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1. NATURAL SCIENCES, 1.3 PHYSICAL SCIENCES, Condensed matter physics, Optics, Polymer science
Results from the investigation of the diffusion processes in a dry acrylamide-based photopolymer system are presented. The investigation is carried out in the context of experimental work on optimization of the high spatial frequency response of the photopolymer. Tracing the transmission holographic grating dynamics at short times of exposure is utilized to measure diffusion coefficients. The results reveal that two different diffusion processes contribute with opposite sign to the refractive index modulation responsible for the diffraction grating build up. Monomer diffusion from dark to bright fringe areas increases the refractive index modulation. It is characterized with diffusion constant D0=1.6E-7 cm2/s. A second diffusion process takes place during the recording. It decreases the refractive index modulation and we ascribe it to diffusion of short chain polymer molecules and/or radicals from bright to dark fringe areas. The estimated diffusion coefficient for this process is D0= 6.35E-10 cm2/s. The presence of the second process could be responsible for poor high spatial frequency response of the investigated photopolymer system. Comparison with the diffusion in photopolymer systems known for their good response at high spatial frequencies shows that both investigated diffusion processes measured here occur in a much faster time scale.
Naydenova, I., Jallapuram, R., Howard, R., Martin, S., Toal, V.: Investigation of the Diffusion Processes in Self-Processing Acrylamide-Based Photopolymer System. Applied Optics, Vol. 43 Issue 14, pp.2900-2905. 2004.