Method Of Digital Holography Reconstruction

In this thesis, the principle and applications of the digital holography are introduced. Diffraction patterns are characterized directly from in-line holograms by using the Gabor transform, and a series of holograms are recorded and employed to recover the wave front completely.The Gabor transform, which was proposed by D. Gabor, is a time-frequency tool for signal processing. It can present both the frequency and time information of a signal simultaneously, In this work, the Gabor transform is employed to character the diffraction pattern of the object directly form its in-line hologram. The relation between the Gabor angle and the location of the object is established. Three-dimensional locations of the object can be determined from the Gabor transform spectrum of the in-line hologram. It was shown that the Gabor transform is an effective mathematical tool for extracting information from in-line hologram.Digital holography is an increasingly important tool for image analysis. A new approach is proposed for wave field reconstruction in this thesis. By processing a series of holograms, the phase distribution on a hologram plane can be retrieved completely, and then the complex wave field can be ascertained finally, thus the object can be reconstructed using the inverse Fresnel transform. Simulation results demonstrate the validly of this new method. Furthermore, the size of the recording object can be enlarged, and the signal-noise-ratio of the system can be improved, when the Rayleigh-Sommerfeld approximation is adapted.