Study On Digital Holography With Single Phase-shifting Operation

The principle of holography is a new imaging technology that was first brought by the British scientist Dennis Garbor in 1948,and it is based on the theory that the reason why man's eyes can see the object is that the retinal cell can receive the object wave that comes from the object and reaches the eye's retina in order to form the vision of the three-dimension space. That is to say, as long as a wave, which is as same as the object wave, exists, even without the existence of the object, man's eyes can still see the object. According to this, Dennis Garbor put forward a method that can record the distribution of both amplitude and phase of the original object wave that carry the information on the 3-D object and can reconstruct the object wave under some conditions, and this method based on the principle of interference and diffraction is different from traditional photography. Because of the specialty of holography in displaying the information of 3-D object, holography has been widely applied to various fields in science and technology, and the most representative applications include holographic display, holographic interferometry, holographic optics element and so on.With the fast development of computer technology, computer has been more and more widely applied to any field and more and more closely linked with other relative scientific branches. Of course, the applications of computer in optical field also promote the development of holography. Especially under the precondition of the rapid development of digital photoelectric element, the close combination of the computer technology and holography produces some new research fields, such as digital holography, computer generated holography and embossed holography and so on. Goodman proposed digital holography in 1967 and it replaces digital photoelectric element for holographic plate to record and store hologram in computer by digital mode, and substitutes the method of digital calculation for the process of optical diffraction in order to reconstruct the image of the object. With the fast development of computer technology and the invention of CCD (Charged-coupled Device), more and more research was put on digital holography. Contrasted with traditional optical holography, digital holography can save the procedure of chemical process and eliminate aberrations,noises and nonlinearity. The entire process is not only simple but also applicable to real-time and quantitative analysis and measurement; so digital holography has become a hotspot in the research of holography. However, its main problem lies in the resolving power of CCD devices, which is usually lower by at least 1 order than that of the conventional recording media used in holography. So digital holography often adopts an in-line recording setup, but in the reconstruction process of the in-line recording setup the appearance of conjugate image and zero-order diffraction spot will affect the quality of reconstructed image.This thesis will base on digital holography to introduce a theory based on the diffraction theory and called phase-shifting holography .By changing the phase of reference or object beam (The method of changing the phase of reference is adopted in this thesis.) for several times and by receding the corresponding holograms, and then applying digital subtraction method to these holograms in order to get the distribution of amplitude and phase of the original object wave, the image of object can be reconstructed by phase-shifting holography .The advantage of this method is to eliminate the effect of the conjugate image and zero-order diffraction spot on the reconstructed images appearing in the reconstruction process of the in-line recording setup ,which is adopted in order to overcome the limitation of resolving power of CCD.The work of this thesis includes five parts:In the first part, we will briefly describe the history of holography, with the emphasis on Gabor holography and the actual situation of digital holography. In the second part of this thesis, the basic pri...