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conference on Advanced Wavefront Control - Methods, Devices, and Applications IV

作者： Teare, Scott W. Martinez, Ty Andrews, Jonathan R. Wilcox, Christopher C. Restaino, Sergio R. Romeo, Robert Martin, Robert Payne, Don M. New Mexico Inst Min & Technol Dept Elect Engn 801 Leroy Pl Socorro NM 87801 USA US Naval Remote Sensing Div Res Lab Kirtland AFB NM 87117 USA Composite Mirror Applicat 1638 S Res Loop Tucson AZ 85710 USA Narrascape Inc Albuquerque NM 87106 USA

ISBN: (纸本)081946385X

Adaptive optics systems are commonly added onto conventional astronomical telescopes to improve the wavefront quality in the presence of atmospheric turbulence. Recent successes in the development of carbon fiber reinforced polymer telescopes have significantly reduced the weight of meter class telescopes making them portable, however, most adaptive optics systems continue to be constructed on large optical benches. The Navy Prototype optical Interferometer is developing several 1.4 m portable telescope with internal wavefront correction. As part of this upgrade, a prototype 0.4 m aperture telescope has been constructed and a light weight, compact adaptive optics system is being developed. We present in this paper the design of an adaptive optics system for the lightweight telescope. The key to this system is the incorporation of a compact wavefront correction device and a novel collimation optic within the base of the telescope.

关键词： light weight telescope adaptive optics

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optical derotator for scanning vibrometer measurements on rotating objects

Optical derotator for scanning vibrometer measurements on ro...

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7th International conference on Vibration Measurements by Laser Techniques

作者： Boedecker, Sebastian Draebenstedt, Alexander Heller, Lars Kraft, Arne Leonhardt, Andreas Pape, Christian Ristau, Sergej Reithmeier, Eduard Rembe, Christian Polytec GmbH R&D Polytec Pl 1-7 D-76337 Waldbronn Germany Leibniz Univ Hannover Inst Mess & Regelungstech D-30167 Hannover Germany

ISBN: (纸本)081946421X

In this paper we present an optical derotator for scanning vibrometer measurements on rotating objects. The main part of an optical derotator is a rotating prism. Several concepts are known from literature. We have chosen a Dove prism because it can derotate the rotation of the specimen by simply watching through the prism, which rotates with half the speed. The design of our derotator is presented in this paper as well as a discussion of the system performance. In addition we show experimental measurement results on a fan rotating with 3000 rpm.

关键词： Prisms Tolerancing Control systems Fluctuations and noise Electronics optics manufacturing Computer programming optical simulations Beam splitters Vibrometry

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Acceleration of AO simulation using programmable logic

Acceleration of AO simulation using programmable logic

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conference on Advances in Adaptive optics II

作者： Basden, Alastair G. Wilson, Richard W. Assemat, Francois Bharmal, Nazim A. Butterley, Timothy Geng, Deli Goodsell, Stephen J. Harrison, Mark A. Morris, Tim J. Myers, Richard M. Saunter, Chris D. Univ Durham Dept Phys Ctr Adv Instrumentat South Rd Durham DH1 3LE England

ISBN: (纸本)081946337X

Numerical Simulation is an essential part of the design and optimisation of astronomical adaptive optics systems. Simulations of adaptive optics are computationally expensive and the problem scales rapidly with telescope aperture size, as the required spatial order of the correcting system increases. Practical realistic simulations of AO systems for extremely large telescopes are beyond the capabilities of all but the largest of modern parallel supercomputers. Here we describe a more cost effective approach through the use of hardware acceleration using field programmable gate arrays. By transferring key parts of the simulation into programmable logic, large increases in computational bandwidth can be expected. We show that the calculation of wavefront sensor images (involving a 2D FFT, photon shot noise addition, background and readout noise), and centroid calculation can be accelerated by factor of 400 times when the algorithms are transferred into hardware. We also provide details about the simulation platform and framework that we have developed at Durham.

关键词： Adaptive optics Numerical simulation FPGAs hardware acceleration reconfigurable logic high performance computing

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Flow-induced birefringence: the hidden PSF killer in high performance injection-molded plastic optics

Flow-induced birefringence: the hidden PSF killer in high pe...

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conference on Endoscopic Microscopy

作者： Chidley, Matthew D. Tkaczyk, Tomasz Kester, Robert Descour, Michael R. Univ Arizona Coll Opt Sci 1630 E Univ Blvd Tucson AZ 85721 USA

ISBN: (纸本)0819461245

A 7-mm OD, NA = 1 water immersion injection-molded plastic endoscope objective has been fabricated for a laser scanning fiber confocal reflectance microscope (FCRM) system specifically designed for in vivo detection of cervical and oral pre-cancers. Injection-molded optics was selected for the ability to incorporate aspheric surfaces into the optical design and its high volume capabilities. Our goal is high performance disposable endoscope probes. This objective has been built and tested as a stand-alone optical system, a Strehl ratio greater than 0.6 has been obtained. One of the limiting factors of optical performance is believed to be flow-induced birefringence. We have investigated different configurations for birefringence visualization and believe the circular polariscope is most useful for inspection of injection-molded plastic optics. In an effort to decrease birefringence effects, two experiments were conducted. They included: (1) annealing of the optics after fabrication and (2) modifying the injection molding parameters (packing pressures, injection rates, and hold time). While the second technique showed improvement, the annealing process could not improve quality without physically warping the lenses. Therefore, to effectively reduce flow-induced birefringence, molding conditions have to be carefully selected. These parameters are strongly connected to the physical part geometry. Both optical design and fabrication technology have to be considered together to deliver low birefringence while maintaining the required manufacturing tolerances. In this paper we present some of our current results that illustrate how flow-induced birefringence can degrade high performance injection-molded plastic optical systems.

关键词： birefringence injection-molded optics plastic optics

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FPGA developments for the SpartA project: part 2

FPGA developments for the SPARTA project: Part 2

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conference on Advances in Adaptive optics II

作者： Goodsell, S. J. Geng, D. Fedrigo, E. Soenke, C. Donaldson, R. Saunter, C. D. Myers, R. M. Basden, A. G. Dipper, N. A. Univ Durham Dept Phys Ctr Adv Instrumentat S Rd Durham DH1 3LE England European So Observ D-85748 Garching Germany

ISBN: (纸本)081946337X

The European Southern Observatory (ESO) and Durham University's Centre for Advanced Instrumentation (CfAI) continue to progress the design of a next generation Adaptive optics (AO) Real-Time Control System (RTCS). This common flexible platform, labelled SpartA 'Standard Platform for Adaptive optics Real-Time Applications' will control the AO systems for a set of 2(nd) generation VLT instrumentation, and will scale to implement the initial AO systems for the European Extremely Large Telescope (E-ELT). Durham has used Field Programmable Gate Arrays (FPGA) to design a front-end Wavefront Sensor (WFS) Processing Unit (WPU) for SpartA. FPGA devices have been used to alleviate the highly parallel computationally intensive WPS processing task from system processors to increase the obtainable control loop frequency and reduce the computational latency in the control system. The FPGA device reduces WFS frames to gradient vectors before passing the data to the system processors. The FPGA allows the processors to deal with other tasks such as wavefront reconstruction, telemetry and real-time data recording, allowing for more complex adaptive control algorithms to be executed. Durham has design, coded, implemented and tested a FPGA core incorporating the VITA 17.1 standard serial Front Panel Data Port (sFPDP) protocol to allow a data transfer rate of 2.5Gbps(-1) from the WFS Controller to the SpartA platform. This paper overviews the SpartA WPU requirements and design, the sFPDP FPGA Core and a description of the platform's implementation phase.

关键词： AO SpartA Durham RTCS FPGA

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Unconventional optical imaging using a high speed, neural network based smart sensor - art. no. 62310B

Unconventional optical imaging using a high speed, neural ne...

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conference on Unattended Ground, Sea, and Air Sensor Technologies and Applications VIII

作者： Arrasmith, William W. Florida Inst Technol Melbourne FL 32901 USA

ISBN: (纸本)081946287X

The advancement of neural network methods and technologies is finding applications in many fields and disciplines of interest to the defense, intelligence, and homeland security communities. Rapidly re-configurable sensors for real or near-real time signal or image processing can be used for multi-functional purposes such as image compression, target tracking, image fusion, edge detection, thresholding, pattern recognition, and atmospheric turbulence compensation to name a few. A neural network based smart sensor is described that can accomplish these tasks individually or in combination, in real-time or near real-time. As a computationally intensive example, the case of optical imaging through volume turbulence is addressed. For imaging systems in the visible and near infrared part of the electromagnetic spectrum, the atmosphere is often the dominant factor in reducing the imaging system's resolution and image quality. The neural network approach described in this paper is shown to present a viable means for implementing turbulence compensation techniques for near-field and distributed turbulence scenarios. Representative high-speed neural network hardware is presented. Existing 2-D cellular neural network (CNN) hardware is capable of 3 trillion operations per second with peta-operations per second possible using current 3-D manufacturing processes. This hardware can be used for high-speed applications that require fast convolutions and de-convolutions. Existing 3-D artificial neural network technology is capable of peta-operations per second and can be used for fast array processing operations. Methods for optical imaging through distributed turbulence are discussed, simulation results are presented and computational and performance assessments are provided.

关键词： horizontal path imaging adaptive optics image reconstruction cellular neural networks turbulence compensation image processing

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Optimal selection of aspheric surfaces in optical design

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optics EXPRESS 2005年第18期13卷 7233-7242页

作者： Yabe, A Schwaighofstr 34 D-86899 Landsberg Germany

optical systems frequently use aspheric surfaces to improve performance. Typically the designer uses a combination of experience and trail and error to decide which surfaces to make aspheric, then the shape of the aspheric surface is optimized as part of the optical system. In this paper, a method of optimally choosing which surfaces are to be made aspheric is developed. This is implemented by allowing the surface number of the asphere to become a variable in the optimization. Imaginary surfaces are used as an intermediary to make the problem continuous for the optimization. The method of implementation and design examples are given. (c) 2005 optical Society of America

关键词： .selection imaginary optical systems lenses lens design global optimization aspherical eds Proc spie optical design aspheric surface surface number Aspherics design conference International optical escape function

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Laser countermeasures for commercial airlines

Laser countermeasures for commercial airlines

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conference on optics and Photonics in Global Homeland Security

作者： Keirstead, B BAE SYST Nashua NH USA

ISBN: (纸本)0819457663

Since the attempted shoot down of an Israeli airliner departing from Mombasa, Kenya in November of 2002, there has been heightened concern that Al Qaeda, or other terrorist factions, will use shoulder-fired heat seeking missiles as part of their tactics. These weapons, known more formally as man-portable air defense systems, or MANPADS, have been widely proliferated, are easy to conceal and deploy, and can be purchased on the black market for as little as $10,000. Recognizing that MANPADS pose a potential threat to commercial airplanes throughout the world, the Department of Homeland Security (DHS) is executing a system design and development (SDD) program to evaluate the viability of missile countermeasures that would be installed on commercial airplanes. This paper provides an overview of the MANPADS threat, a discussion of associated countermeasure requirements for systems installed on commercial airplanes, and a description of a laser countermeasure system that is being prototyped and demonstrated as part of the DHS Counter-MANPADS program.

关键词： Missiles Laser countermeasures Directed infrared countermeasures Homeland security Weapons Receivers Infrared radiation Sensors Aluminum Laser systems engineering

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design of a low-power wireless structural monitoring system for collaborative computational algorithms

Design of a low-power wireless structural monitoring system ...

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conference on Health Monitoring and Smart Nondestructive Evaluation of Structural and Biological systems IV

作者： Wang, Y Lynch, JP Law, KH Stanford Univ Dept Civil & Environm Engn Stanford CA 94305 USA

ISBN: (纸本)0819457493

In this study, a new wireless sensing unit for operation within an automated Structural Health Monitoring (SHM) system is proposed, designed and validated. The design of the wireless sensing unit emphasizes minimization of its power consumption characteristics to ensure it is suited for long-term field deployment in civil structures. The wireless modem integrated with the unit has a long communication range that permits wireless sensors to be spaced over 100m apart. A multi-channel high-resolution analog-to-digital converter is included within each sensing unit to provide flexibility for high-fidelity data collection. A key feature of the wireless sensing unit design is the inclusion of a sophisticated computing core that is capable of locally executing engineering algorithms in real-time. As pail of the embedded software.. a novel communication protocol is written that can accomplish low-latency communications for accurate time synchronization between spatially distributed wireless sensors. To illustrate the capabilities of the wireless monitoring platform, including the execution of extensive computational tasks, a prototype system is fabricated and tested in the laboratory and field. As part of validating the system performance in the field, the vertical acceleration response of the Geumdang Bridge under traffic loading is measured by 14 wireless sensing unit prototypes.

关键词： wireless structural monitoring wireless sensor networks structural health monitoring modal testing

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Study on the application of Fiber Bragg Grating sensors for the containment structures of nuclear power plants

Study on the application of Fiber Bragg Grating sensors for ...

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Smart Structures and Materials 2005 conference

作者： Kim, KS Song, YC Pang, GS Yoon, DJ Hoseo Univ Dept Innovat Ind Technol Asan 336795 South Korea

ISBN: (纸本)0819457469

In this paper, a Fiber Bragg Grating (FBG) sensor system for smart structures is described. FBGs are well-suited for long term and extremely severe experiments, where traditional strain gauges fail. In the system, a reflect wavelength measurement method which employs a tunable light source to find out the center wave-length of FBG sensor is used. The real field test was performed to verify the behaviors of fiber Bragg grating (FBG) sensors attached to the containment structure in Uljin nuclear power plant as a part of structural integrity test which demonstrates that the structural response of the non-prototype primary containment structures within predicted limits plus tolerances when pressurized to 115 % of containment design pressure, and that the containment does not sustain any structural damage. The system works very well and it is expected that it can be used for a real-time strain, temperature and vibration detector of smart structure.

关键词： Fiber Bragg gratings Sensors Fiber optics sensors Computing systems Lead optical design Smart structures Signal processing Tolerancing Light sources

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