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Viscoelastic control layers for solid-state light valves

: Tepe, R.; Gerhard-Multhaupt, R.; Brinker, W.

Penn, W.A. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Liquid crystals and spatial light modulator materials
Bellingham/Wash.: SPIE, 1986 (Proceedings of SPIE 684)
ISBN: 0-89252-719-6
International Technical Symposium on Optical and Optoelectronic Applied Sciences and Engineering <30, 1986, San Diego/Calif.>
Conference Paper
Fraunhofer HHI ()
electro-optical devices; optical modulation; plastic deformation; schlieren systems; viscoelasticity; electrical excitation; stability problems; interferometric measurements; thin viscoelastic control layers; schlieren light valves; spatial-frequency response; geometries; diffraction measurements; control-layer deformation; deformation amplitudes; light-valve projection; viscoelastic material; electrical addressing

The deformation behavior of thin viscoelastic control layers for eventual use in schlieren light valves is investigated theoretically as well as experimentally. Electrical excitation and viscoelastic properties of the control layer are incorporated in a differential equation which is solved analytically. Based on a quantitative evaluation of this solution, the time behavior and the spatial-frequency response of the control-layer deformation are described and the influence of several parameters is considered. Stability problems and alternative geometries are discussed in view of the analytical results. Interferometric and diffraction measurements of the control-layer deformation confirm the analytical results at least in principle. Maximum deformation amplitudes of approximately 0.1 mu m and time constants on the order of a few ms are obtained in agreement with the theory. It is concluded that viscoelastic control layers are suitable for light-valve projection if the viscoelastic material, the control-layer geometry, the electrical addressing, and the optical system are optimized.