Several classes of planetary science observations require high spatial resolution in UV and visible wavelengths. Key examples include (a) the detection of satellites and characterization of their orbits, (b) the discovery of faint and small objects among the NEO, asteroid, Kuiper belt or Sedna-like populations and (c) cloud or trace gas observations in planetary atmospheres. Hubble Space Telescope (HST) observations have been very productive in these areas: consider the recent discovery of Makemake's satellite (Parker et al., 2016), the discovery of 2014 MU69 (now the flyby target of the New Horizons spacecraft) or the OPAL (Outer Planet Atmospheres Legacy) program.
Like HST, large-aperture ground-based telescopes with adaptive optics can also achieve spatial resolutions of 50 mas, but normally at wavelengths longer than ~1 μm. Projects like MagAO-2K are working on improving image quality at visible wavelengths, but while the core PSF (Point Spread Function) width might be narrow (projected to be 15 mas at the Magellan telescope), the Strehl ratio drops steeply with wavelength (Males et al., 2016). Not all science goals suffer equally from low Strehl ratios, however: cloud tracking on Venus is more tolerant of a low Strehl ratio than searching for a close satellite of Makemake.
A telescope on a NASA super-pressure balloon would float above 99.3% of the atmosphere, where the inner Fried parameter is thought to be two meters or more. While atmospheric turbulence is not expected to impact image quality, there are other sources of wavefront error (WFE), such as mirror figuring, misalignment of the OTA (Optical Telescope Assembly) or asymmetric heating from the Sun or Earth. We reference recent work that estimates balloon telescope WFEs from different sources to generate a suite of plausible PSFs. We apply these PSFs to the UV and visible wavelength science cases outlined in the GHAPS/SIDT report (Gondola for High Altitude Planetary Science/Science Instrument Definition Team). We quantify the impact that WFE has on achieving the planetary observations outlined in the SIDT report.
The environment of a balloon based telescope puts opto-mechanical stability demands that wavefront sensing and focus control are important features to consider. The GHAPS telescope is designed to correct for rigid body motion of the secondary mirror based upon wavefront sensing from reference stars. In order to support the concept of operations of this approach, the precision of wavefront sensing with candidate reference stars needs to be addressed. Precision is expected to degrade with reduction in irradiance. To confirm this, a study was conducted to determine the relationship between broadband and narrow spectral irradiance and wavefront measurement precision. The results of the study demonstrate that a precision of 5 nm RMS can be achieved with a 20 x 20 sampling of the wavefront with an irradiance of a visual magnitude 5 star on 1 meter aperture with an exposure of 30 msec.
Balloon based telescopes represent an opportunity to observe science in an environment with almost no atmospheric effects. However, balloon based platforms include a wide range of thermal environments as well as pointing a lightweight telescope over a large elevation range. The Gondola for High Altitude Planetary Science (GHAPS) was designed to provide nearly diffraction limited performance observations over the visible and infrared spectrum with a 1- meter aperture. To achieve such performance, detailed Structural Thermal Optical Performance (STOP) was used to predict telescope performance. Software was built to automate the process of analysis, enabling thermal, structural and optical analyses to be executed quickly with less effort. The end result was the capability to analyze both generic operating conditions and Design Reference Mission conditions, producing predictions that could be used to evaluate the quality of science return.
The Next Generation Balloon-borne Large Aperture Submillimeter Telescope (BLAST-TNG) is a submillimeter mapping experiment planned for a 28 day long-duration balloon (LDB) flight from McMurdo Station, Antarctica during the 2018-2019 season. BLAST-TNG will detect submillimeter polarized interstellar dust emission, tracing magnetic fields in galactic molecular clouds. BLAST-TNG will be the first polarimeter with the sensitivity and resolution to probe the ∼0.1 parsec-scale features that are critical to understanding the origin of structures in the interstellar medium. With three detector arrays operating at 250, 350, and 500 μm (1200, 857, and 600 GHz), BLAST-TNG will obtain diffraction-limited resolution at each waveband of 30, 41, and 59 arcseconds respectively. To achieve the submillimeter resolution necessary for its science goals, the BLAST-TNG telescope features a 2.5 m aperture carbon fiber composite primary mirror, one of the largest mirrors flown on a balloon platform. Successful performance of such a large telescope on a balloon-borne platform requires stiff, lightweight optical components and mounting structures. Through a combination of optical metrology and finite element modeling of thermal and mechanical stresses on both the telescope optics and mounting structures, we expect diffractionlimited resolution at all our wavebands. We expect pointing errors due to deformation of the telescope mount to be negligible. We have developed a detailed thermal model of the sun shielding, gondola, and optical components to optimize our observing strategy and increase the stability of the telescope over the flight. We present preflight characterization of the telescope and its platform.
Avionics has experienced an ever increasing demand for processing power and communication bandwidth. Currently
deployed avionics systems require gigabit communication using opto-electronic transceivers connected with parallel
optical fiber. Ultra Communications has developed a series of transceiver solutions combining ASIC technology with
flip-chip bonding and advanced opto-mechanical molded optics. Ultra Communications custom high speed ASIC chips
are developed using an SoS (silicon on sapphire) process. These circuits are flip chip bonded with sources (VCSEL
arrays) and detectors (PIN diodes) to create an Opto-Electronic Integrated Circuit (OEIC). These have been combined
with micro-optics assemblies to create transceivers with interfaces to standard fiber array (MT) cabling technology. We
present an overview of the demands for transceivers in military applications and how new generation transceivers
leverage both previous generation military optical transceivers as well as commercial high performance computing
optical transceivers.
In this paper the opto-mechanical modeling of the Herschel infrared space telescope at ESA/ESTEC is presented. The aim of the paper is to give an overview of all modeling activities that took place between 2006 and 2010. In 2006 ESA commissioned a Tiger Team to review the discrepancy between the prediction and measurement of the change in telescope back focal length of the Herschel infrared space telescope. The understanding of the discrepancy was essential since the telescope did not have a refocusing mechanism and hence had to be shimmed to the focus position at cryogenic operational temperature. A team of 16 engineers and scientists collocated at ESA/ESTEC to review the finite element models, optical models and test data used for the prediction of the telescope back focal length. The methodology of prediction, the uncertainties and the obtained results were critically assessed. The team used various modeling techniques including paraxial optical models, first order linear thermal expansion models, full system and metrology ray tracing, deterministic and stochastic thermo-elastic finite element analyses. The opto-mechanical analysis techniques, assumptions and results are discussed. In addition the impact of new measurements of coefficients of thermal expansion, performed after shimming of the telescope flight model, are addressed.
KEYWORDS: Telescopes, Mirrors, Space telescopes, Silicon carbide, Optical testing, Data modeling, Finite element methods, Point spread functions, Cryogenics, Distortion
Successful launch and imagery from the Herschel Space Telescope has demonstrated a nominally in focus telescope.
There still remains a discrepancy between the prediction and measurement of the telescope back focal length prior to
launch. New material strain data has been applied to the structural/optical model of the telescope. The new data
significantly closed the gap between the previous optical test measurement and prediction. However, a discrepancy still
exists. Model results and techniques will be presented and discussed.
Stroke is the one of the leading causes of mortality in the United States, claiming 600,000 lives each year. Evidence
suggests that near infrared (NIR) illumination has a beneficial effect on a variety of cells when these cells are exposed to
adverse conditions. Among these conditions is the hypoxic state produced by acute ischemic stroke (AIS). To
demonstrate the impact NIR Transcranial Laser Therapy (TLT) has on AIS in humans, a series of double blind, placebo
controlled clinical trials were designed using the NeuroThera(R) System (NTS). The NTS was designed and developed
to treat subjects non-invasively using 808 nm NIR illumination. TLT, as it applies to stroke therapy, and the NTS will
be described. The results of the two clinical trials: NeuroThera(R) Safety and Efficacy Trial 1 (NEST-1) and
NeuroThera(R) Safety and Efficacy Trial 2 (NEST-2) will be reviewed and discussed.
Clinical testing of human blood requires adherence to a number of regulatory standards, including maintaining a
temperature that is representative of the human body (e.g. 37 C). The economics of private and public healthcare drives
blood assays to be conducted using low cost, disposable assay devices that also eliminate the possibility of cross
contamination. Unfortunately, the materials that meet the economic and disposable constraints of the marketplace are
thermal insulators, not ideal for rapid heating. We present a novel means of optically heating blood samples in plastic
assay devices within a time period suitable for point-of-care use. The novel approach uses LED's in the red portion of the
visible spectrum. The lower absorption of optical radiation in the visible spectrum enables the absorption of energy deep
into the assay device. This produces even heating, avoiding the gradients that can occur by surface heating (conduction)
or surface absorption (highly absorbing wavelengths). Analytical and computational models will be discussed. A specific
application to a point-of-care blood assay instrument will be reviewed. In this application, optical heating was achieved
using a small array of high brightness LED's. Experimental results will be discussed. The experimental results with this
instrument validated the predictions.
Large core multimode fibers (MMF) in the range of 100-1000 μm core diameter are commonly used
with infrared lasers in medical, bio-photonics and other fiber optics applications. Angular misalignment of the laser
source to the multimode fiber can lead to unusual angular patterns at the exit of the fiber. The angular content of the
launch beam can result in under-filling, non-uniform angular filling, or over-filling of the MMF modes. Typically,
the beam condition optics at the distal end of the device has a limited impact on these angular modes. The result is
often loss of output power at the distal end or an uncontrolled angular and/or spatial distribution of light. We have
investigated angular misalignment perturbations of various fiber and coupling optics combinations in a medical laser
therapy device. We have quantified the resulting far field perturbations, as well as the resulting broadening of the
fiber output numerical aperture (NA). Angular misalignment may cause the development of so called "donut modes"
with highly inhomogeneous far field mode distribution, as well as a substantial NA broadening effect which may
impact therapy. We have shown that in order to avoid these perturbations, tight tolerancing of fiber coupling opto-mechanics
as well as a thorough alignment procedure is required.
ESA commissioned a Tiger Team to review the discrepancy between the prediction and measurement of the telescope
back focal length. A team of 16 engineers and scientists collocated at ESA's Estec facility to review the finite element
models, optical models, and supporting data to validate the methodology of prediction and verify the results. The team
used several modeling techniques including: paraxial models, first order thermal expansion models, full system and
metrology raytracing, deterministic and stochastic finite element models. The techniques, assumptions, and results will
be discussed.
ESA commissioned a Tiger Team to review the discrepancy between the prediction and measurement of the telescope
back focal length. A team of 16 engineers and scientists collocated at ESA's Estec facility to review the test results in
the context of the mission requirements and predictions for behavior of the telescope. Extensive analysis was performed
on the random and systematic errors in the test results. Both room temperature and cryogenic test data was scrutinized.
Error budgets, test results, and conclusions from the Tiger Team will be discussed.
A compact, binocular see-through, monocular display HMD has recently been manufactured by Rockwell Collins. This HMD allows for the projection of symbology on one eye using a unique see-through display while leaving the user's unaided eye completely unobscured. The HMD uses a prismatic element to project the symbology near infinity. An aspheric corrector is used in conjunction with the prismatic element to enable the user to experience binocular vision as well as symbology overlay. Distortion, resolution, dipvergence/convergence, contrast, and luminance are discussed.
Hyperspectral imaging in the 2-5 um band has held interest for applications in detection and discrimination of objects of
interest. Real time instrumentation is particularly powerful as a tool for characterization and field measurement. A
compact, real-time, refractive MWIR hyperspectral imaging instrument has been designed and tested. The system has
been designed for cryogenic operation to improve signal to noise ratio, reduce background noise, and enable real-time
hyperspectral video processing. The system is a a 2-5 μm 32-band hyperspectral imager capable of collecting and
processing complete hyperspectral image cubes at 15 cubes-per-second. Details of the system and object discrimination
using this system are presented.
As an offshoot of hyperspectral imaging, which typically acquires tens to slightly more than 100 spectral
bands, ultraspectral imaging, with typically more than 1000 bands, provides the ability to use molecular or
atomic lines to identify surface or airborne contaminants. Surface Optics Corporation has developed a very
high-speed Fourier Transform Infrared (FTIR) imaging system. This system operates from 2 μm to 12 μm,
collecting 128 ×128 images at up to 10,000 frames-per-second. The high-speed infrared imager is able to
synchronize to almost any FTIR that provides at least mirror direction and laser clock signals. FTIRs rarely
produce a constant scan speed, due to the need to physically move a mirror or other optical device to
introduce an optical path difference between two beams. The imager is able to track scan speed jitter, as
well as changes in position of the zero path difference (ZPD) position, and perform real-time averaging if
desired. Total acquisition time is dependent on the return stroke speed of the FTIR, but 16 cm-1 (1024
point) spectral imagery can be generated in less than 1/5 second , with 2 cm-1 (8192 point) spectral imagery
taking proportionately longer. The imager is currently configured with X-Y position stages to investigate
surface chemistry of varied objects. Details of the optical design, focal plane array, and electronics that
allow this high-speed FTIR imager to function are presented. Results of using the imager for several
applications are also presented.
A novel, compact visible multispectral, polarimetric camera is under development. The prototype is capable of megapixel imaging with sixteen wavebands and three polarimetric images. The entire system encompasses a volume less than 125mm x 100mm x 75mm. The system is based on commercial megapixel class CMOS sensors and incorporates real time processing of hyperspectral cube data using a proprietary processor system based on state of the art FPGA technology.
Laser devices in clinical applications must eventually be tested via clinical trials. An essential component in clinical
trials is the double-blind study whereby the patient and the treating physician have no knowledge as to whether a given
treatment is active or placebo. In pharmaceuticals, the problem is easily addressed. With laser therapy this can be very
challenging. For some optical therapies, laser heating of tissue, by even as little as a few degrees can indicate to the
patient and/or the physician that the device is active, un-blinding the study. This problem has been analyzed for a
specific laser therapy using a combination of clinical data, analytical methods, finite element modeling, and laboratory
testing. The methods used arrived at a solution, but not necessarily one that could have been predicted easily. This
paper will present a model of tissue heating and the methods used to mask the effects from the laser in an effort to make
active treatment and placebo indistinguishable.
The Hyperspectral Polarimetric Imaging (HPI) Testbed system combines a dual-band hyperspectral imager (VNIR and SWIR), a 3-axis polarimetric imager, and a high resolution panchromatic imager. All imagers operate through a common fore-optic, and thus have identical fields of view, with simultaneous image capture. The HPI testbed system was developed to aid a sentry in the surveillance of broad sectors for intrusion by ground vehicles or other non-natural objects. The various image components are readily combined through image fusion, which lends itself well to anomaly detection algorithms. This paper describes the general HPI testbed system design and performance, and also provides a detailed description of the polarimetric imaging system, calibration methods, and performance.
KEYWORDS: Sensors, Prototyping, Capillaries, Near field optics, Diffraction, Temperature metrology, Optical flow, Computer simulations, Modulation, Signal detection
External and implantable infusion pumps are deployed in an ever widening variety of therapies. These devices are continually driven to increasing accuracy, smaller size, and lower cost. One opportunity for advancement in infusion pump technology is the improvement of closed loop monitoring of the delivery dosage of pharmaceuticals. An optical flow sensor has been designed, developed, and demonstrated based on a non-contact thermal time of flight architecture. The device is a diffraction based sensor. An analytical theory of operation will be presented. Simulations were conducted using a computational model based on heat transfer and computational fluid dymanics combined with diffraction optics calculations. These simulations were corroborated by experimental observations. The sensor has been demonstrated on several prototype platforms, including a prototype using telecommunications devices and packaging technology at a size of 20 mm x 20 mm x 5 mm. Experimental results will be presented demonstrating monitoring of flow rates between 240 nl/sec to 800 nL/sec with accuracies of better than 1% CV.
Hyperspectral imaging in the 2-5 um band has held interest for applications in detection and discrimination of targets. Real time instrumentation is particularly powerful as a tool for characterization and field measurement. A compact, real-time, refractive MWIR hyperspectral imaging instrument has been designed and is undergoing integration and test. The system has been designed for cryogenic operation to improve signal to noise ratio, reduce background noise, and enable real-time hyperspectral video processing. Partial testing has been completed on cryogenic elements and “first light” 2-5 μm hyperspectral images have been collected at room temperature.
Multispectral imaging is a well accepted technique for object discrimination. Hyperspectral imaging can result in highly complex optical systems that have frame rate limitations. For fast frame rate applications, dual band imaging can provide sufficient discrimination without sacrificing signal to noise ratio. The design of a fast frame rate (> 200 Hz) SWIR/MWIR and MWIR/LWIR camera is described. Two strategies for cooling the array are explored.
Hyperspectral imaging in the 2-5 μm band has held interest for applications in detection and discrimination of targets. Real time instrumentation is particularly powerful as a tool for characterization and field measurement. A compact, real-time, refractive MWIR hyperspectral imaging instrument has been designed, and is undergoing testing. Using a combination of dispersive and corrective elements, the system has been designed for integration and preliminary test at room temperature with passive focus correction for the cryogenic elements. The F/1.75 design supports near diffraction limited performance from 2.5 μm to 5.0 μm. This paper will review the challenges in manufacturing such a system as well as the alignment and performance data.
Balloon borne instruments offer opportunities for astronomical observation in an environment that is superior to many ground observatories and less expensive than space borne observatories. BLAST is an infrared astronomical telescope that will use a high altitude balloon as an observation platform. The BLAST telescope has a unique set of requirements: lightweight, low cost, zenith to horizon pointing, 10 arc-second pointing accuracy, high Strehl ratio far infrared/sub-milllimeter observation. The design of the BLAST telescope takes advantage of a pre-existing 2-m experimental lightweight carbon fiber mirror. Using this spherical primary, an aspheric secondary was designed to produce a diffraction limited telescope at 250 microns. The telescope metering structure was designed and fabricated using high stiffness, low mass, thermally stable carbon fiber. The secondary mirror was aggressively lightweighted and fabricated using state of the art diamond turning technology. Design was verified prior to manufacturing using finite element structural analyses in order to demonstrate compliance with the deflection requirements of the secondary mirror when pointing zenith and near horizon. This paper will review the optical and opto-mechanical design, fabrication, integration and alignment of the BLAST telescope.
The CALIPSO LIDAR is a two-channel visible/infrared, polarization sensitive space based instrument. The mission specifies a lightweight, thermally stable platform for the lasers, 1-m telescope, and LIDAR instrumentation. Stability requirements include ±26 μrad boresight stability between the telescope and the laser as well as ±10 μm optical bench thickness stability and ±70 μm stability of components on the optical bench. The environment for these performance criteria is a 0 C to 50 C space environment. In order to demonstrate performance, a laser tracker, a laser comparator, and an electronic autocollimator were used in conjunction with an environmental chamber to measure the stability of the structure over the operating temperature range.
The Herschel Space Observatory (formerly known as FIRST) consists of a 3.5 m space telescope designed for use in the long IR and sub-millimeter wavebands. To demonstrate the viability of a carbon fiber composite telescope for this application, Composite Optics Incorporated (COI) manufactured a fast (F/1), large (2 m), lightweight (10.1 kg/m2) demonstration mirror. A key challenge in demonstrating the performance of this novel mirror was to characterize the surface accuracy at cryogenic (70 K) temperatures. A wide variety of optical metrology techniques were investigated and a brief survey of empirical test results and limitations of the various techniques will be presented in this paper. Two complementary infrared (IR) techniques operating at a wavelength of 10.6 microns were chosen for further development: (1) IR Twyman-Green Phase Shifting Interferometry (IR PSI) and (2) IR Shack-Hartmann (IR SH) Wavefront Sensing. Innovative design modifications made to an existing IR PSI to achieve high-resolution, scannable, infrared measurements of the composite mirror are described. The modified interferometer was capable of measuring surface gradients larger than 350 microradians. The design and results of measurements made with a custom-built IR SH Wavefront Sensor operating at 10.6 microns are also presented. A compact experimental setup permitting simultaneous operation of both the IR PSI and IR SH tools is shown. The advantages and the limitations of the two key IR metrology tools are discussed.
The effects of specific aberrations on the optical performance of the all-composite design for the Herschel Space Observatory are examined. A review of the all-composite design for the large aperture (3.5 m) telescope that satisfies the target specifications is presented. Cyrogenic experiments with a carbon fiber reinforced polymer (CFRP) 2 m demonstration mirror have yielded empirical bounds on the high- and low-order spatial frequency aberrations that will be anticipated in the full 3.5 m Ritchey-Chretien telescope design. Detailed analysis is presented on the effect of the low order aberrations of the primary mirror on the system wavefront error and encircled energy. Predictable limits of correction via low order shaping of the secondary mirror are described. The impact of higher order surface errors on the encircled energy and the stray light will also be presented. Comments are made regarding the impact of the optical prescription and CRFP design on flight telescope testing.
The Herschel Space Observatory (formerly known as FIRST) consists of a 3.5 m space telescope. As part of a JPL- funded effort to develop lightweight telescope technology suitable for this mission, COI designed and fabricated a spherical, F/1, 2 m aperture prototype primary mirror using solely carbon fiber reinforced polymer (CFRP) materials. To assess the performance of this technology, optical metrology of the mirror surface was performed from ambient to an intended operational temperature for IR-telescopes of 70K. Testing was performed horizontally in a cryogenic vacuum chamber at Arnold Engineering Development Center (AEDC), Tennessee. The test incorporated a custom thermal shroud, a characterization and monitoring of the dynamic environment, and a stress free mirror mount. An IR-wavelength phase shifting interferometer (IR PSI) was the primary instrument used to measure the mirror surface. From an initial surface figure of 2.1 microns RMS at ambient, a modest 3.9 microns of additional RMS surface error was induced at 70K. The thermally induced error was dominated by low-order deformations, of the type that could easily be corrected with secondary or tertiary optics. In addition to exceptional thermal stability, the mirror exhibited no significant change in the figure upon returning to room temperature.
The Herschel Space Observatory (formerly known as FIRST) consists of a 3.5 m space telescope. Stitching sub aperture interferograms may offer considerable cost savings during testing of the flight telescope as compared to other techniques. A comparative demonstration is presented of interferogram stitching techniques that enable a composite map of a 3-D surface to be assembled from a sequence of sub-aperture measurements. This paper describes the fundamental procedures for stitching together component data sets and demonstrates such techniques with real data sets. A set of 14 sub-aperture measurements was made of a 2 m diameter all-composite mirror developed as part of the Herschel Space Observatory program and two different stitching software packages were employed to stitch together the sub-aperture surface maps. The software packages differ fundamentally in the way the sub-aperture maps are three-dimensionally stitched, one employing a local technique and the other using a global technique. The processed results from both algorithms are compared with each other and with a full-aperture reference measurement made of the same test optic. A summary of the results is presented and potential modifications and enhancements to the stitching techniques are discussed.
The UAV platform is ideal for remote sensing. A powerful remote sensing tool is a laser based lidar system. Two significant constraints on this platform are the size and mass of payloads. An additional constraint is the opto-mechanical precision required for a diffraction limited lidar telescope. A solution to these challenges can be found using lightweight, stiff carbon fiber composite materials. The authors report on the requirements, design, analysis, and manufacturing of a carbon fiber composite telescope for a UAV platform. In addition to meeting the required precision assembly and tolerances under various load cases, the telescope features a moisture barrier. Typical carbon fiber composites absorb moisture from ambient humidity, causing minute expansion of the material. The moisture barrier of prevents moisture from being absorbed by the material, eliminating distortions in the telescope due to moisture.
A thermally conductive, dimensionally stable optical bench has been fabricated from advanced composite materials for use at temperatures below 180 K (-93 degree(s)C). The optical bench comprises the main structure of the interferometer for the TES (Tropospheric Emission Spectrometer) instrument which will be part of the EOS CHEM satellite scheduled for launch in late 2002.
The mass of the primary mirror has dominated the mass of larger aperture (> 1 m class) telescopes. Spaceborne telescopes have much to gain from a significant reduction in areal density. Areal density is often limited by the stiffness to weight ratio of the primary mirror. Two key factors drive this criteria: telescope structural characteristics (launch and deployment) and fabrication requirements. A new class of hybrid composite mirrors has been designed, prototyped, and fabricated to demonstrate the advantage of the high stiffness to weight ratio of carbon fiber composite materials and the superior optical fabrication for low expansion glasses. This hybrid mirror utilizes a unique `set and forget' fabrication technique. A thin meniscus of glass is mounted to a stiff composite support structure using composite flexure rods. The meniscus is lightweighted using waterjet pocket milling and is conventionally polished to a precise radius of curvature. This meniscus is then supported on the flexures and actuated to a precise figure. The flexures are fixed and the actuators are removed. The substrate is then ion figured to achieve the final figure. The areal density of this mirror is 10 kg/m2. Surface figure on a 0.25 m aperture prototype was demonstrated at better than (lambda) /4 (visible) prior to ion figuring. Two 0.6 m mirrors are under fabrication. The design of the mirror and results of the fabrication and testing will be discussed.
Challenges in high-resolution space telescopes have led to the desire to create large primary mirror apertures. One such telescope is the Next Generation Space Telescope (NGST, 8-m primary). In order to accommodate launch vehicles, the optical systems using these large apertures are being designed to accommodate extremely lightweight, deployable, segmented primary mirrors. The requirements for these segments include: meter-class diameter, areal densities of the order of 15 kg/m2, aspheric surface figure, near infrared and visible spectrum operation, diffraction limited surface figure, high stiffness, tight radius of curvature matching, and excellent thermal stability. Operating temperatures for various systems include ambient as well as cryogenic ranges. A unique ceramic, carbon fiber reinforced silicon carbide, developed by the Industrieanlagen- Betriebsgesellschaft mbH, has shown potential for use as a mirror substrate. This paper presents the deign and predicted performance of this mirror system in various applications. Also included are issues related to the fabrication of the Advanced Mirror System Demonstrator.
Composite materials are an ideal choice for the FIRST Telescope, since they provide dimensional stability, excellent stiffness to weight ratios, near zero thermal expansion, and manufacturing flexibility. The most challenging aspect of producing an all-composite FIRST telescope, is the development of the lightweight primary mirror. The design of the primary mirror must satisfy requirements for surface accuracy to operating temperatures of 80 +/- K as well as stiffness and strength considerations during launch.
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, has 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.
E. Friebele, Heather Patrick, Barbara Wright, A. Greenblatt, E. Bolden, W. Simon, Daron Giles, M. Stringfield, G. Hidalgo, Brian Catanzaro, M. Maher, Kevin Uleck, M. Fox, Anthony Vizzini
Ultrahigh sensitivity fiber cavity etalon (FCE) sensors have been embedded in graphite-reinforced polymer tubes fabricated by two different methods: resin transfer molding (RTM) and standard autoclave curing, and FCEs have been embedded in autoclave-cured unidirectional flat laminates. Significant issues encountered in embedding the sensors include protecting the fiber egress during layup, curing, and breakout, survival of the butt-coupled splice between the cavity and lead fiber during composite cure, maintaining sensor location, and sensor reliability and response. Methods were successfully devised to overcome these obstacles.
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.
Multistage interconnection networks (MINs) are used to create wide diameter networks with a logarithmic number of stages. To further reduce the costs of constructing and operating this type of network, these stages can be stored in a volume hologram and accessed sequentially to achieve the same functionality as a MIN. We discuss the design of such a system and demonstrate a prototype that uses infrared sensitive photorefractive lithium niobate to store a wavelength multiplexed volume holographic lens array. The holograms were recorded at 800 nm and several stages were multiplexed in a single hologram, each separated by as little as 0.6 nm. The optical system performance was analyzed and the results discussed.
To design and package optoelectronic (OE) systems more effectively, computer-aided design (CAD) systems are needed in the engineering environment. The use of CAD systems for designing electronic
computing systems is well accepted by the electronic community. CAD systems for engineering optical design are also widely used in the optics community. However, design automation of OE engineering requires more than the existing tools for system component design. Also required is research on OE design methodology and a complete set of tools. We explore a new area that will be important to OE system design: OE system CAD. We present an integrated CAD system for free-space optical interconnected optoelectronics that leverages on existing CAD technologies. The details of the system and the guidelines for developing compatible tools are described. Case studies of two OE CAD tools developed using these guidelines are also presented.
The packaging opto-electronic interconnects has the potential to create compact, highly dense communication networks. We present a packaged space-variant optical interconnect module using wavelength multiplexed volume holographic elements recorded in photorefractive materials. The input/output arrays (4 X 4), an illumination lenslet array, and a set of two wavelength multiplexed off-axis volume holographic lenslet arrays were integrated with a series of several glass substrates to form a free-space optical interconnect. The size of the packaged optical interconnect module was 40 mm X 24 mm X 37 mm. Reconfigurable interconnection was demonstrated on the packaged module by performing the perfect shuffle and butterfly networks, at different wavelengths. Several packaging issues, such as alignment, bonding, energy efficiency, and system scalability were studied.
The architecture of an integrated CAD system to automate the design of optoelectronic systems is presented in this paper. Optoelectronic technology with free-space optical interconnects offers the potential to build high-performance computers. As this technology matures increased design complexity will mandate the use of CAD. CAD tools and specifications for the design process of optoelectronic systems are described. The proposed architecture extends existing CAD technologies to optoelectronics.
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