Optical tools response to internal vibration that can be excited by the external acoustic environment. The degree to which this occurs depends on many factors, but primarily the correspondence between the resonance characteristics of the tool and the frequency content of the acoustic environment in which it operates. Adverse noise environments, such as those often found in operating laboratories and microelectronics fabrication facilities, can affect the threshold of resolution achievable by the tool. This paper reviews the state of noise specification for optical tools, and the noise levels in typical spaces in which these are intended to operate. Manufacturer's noise specifications often overstates or understates the sensitivity of their tool when the noise sensitivity criterion in oversimplified. More precise and detailed criteria would be useful, for example, in the design of laboratories, or troubleshooting tool operational problems.

Historically, clean room acoustical performance has been specified in the 65 dBA or NC-60 range. As line width geometries continue to shrink and metrology tools are introduced into the clean room at an increasing rate, some consideration on what constitutes appropriate and achievable clean room acoustical performance is long overdue. This paper addresses acoustical performance limitations for clean rooms under various air recirculation systems. The issue of what constitutes practical acoustical limits is also discussed. These limitations are put into the context of manufacturer specifications for metrology tools while addressing resulting consequences.

The vibration criterion (VC) curves, commonly used in the design of facilities which house vibration-sensitive instruments and tools, were developed by the author and his colleagues, in the early 80's, published by SPIE in 1991 and by IEST in 1993. Each of the criterion curves A through E is associated with a 'line width' or 'detail size' which was an attempt by the authors to describe the capabilities of the tools with which each curve might be associated. In the years since the curves were developed there have been substantial developments in tool design and isolation. In this paper the curves are reviewed in the context of present-day tools and processes. Changes are proposed where these might be justified.

Some considerations about vibrations affecting optical telescopes tracking performance are here reported. They are based on experiences done in some very different case studies. Generally speaking the term noise comprises vibrations induced by the telescope to the pillar and vice versa. In some cases undesired mechanical connections between the telescope and the enclosure can produce the same effects namely a deprezation of the telescope tracking performance. Due to the always-different telescope/enclosure design the solution adopted to resolve vibration problems can also be substantially different.

The paper discusses two primary areas of interest in a structural evaluation. First, in situ measurements are used to confirm the predicted structural stiffness and resonance frequencies. Second, the evaluation characterizes the manner in which vibrations are propagated through the structure. Methodologies are presented for carrying out these measurements, and typical data are given.

This paper describes a case study of a mezzanine floor whose footfall-induced vibrations resulted in complaints from the building owner even before the space was occupied. The complaints were focused on a 'beating' characteristic that was sensed intermittently for several seconds after a person ceased walking.

Vibration analyses of advanced technology facilities typically must consider frequency as well as amplitude of vibration. A soil propagation model is proposed which will allow the use of site-specific, measurable, frequency dependent attenuation characteristics. A method is given which allows in-situ determination of those frequency- dependent properties. This approach is applied to the estimation of setback distances for various items of construction equipment at a particular site.

A generic vibratory-response modeling program has been developed as a tool for designing high-precision optical positioning systems. Based on multibody dynamics theory, the system is modeled as rigid-body structures connected by linear elastic elements, such as complex actuators and bearings. The full dynamic properties of each element are determined experimentally or theoretically, then integrated into the program as inertial and stiffness matrices. Utilizing this program, the theoretical and experimental verification of the vibratory behavior of a double- multiplier monochromator support and positioning system is presented. Results of parametric design studies that investigate the influence of support floor dynamics and highlight important design issues are also presented. Overall, good matches between theory and experiment demonstrate the effectiveness of the program as a dynamic modeling tool.

Negative-Stiffness-Mechanism (NSM) vibration isolation system offer a unique passive approach for achieving low vibration environments and isolation against sub-Hertz vibrations. 'Snap-through' or 'over-center' NSM devices are used to reduce the stiffness of elastic suspensions and create compact six-degree-of-freedom systems with low natural frequencies.

Recently a great deal of effort has been made to increase the data access speed and the data storage density of the optical memory disks such as CD-ROM, DVD, ASMO disk, etc. In the viewpoint of increasing the data access speed of the optical disk, it is of great importance to characterize accurately the vibration phenomena of the rotating disk, which is related to the critical speed and the characteristics of the frequency response. In this paper, we suggest a novel method to improve vibration characteristics of disk without deteriorating optical characteristics. The main idea is that the initial stress in the radial direction is to be imposed within the optical disk on purpose. By the synergy effect from the residual stress frozen in the disk combing the stress induced by the centrifugal force, the stiffness of the disk increases to have stronger resistance to disturbance, resulting in increasing critical speed. In order to enhance the synergy effect, parametric modifications related to the disk design and manufacturing were presented and evaluated. Based on the computer simulation and experiments, we verified the suggested ideas that it clearly improves the vibration characteristics of disk.

Vibrations that occur within buildings that effect vibration sensitive equipment are of periodic, random or transient nature. The common way to describe a vibration is to transform its information into the frequency domain and show a graph as a function of frequency. The fundamental problem is that there is no obvious way to scale the y-axis in such a graph so that vibrations of the three classes may be compared. A working group within ISO is now presenting a Technical Specification, ISO TS 10811, 'Vibration and shock in buildings with sensitive equipment'. We introduce a new concept to handle all vibration types with only one method. The vibration under investigation is set to excite a single degree of freedom mechanical system with a certain resonance frequency. A sine wave with this frequency is exciting another identical single degree of freedom system. The amplitude of the sine wave is then varied, until both system gets the same maximum response. The vibration under investigation is then characterized for this frequency by the equivalent sine amplitude, given as peak velocity, to be compatible with other methods. The response equivalent peak velocity as a function of frequency, characterizes the vibration.

A loudspeaker at certain frequencies, producing vibrating sound wave causes periodic pressure variations in air. This pressure variation can be displayed in the form of a corresponding variations in the refractive index of air. The induced variation of the refractive index of air lead to a deflection of light rays traveling through the disturbed area of air by the vibrating sound waves. Speckle photography technique has been sued in this work to measure the light deflection along a certain cross-section of the integrated sound fields. The deflection angle of light rays can be measured as a speckle shift in the image plane leads to the formation of interference fringes similar to Young's fringes pattern. In the present work, a fringe pattern displaying the speckle shift due to the refractive index variation has been obtained using the electronic speckle pattern shearing interferometry. This fringe pattern in a measure of the speckle displacement due to light deflection caused by a vibrating sound source making a periodic pressure and refractive index variations of air.

In this technique the speckle shear interferometer is combined with the electronic speckle pattern interferometry technique. Two pinholes of the same diameter 'a', separated by a distance 'd' is used to image through object through an imaging lens. The formed speckle pattern which is the resultant of mutual interference between the two speckle patterns formed by each pinhole, is modulated by a grid structure inside it. This pattern is imaged by a CCD camera combined with a reference beam through a beam splitter. The object under investigation is now photographed in its first state, without any deformation, and this signal is allowed to be stored in the computer as a data file. During the object vibration or deformation, a second signal is to be sorted on the same data filet. A fast Fourier transform has been used to add such tow signals and after processing the two overlapped signals data one can obtain the deformation suffered by the object in the form of interference fringes displaying such deformation.

Composites offer major improvements in key properties over monolithic materials, including high stiffness, strength and thermal conductivity and low density and coefficient of thermal expansion. They are now baseline in a large and increasing number of dimensionally stable structures, optomechanical systems components and in electronic packaging and thermal management. They also are under development in a number of data storage component, including disks and actuators. In this paper, we present an overview of key materials, including polymer matrix composites, metal matrix composites and carbon/carbon composites.

Carbon-carbon composite materials offer greater thermal efficiency, stiffness to weight ratio, tailorability, and dimensional stability than aluminum. These lightweight thermal materials could significantly reduce the overall cost associated with satellite thermal control and weight. However, the high cost and long lead-time for carbon-carbon manufacture have limited their widespread usage. Consequently, an informal partnership between government and industrial personnel called the Carbon-Carbon spacecraft Radiator Partnership (CSRP) was created to foster carbon- carbon composite use for thermally and structurally demanding space radiator applications. The first CSRP flight opportunity is on the New Millennium Program Earth Orbiter-1 (EO-1) spacecraft, scheduled for launch in late 1999. For EO-1, the CSRP designed and fabricated a Carbon-Carbon Radiator with carbon-carbon facesheets and aluminum honeycomb core, which will also serve as a structural shear panel.

Ultrasonic waves are useful for arranging small particles in liquid, since the acoustic pressure exerts a sufficient trapping force on the particles. A composite material with layered structure can be fabricated by solidifying a particle suspension during the process of ultrasonic standing wave excitation. Fabrication of a 2D or 3D lattice structure is also possible by simultaneous excitation of two or three orthogonal ultrasonic standing waves. A polysiloxane resin is appropriate as a host material of such composite materials, since it is easily synthesized from a solution and its yields a small-periodicity structure due to its low sound velocity. Acrylic spheres, glass rods, and metal particles have been successfully arranged in polysiloxane resin forming layers or lattice structures. The spacing of particles was approximately 60 micrometers , which was half of the ultrasonic wavelength used. For heavy particles, a sample cell was continually rotated during the solidification process in order to prevent sedimentation.

The main interest of this paper is to design and analyze the performance of an optically activated optical switching between a single-mode optical fiber and a slab waveguide of a photoactive material. A mathematical model is developed for this structure. The paper includes a report on the trials which have been performed in order to fit a switching material in terms of its refractive index, slightly greater than that of the fiber core and provides the required change in the refractive index. A comparison between the predictions of the developed mathematical model and the experimental measurements is introduced. It has been shown that the switching of light between fiber and slab depends on the relationship between the refractive index values of the fiber core and the slab and the geometry of the switch. Design parameters are determined from these results.

The Microwave Limb Sounder (MLS) is a limb-sounding radiometer sensing emissions in the millimeter and sub- millimeter range. MLS will contribute to an understanding of atmospheric chemistry by assessing stratospheric and tropospheric ozone depletion, climate forcings and volcanic effects. The heart of the antenna is the primary reflector, constructed from graphite/cyanate composites in a facesheet/core construction. The reflector has an aperture of one square meter, a mass of 8.7 kilos and final figure accuracy of 4.37 microns rms. The surface is also modified to ensure RF reflectivity, prevent solar concentration and provide thermal balance to the spacecraft. The surface is prepared by precision bead-blasting, then coated with vapor deposited aluminum and finally a layer of silicon suboxide to control the IR emissivity. The resulting surface has a solar absorptance of 0.43 and an absorptance/emittance ratio of 1.3. BRDF analysis shows that 93 percent of the incident thermal energy is reflected outside a 10 degree angle of cone. For its mass and aperture, we believe this reflector to have the highest figure accuracy yet achieved in a composite antenna construction.

The semiconductor industry utilizes complex patterning tools to achieve the patterning of fine features. These tools require stiff, lightweight, dimensionally stable components in order to reliably pattern photomasks and wafers. Traditionally, these tools have used metals, ceramics, and low expansion glasses. However, a new class of materials, high performance composites, have demonstrated promise for replacing these materials. This paper discusses the design, manufacturing, and test of a carbon fiber composite stage component of an electron beam lithography tool.

Optomechanical sensitivity is the amount of image quality degradation in response to a certain deviation of any primary parameter of an optomechanical system. The sensitivity depends not only on the optical system but also on the mechanical layout. A technique for calculation of optomechanical sensitivity is presented. Only mechanical parameters are used as primary parameters. It is shown that airspaces or element tilts and decentrations cannot be used as primary parameters. The tolerances of an optomechanical system can be determined based on the computed sensitivity. Edge Function is used to evaluate the image quality for projection lenses. Software for realization of this technique has been developed. Examples of optimization of the optomechanical system of a projection lens using the developed technique are presented.

This presentation will include examples of folded optical designs developed using solid modeler tools from conceptual optical design through detailed implementation. A methodology allows control of critical solid models of the optical elements and complex housings. Specific examples will show how a prescription sheet controls all lenses, mirrors, and housings through parametric relationships. Establishing parametric controls allows the possibility of quick and certain implementation of prescription changes.

The process for designing optomechanical devices usually involves independent design optimization within each discipline. For instance, an optics engineer would optimize the optics of the device for image quality using Computer Aided Engineering (CAE) tools such as CODE V and OSLO. The structural engineer would then optimize the design to minimize deformation using CAE tools such as SDRC I-DEAS and MSC/NASTRAN. That is, the optics and structure are typically optimized independent of each other. In this paper, two additional methods for optimizing optomechanical devices are investigated. One method involves sequential design optimization. The other method involves the simultaneous design optimization of both the optics and structure of an optomechanical device. Two example problems are used to ex;lore the types of problems that each method is most suitable for. The first example involves an optomechanical device under thermal and gravity load, while the second example involves two thin lenses resting on a cantilevered beam.

Optimum structural design techniques have been used in the design of lightweight mirror and optical system for the past few years. Their application has been limited to the use of standard structural response as design criteria. This paper addresses the use of optical performance measures as design criteria within the optimum structural design loop. These optical measures could be any Zernike coefficient, the residual RMS or the peak-to-valley after any Zernike term has been removed.

Rugged coatings, originally developed for thermographic purposes in the 8-14 (mu) IR band, have been found to be useful as stray-light suppressants in optical instrumentation. Data on the hemispherical diffuse and goniophotometric reflectances of one formulation of this coating are presented. Diffuse reflectance in the 8-14(mu) wavelength region is below 5 percent, and even lower at 3 (mu) . Normal incidence specular reflectance is below 1 percent in the IR, and increases with angle in accordance with theory for physically rough surfaces. The coatings are moderately electrically conducting. They adhere readily to aluminum, silicon, glass, and other substrates; can be handled routinely with no loss of optical properties; have survived 500 degrees F temperatures at Mach 14; and may be modified to give high absorptivity also in the visible region.

The Multi-Angle Imaging Spectro-Radiometer is a push-broom instrument using nine cameras to collect data at nine different angles through the atmosphere. The science goals are to monitor global atmospheric particulates, cloud movements, and vegetative changes. The camera optomechanical requirements were: to operate within specification over a temperature range of 0C to 10C; to survive a temperature range of -40 degrees C to 80 degrees C; to survive launch loads and on-orbit radiation; to be non-contaminating both to itself and to other instruments; and to remain aligned through the mission. Each camera has its own lens, detector, and thermal control. The lenses are refractive; thus passive thermal focus compensation and maintaining lens positioning and centering were dominant issues. Because of the number of cameras, modularity was stressed in the design.

Recently, two 12.5 inch diameter aperture Small Transportable ISTEF Pedestal System telescopes were designed using all-reflective optics to provide four optical bands, ranging from 0.3 microns to 15.0 microns, on a single instrument mount. The system, located at the Innovative Science and Technology Experimentation Facility, Kennedy Space Center, Florida, represents a simple, modular approach to multi-wavelength, multi-focal length instrumentation for he range. Easily transportable by air, land and sea, the system can be quickly installed in a temporary and primitive field site. The modular approach allows flexibility in planning for rocket launches at the Cape and for to the technical data collection activities worldwide. This paper describes the individual steps which were taken to design, fabricate and assemble two compete telescopes, six months and within budget. The methodology employed serves as a highly cost-effective and efficient model for future optical range instrumentation.

A kinematic, fully adjustable, six degree-of-freedom mirror mount has been developed for a space-based optical system. The optics vary in size from five inches to 10-inches and weigh up to 1.75 Kg. Many of the optics require multiple degrees-of-freedom for alignment and all elements need to be held to micron tolerances during orbit. The mount design described herein provides three-axis linear motions of at least three millimeters and multiple degrees of tilt. Each mount weighs approximately the same as its optic and exhibits gravity deflections less than .0002 radian. Natural frequencies for even the largest mirror mounts in the system are greater than 100 Hz. A unique feature of the mount design is the ability to easily adjust the mirror from behind without the need for complex jigs or tooling. The mirror mount is entirely self contained and is mechanically locked after final adjustments are made. A motion algorithm based on hexapod simulator control laws has been adopted to calculate the leg adjustments required to perform the mirror motions of tip, tilt, yaw, focus, and the two lateral shifts.

A grazing incidence x-ray interferometer design capable of micro-arcsecond level resolution is discussed. This practical design employs a Michelson Stellar interferometer approach to create x-ray interference fringes without the use of Wolter style optics or diffraction crystals. Design solutions accommodating alignment, vibration, and thermal constraints are reviewed. We present the development and demonstration of a working experiment along with tolerance studies, data analysis, and results.

The IASI instrument is a fourier-transform spectrometer (FTS) providing spectra of the Earth's atmosphere observed from space. The heart of the instrument is a Michelson interferometer (IHOS) equipped with hollow cube-corners retro-reflectors in place of the classical flat mirrors. One of the most critical components of the IHOS is its IR beamsplitter dividing and recombining the incident rays in order to create the interferograms. The beamsplitter chromatisms must not exceed a quarter-wave, while the required transmission efficiency should ideally be higher than 0.35 over the whole. Instrument spectral domain, with a particular emphasis on the radiometric performance between 14 and 15.5 micrometers due to mission constraints. Practically, it would dictate the choice of the Potassium Bromide material for the plates substrate, however this material presents severe moisture and mechanical constraints. This is the reason why we have looked for an alternative solution based on the use of thin ZnSe plates. Theoretical analyses and numerical examples of the beamsplitter radiometric and chromatic performance confirm that this design is feasible for two different geometrical configurations: a classical beamsplitter with grouped parallel plates, and a rather unusual design including a remote compensating plate which will be set perpendicular to the transmitted optical beam.

This study presents the athermalization of a forward looking IR system which is one of the tasks of a optomechanical engineer. 3D modeling and optical design of a forward looking IR system are done. Thermal and structural analyses are performed by using the finite element method. Initial conditions and obtained results are verified by a laboratory study. The system parameters are optimized for ensuring the system to perform at different environmental temperatures by determining temperature distributions, expansions and contractions.

The weight and line of sight (LOS) stability are very critical in telescopes used for remote sensing and imaging in the presence of high dynamic loads and vibrations. A high stiffness and low-density material such as beryllium is ideally suited for such applications in spite of its high cost. This paper presents the design of an all-beryllium off-axis telescope in which the three diamond-machined mirrors are pinned and bolted to an extremely lightweight and stiff support structure. A number of design and fabrication techniques were employed to minimize the cost of material and fabrication. The importance of machining tolerances for optimizing the cost and yield of mirrors is also described.

In the next few years a new chip-generation with structure sizes well below 100 nm and high complexity will require novel, so-called 'future lithography' processes. One of these new technologies is the Ion Projection Lithography. Within the framework of a large European project lead by SIEMENS, the necessary technologies are developed and the first pilot system will be built. In this system, one of the most important units is a high precision wafer stage. The heart of the stage system is the so-called metrology - plate with integrated electrostatic wafer chuck and handling unit. The design of this novel stage system is described in this contribution. Extensive FEM-simulations from the basis of the present design. All major components are made from glass-ceramics to guarantee the highest possible thermal and mechanical stability. Not only in the field of lithography many modern precision mechanical systems require position tolerances in the sub-micrometer and seconds of arc range. Strong systems solutions can be developed by the effort of glass-ceramics and new and traditional manufacturing processes.

Alson E. Hatheway Inc. in conjunction with the Schaeffer Magnetics Division of Moog Inc. has developed a dual-stage high precision structural actuator for use in precision spacecraft structures. The actuator is designed to operate equally well anywhere in the range from 20 degrees K to 300 degrees K. A test program has just been completed to evalute the performance of the actuator at the limits of the temperature range and this paper describes the test facilities, the test and the results. The actuator demonstrated a full stroke in excess of 10 millimeters and a resolution of 7.2 nanometers. The performance at cryogenic and room temperature appear to be the same.

The Echellete Spectrograph and Imager (ESI), currently being completed for use at the cassegrain focus of the Keck II telescope, employs two moderate size translating fold mirrors. These mirrors are used to shift between the three instrument modes; medium resolution echellete mode; low resolution prismatic mode; and imaging mode. In order to maintain the optical stability and calibration of these three modes the mirrors must be removed and repeatably located to within 1.3 arcsecs of tip and tilt. In addition, the mirrors must maintain a fixed orientation relative to the telescope axis under a variety of gravity and thermal loads. In this paper we describe a novel concept for moving and locating these mirrors. Analytical analysis of the mounts is presented. Optical and mechanical testing is described.

The TNG is an Italian 3.6 m Alt-Az telescope installed in La Palma, Canary Island. The drive and control system of the main axes is working since October, 1997. It has been used for some months to support the installation of optics and other mechanical subsystems. Since June, 1998 the control system is integrate in the overall TNG informatic environment. In 1998 TNG has seen its first light. After the installation of the rotator drive system and of the Nasmyth 'A' focus instrumentation, the TNG telescope project is in advanced optimization phase. This paper reports the recent updates in TNG axes motion control and the last most significant results.

The TNG is an Italian 3.6 m Alt-Az telescope installed at La Palma international astronomical Observatory Roque de Los Muchachos. It is equipped with two Nasmyth foci where the instrumentation is permanently installed. The first one is devoted to imaging and to support adaptive optics equipment and the other is devoted to spectroscopy. At each of the two foci the rotation of the field implied by the Alt-Az mount of the telescope needs to be compensated by the movement of one of the two rotator axes. The drive and control system and the solutions adopted for the motion control are here briefly described.

The University of Denver is now completing construction of a mid-infrared imaging polarimeter dubbed TNTCAM Mark II. The instrument will be the only one of its kind capable of attaining polarimetric accuracy of 0.2 % across the 5 -- 25 micron spectral interval. This sensitivity is only attainable by cooling the transmissive polarizing optics to liquid helium (LHe) temperatures. A major technical challenge in the design of this instrument has been finding a way to modulate the polarization signature of the incoming beam at a rate sufficient to combat the degrading effects of the atmosphere. Our group has chosen to quickly rotate a half-waveplate situated on the cold (i.e. 4 degrees Kelvin) work-surface. The waveplate is rotated between two fixed positions separated by 45 degrees at a rate of 1 Hz to obtain one of the two Stoke's parameters required to measure linear polarization. The waveplate is then offset by 22.5 degrees and then rotated again at 1 Hz between two positions separated by 45 degrees to obtain the other Stoke's parameter. In addition to rotating the waveplate, the waveplate itself must be moved out of the beam during normal imaging applications. The camera can contribute to the understanding of YSOs and evolved stars, obtaining high resolution mid-IR observations of dusty environments immediately surrounding these objects. In imaging mode mosaics of extended objects can be made in 2'x2' sub-fields. In polarimetry mode, B-fields in YSOs can be probed by dust emission from hot cores, incidentally constraining grain alignment scenarios in young stellar environments. In this paper we present the design and the results of our moving optical componenets susbsytem. Five cryo-stepper motors drive these mechanisms. This instrument is being developed under NSF grant AST-9724506 and is slated for community access in January 2000.

Precise optical stability requirements for a military laser required the establishment of detailed error and tolerance budgets of the mechanical system. In order to verify these budgets and also to fully understand the true dynamic stability of the mechanical mounts, extensive thermal testing was performed. This paper present a test technique established to provide a consistent testing process from which results could be used with confidence. Utilizing a readily available optical measurement device and impose test fixtures, this technique provides the designer with a powerful evaluation tool to verify design performance. Various types of result can be obtained using this technique, such as: optical element distortion at temperature, unrecoverable static shifting to the mount, dynamic movement effects and repeatability. These results can be further extrapolated into qualitative assessments of the thermal stability of specific mount design technique. When compiled into a design database, this will provide invaluable information for future design choices.

The objective of ground based microdynamic testing of deployable space structures is to determine and develop a better understanding of the submicron dynamics that exists between moving contact surfaces. Such measurements often use laser and video metric metrology systems. These measurement however, are corrupted by random environmental perturbations of the metrology optics. This paper represents a statistical method for obtaining the margin of perturbations on the optics. The optics used are those for one of the preliminary flight configurations for the Micron Accuracy Deployment Experiments Space Station laboratory. The approach and method used to determine the extent of the effect of the random environmental perturbations on the measurements is explained and results are obtained. The results indicate that for 100 nanometer total allowable error. The optics need to be stable to within 85 nm of displacement and 10 mArcSec of rotation.

The principle of beam-splitter-multi-chip cameras consists in splitting an image into differential multiple images of different spectral ranges and in distributing these onto separate black and white CCD-sensors. The resulting electrical signals from the chips are recombined to produce a high quality color picture on the monitor. Because this principle guarantees higher resolution and sensitivity in comparison to conventional single-chip camera heads, the greater effort is acceptable. Furthermore, multi-chip cameras obtain the compete spectral information for each individual object point while single-chip system must rely on interpolation. In a joint project, Fraunhofer IOF and STRACON GmbH and in future COBRA electronic GmbH develop methods for designing the optics and dichroitic mirror system of such prism color beam splitter devices. Additionally, techniques and equipment for the alignment and assembly of color beam splitter-multi-CCD-devices on the basis of gluing with UV-curable adhesives have been developed, too.

The Echellette Spectrograph and Imager (ESI), currently being delivered for use at the Cassegrain focus of the Keck II telescope employs an all-spherical, 308 mm focal length f/1.07 Epps camera. The camera consists of 10 lens elements in 5 groups: an oil-coupled doublet; a singlet, an oil- coupled triplet; a grease-coupled triplet; and a field flattener, which also serves as the vacuum-dewar window. A sensitivity analysis suggested that mechanical manufacturing tolerances of order +/- 25 microns were appropriate. In this paper we discuss the sensitivity analysis, the assembly and the testing of this camera.

Complex optical systems are aligned using modular optical alignment by aligning the individual optical components with datum surfaces on precision machined structural modules. This alignment technique exploits the inherent precision of modern manufacturing methods in order to simply the optical alignment problem. By distributing the mass of the system in three dimensions the structural efficiency of a modular optical support structure is improved in comparison with a conventional optical bench. Disadvantages of modular optical alignment include the cost of producing the individual components within the modules, and the nature of the joints between the modules are important in determining the overall success of a modular optical system.

Elemental silicon is a lightweight material that shows great promise for optical applications. Specifically, open-cell silicon foam can be used as a core material for ultralightweight mirrors by bonding single-crystal silicon faceplates to the foam. Not only does silicon have a low density, but it also has a low thermal expansion coefficient and a high thermal conductivity. Further, because of its widespread use in the semiconductor industry, it is an extremely well-characterized material. The fabrication of silicon foam begins with open-cell polyurethane foam, which is available in a wide variety of cell sizes ranging from 3 to 100 pores per linear inch. After chemical conversion to a glassy carbon foam, the individual ligaments are coated with silicon by chemical vapor deposition/infiltration (CVD/CVI), and the carbon cores are removed by oxidation. The end result is an open-cell foam composed exclusively of silicon. CVD/CVI is a very versatile process because it allows the amount of silicon in the foam to be varied. As the relative density of the foam increase, so does its strength and stiffness. Consequently, the mechanical properties of the foam can be tailored to meet the needs of a given application. For example, for space-based applications where light weight is critical, lower density foams can be used. For terrestrial applications requiring high stiffness, higher density foams can be used. In all cases, the relative density of the foam is a parameter that can be optimized to meet the needs of a particular application.

This paper describes a mathematical model, called the Bridging model, for predicting the smoothing of high spatial frequency surface errors in optical surfaces during polishing processes, which use large flexible polishing laps. The mathematical model is developed in two stages. First, the Kirchoff flat plate equation, which is modified to include the effect of shear flexibility of the lap and compressive stiffness of the pitch, is solved for lap pressure distribution over a surface error feature represented by a sinusoidal spectrum. This pressure distribution is used as an input to the Preston's equation for material removal rate. The resulting equation is then solved for material removal and surface error smoothing predictions. Available data from a laboratory test and a real optics fabrication program are compared with analytical predictions of the mathematical model. Good correlation is obtained between the two.

This paper describes the design, fabrication and cryogenic testing of lightweight silicon mirrors. Silicon offers significant advantages over other optical substrate materials. It has superior thermal properties at cryogenic temperatures, is quickly and inexpensively super-polishable, and is comparably lightweight to other substrates such as beryllium, silicon carbide, graphite epoxy and carbon. both bonded single crystal silicon (SCSi) and lightweight composite mirrors have been produced. The bonded mirrors were fabricated from two SCSi half disks joined using a proprietary process to form a slightly oblong three-inch diameter mirror. The nominally three-inch diameter composite mirrors consists of a silicon foam core, with SCSi faceplates bonded to the front and back surfaces. All optics were tested at the JPL's Cryogenic Test Facility. They were mounted in a custom and proprietary OFHC copper test fixture designed to prevent figure loss over the range of test temperature, and provide excellent thermal contact with the cryogenic chamber's cold plate. Results so far indicate that the bonded mirrors maintain their ambient figure at temperatures down to -183 degrees C.

In the performance of tasks of the high-resolving optical system manufacturing, the significant funds are required. This fact can be a reason limiting further development of astronomical research. The aim of this paper is demonstrated of the ways to reduce the fabrication cost of astronomical instrument mirrors.

The large technical-scientific achievements made to date in the field of astronomy, space and laser technology have been feasible to a great extent due to forthcoming of the new high-precision otpical ground and space-based system. In this connection, the requirements to the quality of optical surface have enhanced; a range of their overall dimensions has increased; components with off-axial aspherical surfaces, and with an arbitrary shape of outer perimeter of the components and their holes have been used often. Alongside the traditional materials used in the optical manufacture, non-traditional materials find ever-growing use.

The DEIMOS Spectrograph Camera contains tow doublets and a triplet. Each group contains materials differing in thermal coefficient expansion, mechanical and optical properties. To mate the elements and at the same time accommodate large camera temperature changes, we will fill the space between with an optical fluid couplant. We selected candidate couplants, lens-support materials, and fluid-constraining materials based on published optical, mechanical and chemical properties. We then tested the chemical reactivity between the coupling fluids, lens-support and fluid- constraining materials. We describe here the test configurations, our criteria for reactivity, and the result for various test durations. We describe our conclusions and final choices for couplant and materials.

DEIMOS is a large multi-object spectrograph with an imaging mode that is being built for the W. M. Keck 2 Telescope. The detector is a 2 X 4 mosaic of eight 2048 X 4096 pixel CCDs. The mosaic assembly process must position the CCDs to be planar to within 5 microns rms. We describes the CCD support design and the measurements used to achieve this.

DEIMOS is a large multi-object spectrography with an imaging mode that is being built for the W. M. Keck 2 Telescope. The camera contains nine lens elements in five groups. The overall length of the camera and detector assembly is 0.67 meters, and the largest element is 0.33 meters in diameter. Typical centration and spacing tolerances are at the level of 25 microns. We describe the error budget, the design of the lens-supporting structure, and the assembly procedures.

Historically lenses and windows on many military production programs, are potted, often with less than theoretical athermal potting gaps. Actual gaps may vary by factors of 2 to 4 less than ideal for athermal potting. Yet these military systems have passed rigorous qualification tests and seem to work adequately. Are problems lurking in the extremes of cold or hot for which MTF measurements are not typically done. Are typical stress levels high enough to impact optical performance. This paper will address these issues.

Using the technique of capacitance micrometry it is possible to measure very small displacements. Here, a microcomputer- controlled scanning Fabry-Perot interferometer is presented. In each scanning step, the parallelism of Fabry-Perot interferometer is monitored and adjusted in real-time with the aid of three capacitance micrometers - it is the feature of this system, where the readjustment and scanning are realized with three electrostrictive actuators, and the parallelism and the spacing of the mirrors are controlled by three capacitance micrometers. The light information from the interferometer is detected by a photo-detector. All of these are controlled by a microcomputer in order to realize the scanning and real-time control of Fabry-Perot interferometer. This system removes the problem of the nonlinear response and hysteresis associated with electrostrictive actuators and allows precise control of both parallelism and spacing of the mirrors.

Experimental strain gage techniques are developed for measuring thermal distortion to one-microstrain repeatability over moderate temperature variations from room temperature. A comparison of strain gage considerations such as foil alloy, gage resistance, bonding adhesives, leadwires, curing, stabilizing, soldering and other installation techniques are described.

During the development of a low cost industrial optical sensor an unexpected drift phenomenon has shown to be critical to performance. The sensor is based on LED's as light sources and the main source of error could be tracked to the instability of the spatial radiation pattern of the LED's. This instability due to the construction of the sensor introduced an error in the intensity feedback loop. Alternative designs including a Y-coupler, a scattering arrangement and a mirror beam splitter have been investigated and the results are presented.

In this paper, we will describe the conceptual thermal design of Space Solar Telescope (SST) and the requirement of it. SST will be placed into a 732km, 98.6 degree inclination, solar inertial orbit. For observing the sun, the telescope adds greater flexibility in the control of the heater system. The set points for the telescope and all attached payload elements, and consequently spacecraft heater power requirements, the special thermal control requirement of the focus plane instrument will be discussed in this paper.

Concrete pedestals have many vibration and stiffness characteristics that make them a superior choice for sensitive semiconductor production equipment including scanners, scanning electron microscopes, focused ion beam millers and optical inspection equipment. Among the advantages of concrete pedestals are high inherent damping, monolithic construction that eliminates low stiffness joints common in steep pedestals, ability to reuse and ease of installation. Steel pedestals that have plates attached to the top of the frame are easily excited by acoustic excitation, especially in the range from 50 Hertz to 400 Hertz. Concrete pedestals do not suffer from this phenomenon because of the high mass and damping of the top surface.