To Improve The Quality Of Computer Generated Holograpy ’S Reproduce Image

Holography has the wide range of applications. Computer has the characteristics of flexible programmable, analyze data and with the function of simulation. The computer generated holograph technology integrating holography with computer technology to develop a new research field. The method not only can record all the information in real objects but also the reality does not exist and reproduce a lifelike three-dimensional image. Due to the rapid development of the computer, we can use the computer quickly make different object wave of hologram, convenient, flexible and can be copied. CGH technology has been applied not only in the aspect of3d display, holographic interferometry measurement, and can produce more complex holographic optical element, holographic microscopy, holographic information storage, etc. The CGH represent the image quality is factors that affect the results. Holographic optical researchers have put forward some improved methods in related aspects, but still not get the ideal effect. So to improve computing holographic representation as a qualitative research is extremely necessary.In this paper, through studying the theory and technique of computer generated hologram made by detour phase coding method and modified off-axis reference optical method, new improvement methods are put forward, aiming at the reconstructed image overlap, level by level zero problems like serious interference, low resolution and the influence of speckle noise distribution reproduction. By definition, separation is significantly better, speckle noise reduction and elimination of zero order ideal reconstructed image, and the reproduction of improved image quality was evaluated. The main research contents are as follows:(1) Researching and analyzing of the existing problems, characteristics and current development of CGH technology and existing solutions, and production of the basic theory of the CGH is studied, the imaging characteristics of the discrete fourier transform CGH and application of fourier transform hologram is made:reproduction in the spatial light modulator, the CMOS receiver before the lens is fourier inversion, and distance are the focal length of the lens.(2) The detour phase coding computer-generated hologram:by changing the Roman III sampling number and coding computer-generated hologram aperture number, the quality of reconstructed image, gain makes the calculation holography numerical optimal aperture image,, of high quality; two times using fftshift0function to shift and a cyclic shift reproduction, the reproduction as the overlap is weakened effectively, so as to improve the resolution of reconstructed image.(3) As to the modified off axis holographic reproduction:the method of making change the hologram, hologram was pretreated, and then the reproduction, definition is obviously improved; and then through the research from the carrier frequency parameter axis CGH coding value on image reconstruction, carrier frequency parameters and the positive and negative level representation as the degree of separation rules have to, then select the rational parameters of the positive and negative frequency level as complete separation of reproduction, no longer overlap like, resulting in high definition, separation degree was like reproduction. Combined with the bias parameter loading Boqi in holography is a constant term, effectively eliminating the DC component in the background image with speckle noise reproduction, and obtained the ideal image reconstruction. Computer generated hologram reproducing eliminate DC component and conjugate image for reducing the speckle noise and the separation of image reconstruction method is more convenient and quick speckle noise, spectral filtering method, the phase shift method to reduce the average method than the traditional multi image, and achieves good results.(4) After getting the ideal reconstruction image, the information redundancy is analyzed, and improvement on it on the basis of the existing. Take on the image classification method for making:two-dimensional image in the spatial domain X axis length greater than Y axis length is too long horizontal shaft type, the vertical extension is2times of the original image, the horizontal direction unchanged; and for the image X axis length less than Y axis length as partial vertical type image the horizontal direction, length is extended to2times, the vertical direction and is similar to the original image. This method will be the information redundancy is reduced by25%.(5) Taking the original image as a reference, the peak signal to noise ratio and mean square error theory, using MATLAB programming to reproduce the improved image fidelity is evaluated, the results more reliable.(6) Studying the optical reproducing apparatus, and the pretreated material wave front loading the optical computing, the reconstruction image of the hologram, and the diaphragm to control the beam, the elimination of stray light, get clear optical reconstruction images, the results in line with expectations.