Recording of Diffraction Gratings in Polyvinyl Alcohol/Acrylamide Photopolymers by Pulsed Laser Irradiation

In this communication we present the experimental results obtained when diffraction gratings are stored using pulsed exposure in polyvinyl alcohol/acrylamide photopolymer deposited in a dry film. The influence of the energy of the irradiation pulse was studied and the number of pulses needed to reach maximum diffraction efficiency was obtained. The recording was performed using an holographic copying process. The original pattern employed was a grating of 1000 lines/mm processed according to silver halide sensitized gelatin, with a beam ratio of 1:2 and transmittance of 75%. We exposed the samples by recording holograms with a collimated beam from a frecuency-doubled Nd-Yag (532 nm) Qswitched laser. The pulse duration was ∼ 8 ns and the frecuency of repetition varied between 2 and 10 Hz. The pulse fluence was increased from 0.07 mJ/cm to 6.7 mJ/cm. Our initial results show that it is possible to obtain diffraction gratings with a diffraction efficiency of 60%. The energetic sensitivities achieved are close to those obtained when working with the same material and continuous irradiation, without processing of the gratings.