Study On The Improvement Of Quality Of Digital-hologram Based On Combination Of Light Intensity Subtraction And Grey Value Transformation

Digital holography,as a technique of combination of the traditional optical holography and digital processing technology,has developed very quickly with the development of computer and photoelectric sensor resolution enhancement in these years.During the research of holographic technology,to obtain a high-quality image has always been a key problem.In digital hologram,there are lots of factors affecting the quality of the hologram.Therefore,the solutions are varied accordingly,such as using high-resolution CCD,and the spatial light modulator to control amplitude,phase,polarization and wavelength of light wave,as well as by using image processing software to optimize the hologram.This paper studies mainly on improving the quality of constructed image.The main contents are as following:1.On the basis of optical holographic recording and reconstructing processing,this thesis introduces the recording of digital hologram and reconstructing algorithm,interference and diffraction theory.The recording condition of digital holography is described in detail.2.By comparing with the on-axis and off-axis optical system,the actual measuring optical system has been optimized in the case of the problems to be solved in this paper.In addition,the experiment device and conditions are analyzed specifically.3.In order to improve the quality of the constructed digital hologram,the method of the light intensity subtraction to eliminate the zero-order diffraction is studied.Aiming at reducing influence due to uncertain factors of optical system,a grey value transformation method is applied as well as light intensity subtraction4.Due to the difference of object reflective performance,the hologram may have the problem of uneven distribution of light intensity.By changing the grey value of hologram nonlinearly,the image of object will be the best.5.An experiment verified the feasibility of the measuring optical system.It proved effectively that this system not only weakening the zero-order diffraction,but also improving the quality of the hologram.