This PDF file contains the front matter associated with SPIE Proceedings Volume 6675, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.

This paper is part three of a series describing the ongoing optical modeling activities for the James Webb Space Telescope (JWST). The first two papers discussed modeling JWST on-orbit performance using wavefront sensitivities to predict line of sight motion induced blur, and stability during thermal transients [1-2]. The work here investigates the aberrations resulting from alignment and figure compensation of the controllable degrees of freedom (i.e. the primary and secondary mirrors), which may be encountered during ground alignment and on-orbit commissioning of the observatory. The optical design of the telescope is a three-mirror anastigmat, with an active fold mirror at the exit pupil for fine guiding. The primary mirror is over 6.5 meters in diameter, and is composed of 18 hexagonal segments that can individually positioned on hexapods, as well as compensated for radius of curvature. This architecture effectively gives both alignment and figure control of the primary mirror. The secondary mirror can be moved in rigid body only, and the tertiary mirror is fixed. Simulations are performed of various combinations of alignment and figure errors corrected by the primary and secondary mirrors. Single field point knowledge is assumed in the corrections, and aberrations over the field are reported for the varying cases.

During optical testing of the James Webb Space Telescope (JWST), ground support equipment will be subjected to seismic and facility disturbances. Random Power Spectral Density functions developed from acceleration time history data acquired at Johnson Space Center in August of 2005 are used as the input disturbances. A linear dynamics Finite Element (FE) model has been constructed in order to produce numerical predictions for various optical outputs (e.g., Line Of Sight (LOS), figure vibrate, relative motions) caused by the random disturbances. The numerical simulation performed is a base shake analysis, where the motions of all ground interface degrees of freedom are slaved together in magnitude and phase. As the required LOS error for a successful test is highly dependant on the pointing of the primary mirror, concern arose regarding the effect of uncorrelated disturbances at multiple ground interfaces of the support equipment over the analysis bandwidth. This paper investigates the differences in LOS predictions from applying a uniform, combined disturbance at a centralized base location against using mutually uncorrelated acceleration spectrums at each of the ground interfaces.

SIM PlanetQuest will be the first space-based interferometer and will allow astrometric measurements that are several hundred times more accurate than the previous missions operating at optical wavelengths. SIM promises to achieve microarcsecond accuracy for astrometry on objects as faint as 20th visual magnitude. One of the challenges is to achieve this accuracy at these dim levels, in the presence of even dimmer stars inside the SIM's FOV. Therefore it is important to investigate the effects of "confusion" fields on astrometric performance for SIM. This study will look at effects of Angle Tracking Camera performance for SIM in presence of a crowded or confusion field near a target star. This will lead to a study that predicts SIM astrometric performance in a crowded field. Centroid displacements due to any perturbation including a crowded field cause a shift in the fringe and reduce visibility and performance. In this work we will devise an estimator to estimate the bias in the centroid of SIM Angle Tracking camera in presence of a crowded field. This analysis will examine pointing accuracy performance by estimating Angle Tracking centroid under different parameter variations that affect performance. These parameters are number of neighboring stars, stellar types, and angular separation as well as their relative brightness.

SIM PlanetQuest will measure star positions to an accuracy of a few microarcseconds using precise white light fringe measurements. One challenge for the SIM observation scenario is "star confusion," where multiple stars are present in the instrument field of view. This is especially relevant for observing dim science targets because the density of number of stars increases rapidly with star magnitude. We study the effect of star confusion on the SIM astrometric performance due to systematic fringe errors caused by the extra photons from the confusion star(s). Since star confusion from multiple stars may be analyzed as a linear superposition of the effect from single star confusion, we quantify the astrometric errors due to single star confusion surveying over many spectral types, including A0V, F0V, K5III, and M0V, and for various visual magnitude differences. To the leading order, the star confusion effect is characterized by the magnitude difference, spectral difference, and the angular separation between the target and confusion stars. Strategies for dealing with star confusion are presented. For example, since the presence of additional sources in the field of view leads to inconsistent delay estimates from different channels, with sufficient signal to noise ratio, the star confusion can be detected using chi-square statistics of fringe measurements from multiple spectral channels. An interesting result is that the star confusion can be detected even though the interferometer cannot resolve the separation between the target and confusion stars when their spectra are sufficiently different. Other strategies for mitigating the star confusion effect are also discussed.

This paper presents a top-level architectural overview of the instrument real-time control system currently under development at JPL for the SIM-Planet Quest interferometer. The control system must meet challenging requirements for providing milliarcsecond class pointing and nanometer class delay-line control performance while tracking science stars as dim as 20^th visual magnitude. The driving functional requirements call for a three-interferometer system that also serves as an attitude sensing and tracking system. Due to the dim science requirements and complicated control initialization processes, the control system is architectured using complex estimators, multiloop feedforward signals, and distributed computational infrastructure. Control objectives and requirements are presented and the necessary control sensors and actuators are discussed. Initialization of the interferometer control system is explained, including processes for target star search, acquisition, and tracking. The nominal tracking control modes are then presented, including incorporation of pathlength and angle feedforward signals. The estimation architecture is explained next including its role in generating the necessary feedforward signals. The resulting overall algorithm structure and implementation using distributed processors on a ring-bus architecture is also briefly discussed.

This paper presents a performance analysis of the instrument pointing control system for NASA's Space Interferometer Mission (SIM). SIM has a complex pointing system that uses a fast steering mirror in combination with a multirate control architecture to blend feedforward information with feedback information. A pointing covariance analysis tool (PCAT) is developed specifically to analyze systems with such complexity. The development of PCAT as a mathematical tool for covariance analysis is outlined in the paper. PCAT is then applied to studying performance of SIM's science pointing system. The analysis reveals and clearly delineates a fundamental limit that exists for SIM pointing performance. The limit is especially stringent for dim star targets. Discussion of the nature of the performance limit is provided, and methods are suggested to potentially improve pointing performance.

The SIM Instrument Model performs single tile simulations for the SIM Instrument. It provides a tool to combine the effects of errors in the different subsystems such as the science interferometer, guide interferometer, external metrology sensor, and roll sensor. The inputs to the Instrument Model are the sensor errors for the internal instrument measurements. These errors can be derived from testbeds or other physical models. The Instrument Model perturbs ideal sensors and replicates the fundamental SIM processing called delay regularization. This process reconstructs the science interferometer measurements by using additional sensor measurements. The output of the Instrument Model is the regularized delay, which is the principal science measurement for various observing scenarios such as Wide Angle Grid, and Narrow Angle observations. The primary role of the Instrument Model has been single tile performance prediction but it also serves as variety of different system engineering activities such as validation of the SIM Astrometric Error Budget, demonstration of SIM's capability for picometer sensing for the SIM Technology Milestone 8, development of instrument calibrations, analysis of system level errors, and validation of the averaging approach for the science data processing. The Instrument Model will continue to be an integral part of the SIM modeling plan to predict single tile performance for the SIM mission.

In this paper we investigate the effects of several key system parameters related to development of a space-based observatory for discovering near-earth objects (NEOs). The space-based mission is seen as complementary to ground-based observations for identifying objects with the potential to impact the Earth. A system model is developed from an articial data set of 1218 NEOs with initial orbital elements generated from a probability distribution model similar to that incorporated in the NASA NEO Science Definition Team Report. By running the model over a 7 year period, the statistics of NEO detection can be investigated as a function of changes to telescope parameters. This paper discusses the system model development of orbital models, radiometric calculations and some initial results from parameter studies on the engineering design.

Differing only in implementation details, all current commercially available codes for doing stray light computations are based on the same modified (with ray splitting and importance sampling) Monte-Carlo, non-sequential, forward, ray tracing method pioneered by the GUERAP-III program in the 1970's. The advantages and disadvantages of this method are first presented. Then an alternative technique that is deterministic and exploits the use of bi-directional non-sequential beamlet traces is described. Ironically, this "new" technique is just an extension from two to three dimensions of thesis research done by the author in the late 1970's.

SNAP is a proposed space-based experiment designed to quantify dark energy by measuring the redshift-magnitude diagram of supernovae and to quantify the growth of structure in the universe by measuring weak gravitational lensing over cosmological distances. The baseline SNAP telescope is an ambient temperature three-mirror anastigmat (TMA). The goal of the stray light design is to ensure that stray light in the 0.4 to 1.7 micron wavelength range does not exceed a small fraction of Zodiacal radiation within the mission's target field near the North ecliptic pole. At visible wavelengths, we expect the primary source of stray light will be starlight scattered by the primary mirror. In our longest wavelength NIR band we expect thermal emission from the mirrors and structure will dominate. Scattered stray light is mitigated by an internal field stop, and a cold (140K) internal aperture stop. Stray light scattered by mirror roughness and particulate contamination, as well as scattering from the telescope baffles are modeled and quantified. The baseline design and analyses contained herein ensure that stray light will be less than 10% of Zodiacal in all bands.

Applications involving optical systems with a variety of transient loading conditions in conjunction with tight optical error budgets require new tools to assess system performance accurately and quickly. For example, an optical telescope in geostationary orbit (e.g.: laser communications or weather satellite) may be required to maintain excellent optical performance with sun intermittently crossing near, or even within the telescope's field of view. To optimize the design, the designer would wish to analyze a large number of time steps through the orbit without sacrificing accuracy of the results. Historically, shortcuts have been taken to make the analysis effort manageable: contributing errors are combined in a root-sum-squared fashion; non-linear optical sensitivities to optical motions are made linear; and the surface deformation of non-circular optics and/or footprints are fit with zernike polynomials. L-3 SSG-Tinsley presents a method that eliminates these errors while allowing very fast processing of many cases. The method uses a software application that interfaces with both structural and optical analysis codes, and achieves raytrace-generated results from the optical model. This technique is shown to provide more accurate results than previous methods, as well as provide critical insights into the performance of the system that may be exploited in the design process. Results from the Advanced Baseline Imager ABI telescope are presented as an example.

A MWIR FLIR has been designed as the principal pointing and tracking system for a turret full of other sensors and systems in its payload. The payload is stabilized and vibration isolated but some vehicle disturbances get through these systems to excite the optical bench of the payload. These residual disturbances cause boresight shift and image blur of the IR image on the FLIR's cooled detector. Ivory was used to prepare a thermal and structural dynamic NASTRAN model of the FLIR image's response to the residual disturbances. The physical prescription for the FLIR optics was put into Ivory and it calculated all the influence coefficients between the image on the detector and all the lens design variables and all the lens motions. Ivory then prepared the portion of the NASTRAN model that relates the optical element displacements to the image motions. The Ivory optical model was then attached to an elastic model of the FLIR and payload and the effects on the image of temperature changes, gravitational vector changes and residual random vibrations were analyzed in NASTRAN. This paper discusses the Ivory modeling process, the error budgets associated with the analysis, the debugging of the models and the final analytical results.

Electrostatic stresses represent a phenomenon that is frequently encountered when dielectric media are exposed to an electric field. Depending on the application, they might be considered a spurious effect or an effect that should be enhanced to improve performance. While measuring quadratic electrostriction with an optical interferometer they superimpose on the measurement signal that stems from electrostriction. Designing Maxwell-stress actuators they represent the effect that has to be maximized for best performance of the device. For the purpose of optimization, it is of importance to understand how the electrostatic stresses depend on the elastic and dielectric properties of the materials that are used in an actuator or in an optical instrument. These stresses are also functions of the orientation of the surface of the dielectric material with respect to the electric field and depend on the anisotropy of the material. Using a phenomenological description, it will be shown how they can be predicted for the purpose of improved instrument design. The method of analysis can be represented as an algorithm. It will be discussed what pitfalls should be avoided while deriving the results. The results can also be applied to materials that feature high anisotropy.

In prior work we described a 5x5 ray matrix formalism and how to integrate the effects that are not modeled in wave-optics with the ray matrix model. In this paper we describe how to complete the integration of the two techniques by modifying the Siegman ABCD ray matrix decomposition. After removing the separable effects like image rotation and image inversion, we break the 5x5 ray matrix into two 2x2 sections (a.k.a. the ABCD matrices) that correspond to the two axes orthogonal to the propagation. We then present a general algorithm that breaks any arbitrary ABCD matrix into four simple wave-optics steps. The algorithm presented has sufficient generality to handle image planes and focal planes. This technique allows for rapid and accurate wave-optics modeling of the propagation of light through complex optical systems comprised of simple optics.

In prior work we introduced a method of choosing mesh parameters for a single wave-optics propagation between two effective apertures. Unfortunately, most systems that require wave-optics modeling, like modeling laser resonators with gain media, propagations through the atmosphere, and imaging systems with internal limiting apertures, have multiple apertures and phase screens that induce diffraction. We begin here by augmenting the single propagation theory to include diffraction from both apertures and phase aberrations. We then introduce a technique for analyzing complex systems of simple optics to determine the appropriate wave-optics mesh parameters.

The performance predictions and optimization of blazed diffraction gratings are key issues for their application in hybrid optical systems, both in the case of imaging and analyzing systems. Scalar and vectorial theories are often used for a first performance estimation whenever applicable. However, in the intermediate structure regime, characterized by a grating period within the transition from the validity of the scalar to the fully electromagnetic theory, rigorous numerical simulations are inevitable for accurate modeling of blaze structures with sawtooth-shaped profiles. A variety of electromagnetic algorithms exists to determine the diffraction efficiency, such as integral equation methods, finite element methods or rigorous coupled-wave analyses. An effect known as shadowing occurs and has a significant influence on the diffraction efficiency of the blazed grating. A simple but accurate model describing the shadowing phenomena would be of enormous practical importance for the optical design of hybrid systems. Commonly, dielectric transmission gratings are regarded, when the efficiency behavior due to shadowing is discussed. We succeeded in filling the modeling gap in the intermediate structure regime and have derived a rigorous-based semi-analytical model for dielectric gratings. We are able to extend this model to the case of metallic reflection gratings. For both types of gratings, we find that the blaze efficiency obeys a linear dependence on the ratio of blaze wavelength to grating period, which dominates the performance in the first diffraction order. We define the linear coefficient of shadowing strength and discuss its dependence on the material properties.

3M Polarization Beam Splitter (PBS) technology has been shown to be the most light efficient solution to the needs of LCOS projection. It also provides very high contrast and extremely uniform dark states without the use of lead in the glass prisms. We report on recent improvements in contrast performance, increased understanding of the effects of pupil shape and size on contrast, effects of temperature on optical performance, and improved photostability. We also suggest new light-engine architectures employing the 3M PBSs with associated light budget analyses.

The enormous transmission capacity of the order of thousand of Gb/s offered by single mode fibers cannot be fully utilized with the conventional step index fiber. However for these designs and the new ones to come a numerical technique, which is fast and accurate, is required for calculating the dispersion. Most of the existing numerical approaches are good enough for the calculation of propagation constant only, though some of them are not suited for arbitrary refractive index profile. A powerful numerical technique, the quadratic finite element method [FEM] is used for analyzing the modal characteristic of single mode optical fiber with arbitrary refractive index profile. The simulated results when compared with earlier reported ones for step index profile, confirms the accuracy of the proposed numerical technique. It is shown that multiple cladded fiber is better suited for Wideband Systems. Dispersion flattened fibers have been proposed in the past with W - profile, but all such fiber designs have been observed to be bend sensitive in the long wavelength window, as one has to operate very close to the cutoff of the fundamental mode. A generalized refractive index profile has been used here, which is capable of generaing a variety of earlier proposed profile. Computation shows that by properly optimizing the profile parameters, a wideband fiber can be designed where the dispersion can be kept confined with in ± 1.0 ps/ km - nm over a wide entire wavelength span from 1280 to 1550 nm ( 370 nm). The proposed fiber consists of Quadruply Cladded (QC) Profile and is capable of transmitting high speed data ( > 1 Tb/s). The proposed design is expected to be relatively insensitive to bending losses, as the field even at longer wavelength (1550 nm) is well guided within the QC fiber structure. The wavelength span includes both the low loss transmission window near 1310 & 1550 nm. The results suggest an excellent wideband optical waveguide for future WDM systems.

The present lightwave system prefers to operate near the 1550 nm region. Wideband optical fibers compatible with wavelength division multiplexing (WDM) transmission systems are available which can operate near 1550 nm region, but what basically limits the high transmission capacity is the slow response of the conventional semiconductor amplifiers. To overcome this researchers have devised the optical amplifier, commonly known as erbium doped optical amplifier (EDFA) which can directly amplify in the optical domain near 1550 nm region. Existing EDFAs are available with a relatively narrowband of 25nm centred nearly at 1550 nm. This development has motivated researchers to devise EDFA with broad bandwidth capabilities. In this paper, we present here a technique known as gain cascading of EDFA for designing wideband EDFA centred around 1550nm region. Gain cascading of two EDFAs pumped separately at 980nm and 1480nm combines the advantage of high gain characteristics of 980 nm pumping and broad bandwidth characteristics of 1480 nm pumping. By using pumping at 980nm, we observe that the peak value of gain is around 69dB and gain bandwidth is around 10-15nm. From pumping at 1480nm, it is observed that the peak value of gain has although decreased as compared to 980nm pumping but the gain bandwidth is increased to around 30-32nm. However, by cascading two EDFAs pumped separately at 980nm and 1480nm, the overall peak value of gain is increased to a very high value of around 180dB and bandwidth obtained is about 35 nm. We thus obtain a broader gain-bandwidth product by using gain cascading.

Possibilities of obtaining quantitative information about the deformation influence on the SFMI with a small number of excited modes by using a correlation method are investigated. It was shown that usage of diffusive scatterer allows us to transform the radiation of SFMI to a speckle field which can easily be processed. The value of the measurement error of SFMI elongation is ±10 &mgr;m. The working range of the SFMI deformation measurements is 0 - 160 &mgr;m.

The effectiveness of sensors that use optical measurements for the laser detection and identification of subsurface mines is directly related to water clarity. The primary objective of the work presented here was to use the optical data collected by UUV (Slocum Glider) surveys of an operational areas to estimate the performance of an electro-optical identification (EOID) Laser Line Scan (LLS) system during RIMPAC 06, an international naval exercise off the coast of Hawaii. Measurements of optical backscattering and beam attenuation were made with a Wet Labs, Inc. Scattering Absorption Meter (SAM), mounted on a Rutgers University/Webb Research Slocum glider. The optical data universally indicated extremely clear water in the operational area, except very close to shore. The beam-c values from the SAM sensor were integrated to three attenuation lengths to provide an estimate of how well the LLS would perform in detecting and identifying mines in the operational areas. Additionally, the processed in situ optical data served as near-real-time input to the Electro-Optic Detection Simulator, ver. 3 (EODES-3; Metron, Inc.) model for EOID performance prediction. Both methods of predicting LLS performance suggested a high probability of detection and probability of identification. These predictions were validated by the actual performance of the LLS as the EOID system yielded imagery from which reliable mine identification could be made. Future plans include repeating this work in more optically challenging water types to demonstrate the utility of pre-mission UUV surveys of operational areas as a tactical decision aid for planning EOID missions.

A folded holographic optical system is modeled for use as a building block for a compact imager. The design of the compact imaging system allows for a thin optical configuration and reduction in the size of the optical elements. In the folded design a transmission hologram in a slanted configuration folds the field of view of the lens and points it at a specific direction in the object space. The slanted geometry results in a compressed non-uniform field of view that is defined as a vignetting function and generated by a ray-tracing program. In the compact imaging system, multiple folded holographic imagers are used in an array to extend the field of view. Each imager unit is optimized to collect a segment of light from the object scene. The combination of imager units defines the composite field of view of the compact imaging system. The folded holographic imager is capable of capturing an image with full-field angle of 30°.

PROPER is a library of IDL (Interactive Data Language) routines for simulating optical propagation in the near and far fields using Fourier-based Fresnel and angular spectrum methods. The goal of PROPER is to provide a free, easy-to-use, and versatile means for simulating systems that require diffraction-based rather than geometrical analyses, such as spatial filtering systems with intermediate optics (e.g. a stellar coronagraph for extrasolar planet imaging). It has routines for creating complex apertures and obscurations, wavefront errors (defined by Zernikes, power spectra, or user-supplied maps), amplitude modulators (e.g. coronagraphic occulters), simple lenses, and deformable mirrors. The routines automatically select which propagator (near or far-field) is best at each surface based on analytically propagating a Gaussian pilot beam. The library includes a comprehensive manual and is distributed as IDL source code.

This paper presents the finite element stress and distortion analysis completed on the receiver telescope lens of the Lunar Orbiter Laser Altimeter (LOLA). LOLA is one of six instruments on the Lunar Reconnaissance Orbiter (LRO), scheduled to launch in 2008. LOLA's main objective is to produce a high-resolution global lunar topographic model to aid in safe landings and enhance surface mobility in future exploration missions. A receiver telescope captures the laser pulses transmitted through a diffractive optical element (DOE) and reflected off the lunar surface. The largest lens of the receiver telescope was modeled with solid elements and constrained in a manner consistent with the behavior of the mounting configuration. Twenty-one temperature load cases were mapped to the nodes based on thermal analysis completed by LOLA's lead thermal analyst, and loads were applied to simulate the preload applied from the ring flexure. The thermal environment of the baseline design produces large radial and axial gradients in the lens. These large gradients create internal stresses that may lead to part failure, as well as significant bending that degrades optical performance. The high stresses and large distortions shown in the analysis precipitated a design change from BK7 glass to sapphire.

In this paper, a real-time demosaicing generic model is presented, which is concise, easy to implement, resources-saving and robust. With the model, multiple displaying demosaicing subsystems can be realized in terms of a Bayer pattern color filter array. A LCD displaying subsystem is designed by FPGA, and the waveform simulated is presented. The monitoring results of a real scene are captured and illustrated. To prove the LCD monitoring results, the application background of the LCD subsystem is given, which is a multiple channel CMOS image sampling system. The three images exposed synchronously in the background system and the pictures stored are shown, one of which is identical to the scene monitored by the LCD subsystem. Finally, to demonstrate the generality of the model, the test results of a CRT demosaicing displaying subsystem designed with the model in the background system are given.