Invited paper presented at the Sixth Euro American Workshop on Information Optics, Reykjavik, Iceland 25 - 30 June 2007. 6th International Workshop on Information Optics (WIO'07), Jón Atli Benediktsson, B. Javidi, Karl S. Gudmundsson, eds.; American Institute of Physics, AIP Conference Proceedings 949 (ISBN 978-0-7354-0463-2), p 226-233 (2007) Spatial Light Modulators For Information Processing: Applications And Overview Pierre Ambs 1 , Joaquín Otón 2 , María S. Millán 2 , Albéric Jaulin 1 , Laurent Bigué 1 1 Université de Haute Alsace, ENSISA, MIPS, 12 rue des Frères Lumière, 68093 Mulhouse Cedex France 2 Dep. Optics and Optometry, Technical University of Catalonia, C/ Violinista Vellsolà, 37, 08222 Terrassa (Barcelona), Spain Abstract. We present the characterization of a ferro-electric liquid crystal spatial light modulator and of a nematic liquid crystal spatial light modulator. It is shown that the nematic device can be compensated for its phase distortions and a method is proposed for increasing its frame rate while maintaining a maximum phase modulation of 2π. Several applications in information processing are presented with experimental results. Keywords: Spatial Light Modulators, Liquid Crystal, Optical Information Processing. PACS: 42.30.–d, 42.40.Jv, 42.79.Kr INTRODUCTION One of the biggest advantages of electronic based processing systems is their flexibility due to their programmability. Spatial Light Modulators (SLMs) can bring the same flexibility to optical systems, however, they have been among the weakest components of the optical systems. Since the late nineties, the SLMs development is driven by the very rapid expansion of the consumer electronics for video projectors, digital cameras and displays. Commercially available SLMs are based on two different technologies: mirrors and liquid crystals. There is a large choice of liquid crystal SLMs, they can be optically or electrically addressed, transmissive or reflective, filled with twisted nematic liquid crystals (TN-LC), or nematic liquid crystals (N-LC) or ferro-electric liquid crystals (FLC). It is now possible to find one SLM that will satisfy most of the requirements of a specific information processing application. The SLM characterization and calibration are absolutely mandatory if the SLM has to be used for scientific applications. Moreover, each specimen of SLM is different due to the fabrication process and must be characterized individually. After a short presentation of an analog FLC SLM, we will show the characterization and the calibration of a N-LC SLM, and demonstrate that it is possible to increase the frame rate while maintaining the maximum phase modulation. Then several applications such as dynamic diffractive optical elements (DOEs), wavefront control and polarimetric imaging are briefly presented to show the potential applications of the SLMs.