Study On Fast Readout For Holographic Data Storage

With the developing of information highway and computer technology, the requirement to capacity and transfer rate of information storage is getting higher and higher. It is important to develop storage systems with higher capacity as well as faster readout rate. The aim of this thesis is to design a fast dynamic readout system for holographic memories to get a target readout rate no less than 150 Mb/s.In this thesis, the theory and progress of fast readout technology of holographic data storage in the world is surveyed, some relative conceptions about volume holographic storage and readout mechanism of devices in holographic storage systems are introduced and the factors that affect the readout rate are analyzed based on the disk holographic storage schemes. The experimental fast- readout schemes suitable for the equipment in our laboratory are investigated, and the performances of the necessary devices in the schemes are evaluated.The high-density information storage is the foundation of achieving fast readout. Thus this thesis also discusses the performance optimization of the holographic disc storage medium (Zn:Fe:LiNbO3) by using Track-Division Thermal-fixing Holographic Disk Storage (TDTF) scheme. The result shows that the TDTF scheme suppresses the erasure effect and increases the dynamic range of Zn:Fe:LiNbO3 crystal as well.Based on the spatioangular-multiplexed holographic storage scheme and the equipment available in our lab, the holographic system that could realize the fast readout was designed. The operation process and time scheduler of the system were also worked out. High speed electro-optic switch, addressing equipment (motorized precise rotary stage) and detector array (high-speed CMOS camera) were driven together under the control of the pulse generator with self-developed CVI software. The stability of rotate stage and readout reliability of the system were verified by experiments.In order to verify the feasibility of high-speed dynamic readout under the condition of our laboratory, the achievable readout rate was determined firstly to be 34.2 Mb/s according to the parameters of the equipment available in our lab. Then experimental scheme of recording and dynamic readout of 150 holograms was designed. Finally, the experiment was executed in the Zn:Fe:LiNbO3 disk crystal and readout rate of 34.2 Mb/s was achieved successfully. Meanwhile, we analyzed that the desired readout rate of 150 Mb/s could be realized with some improvements of system. The system requirements for a readout rate of Gb/s order were further discussed.