Dichromated gelatin for the fabrication of holographic optical elements

Hardened dichromated gelatin is the best material available today for the fabrication of holographic optical elements (HOEs) because of its low scattering, large refractive index modulation capacity, and other unique properties such as reprocessibility. On the basis of experimental data accumulated during the last several years, we describe holographic characteristics of the dichromated gelatin, including exposure characteristics with a bulk exposure model, hologram thickness change, and environmental stability. Basic chemistry, hologram formation in the dichromated gelatin, and generalized processing techniques are also discussed.