Phase type hologram mfr. - by bleaching silver image with N-halo cpd. with restricted swelling of binder

摘要

The silver image of amplitude type of hologram is bleached with aq. soln. of N-halo cpd. such as N-bromosuccinic acid imide at 20 degrees C for 30 minutes while the swelling of a binder of silver image-contg. layer (e.g. gelatin) is being restricted. When gelatin is used as binder, liquid such as ethyl alcohol which is miscible with water and acts as solvent for N-halo cpd. is used to make the binder swell by 2 to 3 times that of the dry state. Diffraction efficiency is high (41%), light diffusion is small and resistance to light is excellent.