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25 April 1980 Variable Grating Mode Liquid Crystal Device For Optical Processing
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Proceedings Volume 0218, Devices and Systems for Optical Signal Processing; (1980) https://doi.org/10.1117/12.958511
Event: 1980 Los Angeles Technical Symposium, 1980, Los Angeles, United States
Abstract
In the variable grating mode (VGM) operation of a liquid crystal device, a phase grating is formed whose period depends upon the voltage placed across the cell. Typical spatial frequency variation is from 100 to 600 cycles/mm. By adding a photoconductive layer to the cell, the grating period can be optically controlled. Thus each input intensity level in an optical signal will generate a local grating structure at a different spatial frequency. If the VGM device is placed in the input plane of a coherent optical processor, each point in the Fourier transform domain will correspond to a different grating frequency, and thus to a different input signal level. By varying the attenuation at each point in the Fourier plane, any desired transformation of input intensity to output intensity can be achieved. In particular, level slicing can be achieved by placing a slit in the filter plane so that only a narrow range of spatial frequencies is transmitted and thus a narrow range of input intensities is passed. Several experimental VGM real-time devices have been constructed and the results of a level slicing experiment are presented. This device has the potential to perform a wide variety of real-time, parallel, optical processes.
© (1980) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
B. H. Soffer, D. Boswell, A. M. Lackner, A. R. Tanguay Jr., T. C. Strand, and A. A. Sawchuk "Variable Grating Mode Liquid Crystal Device For Optical Processing", Proc. SPIE 0218, Devices and Systems for Optical Signal Processing, (25 April 1980); https://doi.org/10.1117/12.958511
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