Suppression Method Of Speckle Noise Based On Computer-generated Hologram Reconstructed Image

Holographic three-dimensional display is one of the most potential free stereoscopic display technologies.It can reconstruct three-dimensional images in space and provide real depth perception for human eyes.Compared with traditional optical holography,computer generated hologram(CGH),which is combined with modern optics and computer,has the advantages of easy replicating,flexible function,small noise and wide range of application.It has played its unique advantage in the field of optics,especially in the field of twodimensional display.However,there are significant noises in computer-generated hologram.In recent years,improving the imaging quality of the reconstructed image and reducing the noise interference has become a hot topic in the research of holographic display.This paper mainly focuses on improving the quality of reconstructed images.First of all,this paper briefly introduces the general situation of computer generated hologram to improve image quality and suppress speckle noise.The main algorithm to improve the reconstructed image quality is studied,and each algorithm is analyzed and simulated,the advantages and disadvantages of each algorithm are analyzed and the improvement measures are put forward.Among them,This paper focuses on the the method of random phase-free holography using virtual convergence light,On the basis of the current research,we add the experimental model of ringing artifacts reduction and iterative algorithm,and carry out numerical simulation analysis of the systemThe main contents and structure of this paper are as follows:First,A brief introduction of the research background and current development status of the method for holographic image projection with suppressed speckle noise,and the theoretical knowledge of the basis of the field of CGH and the reconstructed image of hologram with suppressed speckle noise is introduced.It is convenient for us to understand the computer holography generation method and lay the foundation for further research.Secondly,The basic two kinds of computer holographic imaging speckle suppression schemes are experimentally simulated and analyzed.The first class is an iterative phase recovery algorithm with random phase,After analyzing the traditional Gerchberg–Saxton(GS)iterative algorithm,the double restricted iterative Fourier transform algorithm and the double restricted iterative Fourier transform algorithm based on the object-dependent quadratic phase distribution mainly studied.The second class is the theory of random phase-free holography using virtual convergence light.This theory mainly studies the imaging quality using virtual convergence light instead of random phase and adding the iterative scaling Fourier algorithm.;The theoretical analysis and numerical simulation of the two kinds of algorithms are carried out,and the diffraction efficiency,uniform error and iteration convergence are analyzed..Finally,through the above algorithm analysis,we have mainly studied and improved the theory of random phase-free holography using virtual convergence light.Because the size of the computer hologram without random phase is limited(not more than the size of the hologram),we mainly use the aliasing and scaling Fresnel diffraction algorithm to do the diffraction,In view of the characteristics of the noise mainly from the ringing artifact,we add the amplitude inverse filtering method to filter the noise caused by the ringing artifact during the process of generating the hologram,and add phase transportation on this basis,and obtain the required phase substitution for virtual converging by the repeated iteration of the scaling Fresnel diffraction,The proposed algorithm uses this phase to get high quality reconstructed images.The SNR of the algorithm and the structural similarity between the original image and the reconstructed image are analyzed.