Proceedings Volume 7427

Optical Modeling and Performance Predictions IV

Mark A. Kahan
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Proceedings Volume 7427

Optical Modeling and Performance Predictions IV

Mark A. Kahan
View the digital version of this volume at SPIE Digital Libarary.

Volume Details

Date Published: 21 August 2009
Contents: 9 Sessions, 18 Papers, 0 Presentations
Conference: SPIE Optical Engineering + Applications 2009
Volume Number: 7427

Table of Contents

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Table of Contents

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  • Front Matter: Volume 7427
  • Component Design
  • Detectors
  • Radiometry and Stray Light
  • Assembly and Test
  • Thermal
  • Adaptive Optics and Dynamics
  • Integrated Modeling
  • Poster Session
Front Matter: Volume 7427
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Front Matter: Volume 7427
This PDF file contains the front matter associated with SPIE Proceedings volume 7427, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.
Component Design
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Free-space propagation of extreme NA polarized beams using the vector plane wave spectrum method and multi-gigabyte FFTs
Certain lasers can have initial waists only a wavelength or less in size. Therefore, collection optics with extreme numerical apertures (NA) approaching unity are required. Although the design of these macro-optics using geometrical ray-tracing is trivial, determining the exact vectorial field entering them is not. The theory and implementation of Fourier, or plane wave spectrum (PWS), based methods is presented for not only the far-field, but also the near and intermediate. A real-world example is given for which at one point a 12 gigabyte two-dimensional fast Fourier transform (FFT) is required and unexpected polarization effects are observed.
Linear canonical transform sampling: analysis
A new sampling criterion for the linear canonical transform (LCT) was recently proposed by the authors. This criterion was based on an analysis of the consequences of sampling the LCT of a discrete signal. Previous LCT sampling work in the literature considered only sampling the LCT of continuous, band limited signals. This analysis has great significance for numerical simulations of first order optical systems using the LCT, as these simulations must necessarily consider a sampled input function, and evaluate only a sampled output function. It is also significant for the analysis of periodic structures such as gratings. We present a review of this new sampling criterion and the associated analysis. We clarifying its meaning and consider its applications. In particular, we consider the consequences of the analysis for fast LCT algorithms, and for the use of the discrete Fresnel transform in digital holography. We conclude that the spectral method of calculating Fresnel transforms may benefit greatly from recent advances to LCT sampling theory.
Modeling of the zigzag amplifier with exact 3D pixel matching
George N. Lawrence, Nadia Baranova, Anthony Yu
A method of full 3D modeling is described for a zigzag amplifier-a challenging computational problem. In a typical configuration with ten side wall reflections, a complex 3D distribution of population inversion develops because of the overlap regions. Unlike modeling a conventional straight-through laser amplifier, the zigzag amplifier requires about three orders of magnitude greater computation. Seven coupled differential equations are solved for perhaps ten million gain points sufficiently robustly to treat the extremes of Q-switching. A method of exact pixel matching and Frantz-Nodvik theory allows the full 3D problem to be solved in a few seconds on an ordinary PC.
Detectors
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Theoretical evaluation of MTF and charge collection efficiency in CCD and CMOS image sensors
Ibrahima Djité, Pierre Magnan, Magali Estribeau, et al.
Classical models used to calculate the Modulation Transfer function (MTF) of a solid-state image sensor generally use a sinusoidal type of illumination. The approach, described in this paper, consists in considering a point-source illumination to built a theoretical three-dimensional model of the diffusion and the collection of photo-carriers created within the image sensor array. Fourier transform formalism is used for this type of illumination. Solutions allow to evaluate the spatial repartition of the charge density collected in the space charge region, i.e. to get the Pixel Response Function (PRF) formulation. PRF enables to calculate analytically both MTF and crosstalk at every needed wavelengths. The model can take into account a uniformly doped substrate and an epitaxial layer grown on a highly doped substrate. The built-in electric field induced by the EPI/Substrate doping gradient is also taken into account. For these configurations, MTF, charge collection efficiency and crosstalk proportion are calculated. The study is established in the case of photodiode pixel but it can be easily extended to pinned photodiode pixels and photogate pixels.
Development of a human eye model for visual performance assessment
A biometry-based human eye model was developed by using the empirical anatomic and optical data of ocular parameters. The gradient refractive index of the crystalline lens was modeled by concentric conicoid isoindical surfaces and was adaptive to accommodation and age. The chromatic dispersion of homogeneous ocular media was described by Cauchy equations. The gradient equations for the refractive index of crystalline lens were modified at particular wavelengths according to the same dispersion model. Mie scattering was introduced to simulate volumetric light scattering in the crystalline lens. The optical performance of the eye model was evaluated in CodeV and ASAP and presented by the modulation transfer function (MTF) at single and multiple wavelengths. The chromatic optical powers obtained from this model matched that of physiological eyes. The scattering property was assessed by means of glare veiling luminance and compared with CIE general disability glare equation. This model is highly potential for investigating visual performance in ordinary lighting and display conditions and under the influence of glare sources.
Radiometry and Stray Light
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Stochastic modeling of non-Lambertian surfaces for Monte Carlo computations in optical radiometry
The accuracy of Monte Carlo calculations in optical radiometry is often limited by the reflection model employed (usually, diffuse (Lambertian), or simplified specular-diffuse). There are many cases when these models cannot adequately simulate the bidirectional reflection distribution functions (BRDFs) of real materials, which can call into question the results of the calculations. The features and the methods of modeling with the use of importance sampling for various materials are considered with a focus on an acceptance-rejection technique and on a procedural ab initio method. The Monte Carlo algorithms for modeling non-Lambertian reflection are discussed. The simulated and measured BRDFs for several materials are compared.
Stray light characteristics of the Large Synoptic Survey Telescope (LSST)
The Large Synoptic Survey Telescope (LSST) is a proposed large, ground-based telescope that can survey the entire visible sky every three nights to construct a detailed map of the universe while searching for faint and moving objects (www.lsst.org). Stray light control is important for optimum sensitivity over decades of stellar magnitude. A critical / illuminated object study of the baseline design identified several stray light mechanisms that required unique baffling approaches. Point source transmittance (PST) calculations over multiple azimuth angles quantify the stray light background levels and provide an indication of baffle effectiveness. Baffle design trades and their effect on stray light levels are discussed.
Assembly and Test
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Intensity distribution near focal point of high aperture optical system formed by partly polarized light
The paper presents the mathematical technique for calculation of three dimensional intensity distribution near a focal point of a high aperture optical system in case of quasi monochromatic partly polarized light. This technique is extension of the vector diffraction theory for high aperture optical systems. It is based on Huygens-Fresnel principle: spherical wave at an exit pupil is considered as a numerous set of elementary secondary partly polarized light sources. The total intensity is calculated as superposition of complex wave amplitudes taking into account polarization orientation, degree of polarization defined by Stokes parameters, orientation of detector aperture and coherence length of quasi-monochromatic light.
Modeling interferometers with lens design software: beyond ray-based approaches
Bryan D. Stone, Kevin P. Thompson
There are a variety of aspects of interferometers that can be well-modeled by using rays. For example, ray-based models allow predictions to be made regarding the changes to a measurement when aberrations are introduced into the input wavefront. However, there are other aspects that are more difficult (or impossible) to model well with ray-based approaches. For instance, when a surface under test is not conjugate to the detector, the effects due to diffraction from the edge of the surface cannot be modeled with ray-based approaches. Modern lens design software generally includes tools for modeling beam propagation. These tools can be used to go beyond conventional ray-based modeling of interferometers. In this paper, we demonstrate the utility of these beam propagation tools by modeling various aspects of a point-diffraction interferometer that go beyond solely ray-based approaches.
Statistical simulation of selectively assembled optical systems
Max C. Funck, Peter Loosen
Selective assembly is presently employed where fabrication of components to the required precision is infeasible, exceedingly expensive or if extremely high system performance is required. Even though these attributes frequently apply to optical systems, selective assembly is rarely applied. However, current investigations on selective assembly of microscope objectives can be found. A computer simulation approach has been taken to investigate the potential of selective assembly to optical systems, taking optic-specific influences and quality criteria into account. The process of selecting randomly distributed components and finding the best matches was modelled and integrated in ray-tracing simulations. Thus, the development environment originally used to design the optical system can also be used for the analyses. Components with parameters varying randomly according to their tolerance distributions are generated, possible component combinations created and entered in the ray-tracing simulation. Optimization steps can be employed accounting for alignment procedures or compensators. This procedure is repeated for sets of n components that shall be combined to exactly n systems. Out of all possible permutations the best set is chosen. Repetition of the experiment provides data for statistical analysis of the matching process. The method has been successfully applied to centration errors of a laser pump optic.
Thermal
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Fourier theory in temperature measurements
J. G. Suarez-Romero, J. L. Rodriguez-Valdelamar
The instruments in temperature measurements with infrared radiation are the radiation pyrometers or radiometers, some of them of double cavity and with or without imaging lenses. In the case of scale realizations is important to know the function of the instrument. In a previous work we published such a function for the case of instruments without lens considering the partial coherence theory. However the resulted expression consists of a four-fold integral which makes difficult its physical interpretation. In this work we present such functions for instruments with lenses and use Fourier techniques to obtain expressions easier to manipulate and to interpret. The instrument functions are evaluated and discussed its physical interpretation for both cases; with lenses and without lenses, through two practical examples.
Antenna performance predictions of a radio telescope subject to thermal perturbations
Antenna performance predictions and calibration times are estimated on a 37 m diameter radio telescope subject to thermal perturbations. The telescope is designed to operate at frequencies up to 325 GHz with a one-way performance requirement of 1 dB loss in gain accounting for fabrication, alignment, gravity and thermal errors. Thermal gradients acting over the antenna structure due to diurnal air temperature variations are a significant contributor to degradations in antenna performance. Integrated thermal-structural-optical analyses were performed to predict antenna performance as a function of the diurnal variations. Based on the results, design requirements were imposed on the radome thermal control system and the rate of calibration of the hexapod mounted subreflector.
Thermal performance prediction of the TMT telescope structure
Thermal analysis for the Thirty Meter Telescope (TMT) structure was performed using finite element analysis in ANSYS and I-DEAS. In the thermal analysis, the telescope structural parts with simplified optical assembly systems were modeled for various thermal conditions including air convections, conductions, heat flux loadings, and radiations. Thermal responses of the TMT telescope structure were predicted and the temperature distributions of the optical assembly systems were calculated under sample thermal loading conditions. The thermo-elastic analysis was made to obtain the thermal deformation based on the resulting temperature distributions. The line of sight calculation was made using the thermally induced structural deformations. The goal of this thermal analysis is to establish thermal models by the FEA programs to simulate for an adequate thermal environment. These thermal models can be utilized for estimating the thermal responses of the TMT structure. Thermal performance prediction of the TMT structure will be able to guide us to control and maintain the system from the "seeing" effects.
Adaptive Optics and Dynamics
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Investigation of primary mirror segment's residual errors for the Thirty Meter Telescope
The primary mirror segment aberrations after shape corrections with warping harness have been identified as the single largest error term in the Thirty Meter Telescope (TMT) image quality error budget. In order to better understand the likely errors and how they will impact the telescope performance we have performed detailed simulations. We first generated unwarped primary mirror segment surface shapes that met TMT specifications. Then we used the predicted warping harness influence functions and a Shack-Hartmann wavefront sensor model to determine estimates for the 492 corrected segment surfaces that make up the TMT primary mirror. Surface and control parameters, as well as the number of subapertures were varied to explore the parameter space. The corrected segment shapes were then passed to an optical TMT model built using the Jet Propulsion Laboratory (JPL) developed Modeling and Analysis for Controlled Optical Systems (MACOS) ray-trace simulator. The generated exit pupil wavefront error maps provided RMS wavefront error and image-plane characteristics like the Normalized Point Source Sensitivity (PSSN). The results have been used to optimize the segment shape correction and wavefront sensor designs as well as provide input to the TMT systems engineering error budgets.
Integrated Modeling
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Collaborative design and analysis of electro-optical sensors
Jason Geis, Jeff Lang M.D., Leslie Peterson, et al.
Complex products are best developed in a collaborative design environment where engineering data and CAD/CAE results can be shared across engineering discipline boundaries within a common software interface. A new software tool that allows Electro-Optical (EO) sensors to be developed in this manner has been used to conduct an integrated Structural/Thermal/Optical (STOP) analysis of a critical lens subassembly in a flight payload. This paper provides a description of the software environment and a summary of the technical results that were produced with it.
Poster Session
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Study on the distortion prediction of focal plate
Jianping Wang, Jiaru Chu, Hongzhuan Hu, et al.
The focal plate is one of the most important components of the LAMOST, whose shape precision to be centripetal and spherical structure of multi-hole. The hole drilling distortion duing to residual stress becomes one of the striking problems. Studying on the distortion prediction, this paper adopts the finite element simulation based on the metal cutting principles. The distribution to the surface residual stress is achieved by building the FEM model using ANSYS .The influence of cutting depths on the distortion of the focal plate was investigated. With the confirmation of the final CMM test result, the deviation which compared the measuring point with the theoretical sphere is less than 0.066mm. The result showed that the FEM analysis is an effective method which predicts the machining distortion of the focal plate.
Accuracy characteristics of the shift control optical-electronic measurement system
Andrey G. Anisimov, Andrey V. Krasnyashchikh, Alexander N. Timofeev, et al.
High accuracy shift control of the large-size constructions (such as turbine or radio telescopes elements) is one of the tasks that could be solved by means of the optical-electronic autoreflection measurement system. The description of the system built on the autoreflection optical scheme with CCD-sensor, its design, accuracy characteristics and testing results are presented. The point image center determination algorithm with accuracy within 0.05 pixel as well as coordinate system conversion method and the results of theoretical estimate of total system's accuracy are also described. Influence analysis of optical components decenterings on the system's total error and sighting line displacement is also described. It is shown that decentering of focusing optical element is the primary impact. Precision characteristics were approved during the experiment; total error did not exceed 0.1 mm at a distance of 20 m.