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1、哈尔滨工业大学理学硕士学位论文摘要理想的存储材料一直是体全息技术发展的关键。光致聚合物材料具有高灵敏度，高信噪比和制造成本低廉等诸多优点，是高密度全息存储最有希望首先获得突破的材料。PMMA(PQ)光聚物以其较低的曝光收缩性和较大的厚度受到了人们的广泛关注。但是 PMMA(PQ)材料也存在缺点，由于 PQ分子的扩散系数较小，扩散的长期作用会对存储图像的质量产生负面影响，这是影响该类材料实用化的主要障碍之一。如何获得材料曝光后内部反应的真实过程，分析不同曝光和放置时间的扩散作用，对于了解并克服扩散作用对体全息存储性能的影响有着重要意义。本文通过光化学产物分析了 PMMA(PQ)材料的光反应过程,
2、建立了适用于该材料的非局域扩散模型。用时域有限差分方法对该模型进行了数值求解，模拟了材料光栅建立的动态过程，描述了光栅轮廓和折射率的变化。为了研究 PQ分子的扩散作用，我们进行了永久存储实验，分析了扩散对图像质量造成的不利影响，并计算了 PQ分子的扩散系数，其数量级为21 2均匀非相干光照明样品的方法，在提高图像质量的同时能有效地抑制扩散的不利影响，获得了比较理想的实验结果。应用非局域扩散模型获得了适用于光致聚合物的曝光序列，使用该序列单点存储 30幅图像，得到的全息图衍射效率均匀性好于相同条件下等时曝光的结果。关键词光致聚合物；全息存储；扩散模型；均匀衍射效率-I-10 m s 。对于保持存
3、储图像的长期稳定性，本文采用了一种在曝光后应用哈尔滨工业大学理学硕士学位论文AbstractOptimum recording materials play an important role in optical volumeholographic storage technology. It is generally believed that photopolymer is apotential recording material because of its high sensitivity, high signal-to-noiseratio and cheap manufactu
4、ring cost, and great breakthroughs might be madefirstly in this kind of materials, in which PMMA(PQ) photopolymer drawsextensive attention because of its low exposure shrinkage and large thickness.But it also has the weakness of low diffusion coefficient. Long-term diffusion isnegative for stored ho
5、lograms, so this is one of the main obstacles for itsapplication. The reaction process in material after exposure and the diffusionunder different conditions of exposure and placing time are important forunderstanding the influence of diffusion on volume holographic storage.By analyzing the photoche
6、mical process of PMMA(PQ) photopolymermaterials in detail, we present a non-local diffusion model in this thesis. FDTDmethod was applied to solve the diffusion equations and the dynamic process ofgrating formation in PMMA(PQ) materials was simulated numerically, and thetime evolution of grating prof
7、ile and refractive index is presented.The permanent storage experiment was carried out to study the negativeeffect of diffusion of PQ molecule on the quality of volume holographicrecording. The diffusion coefficient of PQ molecule was obtained numerically,21 2the recorded holograms, the uniform inco
8、herent light was used to illuminate thesamples after exposure. This method can overcome the disadvantageousinfluence of diffusion on the quality of the recorded images effectively.The exposure schedule was deduced from the non-local diffusion model inphotopolymer. By using this exposure schedule, 30
9、 holograms were recorded inone point and the uniformity of their diffraction efficiency is much better thanthat in isochronous exposure scheme.Keywordsphotopolymer; holographic storage; diffusion model; uniformdiffraction efficiency- II -whose magnitude is in the order of 10 m s . To keep the long-t
10、erm stability of哈尔滨工业大学理学硕士学位论文目录摘要 .IAbstract . II第 1章绪论 . 11.1课题背景 . 11.2光致聚合物材料简介 . 21.2.1光致聚合物的构成 . 21.2.2光致聚合物的全息存储特性 . 31.2.3光致聚合物材料的研究进展 . 61.3 PMMA(PQ)材料国内外研究现状 . 71.4本课题的研究目的和意义 . 81.5本课题的主要内容 . 8第 2章 PMMA(PQ)光反应过程研究 . 92.1光致聚合物的一般光反应过程 . 92.2非局域扩散模型 . 112.3 PMMA(PQ)光反应过程 . 132.4适用于 PMMA(PQ)材料的扩散模型 . 162.5应用扩散模型得到的数值结果 . 172.5.1光栅轮廓 . 172.5.2折射率变化 .
