Effect of object representation form on depth resolution of restored images obtained by synthesized Fresnel holograms

Subject of the Research. The paper presents the study on the effect of object representation form on the depth resolution of images reconstructed via computer-generated Fresnel holograms-projectors. Method. The study was performed by mathematical modeling of synthesis and reconstruction of holograms-projectors of various objects with a characteristic size of 20 × 20 in virtual space. The method is based on object wave representation at hologram synthesis as a superposition of object waves emanating from two identical objects located at different distances from the hologram synthesis plane. All numerical experiments were carried out using a specialized software package with the following parameters for the synthesis and reconstruction of holograms: the wavelength of the radiation used is 13.5 nm, the pixel size of the hologram is 20 × 20, the distance between the object and the hologram planes is 20.3 μm, the reference wave angle of incidence is 14.7 °. The quality criterion of the reconstructed image was expressed in terms of the number of gradations at the threshold processing of this image with the intensity distribution in the reconstructed image identical to the intensity distribution in the original object. Main Results. Following the carried out experiments, the dependence was drawn out for the depth resolution of the images reconstructed by computer-generated Fresnel holograms-projectors on object representation form. In particular, it was found that full object representation based on transparencies is the most effective rather than representation of just one its part with the small-sized elements of the object structure. Practical Relevance. The application of this method makes it possible to optimize the object structure parameters, that is, the form and sizes of its elements during the synthesis of Fresnel holograms-projectors with the higher depth resolution for holographic photolithography.