Theory And Experimental Research Of Holographic Storage Based On LiNbO₃ Crystal

With the development and the need of the fast storage,the volume holographic memories technology has a lot of advantages such as the high storage capacity,short access time and fast data transfer rate so people pay more and more attention to it and do a lot of research on it,the applications of volume holographic memories are widely used today.In this thesis we introduce the development of the volume holographic memories and the kind of the photorefractive material first.In chapter 2 we systematically discuss the characters of the LiNbO3,including feature,structure, bond,the levy structure model and the dropped materials in the LiNbO₃.We do the fan scattering experiment on the dropped LiNbO₃.We find that there are obviously differences between the photorefractive dropped and damage-resistant dropped LiNbO₃ after they had been irradiated by laser for the same times.In the end of chapter 2 we introduce the processing used mediate frequency furnace to grow the LiNbO₃ crystal.We mainly research on the theory of the photorefractive based on the volume holographic memories in chapter 3.Discussing the processing of the photorefractive and analyzing the two waves coupling and the effect of diffraction based on LiNbO₃,it applies the theory for the future experiment.In the end of the chapter 3,we describe some kinds of the ways about reuse technology.In our experiment we adopt the easily way to realize the angles reuse sucessfully.In chapter 4,we adopt the 3dsmax and Matlab to choose and preprocess the images before they are saved in the crystals.Many image arithmetic operators are used to remove the low frequency and save more high frequency thus we can achieve better edges detection,details sharpening.We also analyze the noises which may be occurred in our experiment systems;some noises of system are simulated by software and are added on the images.We design some kinds of filters to remove the noises and compare the abilities of the filters. In chapter 5 the kinds of the volume holographic memories are introduced,it also introduces the devices in our optical light path.We do some experiments on LiNbO₃ such as the effect of diffraction,light damage to test the character of crystal base on the two waves couplings light path.Through the experiment we explain the curves of the diffraction and certify that the different dropped crystals have different resistant abilities to the light damage,the results of the experiments are analyzed,too.Many images are saved in the LiNbO₃.The holograms are reproduced successfully.