Proceedings Article | 18 April 2021
KEYWORDS: Holography, Diffraction gratings, Silver, Reflection, Diffraction, Visible radiation, Photography, Optical filters, Mirrors, Lenses
The development of new holographic recording materials and the optimization of existing ones is a fundamental field of study, since many of the applications of holography depend directly on the photomaterials properties, as is the case of holographic mirrors, holographic lenses, HUDs as well as augmented reality systems. In this poster we present the results obtained in the optimization of the photochemical process used in the processing of silver halide sensitized gelatin (SHSG). Previous work has shown that excellent results can be obtained in the case of transmission diffraction gratings in BB plates (Colour Holographic Co.), however when the spatial frequency of 3000 l/mm is exceeded, the process is not so good. In the works carried out previously, it has been shown that this photochemical process allows to obtain excellent efficiency values in diffraction efficiency and low level of noise, with excellent spectral sensitivity and energetic sensitivity, but the results that have been obtained in the case of reflection holographic gratings have not been so good, depending on the type of photographic emulsion that has been used as a support. In this work we have made reflection gratings (Denisyuk geometry), using the Color Holographic plate BB640. Given that the gelatin in this plate has a high degree of hardening, we have modified this situation by means of suitable presensitization processes and pH of the developer used. In this way we have achieved good diffraction efficiency results, higher than 80%, and excellent optical quality. Holographic gratings of 5000 l / mm were made, with a He-Ne laser at 633 nm, obtaining a diffraction efficiency of 80%, and a bandwidth of 25 nm., generating a spectral shift of 80 nanometers, due to the Thickness variation during the processing, so it has been possible to obtain excellent reflection filters in the view zone of the visible spectrum. The developer used was AAC, although its composition and pH values have been adjusted to modify the level of differential hardening bias level of the gelatin that supports BB640 plate. These results allow us to make excellent holographic reflection systems, in different areas of the visible spectrum, with good optical quality and sizes that can exceed 10x10 cm2.
