Calculation Of The Hologram And Digital Reconstruction Of The Study

This paper mainly addresses the computer stimulated algorithm of the recording and reconstruction of holograms. Traditional holography consists of wavefront recording and reconstruction. The holographic wavefront recording process records the interference pattern of the object and the reference waves, and thus forms the hologram, which simultaneously records the information about the amplitude and phase of the object waves; the holographic wavefront reconstruction, by means of the diffracted waves, can reconstruct the original object wave from the hologram illuminated by lights. However, the application field of optical holography technology has been restrained, for the lack of the high coherence and intensity of lights and the quite stable optical instrument. Therefore, computer-generated hologram and digital holography has been developed consequently.By combining the advanced computer technology and optical holography technology together, computer-generated hologram can generate holograms, which, with no demand for objects, can be reconstructed through optical ways after the computer has processed the mathematical description of object waves. The basic principle of digital holography is that, by replacing the ordinary films with CCD, the hologram of the object and the reference waves can be obtained and reconstructed by numerical computing.This paper is trying to combine Computer-generated hologram and digital holography together, to give the stimulated algorithm of the Fresnel diffraction and through computational stimulation generate the hologram, which will reconstruct the original image, and ultimately, realize the numerical reconstruction of the hologram. In the first part, we have studied the stimulated algorithm of the diffraction of light; and, through direct integral, convolution, and Fourier transform, we created the numerical algorithm of Fresnel integral and additionally, these three methods have also been compared in this paper. For example, when light propagates through a small round hole, by computing the intensity of the diffracted light field, we can obtain theintensity distribution of Fresnel and Fraunhofer diffracted light field. And also, through the numerical algorithm of Fresnel diffraction, we have realized the computer generation and numerical reconstruction of point hologram and Fresnel hologram. In the second part, the computer-generated hologram of three-dimensional object has also been researched. First, by using coordinate rotation, we have discussed the computer-generated hologram composed by planar object whose plane doesn't run parallel with that of its hologram. Second, through coordinate transform, the computer-generated hologram of curvy planar object has been discussed again, in which, conformal map in Computer Graphics has been creatively applied, and generated the computer-generated hologram of simple curvy plane (e.g. spherical surface); also, in this section, the correctness of transformation has been confirmed by numerical reconstruction. This confirmation will definitely establish a solid base for the further research on the computer- generated hologram of complicated three-dimensional objects.