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飞秒激光三维光盘存储系统及相关技术研究

Research on Femtosecond Laser Three-dimensional Disc Storage System and Related Technologies

【作者】 江兵

【导师】 黄文浩;

【作者基本信息】 中国科学技术大学 , 精密仪器及机械, 2007, 博士

【摘要】 随着网络和多媒体技术的发展,需要存储的数字化信息以惊人的速度增长,如此大的信息量需要大容量的存储设备来支撑。在国家自然科学基金(No.50275140,No.50335050)及“863”项目(MEMS 2003AA404050)的资助下,本论文结合双光子三维共焦荧光存储技术与现有光盘存储伺服技术,提出了飞秒激光三维光盘存储系统设计方案,搭建了一套双光子三维光盘存储实验系统,并对相关问题进行了理论和实验研究。首先,通过对目前国际上研究的多种多层盘片伺服方案的分析,结合在像差校正中应用的双元透镜控制技术,设计了三维光盘存储系统变焦选层方案,并详细分析了系统跟踪和选层过程中,音圈电机的致动曲线。考虑到变焦选层方案控制及光学系统的复杂性,提出了双光头异侧方案,作为本论文飞秒激光三维光盘存储系统的实现模型,并分析计算了由于制造、装配原因导致的双光头轴向、径向同步误差。提出共焦模块光强伺服控制技术,并利用光致漂白材料存储结果的标定行数据进行matlab模拟仿真。其次,利用共焦荧光显微原理及其三维光学传递函数,分析了本实验系统共焦模块参数对单、双光子共焦荧光读取分辨率的影响。单光子共焦荧光系统共焦小孔直径10.4μm时,层析能力比采用208.4μm共焦小孔提高了3.6倍。双光子共焦荧光系统共焦小孔直径7.8μm时,层析能力比采用156.7μm共焦小孔提高了1.56倍。离焦量大时,双光子共焦荧光系统比单光子共焦荧光系统有更好的轴向响应。通过已知大小荧光物双光子共焦荧光成像实验,验证了共焦小孔直径与系统横向轴向分辨率的反比关系。然后,完成飞秒激光三维光盘存储系统伺服模块的硬件设计和制作,实现伺服模块功能,完成共焦模块读写光路的设计和搭建,完成共焦模块同步控制电路的设计和制作。根据实测的双光头同步控制电路聚焦输入输出信号,辨识同步控制电路聚焦控制模型,仿真曲线和实测结果吻合较好,二者符合度为78.0259%。搭建双光头同步聚焦误差检测实验装置,检测、计算各激振频率下的同步聚焦误差幅值。选择二苯乙烯类衍生物光致漂白材料旋涂在DVD盘片上进行双光头原理实验,获得初步的实验结果。最后,改建了基于平移台的存储实验系统,进行飞秒激光三维光存储材料研究。在光致变色材料(二芳基乙烯类衍生物)掺杂的PMMA膜中存储两层数据,点间距4μm,层间距8μm。在光致漂白材料(二苯乙烯类衍生物BPSBP)掺杂的PMMA聚合物膜中实现三层信息存储,点间距4μm,层间距15μm。在微爆材料Sm(DBM)3Phen/PMMA样品中进行了九层微爆信息存储,点间距为4μm,层间距为8μm。通过三种材料光化学物理特性及三维光存储实验研究,本论文的飞秒激光三维光盘存储系统选择光致漂白材料和双光子共焦荧光读取方式。本论文对飞秒激光三维光盘存储系统进行理论和实验研究,并对实用化过程中的相关问题作了讨论和展望,为三维光存储技术产品化打下了一定基础。

【Abstract】 The need for data storage is explosive, triggered by the development of multimedia and electronic communication networks. Mass storage devices are necessary to fulfill the increasing demands.A femtosecond laser three-dimensional disc storage system has been designed based on servo technology used in current optical disc storage devices and two-photon three-dimensional confocal fluorescent data storage. We built the system and researched on related theoretical and experimental issues. This project was supported by National Nature Science Foundation of China (No. 50275140 & No. 50335050) and "863" project (MEMS2003AA404-050).Firstly, we analyzed several servo methods of multi-layer disc storage system. Consulted the two-element lens technology used in compensation for spherical aberration, a varifocal layer-selection technology in three-dimensional storage system was proposed, and the movement of voice coil motor in following and layer-selection process was investigated. Considering the complexity of control and optical system in varifocal layer-selection method, we brought forward a two-pick-up both-side method as implementation scheme of the femtosecond laser three-dimensional disc storage system and studied the axial and radial synchronous errors between two pick-ups because of manufacture and assemblage. We proposed the fluorescence intensity servo technology used in confocal module and simulated it in Matlab with calibration data obtained from photobleaching material storage experiment.Secondly, according to the principle of confocal fluorescent microscope and its three-dimensional optical transfer function, we analyzed the connection between parameters in confocal module and the resolution of sigle-photon and two-photon confocal fluorescent system. The depth-discriminating ability of single-photon confocal fluorescent system with 10.4μm pinhole diameter is 3.6 times higher than that with 208.4μm pinhole diameter. The depth-discriminating ability of two-photon confocal fluorescent system with 7.8μm pinhole diameter is 1.56 times higher than that with 156.7μm pinhole diameter. Also, the two-photon confocal fluorescent system has better axial response than single-photon confocal fluorescent system when defocusing amount is large. We carried out two-photon confocal fluorescent imaging experiment with given-size fluorescent object, which verified the inverse relation between detector size and system resolution.Thirdly, we designed and fabricated the servo module in femtosecond laser three-dimensional disc storage system, and realized its servo function. The recording optical system and two-pick-up synchronous control circuit in confocal module were also completed. The synchronous control circuit was simulated by using its focusing input and output signal. The simulation result and measured data fitted well (fit=78.0259%). We built two-pick-up synchronous focusing error detection device and measured synchronous focusing errors under different excited frequencies. The storage experiment with photobleaching material (diphenylethylene) spin coating on DVD disc was executed, and preliminary result has been achieved.Finally, rebuilding original storage systems based on platform, we carried out three-dimensional optical storage experiments with femtosecond laser. Two-layer optical data storage in PMMA film doped with photochromic material (diarylethene derivative) was achieved. The distance between two bits in each layer and the two adjacent layers interval were 4μm and 8μm respectively. Three-layer optical data storage in PMMA film doped with photobleaching material (diphenylethylene BPSBP) was achieved. The distance between two bits in each layer and the two adjacent layers interval were 4μm and 15μm respectively. Nine-layer microexplosion data storage in Sm(DBM)3Phen/PMMA was achieved. The distance between two bits in each layer was 4μm and the two adjacent layers interval was 8μm. According to storage research on photochemical and photophysical properties of three kinds of materiels, photobleaching material and two-photon confocal fluorescent storage method were chosen in our femtosecond laser three-dimensional disc storage system.In conclusion, we implemented theoretical and experimental research on femtosecond laser three dimensional disc storage system. Meanwhile we discuss and look forward to the related projects in practical process. The work in this thesis is helpful for three-dimensional optical storage devices coming into mass storage market.

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