Ultraviolet spectrally responsive holograms in dichromated gelatin

A method for making ultraviolet-responsive holograms in dichromated gelatin by using the 488-nm radiation from an argon laser is presented. We obtain the main shift toward short wavelengths by swelling the gelatin layer in a high-humidity atmosphere before exposure, and we adjust the final reconstruction wavelength (355 nm) by controlled heating of the holograms. These holograms, which exhibit the high performance of dichromated-gelatin holograms, are quite uniform compared with those made with other swelling agents. The swelling effects are discussed, and some procedures for improving efficiency are given.