| Digital holography is a new holographic imaging technique and has been applied in many fields. However, Digital lensless Fourier transform holography has more outstanding strongpoints and better advantages for shape and deformation measurement of microstructures. The fundamental theory for digital lensless Fourier transform holography and its applications in 3-D object reconstruction and optical metrology are presented in this dissertation.(1) Analytical foundation for numerical reconstruction of digital lensless Fourier transform holography, namely discrete Fourier transform theory, is presented. The basic principle and mathematical model for recording and numerical reconstruction of digital lensless Fourier transform hologram is elaborated. The numerical reconstruction algorithm of digitally sampled holograms, deduced from the scalar quantity diffraction theory, is investigated. The serious recording limitations due to the finite size and resolution of CCD are detailed discussed.(2) The operation for numerical reconstruction of digital lensless Fourier transform holography is experimentally presented. The fundamental principle of digital holographic interferometry is then presented. Based on this, the Poisson's ratio of material and the out-of-plane displacement of a deformed aluminum board are successfully measured. The main influencing factors for experimental results of Poisson's ratio and the settlement approach are further analyzed.(3) A set of digital image processing algorithms for suppression of undesired components and improvement of numerical reconstruction images quality are presented, which consists of hologram contrast-enhancement, band-pass filtering and V-filtering, reconstructed image smoothing, and several reconstructed images adding. Furthermore, it is indicated by the analysis that high-pass, band-pass, wavelet filtering and V-filtering are superior to the former image processing.
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