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Modeling And Simulation Of Optical Characteristics Of Microelectromechanical Mirror Arrays, Peter C. Roberts
Modeling And Simulation Of Optical Characteristics Of Microelectromechanical Mirror Arrays, Peter C. Roberts
Theses and Dissertations
MEMS (Micro-Electro-Mechanical Systems) micromirror devices can be used to control the phase of a propagating light wavefront, and in particular to correct aberrations that may be present in the wavefront, due to either atmospheric turbulence or any other type of fixed or time and space varying aberrations. In order to shorten the design cycle of MEMS micromirror devices, computer software is developed to create, from MEMS micromirror device design data, a numerical model of the MEMS device. The model is then used to compute the far field diffraction pattern of a wavefront reflected from the device, and to predict the …
Demonstrating Optical Aberration Correction With A Mems Micro-Mirror Device, Shaun R. Hick
Demonstrating Optical Aberration Correction With A Mems Micro-Mirror Device, Shaun R. Hick
Theses and Dissertations
This research conducted the first demonstrated use of a micro-electro-mechanical structure (MEMS) mirror array to correct a static optical aberration. A well-developed technique in adaptive optics imaging systems uses a deformable mirror to reflect the incident wave front to the imaging stage of the system. By matching the surface of the deformable mirror to the shape of the wave front phase distortion, the reflected wave front will be less aberrated before it is imaged. Typical adaptive optics systems use piezo-electric actuated deformable mirrors. This research used an electrostatically actuated, segmented mirror array, constructed by standard MEMS fabrication techniques, to investigate …
Performance Analysis Of A Hartman Wavefront Sensor Used For Sensing Atmospheric Turbulence Statistics, Toby D. Reeves
Performance Analysis Of A Hartman Wavefront Sensor Used For Sensing Atmospheric Turbulence Statistics, Toby D. Reeves
Theses and Dissertations
Atmospheric turbulence parameters, such as Fried's coherence diameter, the outer scale of turbulence, and the turbulence power law, are related to the wavefront slope structure function (SSF). The SSF is defined as the second moment of the wavefront slope difference as a function of both time and position. Knowledge of the SSF allows turbulence parameters to be estimated. Hartmann wavefront sensor (H-WFS) slope measurements composed of both signal and noise, allow the SSF to be estimated by computing a mean square difference of H-WFS slope measurements. The quality of the SSF estimate is quantified by the signal-to-noise ratio (SNR) of …
Deconvolution From Wavefront Sensing Using Optimal Wavefront Estimators, Scott R. Maethner
Deconvolution From Wavefront Sensing Using Optimal Wavefront Estimators, Scott R. Maethner
Theses and Dissertations
A cost effective method to improve the space surveillance mission performance of United States Air Force (USAF) ground-based telescopes is investigated and improved. A minimum variance wavefront estimation technique is used to improve Deconvolution from Wavefront Sensing (DWFS), a method to mitigate the effects of atmospheric turbulence on imaging systems that does not require expensive adaptive optics. Both least-squares and minimum variance wavefront phase estimation techniques are investigated, using both Gaussian and Zernike polynomial elementary functions. Imaging simulations and established performance metrics are used to evaluate these wavefront estimation techniques for a one-meter optical telescope. Performance metrics include the average …
Estimation Of Satellite Orientation From Space Surveillance Imagery Measured With An Adaptive Optics Telescope, Gregory E. Wood
Estimation Of Satellite Orientation From Space Surveillance Imagery Measured With An Adaptive Optics Telescope, Gregory E. Wood
Theses and Dissertations
The use of the matched filter to automatically estimate the pose of a Low Earth Orbiting satellite from imagery taken with an adaptive optics telescope is explored. This work represents the first effort to solve the satellite pose estimation problem while considering the broad range of atmospheric turbulence levels and target visual magnitudes that are encountered in ground based space surveillance operations. Several Algorithms are examined in an effort to determine the performance bounds on the matched filter for this application. Results are given over an extremely wide range of seeing conditions. These results are weighted based on historical data …
Linear And Non-Linear Preprocessing Of Wavefront Sensor Slope Measurements For Improved Adaptive Optics Performance, Dennis A. Montera
Linear And Non-Linear Preprocessing Of Wavefront Sensor Slope Measurements For Improved Adaptive Optics Performance, Dennis A. Montera
Theses and Dissertations
New methods for preprocessing wavefront sensor (WFS) slope measurements are presented. Methods are developed to improve the accuracy of WFS slope measurements, as well as estimating key atmospheric and system parameters from the slope signals. Both statistical and artificial neural network solutions are investigated. Also, new atmospheric models for generating slope and phase data with the proper spatial and temporal statistics are developed. The experiments in improving the accuracy of WFS slope measurements include reducing the WFS slope measurement error and compensating for adaptive optics system time delay through temporal slope prediction. The experiments in key parameter estimation include estimating …