Study of the shrinkage caused by holographic grating formation in acrylamide based photopolymer film

We study the shrinkage in acrylamide based photopolymer by measuring the Bragg detuning of transmission diffraction gratings recorded at different slant angles and at different intensities for a range of spatial frequencies. Transmission diffraction gratings of spatial frequencies 500, 1000, 1500 and 2000 lines/mm were recorded in an acrylamide based photopolymer film having 60 ± 5 μm thickness. The grating thickness and the final slant angles were obtained from the angular Bragg selectivity curve and hence the shrinkage caused by holographic recording was calculated. The shrinkage of the material was evaluated for three different recording intensities 1, 5 and 10 mW/cm ² over a range of slant angles, while the total exposure energy was kept constant at 80 mJ/cm². From the experimental results it can be seen that the shrinkage of the material is lower for recording with higher intensities and at lower spatial frequencies.