Dichromated gelatin holograms: an investigation of their environmental stability

An investigation of the stability of the diffraction efficiency of dichromated gelatin (DCG) holograms has been carried out paying specific attention to coated and baked holograms that are subsequently exposed to high humidity (RH > 60%) environment. The investigation has revealed that (a) the environmental stability of DCG holograms can be considerably improved either by coating or baking; (b) the DCG holograms can be used at temperatures well-above room temperature (for example, as high as 175 degrees C) without showing undue detrimental effects regarding their efficiency; and (c) the diffraction efficiency of uncoated and baked holograms can be restored by reprocessing whereas such a thing becomes impossible in coated holograms.