Optical recording of periodic structures in photopolymer layers

The optimal conditions were determined for recording thin phase gratings in photopolymer materials based on the oligourethanacrylates. A substantial increase in the diffraction efficiency was obtained by selecting a preexposure with the optimal amount of energy. On the basis of the experimental material presented, a hypothesis is put forward of the existence of two processes which take place during recording periodic structures in photopolymers. These are the diffusion of the photosensitive initiator into the region of the photopolymer where the interference field is strongest and the preferential growth of radical chains in the direction of the photopolymer regions coinciding with the field minima.