Ferroelectric liquid crystal spatial light modulators : devices and applications

• Main Author: Gourlay, James
• Published: University of Edinburgh 1994
• Subjects: 530.42
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.651668

The inherent parallelism in optics allows very powerful information processing. An electronically addressed spatial light modulator is a device which can perform the function of converting information form the electronic domain to the optical domain. A review of optical system requirements and potential spatial light modulator technologies identified the combination of Ferroelectric Liquid Crystal and Very-Large-Scale-Integration circuitry as a very powerful generic technology. The circuitry allows high levels of addressing functionality and low power requirements in the modulation permit high density arrays. The investigation of the interaction of the two parent technologies to form a useful modulator device is the basis of this study. Ferroelectric liquid crystals were identified as allowing fast switching and good light modulating characteristics. Optimisation of device structures for high optical performance was investigated, particularly cell construction, liquid crystal alignment and cell appraisal techniques. Various liquid crystal configurations were studied chiefly the Surface-Stabilised structure, but also the Soft-mode Electroclinic effect, the Distorted Helix, and Twisted Smectic. The Surface-Stabilised device structure was identified as being the most applicable for use with silicon backplanes and its fabrication parameters were optimised for good performance. Spatial light modulators were constructed and their performance evaluated. The performance of the devices constructed initially did not approach that obtained in the preliminary liquid crystal studies. Post-processing improvements to the silicon backplane, particularly planarisation, allowed tremendous improvement. Spatial light modulators were used in real-time optical systems, and their performance gauged. A novel non-coherently illuminated system, which allowed the determination of the Hadamard transform of input images, was constructed and evaluated.