Imaging mechanism of the holographic recording material dichromated cellulose triacetate.

Dichromated cellulose triacetate (DCCTA), a new, to our knowledge, holographic recording film, is presented. The material has some special properties, such as good environmental stability, a stronger real-time effect, strong relief modulation, a stratified sensitivity without the use of any coating technique, a light weight, flexibility, easy fabrication in a large area, and more. By the systematic study of the physicochemical changes of the microstructure of DCCTA in photochemical reaction processes with an electron paramagnetic resonance spectrometer, an infrared spectrometer, an UV spectrophotometer, and interferometric microscopy, we found that, as a dichromated light-sensitive system, DCCTA has a novel imaging mechanism: Light irradiation causes not only the formation of the cross links between Cr(3+) and molecular chains but also the decomposition of the main molecular chains of the film. In the real-time imaging process of DCCTA holograms the former plays a dominant role after the holograms are postprocessed; however, the latter is more important in the imaging process, and the holograms exhibit a positive etching property, which differs completely from that of other well-known dichromated materials, such as dichromated gelatin and dichromated poly(vinyl) alcohol.