Recording Materials for Holography

This chapter discusses various recording materials for holography, including silver halide materials, photopolymer, photoresist, and dichromated gelatin (DCG). The silver halide materials chosen for holography are essentially gelatin‐based suspensions which are traditionally known as “emulsions”, although technically defying the definition of “emulsion”. These are, in the case of holographic recording materials, definitively based upon silver bromide, although silver chloride is also well known as a really useful photosensitive material, which is used extensively in the emulsions used for photographic papers. DCG has played a rather glorious role in holography in the past. As gelatin is such a remarkably inexpensive material, this method, which is capable of very high index modulation and diffraction efficiency over both narrow and wide spectral bandwidths, appeared to have a promising future until the advent of the photopolymer recording materials for holography.