Computer-simulated Fresnel holography

This paper presents a method of producing a computer-generated hologram for an object that has depth. It is a continuation of the author's previously published work on computer-simulated holography, which dealt with the generation of Fraunhofer holograms for planar objects. The technique is now extended to the case of Fresnel holograms for simple objects whose points do not lie in a single plane. The method utilizes the computer's ability, using packaged mathematical software, to compute the Fresnel diffraction pattern of a planar aperture by taking the Fourier transform of a modified aperture function. By adding a plane wave reference beam to the diffraction pattern, a hologram for each plane of the object is constructed, and the superposition of these holograms yields a resultant hologram whose reconstruction exhibits the depth of the object. Since computer-simulated holography is based on the interference and diffraction of light waves, the material presented in this paper could serve to enhance the understanding of these topics in a university course in optics.