镀膜机电子束扫描蒸发的数字化控制系统的研究
文献类型：学位论文
| 作者 | 周婧 |
| 学位类别 | 硕士 |
| 答辩日期 | 2007 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 易葵 |
| 关键词 | 光学薄膜 蒸发分布 数字化 停留时间 扫描模型 数字电位器 |
| 中文摘要 | 目前，广泛应用在高功率激光和光通信系统的高性能光学薄膜的需求日益增长。高性能的光学薄膜与膜料均匀的温度和稳定的蒸发分布紧密相关。为了能够在电子束蒸发沉积的过程中，达到更稳定的蒸发速率和蒸发分布，必然对电子束蒸发沉积系统的性能提出更高的要求，这就需要从电子束的扫描频率、扫描的可变性和可控性、电子束的轨迹、电子束功率的分布等方面进行改进和优化。本课题主要从扫描的可变性和可控性角度提出改进方案。 本文首先介绍了光学薄膜在工业、农业、日常生活的领域的广泛应用。介绍了一系列的光学薄膜镀制方法，从不同程度改善光学薄膜的性能。电子束蒸发具有适用范围广，成膜质量高等优点，是真空镀膜技术中的一种重要加热方法。 第二章介绍了蒸发系统中的主要组成部分——电子束加热蒸发源装置的结构和工作原理。详细介绍直式电子束加热蒸发源、环式电子束加热蒸发源、E型电子束加热蒸发源的功能和特点。其中E型电子束蒸发源设计合理，实用性强，是目前普遍使用的一种装置。由于装置采用了电子束磁偏转的原理，磁场分布对电子束聚焦特性影响很大。装置结构上的差异，导致束斑散焦，破坏蒸发分布的稳定性，是目前急需解决的问题之一。 第三章，分别从电子束的扫描频率，扫描的可变性和可控性，电子束的轨迹，电子束功率的分布等方面提出存在问题及解决方案。重点讨论了扫描的可变性和可控性，提出了一套电子束扫描蒸发的数字化控制系统，目标是保证蒸发膜料表面的平整度，提高蒸发速率和蒸发分布的稳定性。整套系统采用了可编程扫描模型思想，针对膜料特性，设定所需要的扫描模型，数字化地控制电子束行走路线、扫描区域大小、扫描频率等。 第四章，详细介绍电子束扫描蒸发数字化控制系统的硬件及软件部分。硬件部分包括三个部分：一台计算机、偏转控制装置和扫描装置。计算机用于应用程序的编写，从并口输出控制参数。偏转控制装置中采用了Xicor公司的X9319和X9C103型号的数字电位器，数字电位器能与计算机直接接口，快速响应数字信号，控制方便，主要用于调节和控制通入X/Y方向电磁线圈电流大小。扫描装置包括一组电磁线圈，在电磁线圈中通入变化的电流，产生变化的磁场对电子束施加力的作用，使电子束能在X/Y轴方向运动。在Delphi的开发环境下开发程序控制界面，用户设置参数控制数字信号输出。 整个数字化控制系统的硬件电路的搭建和调试及控制软件的设计已经完成，用户可选取有限点，设定一些基本的扫描模型，如类似螺旋状的扫描模型和直线扫描模型。由于束斑的聚焦性不是很理想，停留时间长短的设定还需要进一步的实验研究。 最后对整个论文工作进行了总结，并且提出了今后改进的思路和发展方向。 |
| 英文摘要 | Nowadays，demand for high-performance optical coatings is growing for a range of applications such as high-power lasers and optical communication systems. Optical coatings with high performance require coating materials with uniform temperature distributions and stable vapor distributions. During the electron-beam deposition process, stable deposition rate and vapor distributions depend on the performance of electron-beam deposition systems including beam sweep frequency, sweep variability and control, beam trajectory, and control of beam power profiles. This paper focuses on the improvements of sweep variability and control of the electron beam sweep evaporation. Firstly, applications of optical coatings in the industry, agriculture and daily life are introduced. Several coating methods for improving performances of optical coatings are introduced. As Electron beam evaporation is an important heating method in the vacuum coating technology, it is widely used and produces coatings with high quality. In chapter 2，several structures and principles of electron beam heating evaporation sources are introduced, such as the Pierce type, toroidal type and E type. E type electron beam heating evaporation source has been widely used for its rationality and practicability. Because this device is based on the principle of electron beam magnetic deflection, distributions of magnetic field have great effect on the focus of the electron beam. The defocus of the beam which breaks the stabilization of vapor distributions is attributed to differences of the equipment structure. It is one of the problems to be solved as soon as possible. In chapter 3, the problems and improvement methods of beam sweep frequency, sweep variability and control, beam trajectory, and control of beam power profile are introduced. Especially sweep variability and control are discussed. For keeping the coating material surface flat and enhancing the stabilization of vapor distributions, a digitally controlled system of electron beam sweep evaporation is presented. The system is based on the principle of programmable sweep pattern. Arbitrary electron beam sweep patterns can in theory be designed based on characteristics of source material, the beam trajectory, so sweep area or size and sweep frequency can be controlled. In chapter 4, hardware and software of the digitally controlled system of electron beam sweep evaporation are introduced. Hardware includes three parts: a computer, deflection controlled device and sweeping means. A computer is used for programming and outputs control parameters through parallel port. In the deflection controlling device, the digitally controlled potentiometers Xicor’s X9319 and X9C103 are used. The digitally controlled potentiometers have the flexibility of computer-based digital controls and are mainly used for controlling strength and direction of current applied to longitudinal and lateral electromagnets. Sweeping means includes longitudinal and lateral electromagnets. By applying currents of variable strength and direction to electromagnets, magnetic fields can be established within the region bounded by the electromagnets. The magnetic field has lines of force of variable or controllable orientation. As the beam passes through this region, it may be deflected according to the orientation of the lines of force. By appropriate control of the direction and strength of the lines of force, the beam may be moved or swept across the surface of the coating materials within the crucible. Program controlled interface is developed in Delphi, so parameters can be set to control the output of the digital signals. The hardware and software of this system have been finished. A series of points can be chosen and several basic sweep patterns can be designed, such as spiral pattern and line pattern. Due to the defocus of the electron beam, more experiments and researches should be conducted in order to set the appropriate dwell time. At last, the summary of this paper and advice for future work are presented. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16623]  |
| 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 | 周婧. 镀膜机电子束扫描蒸发的数字化控制系统的研究[D]. 中国科学院上海光学精密机械研究所. 2007. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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