Preparation and Characteristic Study of the PMMA/PQ Photopolymer and its Application on Optical Data Storage
在高分子材料製程方面，首先，我們製作出合適於填充樣品的玻璃容器，再以染料PQ (9,10-phenanthrenequinone)及啟始劑AIBN (Azobisisobutyronitrile)摻合入純化的MMA (Methyl methacrylate)單體中，裝入事先製做完成的容器內。經由不同反應條件，最後以45℃、反應3天為標準製程，製作出不同組成濃度及厚度的PMMA/PQ感光高分子材料。
In this thesis, we synthesize a high optical quality photopolymer for holographic memory. Chemical analyses are performed to study on the recording mechanism. Based on these results, characteristics for holographic data storage are obtained. Then, a volume holographic storage system is constructed using our polymer block. Our samples are prepared by dissolving 9,10-phenenthrenequinone (PQ, up to 0.7%) and initiator azobisisobutyronitrile (AIBN, up to 1.5%) in the purified Methyl methacrylate (MMA) monomer. The solution is poured into different glass flasks to fabricate the samples in a variety of dimensions. The samples with different concentration of AIBN and PQ are then placed in a temperature-controlled chamber at 45℃ for three days to polymerize MMA monomer. Then, the samples are turned into solid blocks. Analyzing of the optical exposed samples by using UV, TGA, GPC, Mass, FT-IR and NMR indicates that in our PMMA/PQ samples, the PQ molecules reacted with MMA monomers one by one. The products contain two different compounds. We have also studies the influence of the concentrations of PQ and AIBN for the holographic recording. The results show that the diffraction efficiency of the grating increases with the concentration of PQ, and increases slightly as that of AIBN increases. However, the increase of the AIBN will reduce the optical transmission of the samples. Based on these results, up to 2.5x2.5x2.5 cm3 PMMA/PQ photopolymer volume with high-optical-quality can be made. We have performed multiple plane wave holograms storage experiments in our PMMA/PQ photopolymer samples to study photo-sensitivity, dynamic range, angular selectivity, exposure schedule and fanning effect. The results show that the dynamic range and the response energy of our polymer increase with the thickness. The angular selectivity decreases with the thickness. In addition, a special exposure schedule is proposed to obtain uniform diffraction efficiency of multiple holograms. Finally, multiple storage of 250 image holograms recorded in a single spot of a 1cm3 sample block using scheduled exposure and 90-degree angle-multiplexing geometry is demonstrated.
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