Title

Wavefront control with realistic spatial light modulator in a multi-aperture imager

Author

Guimin Wu

Date of Award

2013

Degree Name

M.S. in Electro-Optics

Department

Department of Electrical and Computer Engineering. Electro-optics Graduate Program

Advisor/Chair

Advisor: Paul F. McManamon

Abstract

A multi-aperture imaging system with a non-mechanical steering device replacing each lens sub-aperture was considered. This setup allows for focusing and tracking of a target over a fine angle while preserving high resolution imaging in a compact system. An imaging system has the ability to digitally add focus for receiving. However, in the case of transmitting the focus must be provided by optical components. Even when receiving, at a short enough range it might be necessary to introduce optical corrections to avoid phase aliasing. To this end, the effects of implementing a real device such as the BNS Spatial Light Modulator (SLM), a reflective 512x512 pixels with 83.4% area fill factor steering device, on the multi aperture imaging system were investigated. The pixelated phase of the SLM, and the use of 2π resets to provide stepped blazed phase profiles for steering and stepped quadratic phase focusing, are modeled. Each pixel of the SLM is modeled by an array of 10x10 elements with 9 active and 1 inactive in both the x and y direction. As expected, and shown by the simulation results, the periodic reset of the quadratic phase bowl introduced phase grating modulations, which produces the so call ghost image" around the center image. By only providing stepped blazed profile to steer, the simulation shows that with increasing phase steps within the blazed profile the diffraction efficiency increase but at the cost of decreased steering angles. The ability of the SLM to correct for aberrations and its limitation in correcting aberration is investigated. Further, the basic concept of conformal aperture, enabled by the multi-aperture, was investigated and simulated."

Keywords

Optics, Adaptive, Imaging systems Image quality, High resolution imaging, Optics; wavefront control; SLM; multi-aperture imaging; beam steering; conformal aperture

Rights Statement

Copyright 2013, author

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