Photopolymerization shrinkage in holographic hybrid sol-gel material

A novel water-resistant photopolymerizable glass is a potential choice for Holographic optical elements (HOEs) development due to its exceptional resilience to humidity, high thermal stability, and high exposure sensitivity. Photopolymerization shrinkage is the main issue that causes the shift in the position of maximum diffraction efficiency, resulting in reduced image clarity. The main objective of this work is to investigate the shrinkage in the novel water-resistant photopolymerizable glass using the fringe plane rotation model. Shrinkage was investigated by considering various holographic grating parameters and was found to increase with spatial frequency and slant angle. Besides, the absolute shrinkage varied from 0.5 – 1.7 µm as the layer thickness was reduced from 214 to 30 µm at the spatial frequency of 900 lines/mm. This study will facilitate the development of compensation methods to optimize the initial grating parameters and achieve the optimum performance of HOEs.