| As a highly potential information storage technology, holographic storage has been a research focus for a long time. Research on holographic storage medium is of great significance because the highest possible mass storage and high-speed data addressing are also the key focuses of research in this field. Apart from satisfying the requirement of bulk-storage memory of information, an ideal holographic storage medium should be able to make timely and quick response to data message and obtain high fidelity reconstruction images. In existing research on holographic storage medium, people are still exploring for a perfect medium that meet all the requirements about memory capacity, memory property and low cost. In terms of realizing broad commercial application of holographic storage, the first problem that must be solved is the discovery of an ideal holographic storage medium.This paper is focused on the theoretical analysis and experimental research on the holographic storage characteristics of KNSBN crystal.The research contents mainly include:(1) Theoretical study of holographic storage technology, holographic storage mechanism, photorefraction effect and coupled-light theory. It is assumed through the theoretical study that KNSBN crystal can be used as holographic storage medium. Then the assumption is verified by experiments.(2) Influence of incident light spot size on the quality of reconstruction image of hologram. Incident light spot sizes of the object light and reference light are changed to make the spot size of object light bigger, equal or smaller than that of reference light respectively. Then quality of reconstruction images of hologram under the said three conditions is analyzed. The experiment results indicate that the best quality reconstruction image of hologram can be achieved when object light spot size is bigger than reference light spot size.(3) Research on holographic storage incident angle range (dynamic range) of KNSBN crystal. Single variable is maintained in the experiment. Corresponding quality of the reconstruction image of hologram is analyzed via changing reference light incident angle in the light path of the experiment. The research results indicate that the storable incident angle of KNSBN crystal ranges between 20°36’～40°07’,of which the structure reflects indirectly the dynamic range of KNSBN crystal.(4) Diffraction efficiency research of KNSBN crystal. Firstly, changes in duration time of reconstruction image of hologram are studied with volume phase grating in different positions of the crystal. Then, the research result is followed through further research on the diffraction efficiency of the reconstruction image. It is concluded that the longest time of duration of reconstruction image,262s, appears when the volume phase grating shaped in the crystal is totally within the crystal, and the maximum diffraction efficiency of 31% is thus achieved.(5) Response time research of KNSBN crystal. Diffraction efficiencies of reconstruction image of hologram obtained under different time of exposure are studied through controlling the exposure time of the crystal. With the definition of response time taken into consideration, the response time of KNSBN crystal is determined to be 3s.(6) Storage durability research of KNSBN crystal. With information recorded, the crystals are placed in darkness without changing any other experimental conditions. Then the reconstruction images after different time of storage are analyzed, which finally indicates that the time of duration of KNSBN crystal is 16 hours. |
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