ABSTRACT
This chapter provides an overview of the main developments, properties, and limitations of materials that have been widely used in the past as well as some of the newer and more promising materials and reviews some of the more successful and commonly used materials. It focuses on inorganic photorefractive crystals, while photorefractive polymers and holographic photopolymers. The success of a hologram design is highly dependent on the properties and capabilities of holographic recording materials. Furthermore, each holographic application generally has different requirements and places further demands on the material characteristics. Holographic silver halide emulsions consist of a mixture of compounds such as AgBr, AgI, AgCl, gelatin, sensitizing dyes, and stabilizers. Photorefractive materials are electro-optic which allows for localized light-induced changes in the refractive index and the formation of holographic phase gratings. Photopolymers show great promise as a holographic recording material. Thermoplastic material systems have been developed since the 1960s as a rewritable, surface relief holographic recording material.
