Increasing the Spatial Resolution of Digital Holograms Based on the Fourier Transform

Abstract

The paper considers possible methods of increasing spatial resolution in digital holographic microscopy. A new original approach to increase the spatial resolution of digital holograms obtained in optical-electronic interference measuring systems is proposed. The approach is based on forming a "mosaic" consisting of a set of digital holograms with low spatial resolution. Image reconstruction of an object is obtained by Fourier transformation of such a synthesized digital hologram. A method for forming a digital hologram with high spatial resolution is shown by increasing the spatial resolution of a digital hologram with low spatial resolution by a factor of two horizontally. The optical scheme and design of a digital microscope that implements the proposed approach are shown. The results of practical application of the proposed approach are presented. It is shown that a synthesized digital hologram with high spatial resolution completely reconstructs an image of an object without diffraction limitations inherent in holograms with low spatial resolution. The number of digital holograms with low resolution required to form a digital hologram with high spatial resolution is determined as a product of scale factors in the horizontal and vertical directions. The proposed approach can be easily adapted to arbitrary values of scale coefficients of original holograms.