光学面形的轮带光学抛光方法研究

鉴于光学零件高陡度凹曲面的抛光是光学加工的一个难题,轮带光学确定性抛光方法是解决此类零件抛光的有效方法之一;提出轮带光学抛光技术的原理和方法。研究了轮带光学抛光方法修形的可行性,采用五轴精密数控机床系统对一块直径Ф80 mm的K9玻璃平面样镜进行了修形试验,经过3次迭代修形使其面形精度均方根误差(RMS)由初始的0109 λ提高到0028 λ,平均每次收敛率达到13。实验结果表明,应用轮带光学抛光技术进行光学镜面修形,面形收敛速度较快,加工精度较高。本实验验证了轮带光学抛光技术的修形能力,为高陡度光学零件的抛光提供了研究基础。     

超光滑加工的后置处理算法研究

为了精确控制超光滑加工过程中磨头的运动轨迹,从而实现光学元件材料去除的均匀稳定,研究了超光滑加工的后置处理算法。分析了超光滑加工工艺的特点和相应的超光滑机床的机械结构,建立了机床的坐标系统,构造了机床的运动学模型。对于光学元件母线为任意平面曲线的情况,研究了磨头运动轨迹的等误差直线逼近算法。在曲率半径为290mm,相对口径为1∶2.9的凹球面上进行了超光滑加工实验。结果表明,利用所述算法可以精确地控制磨头的运动轨迹,从而保证材料去除的稳定性。     

Removal of scratch on the surface of MgO single crystal substrate in chemical mechanical polishing process

Etching and chemical mechanical polishing (CMP) experiments of the MgO single crystal substrate with an artificial scratch on its surface are respectively performed with the developed polishing slurry mainly containing 2 vol.% phosphoric acid (H₃PO₄) and 10-20 nm colloidal silica particles, through observing the variations of the scratch topography on the substrate surface in experiments process, the mechanism and effect of removing scratch during etching and polishing are studied, some evaluating indexes for effect of removing scratch are presented. Finally, chemical mechanical polishing experiments of the MgO substrates after lapped are conducted by using different kinds of polishing pads, and influences of the polishing pad hardness on removal of the scratches on the MgO substrate surface are discussed.     

Effect of surface roughness on the optical constants of bulk polycrystalline gold samples

Four bulk polycrystalline samples of gold were subjected to different polishing treatments using diamond pastes of grain size 10, 6, 3 and 1 μm. The effect of surface roughness on the optical constants n and k is studied by 45° angle-of-incidence ellipsometry at 632.8 nm. Results for n and k are extrapolated to the case of an ideal surface which we believe to be highly representative of gold. Comparison with published results for the optical constants of gold thin films is presented.     

利用功率谱密度评价离子束抛光光学元件表面粗糙度

利用功率谱密度(PSD)评价光学表面粗糙度具有传统评价手段(Ra)所不具备的优势。给出了功率谱密度的计算方法,以及抽样方向与一维PSD曲线的关系。在离子束抛光K9玻璃实验中引入PSD曲线,以评价抛光光学零件的光学表面粗糙度,结合PSD曲线与Ra值能够更全面的指导光学加工。     

Effect of surface roughness on the determination of tissue optical properties

The scattering phase functions of the nylon film with different surface roughnesses were measured by the goniophotometric measurement technique, and the corresponding anisotropy factors of the nylon film with different surface roughnesses were determined subsequently. Consequently, the scattering coefficients of nylon with different surface roughnesses were determined. The fluence rates of intralipid with different interface roughnesses for a board beam irradiation were measured and the penetration depths were determined. The experimental results indicate that the surface roughness obviously affects the determination of the optical properties of nylon. This study suggested that the determination of tissue optical properties should take surface roughness into account.     

抛光液的pH值对抛光元件表面粗糙度的影响

减小大孔径超光滑玻璃表面的粗糙度是提高抛光质量的关键。实验研究了抛光过程中pH值对抛光元件表面粗糙度的影响。结果表明:抛光液的pH值对抛光元件表面粗糙度有较明显的影响;抛光过程中抛光液的pH值会随抛光时间而变化;抛光过程中,当保持抛光液处于微碱状态,且离抛光粉的等电离点较远时,抛光元件表面具有较小的粗糙度。     

计算机控制光学表面抛光的磨头运动方式和参数的优化研究

对影响计算机数控抛光表面误差收敛速度的主要因素———磨头工作函数进行了详细的讨论。提出了以趋近因子作为评价磨头参数优化的参量。对目前流行的行星式磨头和平转动磨头分别作优化,给出了最佳参数组合,为提高计算机控制抛光的效率提供了理论依据。     

Experimental investigation of a modified Beckmann-Kirchhoff scattering theory for the in-process optical measurement of surface quality

An experimental investigation of a modified Beckmann-Kirchhoff scattering theory applied in an in-process optical measurement of surface quality is described. The proposed theory describes the scattered light intensity distribution from a surface with the additional layers, and can be employed to analyze the surface characteristics in in-process measurement. Based on light scattering principle and machine vision method, the surface roughness is extracted to testify the correction of the modified Beckmann-Kirchhoff scattering theory. The experimental apparatus consists of a collimated laser diode, a beam splitter, a screen, a measuring lens and a camera. Test specimens with different surface roughness are studied. The results obtained demonstrate the feasibility of in-process optical measurement of surface quality using the modified model.     

Computation of surface roughness using optical correlation

The laser speckle photography is used to calculate the average surface roughness from the autocorrelation function of the aluminum diffuse objects. The computed results of surface roughness obtained from the profile shapes of the autocorrelation function of the diffuser show good agreement with the results obtained by the stylus profile meter.      

The angle-limited integrated scattering (ALIS) measurement system for in-workshop inspection of the optical polishing process

A simple angle-limited integrated scattering (ALIS) measurement technique is described. The relation between the measured scattering within a limited solid angle (ALIS) and the root-mean-square (RMS) roughness of the surface under test is investigated. The technique is applied to the in-workshop inspection of the optical polishing process.     

大尺寸硅镜超光滑表面加工的面型控制

使用机械-化学抛光法加工大尺寸单晶硅可获超光滑表面,但很难保证良好的面型.提出通过采用开圆孔并连续注入抛光剂的方法来避免抛光盘中心蜂窝眼的出现,可以保证得到良好的面型.最后实验达到较好的面型精度,PV值0.268λ,rns值0.065λ.     

非球面超光滑加工磨头控制技术研究

为了避免在超光滑加工过程中破坏光学元件的原有面形,同时保证整个表面粗糙度的均匀一致,研究了超光滑加工过程中的磨头控制技术.首先分析了超光滑加工机床的结构形式及超光滑加工工艺特点;然后研究了非球面母线的双圆弧拟合算法以及磨头进给速度的控制方法;最后将所研究的磨头运动控制算法应用于超光滑加工控制软件.以顶点曲率半径为300...     

气囊抛光工艺参数的正交实验分析

针对平面光学零件,以抛光去除率和表面粗糙度为考核指标,应用正交试验法分析了气囊抛光过程中的主要工艺参数,包括抛光工具气囊的压缩量、气囊转速、气囊内部充气压力、抛光液的浓度对抛光去除效率和表面粗糙度的影响规律。结合气囊抛光的抛光机理对其进行了分析,根据实验结果对工艺参数进行了优化,并进行了综合参数的气囊抛光加工实验,获得了超精密光滑的表面。     

超光滑表面的形成与抛光时间之间的关系研究

由于加工超光滑表面的古典法对加工者的经验要求较高,而且不同的加工者对抛光时间长短的控制也有较大的差别,因而下盘时机的准确判断将会对超光滑表面的加工质量产生严重的影响。为此,对所加工的全反射棱镜的超光滑表面抛光不同的时间,并在全反射条件下,根据全反射棱镜背向散射光斑的大小和亮暗的程度来判断所加工超光滑表面加工质量的检测方法,最终给出超光滑表面的抛光质量随抛光时间的变化。在实验结果的基础上得出了抛光质量随抛光时间交替变化的基本规律,并根据加工经验总结出了超光滑表面加工过程中的注意事项和判断下盘时机的基本方法。     

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。     

Localized corrosion effects and modifications of acidic and alkaline slurries on copper chemical mechanical polishing

This study demonstrates the CMP performance can be enhanced by modifying the corrosion effects of acidic and alkaline slurries on copper. A corrosion test-cell with a polishing platform is connected with the potentiostat to investigate the corrosion behaviors of copper CMP in various alumina slurries. Experiments show that the slurry needs to be maintained in acidic pH<4.56 or alkaline pH>9.05 surroundings and thus better dispersion of alumina particles and less residual contaminant on copper surface can be obtained. The surface defects after copper CMP using acidic and alkaline slurries are described by pitting corrosion mechanisms, and these mechanisms can be regarded as a basis to modify their corrosion effects. Experimental results indicate that it is necessary to modify the dissolution of HNO₃ and oxidization of NH₄OH for copper CMP slurries. Consequently, the slurries of 5 wt.% HNO₃ by adding 0.1 wt.% BTA or 5 wt.% KNO₃ by adding 1 wt.% NH₄OH achieve good CMP performance for copper with higher CMP efficiency factor (CMPEF), 1460 and 486, and lower surface roughness (R_q), 4.019 and 3.971 nm, respectively. It is found that AFM micrographs can support the effectiveness of corrosion modifications for copper CMP in various slurry chemistries.     

平面元件数控加工技术研究

利用从俄罗斯引进的ＡＤ １０００ 数控研磨抛光机对Φ３３０ｍｍ ×３５ｍ ｍ 、２３０ｍ ｍ ×２３０ｍ ｍ ×４０ｍ ｍ 两块Ｋ９材料平面光学元件进行计算机控制抛光工艺研究。通过工艺研究全面熟悉了设备的技术特性和工艺软件特性,验证了ＡＤ １０００ 数控研磨抛光机在加工高精度光学元件基板方面Ｐ Ｖ、ＲＭＳ值收敛效果明显,较传统加工方法在效率上有极大提高。     

纳米级面形精度光学平面镜加工

为实现纳米级面形精度光学平面镜的高效精密抛光,提出了一种由传统环带抛光技术和先进离子束抛光技术相结合的组合式加工方法。介绍了环带抛光技术和离子束抛光技术的原理,通过实验研究了离子束抛光的材料去除函数,并采用这种组合抛光方法对口径为150 mm的平面镜进行抛光,抛光后平面镜的面形误差和表面粗糙度分别达到1.217 nm RMS和0.506 nm RMS。实验结果表明,这种组合抛光技术适合纳米级面形精度光学平面镜的加工。     

Measurement of surface figure of plane optical surfaces with polarization phase-shifting Fizeau interferometer

A Fizeau interferometer based set up for measurement of surface forms of plane optical surfaces has been discussed. Phase shifting interferometry has been applied using polarization phase shifter. A linearly polarized (632.8 nm) He–Ne laser has been used as the source. Light reflected from the object and the reference/master surfaces are made circularly polarized in opposite senses by means of two properly oriented quarter wave retardation plates placed at appropriate positions, one inside and other outside the interference cavity of the interferometer, and phase shifts are introduced between the object and the reference/master waves by varying angular orientation of a polarizer/analyzer. Final result is made free from any residual wave-front aberrations introduced by the (intra-cavity) wave plate by subtracting phase values obtained by PSI technique between a high optical quality master surface and the reference surface from that obtained for the test object surface with respect to the same reference surface for each point of the interference field. Results are shown for a plane surface.Advantages of the technique presented are linearity and high accuracy in phase stepping, no perturbation of the interference cavity during the phase shifting and possibility of real time or dynamic interferometry.