Dichromated pullulan as a novel photosensitive holographic material

We found that pullulan [an a -glucan with (1?4) and (1?6) linkages] doped with chromium ions posseses promising holographic properties. It is environmentally stable and is capable of registering high spatial frequencies (as many as 1500 lines/mm) and producing surface relief. At 1000 lines/mm pullulan's diffraction efficiency was 4%. Chemical treatment of pullulan with a mixture of water and isopropyl alcohol is simple. However, as expected from analogy with dichromated gelatin, pullulan is sensitive in only the blue-green region of the spectrum.