This chapter describes electro holography that makes use of liquid crystals for active optics. It provides in-depth descriptions of the principle of liquid crystal optics that can actively control the light wavefront, and detailed information on its practical applications. The chapter examines electro holography that makes use of liquid crystal devices, including the basics of holography and liquid crystals. It explores the basics of complex amplitude modulation of light waves by liquid crystal devices and discusses a liquid crystal spatial light modulator for electro holography. For the materialization of electro holography, fine and active control of the light wavefront is indispensable, and for that purpose a spatial light modulator with high resolution is required. An electro holographic system using liquid crystal device (LCD) is composed of independent recording and reconstructing optics in which a CCD is used for image pickup of interference fringe patterns, and an LCD for hologram display.