Liquid Crystals Light Valves for Spatial Amplitude and Phase Control of Laser Beams
J.P. Huignard, J. Bourderionnet, A. Brignon, M.S.L. Lee and B. Loiseaux
Liquid crystal spatial light modulators (LC-SLM) is now well established technology which plays a major role in the display industry for the consumer and professional markets. Due to the remarkable electro-optic properties of LC molecules, they permit to realise high resolution flat TV screen either for direct view or projection applications. The technology is based on the electrical addressing of individual pixels through a thin film transistor driven by matrix electrodes. Beside the display of TV images, LC-SLM are also very well suited for a variety of applications in laser optics as an active optical element which can accurately modulate the phase or the amplitude of a laser wavefront in the visible or near IR spectral regions. This capability of beam shaping with programmable (or a fixed) optical components is now important in growing applications of diode pumped lasers for industry or scientific purposes [1–5]. For these specific applications THALES Research & Technology has developed a particular SLM technology where the addressing of the LC layer is performed optically . This device which consists of a LC photoconductor sandwich is a non pixelated structure. It exhibits high optical quality and no spurious diffraction effects due to periodic electrodes usually used for electrical addressing. We present in the following the SLM technology, its typical performances, and original applications to adaptive optics or intracavity laser beam control. Also, application of holographic photopolymer optical element to laser beam shaping is presented.