减少光学元件亚表面缺陷的方法研究

针对强激光光学元件的应用要求,对光学材料在研磨和抛光过程中形成的亚表面缺陷进行了分析,并借鉴小工具数控抛光和Marangoni界面效应,提出采用数控化学刻蚀技术来实现光学表面面形和微结构形貌的高准确度加工．通过实验对亚表面缺陷的分布位置和特性进行了分析,实验验证了在静止和移动条件下Marangoni界面效应的存在．对材料的定量去除进行了实验,提出了亚表面缺陷的去除方法．     

减少光学元件亚表面缺陷的方法研究

针对强激光光学元件的应用要求,对光学材料在研磨和抛光过程中形成的亚表面缺陷进行了分析,并借鉴小工具数控抛光和Marangoni界面效应,提出采用数控化学刻蚀技术来实现光学表面面形和微结构形貌的高准确度加工.通过实验对亚表面缺陷的分布位置和特性进行了分析,实验验证了在静止和移动条件下Marangoni界面效应的存在.对材料的定量去除进行了实验,提出了亚表面缺陷的去除方法.     

基于Marangoni界面效应的数控化学抛光去除函数的研究

 利用基于Marangoni界面效应对化学抛光去除函数的理论及实验进行研究，提出采用湿法化学抛光（刻蚀）方法为大口径高精度光学元件的加工提供新的解决途径。介绍了Marangoni界面效应及其验证实验，运用WYKO轮廓仪对熔石英基片局域刻蚀前后的粗糙度进行检测，结果表明，粗糙度基本无变化，刻蚀前后粗糙度分别为0.72 nm和0.71 nm。基于Preston假设， 建立了数控化学抛光理论模型，运用WYKO干涉仪观察实验现象可知，化学抛光刻蚀曲线基本上成平底陡峭的去除函数曲线，小磨头抛光是倒置的仿高斯函数曲线。     

高精度数控化学抛光技术

用已有的刻蚀发生器与AD250数控抛光设备进行有效地整合，建立了定域数控刻蚀平台，此实验平台在基片装夹和软件编程上都得到了一定提高，可以根据事先检测基片的干涉图在任意区域内进行编程加工，由于AD250数控抛光设备能够实现三维坐标控制，对刻蚀区域的大小和刻蚀深度可通过编程来实现，完全实现了数字控制加工的目的。在前期实验工作的基础上，根据Marangoni界面效应理论对刻蚀发生器进行改进，改进后的装置在Marangoni效应的稳定上有了很大提高，可以持续不间断的使被加工基片的区域保持Marangoni效应，由于此效应在整个数控化学加工中起核心作用，所以此项单元的改进使得对加工基片的尺寸得到很大扩展，理论上完全满足原型玻璃尺寸的要求，也为后期的数控化学大尺寸面型的修正提供了很好的技术基础，使这项技术在光学加工中的应用得到了保障。     

高精度数控化学抛光技术

高精度光学表面数控化学抛光技术研究是针对强激光光学元件的应用需求，研究光学表面的化学抛光加工机理；基于Marangoni界面效应，采用数控化学抛光技术来实现光学表面面形及微结构形貌的高精度控制；为完成高精度激光光学元件(包括传统意义上的激光光学镜面和新型的静态连续波前校正板等)的制造进行新原理和新手段的探索。     

空间光学元件超精密气囊抛光的去除特性研究

为得到空间光学元件超光滑表面,对超精密气囊抛光方法的去除特性进行了理论和实验研究.以Preston方程为基础,应用运动学原理建立了气囊抛光"进动"运动的材料去除模型,针对抛光气囊工具的物理特性,按照Hertz接触理论对去除模型进行了修正;利用计算机仿真的方法,分析了几个主要工艺参数对"进动"抛光运动去除特性的影响规律,并在超精密光学数控抛光机上进行了正交实验;仿真和实验结果吻合较好,总结得到4点气囊抛光方法中重要的结论,给出了"进动"角与压缩量的取值范围,以此得到了面型精度RMS值为0.024λ(λ=0.6328 μm)的超光滑表面,为开展光学元件气囊抛光工艺研究提供依据.     

光学元件亚表面缺陷的损伤性检测方法

在磨削、研磨和抛光加工过程中产生的微裂纹、划痕、残余应力等亚表面缺陷会导致熔石英元件抗激光损伤能力下降,如何快速、准确地检测亚表面损伤成为光学领域亟待解决的关键问题。采用HF酸蚀刻法、角度抛光法和磁流变斜面抛光法对熔石英元件在研磨加工中产生的亚表面缺陷形貌特征及损伤深度进行了检测和对比分析,结果表明,不同检测方法得到的亚表层损伤深度的检测结果存在一定差异,HF酸蚀刻法检测得到的亚表面损伤深度要比角度抛光法和磁流变斜面抛光法检测结果大一些。且采用的磨粒粒径越大,试件表面及亚表面的脆性断裂现象越严重,亚表面缺陷层深度越大。     

低亚表面损伤石英光学基底的加工和检测技术

制备低亚表面损伤的超光滑光学基底,是获得高损伤阈值薄膜的前提条件。针对石英材料在不同加工工序中引入亚表面损伤层的差异,首先利用共焦显微成像结合光散射的层析扫描技术,对W10和W5牌号SiC磨料研磨后的亚表面缺陷进行了检测,讨论了缺陷尺寸与散射信号强度、磨料粒径与损伤层深度间的对应关系;同时,采用化学腐蚀处理技术对抛光后样品的亚表面形貌进行了刻蚀研究,分析了化学反应生成物和亚表面缺陷对刻蚀速率的影响、不同深度下亚表面缺陷的分布特征,以及均方根粗糙度与刻蚀深度间的联系。根据各道加工工艺的不同采用了相应的亚表面检测技术,由此来确定下一道加工工序,合理的去除深度,最终获得了极低亚表面损伤的超光滑光学基底。     

平面和曲面光学零件气囊抛光材料去除的比较研究

气囊数控抛光是近年来一种新兴的先进光学制造技术,采用柔性的气囊作为抛光工具并以进动的方式进行加工。首先简要阐述了气囊抛光的抛光原理,然后针对平面和曲面光学零件,在自行研制的气囊抛光实验样机上进行了抛光实验。被抛光光学元件的材料去除是在抛光区内实现的。研究了进动角、气囊压缩量、气囊内部压力、气囊转速、抛光时间以及工件的曲率半径几种重要的工艺参数对平面工件和球面工件抛光接触区大小和形状影响情况的异同。在此基础上,总结了气囊抛光材料去除的影响规律。给出了几种重要工艺参数在平面工件和球面工件上取值范围。     

小工具数控抛光对元件表面中频误差的匀滑研究

数控抛光已被广泛应用于光学元器件的加工制造,而抑制元件表面中频误差是加工过程中一项十分重要的内容。基于Presston方程对数控小工具抛光盘去除函数进行了建模,得到了理论化的去除函数表达式。结合去除函数,在参数化匀滑模型基础上通过建立多参数的时变理论模型,表明元件表面中频误差是随抛光过程呈指数型收敛的,其收敛效率取决于材料参数、体积去除率等抛光工艺参数。对理论模型的匀滑曲线进行了模拟分析,实现了不同工艺条件下的匀滑效率的对比。结果表明:在不同抛光盘材料的匀滑过程中,材料系数越大,其整体匀滑效率越高。同样,抛光盘体积去除率越大,对表面误差的匀滑效率也会越高。进行了一组空间周期分别为3,5,7 mm的波纹误差的匀滑实验,其结果表明,在相同的抛光参数下,具有较大空间频率的波纹匀滑效率会更高,收敛曲线下降得更快。最后对比了不同材料抛光盘匀滑效率,从实验上证实了沥青盘在波纹匀滑效率上远高于聚氨酯材料的抛光盘。     

Subsurface damage in optical substrates

The origin, character, analysis and treatment of subsurface damage (SSD) were summarized in this paper. SSD, which was introduced to substrates by manufacture processes, may bring about the decrease of laser-induced damage threshold (LIDT) of substrates and thin films. Nondestructive evaluation (NDE) methods for the measurement of SSD were used extensively because of their conveniences and reliabilities. The principle, experimental setup and some other technological details were given for total internal reflection microscopy (TIRM), high-frequency scanning acoustic microscopy (HFSAM) and laser-modulated scattering (LMS). However, the spatial resolution, probing depth and theoretic models of these NDE methods demanded further studies. Furthermore, effective surface treatments for minimizing or eliminating SSD were also presented in this paper. Both advantages and disadvantages of ion beam etching (IBE) and magnetorheological finishing (MRF) were discussed. Finally, the key problems and research directions of SSD were summarized.     

Experimental investigation on laser-induced surface damage threshold of Nd-doped phosphate glass

Nd-doped phosphate glass is the dominant amplifier material used in solid state high average power laser systems.Surface imperfection and subsurface damage(SSD)of the glass,resulting from the optical fabrica-tion process,limit the increment of laser system energy output.Thus,it is important to enhance the surface damage threshold of Nd-doped phosphate glass surface.The influence of abrasive size,polishing powder,grinding mode,and chemical treatment on the laser-induced damage threshold(LIDT)of Nd-doped phos-phate glass surface is investigated.Results show that the LIDT is affected little by different polishing powders and grinding modes.The LIDT correlates with the abrasive size,which produced different depths of SSD.A suitable acid etching treatment can remove the imperfection and the SSD for improving the LIDT of Nd-doped phosphate glass surface.The combination of several effective techniques and methods,which are low-cost and practical,should be useful to enhance the LIDT of Nd-doped phosphate glass surface.     

Analytical prediction for depth of subsurface damage in silicon wafer due to self-rotating grinding process

Subsurface damage (SSD) induced by silicon wafer grinding process is an unavoidable problem in semiconductor manufacturing. Although experimental attempts have been made on investigation of the influential factors on the SSD depth, however, few theoretical studies have been conducted to obtain SSD depth through grinding parameters. To fill the gap, an analytical model is developed to predict the SSD depth in silicon wafer due to self-rotating grinding process, which can reveal the relationship among SSD depth and the grinding parameters, the size of the abrasive grains and the radial distance from the wafer center. The establishment of the proposed model is based on scratch theory and fracture mechanics of isotropic brittle materials, and we further consider the effects of elastic recovery, cleavage plane and crystalline orientation on SSD formation. To validate the applicability of the proposed predictive model, grinding experiments with varied grinding parameters are performed and the depths of SSD along the <110> and <100> crystal directions are also measured and analyzed. The results given by the proposed model present reasonable accuracy of less than 20% deviation with experimental results. Effects of grinding parameters, wafer radial distance, crystalline orientation, and abrasive grain size on SSD depth are discussed in detail.     

Experimental investigation of enhancing the subsurface damage threshold of Nd-doped phosphate glass

Experimental investigation was performed with a 1064-nm, 10-ns Nd:YAG laser to determine the effects of the surface hydrogen acid etching on laser damage, compared with damage of conventionally polished surface. The investigation was helpful for us to understand the negative effects of Nd-doped phosphate glass surface and subsurface damage (SSD) on laser induced damage threshold (LIDT). A set of samples was polished, and then chemically etched in a cool buffered 10%HF 20%H2SO4 solution at different times. Another set of samples was ground and etched in the hot-buffered solution, and then polished. All the samples were irradiated with Nd: YAG laser and characterized by optical microscopy. Results of LIDT were obtained according to International standard ISO/DIS 11254-1.2. Chemical treatment can remove the contaminants in the polished re-deposition layer and the SSD for improving the laser damage resistance of Nd-doped phosphate glass surfaces. The method of using hot solution was more effective than that ofusing cool solution.     

基于MEMS传感器的无线位置跟踪控制仿真应用

针对嵌入式工业控制系统终端显示的需要,提出了一种基于微处理器R1610和LCD控制器SSD1963的液晶显示模块的设计方法。详细阐述了硬件接口电路的设计和控制软件的编程,重点介绍了R1610、SSD1963以及TFT液晶屏AT070TN83之间的硬件连接方法,分析了SSD1963液晶控制的使用方法以及针对液晶屏显示时序的系统设置。结合显示控制实例实现了图像在液晶屏上的显示,显示效果良好。该显示模块的设计具有一定的应用前景和参考价值。     

采用透镜列阵与光谱色散改善三倍频小焦斑辐照均匀性

通过数值模拟研究了高功率激光驱动器的光束均匀辐照情况, 分析了三倍频激光辐照下小焦斑的光强分布及空间功率谱. 采用透镜列阵可降低光束近场畸变的影响并控制靶面焦斑的包络形状; 采用二维光谱色散匀滑技术可明显地消除焦斑内部大反衬度的强度调制, 且该方法在焦斑非常小的情况下也仍然有效. 大量的数值模拟结果表明, 光谱色散匀滑技术应用于尺寸不同的焦斑时, 其效果是有差异的. 对大焦斑而言, 光谱色散匀滑主要抹平其内部细密的条纹, 即消除中高空间频率范围的强度调制; 对小焦斑而言, 光谱色散匀滑主要消除中低空间频率范围的强度调制, 故将影响焦斑的整体包络形状. 本文所得的数值结果对间接驱动实验中激光束匀滑方案的选择和优化具有参考价值.     

基于LPC2210和SSD1339的PM-OLED驱动控制电路

为了避免早期无源矩阵有机电致发光器件驱动控制电路的一些缺陷,如:"串扰"和"交叉"效应以及电路连接比较复杂,用两种方法实现了基于飞利浦公司生产的LPC2210控制芯片和晶门科技公司的SSD1339驱动芯片的驱动控制电路。首先介绍了有机电致发光器件的结构和发光原理以及芯片SSD1339和LPC2210的主要的特点;分析和比较了SSD1339的8080系列并行口和LPC2210外部存储控制单元的读写时序;分别利用LPC2210的通用输入输出单元和外部存储控制单元,成功的控制SSD1339驱动128RGB×128点阵有机电致发光屏。实验结果表明:两种方法不仅可以有效地克服早期驱动控制电路的缺陷,而且可以使有机电致发光屏显示出高质量的图片;用外部存储控制单元实现的驱动控制电路,可以实现约80 Hz的驱动帧频;而使用通用输入输出单元实现的驱动控制电路,可以单步跟踪数据的传输,因此它具有方便查错的优势。本次实验为在不同的集成环境下无源矩阵有机电致发光器件驱动控制电路的设计奠定基础。     

光谱色散匀滑技术与衍射光学器件联用性能的空间频谱分析

基于空间频谱分析方法，建立了光谱色散匀滑技术(SSD: Smoothing by Spectral Dispersion)与衍射光学器件(DOE: Diffractive Optical Element)联用性能的简化分析模型，为SSD与DOE联用时，SSD参量的优化提供了理论依据.数值模拟了SSD各参量，包括脉冲时间、调制频率、位相调制系数、光栅线色散系数等对束匀滑性能的影响.模拟结果表明，SSD参量经过优化选取，且波前畸变随时间快速变化时，能获得良好的束匀滑性能.     

Beam smoothing by lens array with spectral dispersion

A scheme of combining technology of lens array (LA) and smoothing by spectral dispersion (SSD) is introduced to improve the irradiation uniformity in laser fusion based on the earlier works on LA. The feasibility of the scheme is also analyzed by numerical simulation. It shows that a focal pattern with flat-top and sharp-edge profile could be obtained, and the irradiation nonuniformity can fall down from 14% with only LA to 3% with both SSD and LA. And this smoothing scheme is depended less on the incidence comparing to other smoothing methods. The preliminary experiment has demonstrated its effectiveness.     

The study of the solution concentration influencing on laser-induced electrochemical etching silicon

The laser electrochemical etching process, which combines the laser direct etching process and the electrochemical etching process, is a compound etching technique. In order to further understand the solution concentration influencing on the laser-induced electrochemical etching of silicon; a 248 nm excimer laser as a light source and KOH solution as an electrolyte were adopted in this study. The experiments of micromachining silicon by laser-induced electrochemical etching were carried out. On the basis of the experiments results, the solution concentration influencing on the etching rates in the process of laser electrochemical etching of silicon was researched. The reasons of the etching phenomena were analyzed in detail. The experimental results indicate that the solution concentration influencing on the etching process is mainly rooted in the absorption of different concentration solutions to laser. In general, less absorption and low solution concentration are good for the etching role in the process of laser electrochemical etching.