Shaad B Bidiwala

62484877, Jun 19, 2001

Apr 26, 1999

9/538245

Robert W. Cohn - Louisville KY
Shaad Bidiwala - Lexington KY

The United States of America as represented by the Secretary of the Air
Force - Washington DC

G03C 500

430 30

Spatial light modulators (SLMs) can be amplitude-only modulated, phase-only modulated, or the pixel amplitudes can even be a function of phase. However, practical devices providing independently controllable values of phase and amplitude are not expected for some time. It has been possible to design modulation patterns for these limited range SLMs that do produce diffraction patterns similar to those possible from full complex SLMs, but hours of intensive iterative optimization usually have been required. Our approach instead develops and evaluates direct, pixel-by-pixel encoding algorithms that map the limited range modulation properties onto the entire complex plane. The advantage of these algorithms (generally recognized by the name pseudo random encoding) over iterative optimization is that designs can be performed in real-time making systems adaptable to rapidly changing situations. For laser scanning using SLMs, encoding enables multiple spots to be generated and their positions to be maintained on multiple moving targets. For correlators, a fast encoding method would provide a way to adaptively construct composite filters (capable of recognizing objects from many perspectives, or classes of objects) by linearly combining individual matched filters.