting of the surfaces to a monomial representation, allowing the determination of the different primary aberration coefficients. Finally, differences in the geometrical PSF and the energetic distribution calculated are plotted, to show they may achieve maximum deviations of up to 11% of the PSF value for the doublet, and 25% for the triplet. In addition, the deviations may be seen not to be a mere scaling factor, but a distribution depending on the image plane position. The wavefront descriptor presented is aimed to provide energy-based lens optimizations, as part of a global project named ROSA (Real Optical System Analysis) under current development in the Center for the Development of Sensors, Instrumentation and Systems (CD6) in the Universitat Politecnica de Catalunya.

The numerical calculation of diffraction integrals in systems with aberrations is addressed from the point of view of a new geometrical interpretation of the diffraction phenomena. This interpretation is based on the division of the integration domain in semiperiodic zones that isolate the integrand oscillations. Moreover, the critical points of the aperture allow to identify the zones with a net contribution to the diffracted field. With the help of this interpretation it is possible to define methods for calculating the diffraction of a spherical wave incident on an aperture. We study the problems that arise when these methods have to be applied to waves in aberrated systems and we propose a solution based on the analysis of the behavior of the optical path of the wave incident on the exit pupil of the system.

Application Specific Integrated Filters (ASIFs), based on a unique holographic polymer dispersed liquid crystal (H-PDLC) material system offering high efficiency, fast switching and low power, are being developed for microdisplay based projection applications. A new photonics technology based H-PDLC materials combined with the ability to be electrically switched on and off offers a new approach to color sequential filtering of a white light source for microdisplay-based front and rear projection display applications. Switchable Bragg gratings created in the PDLC are fundamental building blocks. Combined with the well- defined spectral and angular characteristics of Bragg gratings, these selectable filters can provide a large color gamut and a dynamically adjustable white balance. These switchable Bragg gratings can be reflective or transmissive and in each case can be designed to operate in either additive or subtractive mode. The spectral characteristics of filters made from a stack of these Bragg gratings can be configured for a specific lamp spectrum to give high diffractive efficiency over the broad bandwidths required for an illumination system. When it is necessary to reduce the spectral bandwidth, it is possible to use the properties of reflection Bragg holograms to construct very narrow band high efficiency filters. The basic properties and key benefits of ASIFs in projection displays are reviewed.

In the latest ten years, great efforts have been taken to miniaturize the biochemical and chemical analysis systems, and many kinds of biochips with functions of biology sample preparing, chemical assay reacting and result detecting, or mixture of some of these functions have been reported. An aspherical micro lens array with large numerous aperture is developed for a biosensor to achieve high fluorescence collection and high sensitivity. The optimized design and fabrication with new organic-inorganic sol-gel materials of micro lens arrays are discussed in this paper. Because of merits of micro size, low cost, facility to reproduce, flexibility to design and multi-channels detection, these elements are suitable to form a compact, multi-channel fluorescence biosensor that can address multiple biology samples simultaneously without loss in detection sensitivity. Packaging and alignment strategies for a sensor consist of micro lens arrays detecting fluorescence labeled DNA assay arrays are also presented, which is promising to be integrated into a micro total analysis system (u-TAS).

Currently, the requirement of wide field view fluorescence observation is increasing in the biological field, but the existing microscopes have difficulty in imaging lower magnification fluorescence images. It is very easy to image in higher magnification with higher resolution and brightness using existing microscopes, but it is very difficult to image in lower magnifications that are also bright. We focused on two applications in which a macro lens would be useful. The first application is DNA array reading. The second application is In Vivo imaging. Both applications require wide observation areas and bright images which are needed to lower magnification and fluorescence capability. The macro lens needs to have high numerical aperture (N.A.) And low magnification. We also believe that if the macro lens can be attached to the existing microscopes, it will be quite useful to various applications because the scientists can then observe fluorescence images from low magnification to high magnification. To fulfill these needs, we designed macro objective lenses. Listed bellow are our macro lens' unique features. 1. Specification for the macro objective lenses are 2X, N.A. 0.14 and 4X, N.A. 0.28. These N.A. is higher than the existing microscope objective lenses of equal magnifications. 2. The 4X and 2X macro lens can be attached to existing microscopes. 3. These macro lenses can be used with the video lens such as 0.5X.

A modified ellipsometric optical system has been designed for an in-vitro medical diagnostic instrument using an off- the-shelf 525-nm LED source. System requirements included a 20 degree (+/- 1 deg) incident angle, 1 uW (min) assay surface incident power, 300 um (max) incident spot diameter (full spatial extent) and 500:1 (min) detector S/N in normal room light. The fixed polarization ellipsometric optical analysis method is discussed, and the lens prescription used in a prototype instrument is given. Zemas spot size analyses are given, as well as a theoretical model for S/N assessment. Incident spot size and optical power data are provided which agree with the theory presented. Finally, the application of results and typical scanned signal output are discussed.

A Digital Micromirror Device (DMD) consists of an array of e.g. 1024 x786 small micromirrors. Each of these mirrors has a size of 16 μm and can be individually switched to an angle of +10° or -10°. Depending on how these micromirror pixels are switched various reflected patterns or images can be projected digitally when the DMD is properly illuminated. Whereas classical applications for DMDs include digital image- and video-projection, further applications in the field of optical metrology are possible as well. Since the DMD can also act as a pinhole, a new type of optical surface- profiler resembling a confocal microscope but using the DMD for flexible illumination and lateral scanning of the specimen has currently been set up at the Fraunhofer IPT. There are various process-parameters that influence the measurement, among these are e.g. pinhole-size, pinhole- shape, lateral step-size and the number of pinholes used simultaneously. With the presented instrument these process-parameters can not only be easily configured for individual measurements by simply programming the DMD, but also adaptive control of these parameters during the measurement may be achieved. The paper explains basics of DMD technology and confocal microscopy, illustrates the principle of the newly designed instrument, discusses difficulties and shows first results achieved with a set-up demonstrator.

Several large telescopes are now being proposed that would benefit from the cost reduction due to the use of spherical primary mirror. However, structural cost constraints require compact formats that tend to impose very high speeds, e.g. f/1.5, which renders difficult the correction of the resulting very large spherical aberration. A technique is described here in which a spherical concentric Cassegrain-like primary-secondary combination is followed by a simple catadioptric focal modifier. The spherical primary is 9m diameter, f/1.5, and the final focus is f/5 with a sub-arcsecond resolution over a 5 arcminute angular field for a passband of 480-850nm. Primary- secondary separation is only 11m and central obscuration is only 11% of pupil area. The two relatively small corrector components provide the functions of concentric meniscus and zonal corrector plate and are made from the same single glass- BK7 is the example given, but silica or any other preferred glass is possible. The relatively small zonal corrector is the only aspheric surface in the entire system. A related system is described elsewhere in which a 30 arcminute angular field can be achieved with a similar resolution, but with more complex glass requirements. However, supply of such exotic glasses may be difficult in large diameters, and the system presented here may find a place in some specialized applications.

A simple closed form solution was derived for the optimum weight design of a cylindrical sandwich mirror for a given self-weight deflection and mirror radius. This optimum solution is based on the generalized deflection equation for an axisymmetrically supported thick circular plate. This two parameter equation of deflection captures the deflection of the plate caused by bending and transverse shear. The solution yields the optimum facesheet thickness, core thickness, and core density. The derived optimum solution was used in a case stud for the GLAS (Geoscience Laser Altimeter System) primary mirror. This Beryllium mirror is manufactured with an open back isogrid pattern. The objective of this study is to determine a lightweight mirror design using Aluminum sandwich construction that can meet the performances of the current mirror and reduce fabrication costs. With the optimum solution several first order approximations using Aluminum honeycomb or foam core were determined. The performance, 1 g deflection, and wave front error of these designs was determined from Finite Element Analysis. The results conclude that sandwich construction outperforms the isogrid design by significant margins on both weight and distortion if the same material is used. Because of its superior specific stiffness the Beryllium isogrid design still marginally outperforms the optimum Aluminum sandwich design. However, the Aluminum sandwich design should provide significant advantages on cost and ease of fabrication over Beryllium isogrid designs.

A segmented array of mirrors was designed for a solar concentrator test stand at MSFC for firing solar thermal propulsion engines. The 144 mirrors each have s spherical surface to approximate a parabolic concentrator when combined into the entire 17-foot diameter array. The mirror segments are aluminum hexagons that had the surface diamond turned and quartz coated. The array focuses sunlight reflected from a heliostat to a 4 inch diameter spot containing 8 kilowatts of power at the 15 foot focal point. The derivation of the surface figure for the respective mirror elements is shown. The alignment process of the array is discussed and test results of the system's performance are given.

The cost of astrographs with pupil diameters greater than 1 or 2 meters can be somewhat reduced if the primary mirror is made spherical and the aberration corrected at or near the prime focus, thus avoiding the classical Schmidt or Maksutov full pupil diameter refractive components. Such a corrector solution is presented here for large spherical primaries with speeds up to f/4. This is based on the KiwiStar principle presented here in 1997, in which a large spherical-concentric catoptric is combined by pupil transfer with a smaller spherical-concentric catadioptic to give well-corrected wide-field images of high speed and broad passband. The designs studied at the time were limited to those with entrance pupils <2m diameter, but it has been found possible to extend the aberration correction capability to pupils of larger diameter. The only significant constraint found in the present study is that the spherical aberration of primaries faster than f/4 is difficult to control. The design presented here is a 4m entrance-pupil-diameter, f/1.4 optic of 0.2 arcsec rms resolution over the whole of a 0.5° field (50mm diameter), for a bandpass of 486-850nm. To fully sample this field would require 10⁸ pixels of 5μm dimension. An extended design with an 8m diameter primary is also shown, that may be scalable to ~30m. To achieve this performance, the strictly concentric format of the original KiwiStar design has been relaxed, thus providing extra degrees of freedom to compensate the large pupil aberrations introduced by the spherical aberration of the primary. Nevertheless, the new design still has only one relatively small and weak aspheric surface to provide zonal correction, all other surfaces being spherical.

The productive and accurate ablation of microstructures demands the precise imaging of a mask pattern onto the substrate under work. The job can be done with high performance wide field lenses as a key component of ablation equipment. The image field has dimensions of 20 to 30 mm. Typical dimensions and accuracy of the microstructures are in the order of some microns. On the other hand, the working depth of focus (DOF) has to be in the order of some 10 microns to be successful on drilling through 20 to 50 μm substrates. All these features have to be reached under the conditions of high power laser UV light. Some design principles for such systems are applied, such as optimum number of elements, minimum tolerance sensitivity, material restrictions for the lens elements as well as mechanical parts (mounting), restrictions of possible power densities on lens surfaces (including ghosts), matched quality for the manufactures system. The special applications require appropriate performance criteria for theoretical calculation and measurements, which allow to conclude the performance of the application. The base is wave front calculation and measurement (using Shack- Hartmann sensor) in UV. Derived criteria are calculated and compared with application results.

New panoramic and immersive digital imaging developments have generated increased interest in high performance fisheye camera lenses suitable for 35 mm single lens reflex (SLR) cameras. Special concerns for such applications are the uniformity of illumination and radial image mapping. Because two hemispherical images are digitally stitched together to form a complete 360-degree x 180-degree image, the performance of the lens at the 90 degree (preferably more than 90 degree) edge of the fisheye image is just as important as the center of the image. Lateral color, high order distortion (edge compression) and severe drop-off of illumination at the full field become obvious image defects and cause seams in the immersive image. Fisheye lens designs have widely varying relative illumination and distortion across the hemispherical field of view of the lens. After describing the contributing factors to relative illumination, we survey a collection of fisheye designs and compare their illumination performance, radial mapping and lateral color. A new method of measuring relative illumination and radial mapping in the laboratory is described and results on commercially available fish-eye lenses are presented.

If intended to operate outside the Earth's atmosphere, the imaging optics demanded of a designer become critical. A typical specification would be diffraction-limited imaging over a usefully wide field angle with a broad spectral bandpass, high transmittance, no distortion and no vignetting. When combined with demands for a light and compact structure, such a specification calls for some trade-offs if a real system is to be devised. This paper describes an exceptionally compact imaging system in which the only significant trade-off is the 21% transmittance loss caused by the central obstruction of a Cassegrain-like optic. The entire 1° field angle is diffraction limited for all pupil diameters up to 1m (which would give 0.2 arcsec resolution), while providing a flat, distortionless, unvignetted, f/2.4 image, bandpass-limited only by the reflective coatings of the totally catoptric design. For fields less than 1 degree(s), scaling is possible to very large pupil diameters while maintaining full-field diffraction-limited imaging. By employing a single-axis, double-pass, four-reflection format, compactness is such that the overall length is less than the pupil diameter. The primary and tertiary mirror surfaces are formed from a single substrate. The primary, secondary and tertiary mirrors are hyperboloids of increasing eccentricity, and the quaternary is a weak aspheric zonal corrector. The geometry is such that stray light exclusion is simply achieved without occluding the optical path. The rearward propagating final beam provides significant useful free surrounding volume for cryostat structures, filters and shutters. A further example is given of a scalable f/1.25 version of the system.

A linear systems approach (multiplying MTFs or convolving PSFs) to performing a complete systems engineering analysis of image quality is described. This includes not only the traditional diffraction analysis and the evaluation of image degradation from residual design errors: but also includes image degradation due to scattering effects from residual optical fabrication errors, assembly and alignment errors, and all other potential error sources appearing in a detailed error budget tree. The effects of mosaic detector arrays upon systems performance and the optimum system design will also be discussed. This analysis allows optical fabrication tolerances to be determined during the design phase of a program, frequently resulting in substantial cost and schedule savings. Inaccuracies in the linear systems assumption will be presented for several different applications.

A new program for the tolerancing of optical designs is presented. This software was developed using a combination of theoretical understanding and practical experience. A comprehensive sensitivity analysis provides insight into the key parameters. Tolerance editors allow the user to define satisfactory tolerances in an interactive process involving parameter and defect variations; a key feature is the statistical prediction of system performance, which provides rapid feedback on the impact of any change. The production of a batch of optical systems under the current tolerances can be modeled in a Monte Carlo simulation; the resultant aberration variations are shown in multiple dynamic graphs.

Recently, telescopes with segmented primary mirrors are becoming increasingly popular due to their ability of achieving large apertures without the inconveniences caused by the fabrication and handling of monolithic surfaces with 8m (or over) in diameter. The difference in position of each pair of adjacent segments along the local normal of their interface (called piston hereafter), however, needs to be precisely measured in order to provide a diffraction- limited image. If a system yielding the nanometric accuracy required in piston measurements worked in daylight hours, the resultant saving in observation time would be an important advance on a majority of the state-of-the-art piston measurement systems. An interferometric piston measurement instrument accomplishing such objectives has been designed starting from the usual Michelson configuration at the CD6 (Terrassa, Spain), and its final test has been carried out in the test workbench of the Instituto de Astrofisica de Canarias (IAC, Canary Islands, Spain). Its optical layout relies on projecting the reference arm of the interferometer onto one of the segments of the pair considered, along the direction of the local normal to the surface while the measurement arm is projected onto the interface which divides the pair of segments considered. The field of view and its illumination are calculated to be equivalent in both segments. The lateral shift of the fringes in both interferograms determines the piston error present. A combination of monochromatic and white light is used, in order to remove the (lambda) /2 phase ambiguities present in piston measurements without losing the required resolution in the measurement. In this paper, the optical design of this interferometric piston measurement instrument will be presented. The particular configuration used in the interferometer, the implementation of an imaging system allowing to see both the interface of the segments and the interference fringes, the effect of the extension of the source and the use of both monochromatic and whit light will be discussed. A detailed study of the wavefront errors embedded in the wavefront at different stages of the interferometer is performed. The analysis shows the validity of the design of the instrument, and some experimental results obtained at the test workbench are provided to demonstrate the ability of the instrument to perform nanometric piston measurements under daylight conditions.

A time-of-flight (TOF) system based on a novel Photonic Mixer Device (PMD), which detects and demodulates light simultaneously, has demonstrated that it is feasible to realize a 3-D imaging system with compactness, low cost and sufficient resolution for many applications. Active illumination is used in the TOF imaging system. Because of the limited available light source with large bandwidth and in consideration of eye safety, LEDs or low power laser diodes are used as preferable light sources. The received light may be strongly damped in an order of 40- 50dB, depending on the surface characteristics of the objects. Therefore the optical transmissoin in the light transmission chain of light source-sender lens-object- reciever lens-(PMD) detector array need to be simulated and optimized in order to achieve better performance and maximal power transmission, by the design of such a 3-D camera. Based on the modeling of the light source (laser diodes and LEDs), lens system and statistical characteristics of objects one is able to simulate the light transmission and the light distribtion on the object and the PMD detector array. By the use of time-of-flight of the sensing light it is necessary to keep the phase uniformity of the illumination light, because every detector can possibly receive light from different light ways. This would result in a reduction of detection resolution. The optical-path-differences (OPD) representing the time differences from different paths have been simulated from the source to the related pixel for the designed transmitter lens and the receiver lens. Only one source is usually used by direct current modulation of laser diode or LED for uniform modulation phase. The simulatoin of the light distribution has given estimation of the light gathering efficiency of every pixel and of possible cross talk between adjacent pixels.

We propose a new method for synthesizing long period fiber gratings. The proposed method which employs the simulated annealing and steepest descent algorithms is capable of controlling the phase as well as the magnitude characteristics. To verify the validity of the proposed method, we have synthesized three simple structures; a single long period fiber gratings structure and two piecewise-uniform long period fiber gratings structures.

The Tropospheric Emission Spectrometer (TES) is one of the instruments slated to fly on the EOS Aura satellite in 2003. TES is a Fourier transform spectrometer designed to measure the concentration of various tropospheric chemical species. The Focal Plane Opto-Mechanical Assemblies (FPOMAs) are situated at the end of the TES optical train and are comprised of cryogenic telescopes, reimaging optics, and focal planes. We present the cryogenic optical design of the FPOMA units and discuss optimization parameters and predicted performance. We present measured performance data and compare it with the predicted performance.

The increasing use of the next generation focal plane array infrared detectors has resulted in a growth in the number and types of Thermoelectric Thermal Reference Sources (TTRS). These TTRSs provide a temperature controllable radiometrically uniform, high emissivity surface. When viewed by the system detectors, the TTRS allows the system electronics to perform gain and offset calibration as well as DC restoration. Until now little has been published to aid design engineers trying to incorporate TTRSs into infrared systems. This paper describes the optical, system, electrical, and mechanical parameters of TTRSs. It provides infrared system design engineers with an overview of the critical TTRS parameters as an aid during their design process. TTRSs for scanning and starring arrays are addressed as well as hermetically sealed versus unsealed units. Examples are provided of currently available TTRSs. A discussion of the advantages and disadvantages of hermetically sealed TTRSs as compared to unsealed units is included. The critical parameters of available TTRSs are also discussed.

We report on the development of a novel industrial process, embodied in a new robotic polishing machine, for automatically grinding an polishing aspheric optics. The machine is targeted at meeting the growing demand for inexpensive axially symmetric but aspherical lenses and mirrors for industry and science, non-axisymmetric and conformal optics of many kinds, the planarization of silicon wafers and associated devices, and for controlling form and texture in other artifacts including prosthetic joints. We describe both the physics and the implementation of the process. It is based on an innovative pressurized tool of variable effective size, spun to give high removal rate. The tool traverse and orientation are orchestrated in a unique (and patented) way to avoid completely the characteristic fast peripheral-velocity and center-zero left by conventional spinning tools. The pressurized tooling supports loose abrasive grinding and polishing, plus a new bound-abrasive grinding process, providing for a wide range of work from coarse profiling to fine polishing and figuring. Finally we discuss the critical control, data handling and software challenges in the implementation of the process, contrast the approach with alternative technologies, and present preliminary results of polishing trials.

This study deals with lapping process with loose abrasives in large diameter lens manufacturing. Loose abrasive lapping, is a three-body abrasive process in which a fixed load is applied to a plate that presses a slurry consisting of a coolant and abrasive particles onto the optical surface being manufactured. This process is analyzed by examination of the influence of optical glass material parameters on material removal and surface roughness for lens manufacturing conditions. The model established for this analysis uses the concept of lateral fracture, which is based on removal of optical glass material by rolling abrasive particles. The particles remove glass material by lateral cracking. The concept of lateral fracture by rolling abrasive particles is verified as the lapping model, which was found to give a good description of the experimental results. Removal rates and lapping time values at the conventional removal depth are found and which will allow the automation of lapping process for lens manufacturing. The abrasive mineral Barton Garnet was used in the lapping experiments.

A pair of special Fourier transforming objectives intended for use in a Holographic Memory Card (HMC) writing/reading equipment have been designed and fabricated. At writing in, the objective Fourier transform a binary pattern, representing the data displayed by an SLM, into the storage medium of the HMC, where the Fourier transform is recorded as a polarization hologram. At reading out, the objectives inverse Fourier transform the reconstructed hologram onto the surface of a CCD array. The Fourier space NA of the objectives is high enough to achieve a theoretical data density of 1 bit/μm². For comparison reasons we designed two optically identical objectives of basically different structures: one is an aspheric glass doublet, the other is an all-spherical five-element system (arranged in two lens groups). Computer analysis of the objectives shows that both systems are diffraction limited in object and Fourier space and have a distortion of less than 1%. In this paper we overview the theory of Fourier objectives, present our design method, describe the optical behavior of the designed systems, show our test results performed on the fabricated aspheric objective and present our experiences at manufacturing aspheric glass lens prototypes.

Eyepieces are a part of visual optical systems. Because of their wide field of view and long eye-relief, it is difficult to further improve the existing eyepieces using all-refractive surfaces. Since diffractive elements demonstrate unique characteristics: negative dispersion and non-field curvature, the eyepiece design can be improved by using refractive-diffractive hybrid surfaces. In this paper, several design examples using refractive-diffractive hybrid surfaces to design moderate field of view (FOV) eyepieces were studied. Firstly, a design example using a diffractive surface to replace the negative piece in the cement doublet of a conventional Kellner type eyepiece is presented. Then a design example is given by employing two diffractive elements to replace the negative elements used in the conventional symmetrical eyepiece. For the above examples the eyepiece aberration correction techniques were also analyzed.

In this paper, we present an optical design of a near- infrared (at FeI 15648.5A) birefringent filter system which is used to obtain the chromatic images of the sun and measure the solar magnetic field at the Big Bear Solar Observatory (BBSO). This system consists of a prefilter,a liquid crystal analyzer, a wavelength-tunable birefringent filter and a Fabry-Perot Etalon. This system is expected to achieve a clean narrow pass band (1/8A). It can also be tuned across the spectral line to obtain line profiles of two0dimensional fields of view. During the design of the tunable near-IR birefringent filter and the test of its components, we found the value of birefringence index μ(n_e-n_o) of calcite at spectral range near 15648.5A is very different from the value in literature. Because the birefringence index is important for the design of birefringent optical components, the birefringence index of calcite and its thermal coefficient are measured. Some test results of the four pairs of calcite plate used in the birefringent filter are presented.

Traditional Rowland-circle concave gratings suffer large aberrations especially in the case of flat-field receiving. With the development of vertical photolithography, the fabrication of gratings with arbitrary profile and groove distribution comes into practice. To overcome the restrictions existing in the traditional geometries, a general iterative design geometry based on the optical path function is developed in this paper. The structure of a grating is determined by two explicit of implied constraint equations containing the grating profile and the groove function. Constraints in some typical cases are studied. Finally some numerical examples of flat-field concave gratings for micro-spectrometer are shown by the proposed equations. The aberration of the device based on stigmatic points can be lower than λ/4.

Application of advanced composite material for lightweight mirror for space optics needs to know the exact thermal expansion behavior of the composite in space thermal environment. In this paper, thermal expansion behaviors of plasma thermal sprayed and powder metallurgy processed ceramic particulate reinforced aluminum metal-matrix composites in simulated space thermal environment were studied. Thermal cycling was found to cause hysteresis and non-linear thermal expansion responses to the composites when the thermal stress within the composite exceeds the yield strength of the matrix, and subsequently causes matrix plastic flow. High matrix yield strength is necessary for MMC to have linear, stable and repeatable thermal expansion response in severe space thermal environment. The study lays out a fundamental for choosing existed or developing a new MMC for lightweight mirror application.

After the experience of GIOTTO fly-by to comet Halley in 1986, the European Space Agency planned to improve the scientific knowledge of these astronomical objects by means of an even more ambitious rendezvous mission with another comet (P/Wirtanen). This mission, named ROSETTA, will go on from 2003 to 2013, ending after the comet perihelion phase and including also the fly-by with two asteroids of the main belt (140 Siwa and 4979 Otawara). Scientific priority of the mission is the in situ investigation of the cometary nucleus, with the aim of better understanding the formation and the composition of planetesimals and their evolution over the last 4.5 billions of years. In this context, the Authors were involved in the design of the baffling for the Wide Angle Camera (WAC) of the imaging system (OSIRIS) carried on board of the spacecraft. Scientific requirements for the WAC are : a large field of view (FOV) of 12° x 12° with a resolution of 100 (mu) rad per pixel, UV response, and a contrast ratio of 10^-4 in order to detect gaseous and dusty features close to the nucleus of the comet. TO achieve these performances, a fairly novel class of optical solutions employing off-axis sections of concentric mirrors was explored. Regarding baffling, the peculiar demand was the rejection of stray-light generated by the optics for sources within the FOV, since the optical entrance aperture is located at the level of the secondary mirror (instead of the primary as usual). This paper describes the baffle design and analyzes its performances, calculated by numerical simulation with ray tracing methods, at different angles of incidence of the light, for sources both outside and inside the field of view.

Interferometric Gravitational Wave Detectors, coming online lin late 2000, look for small space strains, leading to apparent motions of test masses of 10-19 m or less; isolation from other forces is crucial. They require a formidable vibration isolation level in a frequency range between few Hz and few kHz. The off-band residual motion must be kept below 10-12 m not to saturate the phase sensors. These exceptional requirements are met, in all degrees of freedom, with a chain of active and passive filters. The key isolation mechanism is the use of mechanical oscillators above their resonant frequencies, pendula horizontally, springs vertically. Very high quality pendular suspensions are needed at the mirror level to limit the thermal noise from fluctuations in the dissipation mechanisms. Off-band electromagnetic actuators on or near the mirror keep its magnitude of attenuation in the longitudinal direction. To provide the bulk of the attenuation, virtually all in the vertical direction, they are suspended from Seismic Noise Attenuation Systems. Attenuation filters, either active or passive, are chained, each providing 2 or 3 orders of magnitude of attenuation. Passive attenuation is obtained with springs and pendula. The vertical is the toughest direction to deal with because the oscillators also fight against gravity. The vertical attenuation requirements, although orthogonal to the beam direction, are only slightly less stringent than the vertical ones due to cross-couplings (Earth curvature is the source of one of them). High internal damping springs organized in hierarchical stacks are used in most early designs. More advanced designs increasingly rely on chains of filters equipped with high quality cantilever springs driven to low resonant frequencies by different mechanisms. The Quality Factors of each resonance are actively and/or passively spoiled at the chain suspension point. IN the latest designs, Ultra Low Frequency Oscillators filter out the microseismic and other low frequency perturbations. This paper addresses one approach to achieving the required seismic isolation level.