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Proceedings Paper

Design and application of liquid crystal spatial light modulators for optical signal processing systems
Author(s): Frank R. Reichel; Peter Gussek; Stefan Breitfelder
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Paper Abstract

The wide range of electro-optical properties such as electrically adjustable optical activity, birefringence and scattering make liquid crystals (LC) suitable for defined alteration of amplitude, phase polarization and spectral composition. The method of incoherent optical space frequency analysis (OSFA) on the basis of liquid crystal light modulators is shown. In an optically addressed image processing camera the objects, which have to become classified, are projected onto an LC-SLM. The reflective SLM gets read-out incoherently. As a 2D- radiator an electronically addressed 'transient-nematic' LC modulator is used. A photo- multiplier serves as detector. It is mathematically exactly proven that the measured intensities are corresponding to the surface integrals of the Fourier transform. In a microscope variant the principle gets translated into action by the way that a telescopic projection of a FLC matrix-display takes place over a condenser and micro-objective into the exit pupil plane. The change-over to incoherent OSFA allows a simple realization of a Fourier processor for detection of particle-size distribution. For this purpose a high speed nematic LC modulator with log-ring structure is incorporated into the aperture stop of the condenser. The coherent OSFA is used in evaluation of particle image velocimetry and laser speckle photographs. The autocorrelator with an optically addressable LC-SLM allows, due to the two 2D-Fourier transforms, a high speed and accuracy.

Paper Details

Date Published: 11 March 1996
PDF: 11 pages
Proc. SPIE 2651, Liquid Crystal Materials, Devices, and Applications IV, (11 March 1996); doi: 10.1117/12.235359
Show Author Affiliations
Frank R. Reichel, JENOPTIK Laser, Optik, Systeme GmbH (Germany)
Peter Gussek, JENOPTIK Laser, Optik, Systeme GmbH (Germany)
Stefan Breitfelder, JENOPTIK Laser, Optik, Systeme GmbH (Germany)

Published in SPIE Proceedings Vol. 2651:
Liquid Crystal Materials, Devices, and Applications IV
Ranganathan Shashidhar, Editor(s)

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