Resarch Of The Design Of Digital Holographic Data Storage System With High Quality And High Density In Photopolymer Materials

In the modern information society, the requirements for high storage density and high data transfer rates are constantly rising. But the traditional technology for storage and data processing device has developed to its limit and new way to store information is needed. Then, a new technology, volume holographic storage, is developed. The development of photopolymer material offers storage material for this technology, and the digital data storage is the way to make it true. In this thesis, the purpose is to study a design scheme for realizing digital data holographic storage with high quality and density.Firstly, the principles of volume holographic storage are introduced, various methods of multiplex technology for storage are summarized and the way to evaluation the quality of storage is also discussed. As a part of my research work, the thesis has accomplished the measurement of different series of photopolymers which are provided by Technical Institute of Physics and Chemistry of Chinese Academy of Science. In those measurements, the scattering noise of photopolymer was deeply investigated by means of Loss of Signal-to-Noise Ratio (LSNR).Based on those background knowledge, the thesis study the way to realize the high density and quality in holographic data storage. Different multiplex methods often mean making use of different kinds of reference beams. So it is necessary to study the influence of reference beams (general plane beam, Gaussian beam, speckle beam, and speckle imaging reference beam) on the quality of holographic storage. The results of the research show that with plane reference, the quality of reconstructed images are very good and with Gaussian beam the noise of the reconstructed images is restrained but the boundary information is also weakened; however, with speckle reference, the quality of the images is not good; although with the speckle imaging reference, the situation is a little better. So, it is necessary to improve the quality of the reconstructed images when the random-phase multiplexing technology is to be used for high density storage. And in order to implement high-density holographic storage with high reconstruct quality, the reference beam must be optimized.According to the discussion above, we go on to study the deterministic phase-modulated multiplex method, the orthogonal phase-coding. Also by numerical simulation we study the new optical setup design of shift-multiplexing method with reference beam which is modulated by orthogonal phase-coding. The results show the storage quality is good and it is calculated that the storage density can be about 120bits/ m2. We will go ahead doing research on holographic storage with this design to realize the high density and high quality digital data holographic storage.