关于锗单晶抛光工艺的点滴体会

锗单晶具有良好的透光性能,而且不易潮解,在红外光学仪器中,常用作光学元件.但是锗单晶质脆较软,加工时要达到比较高的光洁度和较好的平面度比较困难,需要采取一定的措施.由于我们单位科研任务的需要,自己加工了一些锗元件(主要是平行平面锗镜),进行了铭单晶的抛光工艺,现介绍如下,供同志们参考.1.表面细磨 锗单晶磨砂与光学玻璃磨砂差不多.由于锗的硬度较低,在用金钢砂细磨时,表面磨得越细越均匀越好,最后的磨料采用303#-304#.为了保证较好的平面度,最后要在玻璃平板上采用手工细磨几分钟.2.抛光 锗另件的抛光所用的辅料和抛玻璃是不大一样…     

大口径平面光学元件超精密加工技术的研究

为了解决激光核聚变装置中大口径平面光学元件的批量制造难题,将先进制造技术和传统抛光技术相结合,提出了一种新的工艺方法,即使用ELID(在线电解)磨削代替传统的铣磨和初抛工序,以提高生产效率。利用数控抛光将工件抛光至最终的面形精度,以提高生产效率和减少边缘效应。将连续抛光作为最终加工工序,使加工工件的表面粗糙度和波纹度达到工程要求。实验证明这一新的工艺方法是可行的。     

单晶锗双面抛光工艺

<正> 单晶锗光学零件在激光和红外技术中的广泛应用,促进了晶体加工技术的发展。如何提高锗光学零件的平行度和表面光洁度已成为亟待解决的技术问题,因为平行度和光洁度的好坏直接影响着光学膜层的牢固度以及产品的使用性能,其中平行度的优劣对二氧化碳激光器输出功率的影响很大。过去对平行度要求在20″以内的高精度锗平镜的加工,确保质量的加工方法是采用光胶,而晶体零件的光胶,环境条件要求严格,工艺复杂,表面光洁度也难以保证。为此,我     

LiNbO3芯片的无损边缘抛光实验

以抛光垫抛光工艺为基础,研究出一套完整的新型无损边缘抛光工艺,成功实现了高精度光纤陀螺集成光学调制器LiNbO3芯片边缘的无损抛光。即在分析LiNbO3芯片边缘抛光过程中棱边损伤产生原因的基础上,提出3条解决措施:控制研抛浆料中的大颗粒;选择低亚表面损伤的抛光方式;抛光颗粒的大小接近或小于临界切削深度的2倍。加工工件棱边在1 500显微镜下观察无可见缺陷,芯片端面的表面粗糙度Ra0.8 nm,表面平面度优于/2,满足了LiNbO3芯片无损边缘抛光要求。同时,该工艺方法具有较大的推广应用价值。     

超精密环行抛光技术

在大口径超精密平面光学元件加工中，环抛是一种重要的抛光技术，作为古典抛光的一种改进工艺，它在光学加工中得到了广泛的应用。但是它目前还存在着一些问题：对操作者的经验依赖太强，加工效率不高，加工质量也不稳定。根本原因是人们对抛光磨削的规律还认识不够，尤其是—些工艺参数的影响。     

大尺寸氧化铝陶瓷导轨超精研抛工艺研究

为了提高氧化铝陶瓷导轨超精密研抛加工的工作效率,分析了研抛压力、研抛速度以及磨料添加间隔等工艺参数与研磨抛光效率的关系。首先,根据氧化铝陶瓷导轨的特性及物理参数,确定研磨抛光盘以及磨料的选型。然后以高精度平面平晶作为检测工具,平晶与导轨表面形成干涉条纹,利用条纹的数量定量表征研抛效果。最终得到氧化铝陶瓷导轨的最佳工艺参数:每个研抛压力应该控制在40 N;研抛线速度为45 m/min;研磨剂的添加时间为30 min。在同等时间内,应用此套工艺参数可以达到更高的面型精度。     

板条Nd:YAG晶体的合成盘抛光技术

针对高功率板条激光器核心工作器件——板条Nd:YAG晶体的超精密加工开展研究,分析了具有特殊构型的板条Nd:YAG晶体元件的加工性能及工艺难点,提出了一种新的基于合成盘抛光的板条Nd:YAG晶体加工工艺,并对规格为100mm×30mm×3mm的板条Nd:YAG晶体进行了加工实验。实验结果表明,合成盘抛光可以很好地控制元件的塌边现象;通过磨料的优化选择,在合成盘抛光工艺中匹配合适粒度的Al2O3磨料能够实现元件的低缺陷加工,元件下盘后的全反射面平面度达0.217λ(1λ=632.8nm),端面平面度达到0.06λ,表面粗糙度达0.55nm(RMS),端面楔角精度可达2″。     

环形抛光的生产工艺

在大口径超精密平面光学元件加工中，环形抛光（简称环抛）是一种重要的抛光技术。由于抛光的过程复杂，并受很多因素影响，环抛加工技术一直未能取得有效突破，也未能形成稳定的生产能力。文中用主动轮方法精确控制校正盘和元件转速，进行抛光胶配比实验及新抛光胶盘的制作、抛光胶盘开槽改进、新制胶盘面形快速收敛、区域环境的控制改进、改变抛光液pH值控制胶盘老化等，以提高环形抛光的效率。     

会议简讯三则

一种新型的抛光模材料——聚氨酯微孔塑料抛光模片的鉴定会于一九七七年元月在旭光仪器厂举行。聚氨酯微孔塑料抛光模片经过旭光仪器厂和五三所四年多的试制和生产使用,在中小球面、中等精度的高速抛光中效果很显著,已达到设计定型阶段。与会代表一致认为,用这种抛光模片制作的抛光模具有光圈稳定、抛光效率高及使用寿命长等优点,而且制模工艺简单,它为光学玻璃高速抛光实现定时定光圈打下了良好基础。     

超薄型平行平面镜的研制

超薄型平行平面镜的加工难度很高,往往在投入大量的辅助工装和较长的加工工时后,收效甚微。笔者用双平面分离器和平面环抛法相结合的工艺手段,经反复实践和试验,终于研制出厚度与直径的比例达1∶85、N=2、ΔN=0.2、θ=15″的平行平面镜。     

高精度(Δ90°≤0.5″)长方体的制造技术

高精度(Δ90°≤0.5″)长方体的制造技术主要包括了加工方法和检测方法两个方面,即长方体的前期加工阶段采用立方体(方砖)形式加工,以保证一个直角的精度;后期是采用分离器单块精抛的加工方式,以保证其平行差。加工过程中用Φ150激光平面干涉仪检测和控制面形及平行度,用LY Φ80棱镜干涉仪检测和控制直角精度。这种制造技术可以将长方体的直角精度做到Δ90°≤0 5″。     

Determination of the mid-IR femtosecond surface-damage threshold of germanium

To assess the potential uses of germanium as a nonlinear material in the mid IR we have measured the surface-damage threshold of germanium optical windows using femtosecond pulses at a wavelength of 3.9 μm. By working with a wavelength corresponding to a photon energy of less than half the band-gap energy, free-carrier generation due to one- and two-photon absorption was eliminated. The laser pulses had an energy of 5.5 μJ, a duration of 255 fs, and were focused to a waist size of approximately 100 μm. The multi-shot damage threshold of the germanium windows was estimated to be approximately 94 GW/cm². The data should be of immediate benefit to industrial laser researchers and applications engineers working in the mid-IR region.     

Phase-shifting interferometry with four interferograms using linear polarization modulation and a Ronchi grating displaced by only a small unknown amount

A method to reduce the number of captures needed in phase-shifting interferometry is proposed on the basis of grating interferometry and modulation of linear polarization. The case of four interferograms is considered. A common-path interferometer is used with two windows in the object plane and a Ronchi grating as the pupil, thus forming several replicated images of each window over the image plane. The replicated images, under proper matching conditions, superpose in such a way so that they produce interference patterns. Orders 0 and +1 and −1 and 0 form useful patterns to extract the optical phase differences associated to the windows. A phase of π is introduced between these orders using linear polarizing filters placed in the windows and also in the replicated windows, so two π-shifted patterns can be captured in one shot. An unknown translation is then applied to the grating in order to produce another shift in the each pattern. A second and final shot captures these last patterns. The actual grating displacement and the phase shift can be determined according to the method proposed by Kreis before applying proper phase-shifting techniques to finally calculate the phase difference distribution between windows. Related simulations and experimental results are given.     

火炮平行性测量系统的设计

火炮瞄准轴和炮膛轴的平行性直接影响火炮弹着点的散布,是需要检测的重要静态参数之一。火炮平行性测量系统基于准直方法而设计,它以右炮管中心轴线为基准,设置与基准轴平行的瞄准光路和两条准直光路,分时对准左炮管、统调镜和瞄准镜,测量它们的轴线与右炮管中心轴的平行度。该系统能够实现35mm双管火炮的近距离单人操作目视测量,也可实现实时自动判读功能。误差分析表明,该系统的测量精度可以达到70″以内,满足设计要求。     

Applications of photorefractive crystals for optical neural networks

Photorefraction is a nonlinear optical effect in which large nonlinearities can be observed at relatively low optical power levels. This phenomenon has evolved from a laboratory curiosity to a useful device technology for optical information processing applications. In particular, the abilities to form holograms in real time and also to store thern for extended periods of time have aided the implementation of several pattern-reccgnition machines that are adaptive and possess a high degree of parallelism. This paper reviews the photorefractive effect as a device technology for the problem of pattern recognition and describes a photorefractive realization of an adaptive pattern classifier.     

一种基于FPGA的系数对称3×3卷积器的设计

针对实时图像的预处理,介绍了使用 Cyclone 系列 FPGA 器件并采用流水线技术来设计 3×3 的卷积器,详细地论述了卷积器各个功能模块的实现方法。     

Undercooling and solidification of germanium melts studied by differential scanning calorimeter

~~Undercooling and solidification of germanium melts studied by differential scanning calorimeter~~     

Semiconductor detectors and focal plane arrays for far-infrared imaging

The detection of far-infrared (far-IR) and sub-mm-wave radiation is resistant to the commonly employed techniques in the neighbouring microwave and IR frequency bands. In this wavelength detection range the use of solid state detectors has been hampered for the reasons of transit time of charge carriers being larger than the time of one oscillation period of radiation. Also the energy of radiation quanta is substantially smaller than the thermal energy at room temperature and even liquid nitrogen temperature. The realization of terahertz (THz) emitters and receivers is a challenge because the frequencies are too high for conventional electronics and the photon energies are too small for classical optics. Development of semiconductor focal plane arrays started in seventies last century and has revolutionized imaging systems in the next decades. This paper presents progress in far-IR and sub-mm-wave semiconductor detector technology of focal plane arrays during the past twenty years. Special attention is given on recent progress in the detector technologies for real-time uncooled THz focal plane arrays such as Schottky barrier arrays, field-effect transistor detectors, and microbolometers. Also cryogenically cooled silicon and germanium extrinsic photoconductor arrays, and semiconductor bolometer arrays are considered.     

实时全息干涉视频图像自动化处理及应用研究

研究了实时全息干涉条纹视频图像计算机自动处理技术。采用Delphi可视化软件为开发工具,在Win dows环境下播放实时全息干涉图像,并同时获取在播放窗口中任意指定的灰度值、自动描绘灰度 时间以及位移 时间曲线。对测试原理和图像去噪、曲线平滑等关键处理技术进行了介绍。通过对微电子产品热变形研究的实例分析,显示了该自动处理软件的操作便捷、实用和先进性。     

Anisotropy of the mean free paths of phonons in single-crystal films of germanium,silicon, and diamond at low temperatures

The physical aspects of the influence of the elastic energy anisotropy of crystals on the anisotropy of the mean free paths of phonons in single-crystal films of germanium, silicon, and diamond in the diffuse scattering of phonons at the boundaries of the samples have been considered. It has been shown that, for sufficiently wide films of germanium, silicon, and diamond with the {100} and {111} orientations and the lengths of less than or equal to their width, the phonon mean free paths are isotropic (independent of the direction of the temperature gradient in the plane of the film). The anisotropy of the phonon mean free paths depends primarily on the orientation of the film plane and is determined by the focusing and defocusing of phonon modes. For single-crystal films of germanium, silicon, and diamond with the {100} and {111} orientations and lengths much larger than their width, the phonon mean free paths are anisotropic.