EXPERIMENTAL STUDY OF SHRINKAGE DYNAMICS OF HOLOGRAPHIC PHOTOPOLYMER MATERIALS
E. F. Pen
Institute of Automation and Electrometry Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: holographic photopolymer materials, reflection holograms, transmission spectrum
Abstract
The dynamics of effective and physical (geometric) shrinkage of a holographic photopolymer material is studied by measuring the evolution of transmission spectra of volume reflection holograms during their recording. It is shown experimentally for the first time that physical shrinkage occurs to a significant extent already at an early stage of hologram formation, when its diffraction efficiency is insignificant (less than 0.05). It is established that the effective shrinkage values at the end of the exposure for small and large grating periods differ significantly, while the physical shrinkage is approximately the same. For the grating samples studied, the average refractive indices before and after exposure are estimated. A method and device for measuring the shrinkage dynamics of reflection photopolymer holograms have been developed, ensuring the minimal errors in estimating the shrinkage parameters. The research results may be useful for deepening the knowledge about the nature of hologram formation in photopolymer materials, as well as for practical use in the development of holographic elements and devices based on them.
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