Holograms recorded with red light in dye sensitized dichromated gelatin

We have found that phase holograms can be recorded with He—Ne laser light in dye sensitized dichromated gelatin. This material has excellent resolution, and refractive index changes up to 0.02 have been observed. The sensitivity of dye sensitized dichromated gelatin at 633 nm is about five times less than of dichromated gelatin at 488 nm.