| Aero-Optic Measurements Using a Laser-Induced Air Breakdown Beacon (PrePrint) |
04-Jun-2009 |
14 pages |
| Authors:
Matthew Whiteley; R Rennie; Garnett Cross; David Goorseky; David Cavalieri; Eric J Jumper; MZA ASSOCIATES CORP DAYTON OH
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 | An experimental investigation into the optical behavior of a laser-induced air breakdown spark is described. The investigation concentrates on qualities of the air-breakdown spark, particularly the non-point-source character of the spark, that have a critical influence on the accuracy with which aero-optic aberration can be measured using the return light from the spark. Data are presented that show that the spark dimensions conform to established physical models, and baseline spark ... |
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| A New Sodium Guidestar Adaptive Optics System for the Starfire Optical Range 3.5 m Telescope (Postprint) |
18-May-2009 |
6 pages |
| Authors:
ROBERT JOHNSON; Dennis Montera; Timothy Schneeberger; James Spinhirne; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| A new adaptive optics is being installed on the Starfire 3.5 m telescope. Its uses the existing 50 watt pump to create a sodium guidestar. Transmission to the wavefront sensor is improved from 0.16 to 0.75. |
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| Next Generation Image Restoration for Space Situational Awareness |
09-Mar-2009 |
17 pages |
| Authors:
Stuart M Jefferies; Douglas A Hope; C A Giebink; HAWAII UNIV HONOLULU
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| The imaging of Earth-orbiting objects using large aperture telescopes equipped with adaptive optics is a critical component of Space Situational Awareness. Unfortunately, due to limitations in the adaptive optics, compensation of the wave-front distortions imparted by the Earth's turbulent atmosphere is incomplete. Achieving the quality of imagery necessary for high confidence monitoring of the near space environment, therefore requires the use of image restoration methods to remove the unconnected component ... |
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| Misregistration in Adaptive Optics Systems |
Mar-2009 |
79 pages |
| Authors:
Nathan Engstrom; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| An adaptive optics (AO) system is most effective when there is a known alignment between the wave front sensor (WFS)and the deformable mirror (DM). Misregistration is the term for the unknown alignment between the WFS and DM. Misregistration degrades system performance and can make the system unstable. An AO system uses a reconstruction matrix to transform WFS measurements into DM commands. A standard AO system uses a model reconstruction matrix ... |
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| Aero-Optics Code Development: Experimental Databases and AVUS Code Improvements |
Mar-2009 |
72 pages |
| Authors:
Scott E Sherer; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
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| Work has been performed in and coordinated by the Computational Sciences Branch to develop an in-house aero-optics predictive capability. This interim report summarizes the first two years of this effort. The work during this period has focused on acquiring high-quality experimental databases consisting of both aerodynamic and aero-optical measurements for future code validation, and the evaluation and improvement of the unstructured flow solver AVUS to solve representative flow fields. |
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| Modeling the Electrodynamics of the Low-Latitude Ionosphere |
01-Jul-2008 |
201 pages |
| Authors:
Christian S Wohlwend; UTAH STATE UNIV LOGAN
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| The electrodynamics of the Earth's low-latitude ionosphere is dependent on the ionospheric conductivity and the thermospheric neutral density, temperature, and winds present. This two-part study focused on the gravity wave seeding mechanism of equatorial plasma depletions in the ionosphere and the associated-equatorial spread F, as well as the differences between a two-dimensional flux tube integrated electrodynamics model and a three-dimensional model for the same time period. The gravity wave seeding ... |
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| A Level Set Based Geometrical Eulerian Approach to Computing High Frequency Radar Cross Sections and Multiphase Semiclassical Limits of the Schrodinger Equation |
30-Jun-2008 |
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| Authors:
Stanley Osher; LEVEL SET SYSTEMS INC PACIFIC PALISADES CA
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 | Wave propagation in the high frequency regime can be simplified using the geometrical optics approximation. We obtained an eikonal approximation for the phase and transport equations for the amplitude. The general strategy used to find the phase is to solve for its level sets, called wave fronts. This same strategy works to compute semiclassical solutions of Schrodinger's equation, which is the main topic we studied here. Traditional obstacles faced in ... |
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| Image Science Research for Speckle-based LADAR (Speckle Research for 3D Imaging LADAR) |
03 APR 2008 |
32 pages |
| Authors:
Nicholas George; ROCHESTER UNIV NY OFFICE OF RESEARCH AND PROJECT ADMINISTRATION
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| We propose a basic study of image science topics related to a new class of speckle-based laser-ranging radars (LADAR). For this imaging radar we study two basic system configurations: a wavefront sensing configuration and an imaging configuration. Three major research projects are (1) study of speckle patterns to establish 3D qualitative features for a remote object (2) study of performance of this compact ladar at photon counting light levels and ... |
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| Uniform in Time Asymptotic and Numerical Methods for Propagation in Dielectric Exhibiting Fractional Relaxation and Efficient and Accurate Impedance Boundary Conditions for High-Order Numerical Schemes for the Time-Dependent Maxwell Equations |
14 MAR 2008 |
17 pages |
| Authors:
Peter G. Petropoulos; NEW JERSEY INST OF TECH NEWARK DEPT OF MATHEMATICS
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| In this paper we examine the small- and large-depth response of a Cole-Cole dielectric half-space subjected to a prescribed incident pulse; the case of delta-function incidence is employed to determine and analyze the resulting impulse response. Our purpose is to contrast our findings to the corresponding ones obtained for the Debye model in order to ascertain whether the time-domain waveforms obtained in a TDR experiment could serve as a means ... |
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| Limitations of Segmented Wavefront Control Devices in Emulating Optical Turbulence |
MAR 2008 |
111 pages |
| Authors:
Michael D. Plourde; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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| Using a device to act as a surrogate for atmospheric turbulence in a laboratory is necessary to build and test optical systems for imaging, lidar, laser weapons, and laser communications. Liquid-crystal spatial light modulators (LC SLMs) and segmented micro-electro-mechanical-system (MEMS) deformable mirrors (DMs) are commonly used devices for altering wavefronts in order to simulate a portion of atmospheric turbulence. The best location of these devices was theoretically analyzed to obtain ... |
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| Adaptive Optics Performance Model for Optical Interferometry |
10 JUL 2007 |
11 pages |
| Authors:
D. Mozurkewich; S. R. Restaino; J. T. Armstrong; G. C. Gilbreath; NAVAL RESEARCH LAB WASHINGTON DC OPTICAL SCIENCES DIV
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| The optical interferometry community has discussed the possibility of using adaptive optics (AO) on apertures much larger than the atmospheric coherence length in order to increase the sensitivity of an interferometer, although few quantitative models have been investigated. The aim of this paper is to develop an analytic model of an AO-equipped interferometer and to use it to quantify, in relative terms, the gains that may be achieved over an ... |
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| Modeling of Sound Wave Propagation in the Random Deep Ocean (Briefing Charts) |
Apr-2007 |
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| Authors:
Jin S Xu; John Colosi; Tim Duda; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| These briefing charts cover the following topics: Ocean Environmental Measurements; Sound Wave Fluctuation Measurements; Modeling of Acoustic Wave Propagating through Random Deep Ocean; Garret & Munk Internal Wave Spectrum; Rytov Theory; Monte Carlo Numerical Simulations; and Comparison: Observations, Theory and Monte Carlo Simulations. |
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| An Improvement to the Fourier Series Method for Inversion of Laplace Transforms Applied to Elastic and Viscoelastic Waves |
JAN 2007 |
24 pages |
| Authors:
Richard R. Laverty; George A. Gazonas; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| A parametric study of composite strips leads to systems of partial differential equations, coupled through interface conditions, that are naturally solved in Laplace transform space. Because of the complexity of the solutions in transform space and the potential variations due to geometry and materials, a systematic approach to inversion is necessarily numerical. The Dubner-Abate-Crump (DAC) algorithm is the standard in such problems and is implemented. The presence of discontinuous wavefronts ... |
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| High Energy Laser Progressive Wavefront Modeling |
09 DEC 2006 |
28 pages |
| Authors:
Donald M. Needham; Michael J. Izbicki; NAVAL ACADEMY ANNAPOLIS MD DEPT OF COMPUTER SCIENCE
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| High energy lasers have the potential to revolutionize naval warfighting by providing a weapons platform that has greater precision and speed than anything currently available. These lasers can be mounted on ships for surface warfare or mounted on satellites for strikes anywhere around the world. Crucial to the development of these lasers is an understanding of how different atmospheric conditions affect the laser's propagation and the shape of the beam ... |
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| Center for Advanced Sensors, Year One Funding (FY2005) |
30 OCT 2006 |
76 pages |
| Authors:
Carl Halford; Stacie Patterson; MEMPHIS UNIV TN
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| The Center for Advanced Sensors presents the research results for the first year of effort. Research is reported on networked sensors, modeling performance for sensors with image processing enhancements, THz imager modeling, mammalian vision, infrared displays, and wavefront sensors. The Annual Program Plan goals and objectives were met. Milestones included: (1) building an ontology-based, knowledge repository of representative sensors, (2) establishing methodology for incorporating image processing techniques into existing performance ... |
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| How Important is Oblique Vision in Aviation? |
15 AUG 2006 |
24 pages |
| Authors:
Cheng-Jong Chang; TRI-SERVICE GENERAL HOSPITAL TAIPEI (TAIWAN)
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| (A) We propose a basic system layout that combines with the microdisplay for contrast sensitivity function measurement. The optical components need to be modified to eliminate the aberrations. (B) We made the power and control electronics for this system that increase the capabilities to build the specific deformable pattern by our self. (C) We measured the interferences patterns for the deformable mirror and build the influences matrix (D) We did ... |
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| Intensity Redistribution for Multiconjugate Adaptive Optics (postprint) |
10 AUG 2006 |
11 pages |
| Authors:
Troy Rhoadarmer; Jr. Beckner Charles C.; Laura M. Klein; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| Multi-Conjugate Adaptive-Optical (MCAO) systems have been proposed as a means of compensating both intensity and phase aberrations in a beam propagating through strong-scintillation environments. Progress made on implementing a MCAO system at the Starfire Optical Range (SOR), Air Force Research Laboratory, Kirtland AFB, is discussed. As a preliminary step toward controlling a two Deformable Mirror (DM) system, the first-stage intensity redistribution experiment (FIRE) examines one aspect of an MCAO system-control ... |
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| Computational Methods in Advanced Imaging Sciences |
31 MAY 2006 |
11 pages |
| Authors:
Curtis R. Vogel; MONTANA STATE UNIV BOZEMAN MONTANA DEPT OF MATHEMATICAL SCIENCES
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| The broad objective of this project was the development of efficient computational algorithms to solve important problems in optical imaging. This provided support for the Air Force's Partnerships for Research Excellence and Transition (PRET) in Advanced Imaging Sciences, whose goal was to enhance space situational awareness capabilities. The project focused on an advanced optical image enhancement technology known as adaptive optics. Specific goals were to develop fast algorithms for wavefront ... |
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| Multi-Dimensional Wave Front Sensing Algorithms for Embedded Tracking and Adaptive Optics Applications |
MAR 2006 |
157 pages |
| Authors:
Christopher C. Wood; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| Current tracking and adaptive optics techniques cannot compensate for fast-moving extended objects, which is important for ground-based telescopes providing space situational awareness. To fill this need, a vector-projection maximum-likelihood wave-front sensing algorithm development and testing follows for this application. A derivation and simplification of the Cramer-Rao Lower Bound for wavefront sensing using a laser guide star bounds the performance of these systems and guides implementation of a vastly optimized maximum-likelihood ... |
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| Comparison of Climatological Optical Turbulence Profiles to Standard, Statistical and Numerical Models Using Heleeos |
MAR 2006 |
117 pages |
| Authors:
Liesebet E. Gravley; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| Optical turbulence within earth's atmosphere plays a significant role in electromagnetic radiation propagation from a high energy laser. The index of refraction structure constant, Cn2, characterizes turbulent spatial fluctuations due to temperature gradients. These changes in the index of refraction affect the intensity of the laser wave front on its intended target. It is important to characterize this parameter throughout the atmosphere, the boundary layer and above, for its applications ... |
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| High-Frequency Electromagnetic Propagation/Scattering Codes |
31 DEC 2005 |
160 pages |
| Authors:
MONOPOLE RESEARCH THOUSAND OAKS CA
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| The objective of our effort was to develop computational methods for constructing high-frequency asymptotic solutions in scattering on perfectly conducting objects. The emphasis of the first stage of our work was to describe high frequency phenomena in terms of numerically implemented evolution of wavefronts associated with the propagating waves. The wavefront evolution algorithm is implemented for the leading high frequency mechanisms including: free-space propagation, reflection on smooth surfaces, wave-front splitting ... |
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| Optical Beam Control Using Adaptive Optics |
DEC 2005 |
93 pages |
| Authors:
Lisa McLaughlin; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Adaptive optics is a new and growing research area aimed at creating high-quality imagery by correcting aberrations in optical systems caused by turbulence in the earth s atmosphere. This paper concentrates on the basics of physical optics leading into the design of an adaptive optics test bed to study the correction of aberrations using optical beam control. Adaptive optics requires the use of sophisticated optical equipment such as deformable mirrors ... |
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| High Frequency Electromagnetic Propagation/Scattering Codes |
DEC 2005 |
160 pages |
| Authors:
Thomas Jaroszewicz; Elizabeth Bleszynski; Marek Bleszynski; MONOPOLE RESEARCH THOUSAND OAKS CA
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| The objective of our effort was to develop computational methods for constructing high-frequency asymptotic solutions in scattering on perfectly conducting objects. The emphasis of the first stage of our work was to describe high frequency phenomena in terms of numerically implemented evolution of wave-fronts associated with the propagating waves. The wave-front evolution algorithm is implemented for the leading high frequency mechanisms including: free-space propagation, reflection on smooth surfaces, wave-front splitting ... |
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| Wide-Angle Multistatic Synthetic Aperture Radar: Focused Image Formation and Aliasing Artifact Mitigation |
28 SEP 2005 |
371 pages |
| Authors:
Jonathan E. Luminati; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| Traditional monostatic Synthetic Aperture Radar (SAR) platforms force the user to choose between two image types: larger, low resolution images or smaller, high resolution images. Switching to a Wide-Angle Multistatic Synthetic Aperture Radar (WAM-SAR) approach allows formation of large high-resolution images. Unfortunately, WAM-SAR suffers from two significant implementation problems. First, wavefront curvature effects, non-linear flight paths, and warped ground planes lead to image defocusing with traditional SAR processing methods. A ... |
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| Failure Fronts in Brittle Materials and Their Morphological Instabilities |
SEP 2005 |
16 pages |
| Authors:
Michael A. Grinfeld; Scott E. Schoenfeld; Tim W. Wright; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| This report outlines the results of the effort to suggest a theoretical method of describing failure fronts in glasses and ceramics. There are various observations and experiments showing that in addition to standard shock-wave fronts, which propagate with transonic velocities, other much slower wave fronts can propagate within glass or ceramic substances undergoing intensive damage. These moving fronts propagate into intact substance, leaving intensively damaged substance behind them. They have ... |
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| Experimental Validation of Detonation Shock Dynamics in Condensed Explosives |
AUG 2005 |
6 pages |
| Authors:
David E. Lambert; D. S. Stewart; Sunhee Yoo; Bradley Wescott; AIR FORCE RESEARCH LAB EGLIN AFB FL MUNITIONS DIRECTORATE
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| Experiments on the HMX-based, condensed explosive PBX-9501 were carried out to validate a reduced asymptotically derived description of detonation shock dynamics (DSD). The experiments, coined passover experiments' have embedded disks of lead in right circular cylinders of PBX-9501. A range of dynamically changing states, with both divergent and convergent shock shapes are realized as a detonation front is created on one end of the cylinder and passes over the embedded ... |
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| Performance Measurements of a Self-Referencing Interferometer Wavefront Sensor with Optical Amplification (Preprint) |
29 JUL 2005 |
10 pages |
| Authors:
Laura Klein; Troy A. Rhoadarmer; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
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| The Self-referencing Interferometer Wavefront Sensor (SRI WFS) has been shown to outperform conventional wavefront sensors in strong scintillation environments. Recently, the Starfire Optical Range has developed a prototype SRI to evaluate its performance. This paper discusses the purposes of optically amplifying the reference beam. Specifically, it addresses regions of operation where gain improves signal-to-noise ratio (SNR) values, and thus the SRI WFS performance. Conditions are also addresses when Amplified Spontaneous ... |
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| Performance Measurements of a Self-Referencing Interferometer Wavefront Sensor with Optical Amplification--Briefing Charts (Preprint) |
29 JUL 2005 |
18 pages |
| Authors:
Laura Klein; Troy A. Rhoadarmer; AIR FORCE RESEARCH LAB KIRTLAND AFB NM DIRECTED ENERGY DIRECTORATE
|
| The Self-referencing Interferometer Wavefront Sensor (SRI WFS) has been shown to outperform conventional wavefront sensors in strong scintillation environments. Recently, the Starfire Optical Range has developed a prototype SRI to evaluate its performance. This paper discusses the purposes of optically amplifying the reference beam. Specifically, it addresses regions of operation where gain improves signal-to-noise ratio (SNR) values, and thus the SRI WFS performance. Conditions are also addresses when Amplified Spontaneous ... |
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| Evaluation of Acoustic Propagation Paths into the Human Head |
01 APR 2005 |
25 pages |
| Authors:
Jr. O'Briend William D.; Yuhui Liu; ILLINOIS UNIV AT URBANA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
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| The overall goal has been to develop an acoustic wave propagation model using well-understood and documented computational techniques that track and quantify an air-borne incident acoustic wave propagated around, into and in the human head. This model serves as a computational tool to elucidate the acoustic wave propagation around, into and in the human head. Specifically, the model determines two features: (1) alternate acoustic propagation paths to the cochlear shell ... |
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| Detection and Diagnostics of a Coronal Shock Wave Driven by a Partial-Halo Coronal Mass Ejection on 2000 June 28 |
10 MAR 2005 |
9 pages |
| Authors:
A. Ciaravella; J. C. Raymond; S. W. Kahler; A. Vourlidas; J. Li; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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| A fast partial-halo coronal mass ejection (CME) was observed on 2000 June 28 by instruments on the SOHO spacecraft. The CME leading edge and filamentary cold core were detected over the northwest limb at 2.32 R(circle dot solar) by the SOHO UV Coronagraph Spectrometer (UVCS). The broad profile of the O VI lambda-1032 line gives evidence of a shock front at the leading edge, supporting the identification of white-light CME ... |
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| Dynamic Characterization of Thin Deformable PVDF Mirror |
MAR 2005 |
151 pages |
| Authors:
Eric M. Trad; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| Methodology for the design and fabrication of 5 inch diameter membrane-like mirror structures is explored, resulting in test articles with areal densities as low as 1.57 kg/m2 and a thickness of 1.5 mm. Each optical structure has 7 control patches etched into the PVDF layer, which can be used as actuators. These test articles are utilized to demonstrate the capabilities of an acquisition system to make measurements of static and ... |
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| High Brightness Imaging for Real Time Measurement of Shock, Particle, and Combustion Fronts Produced by Enhanced Blast Explosives |
DEC 2004 |
9 pages |
| Authors:
Kevin L. McNesby; Barrie E. Homan; Richard E. Lottero; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| High brightness imaging (HBI) has been used to study the structure of the leading shock, particles immediately behind the leading shock, and the following contact surface of combustion front (i.e., the "fireball") produced during testing of enhanced blast explosives (two kg main charge weight) in real time. These measurements are preliminary, as only six different explosives formulations were tested. However, results show that HBI can provide valuable information regarding the ... |
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| Numerical Modelling of Electromagnetic Wave Propagation and Scattering: High-Order Schemes, Impedance Boundary Conditions and Cole-Cole Dielectrics |
12 SEP 2004 |
19 pages |
| Authors:
Peter G. Petropoulos; NEW JERSEY INST OF TECH NEWARK DEPT OFMATHEMATICS
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| Paper #1 was listed in the report for Grant F49620-99-1-0072 as "to appear" and the work presented there was described previously. In paper #2 we presented an analysis of the perfectly matched layer in cylindrical coordinates discretized with a staggered second-order accurate finite difference time domain method. In paper #3 we conclusively addressed the long-standing issue of the long-time stability of the unsplit Perfectly Matched Layer. In paper #4 we ... |
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| Three-Dimensional Structure of Turbulent Scalar Fields with Applications in Aerooptics |
12 APR 2004 |
19 pages |
| Authors:
Paul E. Dimotakis; Christopher Martin; CALIFORNIA INST OF TECH PASADENA GRADUATE AERONAUTICAL LABS
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| This program aimed to develop an interferometric technique for mitigating the effects of turbulence on visible-light imaging, complementary to techniques such as Adaptive Optics (AO) or speckle imaging. This technique employs a rotation shearing interferometer and high-speed, low-noise digital imaging system. Where an AO system would employ a complex high-bandwidth, electro-mechanical system to mitigate the effects of turbulence, this interferometric technique relies on a novel (low-cost) optical design, high- speed ... |
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| A Novel Wave Front Method Used for Tracking Terrestrial Concentrator Focal Spot Location |
26 MAR 2004 |
13 pages |
| Authors:
Joseph N. Beasley; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
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| This paper presents a new sensing method for tracking terrestrial concentrator focal spot location. The new method utilizes the shape and mirror- like surfaces of the absorber as a wave front sensor. The paper begins with a discussion of wave front sensing and how it can be used in optical systems to measure phase differences in light waves across an aperture. The wave front sensing method is then modified from ... |
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| Simulating a Chromotomographic Sensor for Hyperspectral Imaging in the Infrared |
MAR 2004 |
156 pages |
| Authors:
Anthony J. Dearinger; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| Hyperspectral imaging systems passively sense radiant electromagnetic energy from a remote scene to form a three dimension profile of the remote scene. The data contained in this profile describes real images of the remote scene for a certain number of spectral wavelength bands across a finite spectral range of electromagnetic radiation. Typical grating type hyperspectral imaging systems collect spectral electromagnetic radiation in the visible and near infrared spectral range, by ... |
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| Multimillion Atom Simulations and Visualization of Hypervelocity Impact Damage and Oxidation |
2004 |
7 pages |
| Authors:
Priya Vashishta; Rajiv K. Kalia; Aiichiro Nakano; CALIFORNIA UNIV LOS ANGELES DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Large-scale molecular dynamics simulation involving several hundred million atoms has been performed on parallel computers to study hypervelocity impact damage of high - strength aluminum nitride ceramic, which is of great importance for the design of penetration-resistant and light-weight armors at the Army. Results reveal an atomistic mechanism of damage initiation i.e. the phase transformation wave front acts as a source of dislocations and micro- cracks upon the arrival of ... |
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| Adaptive Compensation of Atmospheric Turbulence in Ground-to-Ground Laser Communication Systems |
DEC 2003 |
54 pages |
| Authors:
Frederic M. Davidson; JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
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| Two silicon based devices were investigated for use as an optical wave-front sensor to provide error signal inputs to an adaptive optic wave-front control system intended to reduce the effects of atmospheric turbulence in ground-to-ground laser communication systems. One device was an active sensor array fabricated in CMOS. The other was a silicon photoconductive optical detector with surface electrodes expected to produce PEMF photocurrents in response to spatial motion of ... |
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| An Electromagnetic/Acoustic Propagation Experiment |
NOV 2003 |
13 pages |
| Authors:
H. T. Banks; NORTH CAROLINA STATE UNIV AT RALEIGH CENTER FOR RESEARCH IN SCIENTIFIC COMPUTATION
|
| We proposed experiments to investigate electromagnetic acoustic waves interaction as part of a technology for pulsed microwave interrogation of materials. The technology involves using reflections of electromagnetic pulses from moving acoustic wavefronts to detect the presence of and determine composition (dielectric and geometric) of hidden objects. Applications of interest to DoD involve non-invasive interrogation of tissue, look-down surveillance and camouflage penetration (e.g., tanks under trees, and subsurface mines and bunkers) ... |
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| Compact Adaptive Optics Systems 2 (CAOS-II) |
21 SEP 2003 |
17 pages |
| Authors:
Alan H. Greenaway; HERIOT-WATT UNIV EDINBURGH (UNITED KINGDOM) DEPT OF PHYSICS
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| This report results from a contract tasking Heriot-Watt University as follows: The contractor will (1) determine the conditions for construction of a null sensor using the phase-diversity principle and implemented using a diffractive optical element (DOE) and a single detector plane; (2) investigate and, if possible, quantify necessary conditions for the use of a null sensor based on phase-diversity and the use of DOEs; (3) investigate whether a null sensor ... |
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| Wave Propagation Over Complex Bathymetry |
JUN 2003 |
54 pages |
| Authors:
Timothy A. Ray; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Swell propagates across thousands of kilometers of ocean in almost unchanged parallel wave fronts. Within the nearshore region however, refraction causes wave fronts to turn toward shallow depths transforming the wave field. The Nearshore Canyon Experiment (NCEX) Pilot, conducted from October 10 to October 17, 2002, observed wave transformation across the Scripps and La Jolla canyon system near San Diego, CA. Four Datawell Directional Waverider Buoys, three Nortek Vector PUV ... |
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| Fluid-Optic Interactions III (Adaptive-Optic) |
10 FEB 2003 |
28 pages |
| Authors:
Eric J. Jumper; NOTRE DAME UNIV IN DEPT OF AEROSPACE AND MECHANICAL ENGINEERING
|
| This report describes fluid-optic interaction research at the University of Notre Dame. When a laser beam propagates through a variable-index- of-refraction, turbulent fluid, its wavefront becomes aberrated, reducing associated optical-system performance. For flight Mach numbers above 0.6 Mach, "compressibility" effects in the flow past the aircraft become important in aberrating wavefronts (aero-optics). This report presents experimental validation for the mechanism responsible for these aberrations in high, subsonic-Mach, free shear-layer flows, ... |
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| Performance Bounds on Atmospheric Acoustic Sensor Arrays Operating in a Turbulent Medium II, Spherical-Wave Analysis |
FEB 2003 |
40 pages |
| Authors:
Sandra L. Collier; D. K. Wilson; ARMY RESEARCH LAB ADELPHI MD
|
| The performance bounds of a passive acoustic array operating in a turbulent medium with fluctuations described by a von Karman spectrum are investigated. This treatment considers a single, monochromatic, spherical-wave source and a line-of-sight propagation path. The Cramer-Rao lower bounds of the wave-front angles of arrival are calculated for an unknown parameter set which includes the propagation distance, turbulence parameters, source phase, and signal-to-noise ratio. |
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| Liquid Crystal Technology for Adaptive Optics: an Update |
2003 |
7 pages |
| Authors:
Sergio R. Restaino; Don M. Payne; Jeff T. Baker; Jonathan R. Andrews; Scott W. Teare; G. C. Gilbreath; Dave Dayton; John Gonglewski; NAVAL RESEARCH LAB WASHINGTON DC REMOTE SENSING DIV
|
| The idea of using liquid crystal (LC) devices as an adaptive optics component has been proposed by several authors. In recent years a vigorous research effort has been carried out, and it is still flourishing, in several countries. Mainly the research and experimental work has been concentrated in the USA, U.K. and Russia. There are several reasons why liquid crystals may represent a valid alternative to the traditional deformable mirror ... |
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| Analysis of the Naval Observatory Flagstaff Station 1-m Telescope using Annular Zernike Polynomials |
2003 |
6 pages |
| Authors:
Sergio R. Restaino; Scott W. Teare; Michael Divittorio; G. C. Gilbreath; David Mozurkewich; NAVAL RESEARCH LAB WASHINGTON DC REMOTE SENSING DIV
|
| The Naval Observatory Flagstaff Station 1-m telescope is evaluated for the addition of adaptive optics capabilities to its instrumentation suite. Zernike decomposition of the optical system based on phase diversity measurements shows that the static optical aberrations are small enough that they will not degrade the performance of the deformable optical element. The analysis makes use of annular pupil Zernike polynomial reconstruction of the wavefront to accommodate the large obscuration ... |
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| Wavefront Coded Microscope and Real-Time Processor |
31 DEC 2002 |
12 pages |
| Authors:
Gregory E. Johnson; CDM OPTICS INC BOULDER CO
|
| A Wavefront Coded microscope and real-time processor were developed and tested Algorithms developed during this work lead to compact implementations yielding over 30 billion operations per second for reconstruction of a Wavefront Coded image Example results were obtained in the laboratory and provided in this report |
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| Improving the Performance of Air Force Adaptive Optics Systems Using High-Resolution Spatial Light Modulators with Deformable Mirrors: Final Report |
30 DEC 2002 |
43 pages |
| Authors:
Michael K. Giles; Mikhail Vorontsov; Michael Roggem; NEW MEXICO STATE UNIV LAS CRUCES
|
| This document presents a comprehensive technical summary of the most significant work accomplished on Air Force Office of Scientific Research Contract Number F49620-99-l-0342. Since closed loop wave front control (WFC) systems currently being developed by the Air Force have residual wave front errors that reduce image quality, New Mexico State University has developed methods to reduce those residual errors and improve the quality (Strehl ratio) of Air Force WFC systems. ... |
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| Development of High Frequency Numerical Simulation Tools for Electromagnetic Scattering and Radiation Problems in Frequency and Time Domain |
04 NOV 2002 |
85 pages |
| Authors:
Elizabeth H. Bleszynski; Marek K. Bleszynski; Thomas Jaroszewicz; MONOPOLE RESEARCH THOUSAND OAKS CA
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| Report developed under STTR contract for topic AF01-T009. The main objective of the Phase I effort was to setup a framework for the wavefront (WF) evolution technique and to investigate the feasibility of incorporating, in a fashion consistent with reciprocity, of the edge diffraction effects into the WF approach. A wavefront is defined as a surface on which the propagating fields have a constant phase. Main advantages of the WF ... |
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| Quasi-static Tearing Tests of Metal Plating |
SEP 2002 |
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| Authors:
Jeffrey C. Woertz; MASSACHUSETTS INST OF TECH CAMBRIDGE
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| Great effort is being focused on making the next generation of naval combatant ships more resistant to the effects of close-aboard explosions. The examination of the deformation modes in blast-loaded metal plating suggests that a physical model can be developed to simulate the force vs. displacement history produced by an impinging shock wave during the holing phase. Similar approaches have been successfully used to approximate damage due to grounding and ... |
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| Compact Adaptive Optics Systems (CAOS) |
27 AUG 2002 |
11 pages |
| Authors:
A. H. Greenway; HERIOT-WATT UNIV EDINBURGH (UNITED KINGDOM) DEPT OF PHYSICS
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| As feasibility study has been conducted to investigate whether compact adaptive optical (AO) systems based on the use of transparent wavefront modulators are viable. The results presented here consider the generic properties of suitable wavefront sensor technologies and establish sufficient conditions for their exploitation. Schemes by means of which these properties might be exploited in a multi-conjugate AO system are then considered. It is shown that the prospects for such ... |
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Reports by Keyword(s)
WAVEFRONTS
