光磁混合存储动态测试系统
文献类型：学位论文
| 作者 | 朱青 |
| 学位类别 | 博士 |
| 答辩日期 | 2008 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 徐文东 |
| 关键词 | 混合存储 热梯度型 动态测试系统 聚焦伺服 像散法 |
| 其他题名 | Dynamical Testing System for Hybrid Magneto-Optical Storage |
| 中文摘要 | 随着信息技术的迅速发展，对信息存储容量的要求越来越高。光磁混合记录技术以激光辅助热磁写入和磁通检测读出为主要特征，克服了超顺磁性效应的影响，是最有希望实现Tbit/in2记录密度的存储技术。展开对于光磁混合存储技术的研究，具有十分重要的意义。存储介质是发展光磁混合存储技术的关键，而动态测试系统是材料实用化过程中必不可少的平台。本论文的主要内容即是设计和搭建光磁混合存储动态测试系统。 论文首先综述了磁存储、高密度光存储的发展历程、研究进展和技术展望；阐述了光磁混合存储的原理，简要介绍了记录介质的要求和分类；说明了三种记录方式的区别；分别介绍了磁场梯度型混合记录装置、热梯度型混合记录装置和双梯度型混合记录系统的国内外研究现状、实现方式和主要参数。 而后，本文介绍了光磁混合存储动态测试系统的基本要求、设计思路及信号调制方式和关键参数的确定；介绍了组成系统的四个模块：激光调制模块、聚焦伺服模块、主轴电机模块和偏置磁场模块；说明了系统中各器件选型的要求和理由；分析了像散法离焦误差探测子模块的设计思路和方法，模拟了四象限探测器分划线的宽度对离焦误差曲线的影响，并给出了相应光路的具体设计结果；最后简单描述了系统的集成，包括机械设计、光路调试及软件的编写。 测试系统是在有一恒定的外部写入磁场作用在记录层上时，由一定数值孔径的物镜将激光光束会聚在样品记录层上，并使会聚光点与样品记录层保持高速相对运动，通过对激光器输出光强进行调制，在一定范围内调节会聚光点的功率和光脉冲的宽度，以实现不同条件下记录层信息写入。再通过磁头或磁力显微镜得到记录点处的磁畴信息，即可研究光磁混合存储介质的读写性质。根据读出信号可以计算介质的信噪比，在不同写入条件下进行记录，就可以给出信噪比、记录点大小随记录功率和光脉冲宽度的变化曲线。 系统采用光场调制方式。激光器输出的平行光被声光调制器调制，衍射的一级光经过小孔滤波后射向扩束镜。激光光束扩束后，经过分光镜和物镜，聚焦到盘片记录层上。声光调制器与其驱动器相连，声光调制器的驱动器与可编程信号发生器连接。计算机控制信号发生器产生所需电信号，并将信号输出至声光调制器的驱动器的调制信号端，对光进行调制得到所需光信号。 系统采用双光束法进行聚焦伺服，即利用蓝光进行信息写入，另外加入一路红光进行聚焦伺服，这样消除了光电探测器对蓝光波段的响应度较小的影响，提高了系统整体的探测灵敏度。从盘片反射回的光束依次经过物镜、光谱分光镜、像散法离焦误差探测光路后打在四象限探测器上，四象限探测器的输出经前置放大电路、数据采集卡输入端口进入计算机，在计算机内进行伺服矫正后，通过数据采集卡输出伺服控制信号至压电陶瓷（PZT）低压放大器，由PZT低压放大器驱动压电陶瓷纳米平台带动物镜在光轴方向运动，以保持会聚激光束准确聚焦在样品记录层上。 利用上述系统对光磁混合存储材料进行了初步实验研究。其中，对TbFeCo薄膜的静态测试结果验证了光磁混合记录的原理；对有机光存储材料的动态测试结果证实系统可以正常工作。 |
| 英文摘要 | With the rapid development of information technology, the requirement of storage capacity is higher and higher. Hybrid Magneto-Optical Recording (HAMR) which combines laser-assisted recording and flux detection readout can overcome super paramagnetic limits. HAMR technology is one of the promising approaches to push the recording density beyond Tb/in2. So it has very important significance to carry out research on hybrid recording technology. Storage medium is the key to develop HAMR technology, and dynamical testing system is absolutely necessary to the practical course of storage medium. The main content of this paper is the design and construction of dynamical testing system for hybrid Magneto-Optical storage. In this thesis, the development course, current status and technology prospect of the magnetic storage and high density optical storage are reviewed. The principle of hybrid recording is expounded, and the requirements and types of recording media are briefly explained. The difference among three hybrid recording modes is described. The research status, design methods and chief parameters of thermal gradient hybrid recording apparatus, magnetic field gradient hybrid recording apparatus and dual gradient hybrid recording apparatus, are introduced. Then, the test requirements and design idea of dynamical testing system for hybrid Magneto-Optical storage, signal modulation mode and key parameters’ identification are shown. The four modules of the test system are introduced, including laser modulation module, focus servo module, spindle motor module and bias magnetic field module. The principles of system components selected are expounded. The method and design idea to realize the subsystem of astigmatic focus error detection are detailed. The influence of the gap of quadrant photo-diode detector (QPD) on focus error signal (FES) is analyzed. The design result of corresponding optical system is also given in this thesis. Finally, system integration process is simply described, including mechanical design, optical path adjusting and software programming. In test system, with a constant bias magnetic field on the recording medium, the laser light is focused on the medium surface by means of objective lens. The converged spot and recording medium are kept with high speed relative motion. Different recording condition is obtained through modulating the power and pulse width of the laser beam. After the above recording process, the information of recorded magnetic domain can be detected by magnetic head or Magnetic Force Microscopy, and the characteristic of the mediu is studyed. Then, the relation between the SNR and size of magnetic domain and the optical power and optical pulse width are obtained. Optical Modulation is adopted in the system. First, the laser beam is diffracted by acoustic-optic modulator, and the first order diffractive laser beam passes through the pinhole and is expanded by expander. Then it passes through beam splitter and objective lens, is focused on data recording layer. Desirable electric signal is send to acoustic-optic driver through signal generator controlled by computer, then corresponding optical signal is obtained. Double-beam method, with information recorded by the blue ray and focus servo completed using red ray, is adopted in this system. Double-beam method eliminates the influence of QPD’s low responsivity to blue band, and increases the whole detection sensitivity of the system. The laser beam reflected from medium passes the objective lens, spectroscope, quarter-wave plate, the FES detection optical path, and irradiates on QPD. Output signals of QPD are collected through photoelectric converting and pre-amplifying circuits, and A/D transformer. Correspongding digital signals is obtained by A/D transformer and transmitted to computer. Corresponding FES is calculated, and correction algorithm is executeed and digital servo signal is output to D/A card by the computer. The converted analog signal from the D/A card is sent to LVPZT amplifier which controlled PZT to move objective lens to certain position. Hybrid recording medium is studied using the above test system. Static experimental results of TbFeCo film are shown which verify the principle of Hybrid Recording. Experimental results of organic optical storage materials film proved that the dynamic tester work properly. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15227]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 朱青. 光磁混合存储动态测试系统[D]. 中国科学院上海光学精密机械研究所. 2008. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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