The production of primary radicals in photopolymers during holographic exposure

Recently, extensive studies have been carried out on the time varying absorption effects, which occur in photopolymer materials, during holographic exposure. The theoretical analysis presented in these studies, assumed that three primary mechanisms determined the dye kinetic behaviour. These mechanisms are: (i) photon absorption, (ii) the regeneration or recovery of absorptive photosensitiser, and (iii) photosensitiser bleaching. Based on this analysis, the generation of primary radicals were then described. In this article, we significantly extend these theoretical analyses. A detailed examination of the photochemical reactions, which take place during the photo-initiation mechanisms, is presented. Then a more accurate representation of the initiation mechanisms is developed. This enables more exact expressions for both the temporal and spatial variations of the photosensitiser and primary radical concentrations, to be generated.