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chi20181130上海光机所朱健强557458In recent years, high-power laser drivers have been rapidly developed. With the increasing demand for output energy of laser drivers, the number of optical paths is increasing, and the aperture of the beam is increasing, so the demand for optical components is increasing rapidly, and the accuracy and quality requirements of optical components become more and more stringent, the demand for a large number of ultra-precision laser optics poses a greater challenge to traditional optical processing. Continuous polishing utilizes a large-diameter annular pitch lap,which usually covers the entire optic surface during the polishing process. This leads to unparalleled superiority in suppressing high-frequency and mid-frequency errors relative to other polishing methods, due to the fluidity of the fluidity of the pitch lap. Consequently, continuous polishing has become the preferred method for processing large-aperture laser optical components for its unique full-spectrum surface shape control advantages. However, due to the current understanding of the internal mechanism of continuous polishing and the law of material removal, the quantitative rule of the influence of various process parameters on material removal haven’t been found. The fabricating process still relies heavily on the processing experience of the optician, and the monitoring component is measured frequently. The shape of the surface is used to judge the change of the shape of the polishing pad, resulting in uncertain processing time and uncertain processing quality, and it is easy to introduce quality problems such as surface defects. Therefore, this dissertation focuses on the related process problems in the processing of ultra-precision laser optical components. Based on the comparative analysis of domestic and abroad ultra-precision laser optical component processing technology, the processing mechanism is studied, and an online detection and control technology based on computer feedback control is proposed, which greatly improving the processing efficiency. The main research contents of this dissertation are as follows: 1. There are many influencing factors of continuous polishing, and the law of interaction is extremely complicated. Considering only the normal deformation of the contact surface, ignoring the lateral effect, a series of idealized assumptions are made for the actual polishing process. The asphalt polishing pad is regarded as an elastic body composed of many "springs", combined with the Preston equation and the Winkler hypothesis, a simplified model of continuous polishing was established. 2. According to the simplified model established, the change rule of the surface shape of the polishing pad is analyzed in detail from two aspects: the repairing effect of the conditioning plate on the surface and the damage of the initial surface shape on the surface of the polishing pad. The results show that: (1) When the conditioning plate is placed at different positions on the polishing pad, the surface shape of the pad surface changes concave or convex at different rates, that is, the inherent characteristic of the system is the rate of change of the surface shape of the disk surface, rather than the specific surface shape; (2) An equilibrium state exist in the system, when the system is in equilibrium state, the surface shape of the polishing pad can maintain a flat surface or a spherical surface with small curvature for a long time; (3) The equilibrium position is related to the size of the workpiece to be processed, and is independent of the initial surface shape of the workpiece. The equilibrium position of the system is approximately linear with the mass of the workpiece being machined. 3. The measurement of traditional optical components is very difficult, and the requirements on the environment, equipment, and operators are all very high, and the optical components are easily damaged during the operation of loading and unloading, cleaning, transportation, and so on. Therefore, it is especially important to realize on-line inspection. However, due to the fact that the surface of the polishing disc is grooved and there is polishing liquid in the actual processing, and there is relative motion between the polishing pad, the workpiece and the conditioning plate, it is very difficult to directly measure the surface shape of the polishing pad. After careful investigation on the working principle of the continuous polishing, the inclination of the conditioning plate was selected as the parameter for online monitoring, thereby achieving the purpose of on-line monitoring of the shape by indirect means. In the experiment, the inclination angle of the conditioning plate is continuously measured by a high-precision goniometer, and the signal with an angle change with time is collected. Since there are many interference signals in the workshop, the effective signal is submerged among many noise signals, and the signal mixed with noise is performed. After the operation of spectrum conversion and filtering, the effective signal is recovered. Finally, the results of online monitoring are compared with the results of offline monitoring with Zygo interferometer. It is found that the two methods have good consistency, which verifies the feasibility and accuracy of the online monitoring scheme. 4. Based on real-time online monitoring, using precise computer feedback control technology, an algorithm that make the surface shape of the polishing pad quickly converges to ideal surface shape is designed. The stepping motor is accurately driven according to the results of online monitoring, the position of the conditioning plate is accurately adjusted, and the surface of the polishing disc is controlled. The surface shape quickly and stably converges to the optimal shape, which realizes the automatic control of the surface shape in the continuous polishing.2019atalunwen2191315364767continuous polishing; equilibrium state; deterministic polishing; online monitoring; automatic controlResearch on In-situ measurement and Control Technology of Surface Shape of Polishing Pad in Continuous Polishing环形抛光中抛光盘表面面形的在线检测和控制技术研究近年来,高功率激光驱动器得到了飞速发展。随着激光驱动器对输出能量的要求日益增长,光路路数不断增多、光束口径不断增大,从而对光学元器件的数量需求在急剧地增长,同时对光学元件的面形精度和表面质量要求也越来越严格,大量的超精密激光光学元件的需求给传统的光学加工带来了更大的挑战。传统的环形抛光利用大口径的环状沥青盘,由于沥青的流动性且抛光过程中沥青盘面覆盖着整个光学元件表面,这导致环形抛光相对于其它抛光方式在抑制中高频误差方面具有无可比拟的优越性,具有独特的全频谱段面形控制优势,成为大口径激光光学元件加工的首选方式。但由于目前对环形抛光的内在机理以及材料去除的规律认识尚不充分,未能发现各种工艺参数对材料去除影响的定量规律,加工过程仍然严重依赖工作人员的加工经验,通过频繁检测监控元件的面形来判断抛光盘面形的变化,导致加工时间和加工质量的不确定,并且容易引入表面疵病等质量问题。因此,本文主要针对超精密激光光学元件加工过程中的相关工艺问题,在比较分析国内外超精密激光光学元件加工技术的基础上,研究其加工机理,提出了一种基于计算机反馈控制的在线检测和控制技术,大大提高了加工效率。本文主要研究内容如下: 1.环形抛光的影响因素很多,相互作用的规律极为复杂,在综合考虑了多种工艺参数对材料去除的影响的基础上,只考虑在接触表面的法向的变形,忽略了横向牵连效应,对实际的加工过程作了一系列理想化的假设,把沥青抛光盘看成许多个“弹簧”所组成的弹性体,结合Preston方程和Winkler假定,建立了环形抛光的简化模型。 2、根据所建立的简化模型,重点从校正板对盘面的修复作用和初始面形较差的工件对抛光盘表面的破坏作用两方面详细分析了盘面面形的变化规律。结果表明:(1)校正板置于抛光盘上不同位置时,盘面的面形以不同的速率变凹或变凸,即系统的固有特征是盘面的面形变化速率,而非具体的面形;(2)系统存在平衡状态,系统处于平衡状态时,盘面可以长时间保持平面或者小曲率的球面;(3)平衡位置与所加工的工件的尺寸有关,与工件的初始面形无关,系统平衡位置与所加工工件的质量近似成线性关系。 3、传统的光学元件检测十分困难,对环境、设备、操作人员的要求很高,而且光学元件在上下盘、清洁、运送等操作的过程中很容易损坏。所以,实现在线检测显得尤为重要,但实际加工过程中由于抛光盘表面开槽且存在抛光液,同时抛光盘、工件和校正板之间存在着相对运动,直接测量面形非常困难。分析了环形抛光的工作原理后,选择了校正板的倾角作为在线检测的物理量,从而通过间接的方式实现在线检测面形的目的。实验中通过高精度测角仪连续测量校正板的倾角,采集得到角度随时间变化的信号,由于车间现场干扰信号很多,有效信号被淹没在众多的噪声信号当中,通过对混有噪声的信号进行频谱变换、滤波等操作后恢复出有效信号,最后将在线检测的结果和用Zygo干涉仪离线监测的结果进行比较,发现两种方法一致性很好,从而验证了在线检测方案的可行性和精确性。 4、在实时在线检测的基础上,采用精确的计算机反馈控制技术,设计了使抛光盘面形快速收敛的算法,根据在线监测的结果精确驱动步进电机,准确调节校正板的位置,控制抛光盘的表面面形快速稳定收敛于最佳面形,实现了环形抛光中面形的自动控制。环形抛光;平衡状态;确定性抛光;在线监测;自动控制中国科学院上海光学精密机械研究所尹进光学工程博士
中文题目: 环形抛光中抛光盘表面面形的在线检测和控制技术研究
外文题目: Research on In-situ measurement and Control Technology of Surface Shape of Polishing Pad in Continuous Polishing
作者: 尹进
导师姓名: 朱健强
学位授予机构: 中国科学院上海光学精密机械研究所
答辩时间: 20181130
中文关键词:
环形抛光;平衡状态;确定性抛光;在线监测;自动控制
英文关键词:
continuous polishing; equilibrium state; deterministic polishing; online monitoring; automatic control
中文摘要:
英文摘要:
文献类型:学位论文
学位级别: 博士
正文语种: chi
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