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1.3 PHYSICAL SCIENCES
Holography is now firmly established as a tool for scientific and engineering studies and also as a display medium. Holographic performance mainly depends on the choice of recording wavelengths, recording material, recording conditions and experimental setup as well as environmental conditions in the laboratory. Acrylamide based photopolymer has significant advantages as a holographic recording material such as self-development, low scatter, high diffraction efficiency, ease of preparation and low cost. The main objective of this project is to determine and minimise the shrinkage of an acrylamide based photopolymer developed in the Centre for Industrial and Engineering Optics for holographic recording. This recording material is sensitized in the visible spectrum with Erythrosine B, a green sensitive dye. The shrinkage of the material is determined for different exposure intensities and thicknesses using different techniques in order to determine the optimum conditions for holographic recording. We also have carried out experiments at different spatial frequencies of recording. The influence of nanoparticle dopants on the shrinkage, diffraction efficiency and the dynamic range of the photopolymer system is also studied. The results shows that careful consideration is needed to attain maximum efficiency and minimum shrinkage during holographic recording. Incorporation of zeolite nanoparticles shows improvement in holographic recording characteristics in the photopolymer material. Diffraction efficiency is improved up to 40% and shrinkage is reduced to one half with increased concentration of nanoparticles. Using Electronic Speckle Pattern Interferometry (ESPI) phase shifting technique a 3D map due to shrinkage has been calculated. The shrinkage map has the same circular symmetry as the profile of the recording beam as expected.
Moothanchery, M. (2013). Studies of Shrinkage in Photopolymerisable Materials for Holographic Applications. Doctoral Thesis. Dublin Institute of Technology. doi:10.21427/D7859T