Noise gratings recorded with single-beam exposures in liquid holographic photopolymers

Abstract

Photopolymers can be considered viable holographic material because of their many attractive features. Among these we could mention their ability to self-develop, the fact dry processing can be used with them, their good stability and thick emulsion layers, their haigh sensitivity, diffraction efficiency and resolution, and finally their non-volatile storage. Among the different sources of noise in holography, noise gratings are due to scattering from inhomogeneities in the recording material and have an important spurious effect on volume holography. Their effect at reconstruction is to bring about a reduction in diffraction efficiency and signal-to-noise ratio. Even though these scatter gratings have been seen in PMMA and other photopolymers, and in photorefractive crystals, they have really only been analyzed extensively for photographic emulsions, and information about these grating structures in photopolymers is quite scarce. In this communication we present the observation of noise gratings in an acrylamide photopolymer for use in real time holography. The possibilities of this noise source as a optimization technique for this type of materials are pointed out. Noise gratings in these polymer films were created upon exposure to a He-Ne laser collimated beam at 633 nm without any subsequent processing step. The influence of intensity on recording noise gratings and angular selectivity are reported showing its influence on the recording of this type of noise source in real time holographic materials.