Studies Of Some Basic Issues In Digital Holography

With the development of computer technology, transducer technology, image processing technology and electron recording equipment, digital holography have been got more attention in recent years. In digital holography, charge coupled device CCD substitutes common recording material to record hologram and computer simulation replaces optical diffraction to digitally reconstruct recorded object field. Digital holography realizes the whole digital process of recording, memory, processing and reconstruction of hologram, it adds a new method for the development and application of holography. Digital holography has been widely applied in many fields such as appearance measurement , distortion measurement , vibration measurement , component defect measurement,optical fiber, micro-electronics and biologic cell, and it has more important meaning.In this dissertation, firstly the development of holography are summarized, then the development, application and study status quo of digital holography are expounded. The principles of traditional optical holography and digital holography and the characteristics of digital holography are introduced in detail, and some basic issues are put forward. Aimed at off-axis Fresnel digital holography, the digital recording and reconstruction algorithms are studied. Based on MATLAB mathematics calculation software, the programs are written and the corresponding algorithms are realized.This work is a basic task in the research of digital holography, in which some basic issues of digital holography are theoretically and experimentally analyzed and studied. It includes the following aspects:(1),Based on MATLAB mathematics calculation software, the recording and reconstruction parameters of digital holography is studied by the method of numerical simulation and also is realized on experiment. Theresults of simulation are basically consistent with that of experiment.(2),By digital holographic grating, the sampling theory and the separation of reconstructed images are researched and the sampling methods and rules during recording process are found. And based on which the common diffracting objects are studied to record and reconstruct. The relationship between recording angle and the reconstructed images separation are in detail discussed and experimentally researched. And recording distance and reconstructing distance are discussed.(3),The digital reconstructing light field is discussed and the conclusion that the incident direction of reconstructing reference light have no influence for the size of reconstructed images and the separation situation is elicited. The quantitative analysis and calculation of digital reconstructed images are primarily studied.(4),By the method of Fourier transformation and frequency spectrum filter and another method of four-step phase-shifting, the separation question of reconstructed images are solved. The zero-order image and conjugate image are eliminated and the qualities of digital reconstructed images are improved.