激光差动共焦透镜中心偏测量系统设计与实现

针对国内外透镜中心偏高精度测量的迫切需求,研制了一套激光差动共焦透镜中心偏测量系统。该系统从中心偏非接触测量的核心定焦原理入手,结合激光差动共焦定焦技术,解决了清晰度法定焦精度差的难题。在光学测量系统误差分析的基础上,对系统再次优化设计,并利用差动共焦轴向光强响应曲线过零点的位置与被测镜猫眼和共焦点精确对应这一特性,实现了透镜中心偏的高精度测量。通过实验表明,该系统测量精度为0.49%,与传统的清晰度法定焦测量相比,透镜中心偏的测量精度有效提高了6倍。该系统将差动共焦定焦技术有效的应用于透镜中心偏测量中,提高了被测镜猫眼和共焦位置的定焦能力,实现了高精度测量系统的设计,在光学测试和透镜加工及装配领域具有广阔的应用前景。     

激光差动共焦曲率半径测量系统的研制

针对国内高精度曲率半径计量需求,研制一套激光差动共焦曲率半径测量系统.该系统采用差动共焦定焦技术,利用轴向光强响应曲线的过零点精确对应物镜聚焦焦点这一特性,借助过零点对被测件的猫眼和共焦位置进行精密瞄准定位,通过干涉测长技术获取两点间的距离,继而实现曲率半径的高精度测量.该测量系统的机电控制由主控软件完成,可实现机电扫描、数据采集及数据处理,自动化程度高.实验证明,该系统定焦灵敏度高,受环境波动影响小,测量精度可达3×10-6,满足了高精度曲率半径的计量需求.     

激光差动共焦透镜中心厚度测量系统的研制

基于高精度光学共焦定位技术研制了一种全新的非接触透镜中心厚度测量系统,该系统利用差动共焦技术的高轴向层析特性和轴向响应曲线的绝对零点对被测透镜的前表面顶点和后表面顶点分别进行精密瞄准定位;同时,利用激光干涉仪获得透镜前、后表面顶点的位置坐标;然后通过光线追迹算法计算透镜中心厚度,进而实现了透镜中心厚度的高精度非接触测量。实验结果表明,该系统测量精度高,测量标准差小于1μm,满足透镜中心厚度测量的精度要求。     

高精度激光共焦半导体晶圆厚度测量

针对半导体晶圆厚度的高精度非接触测量问题与需求,提出了基于激光共焦的高精度晶圆厚度测量方法。该方法利用高分辨音圈纳米位移台驱动激光共焦光探针轴向运动扫描,利用激光共焦轴向响应曲线的峰值点对应物镜聚焦焦点的特性,分别对被测晶圆上下表面进行高精度瞄准定位;通过光线追迹算法精确计算出晶圆表面每个采样点的物理坐标,实现了晶圆厚度的高精度非接触测量。基于该方法构建了激光共焦半导体晶圆厚度测量传感器,实验和分析表明,该传感器的轴向分辨力优于5 nm,轴向扫描范围可达5.7 mm,6种晶圆厚度测量重复性均优于100 nm,单次测量时长小于400 ms。将共焦定焦技术有效地应用于半导体测量领域,为晶圆厚度的高精度、无损在线测量提供了一种新技术。     

五维位姿监测的差动共焦曲率半径测量

为提高球面透镜曲率半径的测量精度,提出基于五维位姿监测调整的差动共焦曲率半径高精度测量方法。通过驱动被测样品回转,在探测器上监测被测件的共焦点轨迹,测量被测件球心点与测量光轴之间的偏心误差,结合位姿调整系统对偏心误差进行自动补偿,确保测量过程中被测件球心与测量光轴重合,消除被测样品球心离轴引入的测量余弦误差,进而消除每次装调的样品位姿误差对测量精度的影响。理论计算和初步实验表明：该方法对曲率半径的相对重复测量精度(RMS)可达到3.2×10^-6。该方法显著提升了曲率半径的重复测量精度,为曲率半径的精密测量提供了有效途径。同时,该方法还为透镜中心偏、焦距、厚度、镜组间隔等多种参数的高精度测量提供了有效方法。     

基于卡尔曼预测的差动共焦轮廓跟踪测量方法

针对轴向扫描式差动共焦测量法(ASDCM)测量轮廓效率低下问题,提出一种基于卡尔曼预测的差动共焦轮廓跟踪测量方法。该方法使用激光差动共焦轴向响应曲线数百纳米量程的线性区间实现了表面连续轮廓高精度线性传感测量,提高了测量效率;同时引入基于卡尔曼预测器的轮廓跟踪原理利用已测轮廓点数据对未测表面预测并跟踪,扩展了线性传感轮廓测量法测量范围。实验结果表明,该方法相对于ASDCM法测量效率提升了8倍,且实现了轮廓PV值大于线性传感测量范围的标准椭圆柱高精度跟踪测量,激光聚变靶丸内轮廓圆度重复测量标准差达3 nm。为精密元器件表面连续轮廓的高精度、快速、无损测量提供了一种高质量方法。     

用于惯性约束聚变靶丸测量的激光差动共焦传感器

针对目前原子力显微镜等方法只能测量激光惯性约束核聚变(ICF)靶丸外表面等难题,研制了高精度、非接触、小型化的激光差动共焦传感器(LDCS).该传感器基于差动共焦原理,利用激光差动共焦轴向响应曲线的零点对靶丸内外表面和球心分别进行定位,并结合物镜微位移驱动技术,实现靶丸内外表面和壳层厚度的高精度测量.该方法减少了靶丸表面的反射率、倾斜等因素对测量瞄准特性的影响,显著提高了系统的抗干扰能力.将传统的显微成像与差动共焦测量光路进行有机融合,实现了对被测样品的精确瞄准.初步实验与理论分析表明:当测量物镜的数值孔径NA为0.65时,LDCS的轴向分辨力优于5 nm,信噪比优于1 160,过零点的标准偏差为10 nm.该传感器为激光惯性约束核聚变靶丸测量提供了一种新的技术途径.     

基于偏心抑制的激光差动共焦焦距高精度测量方法

针对测量球面透镜焦距过程中存在偏心误差导致测量光轴与透镜实际轴线不重合的问题,提出了一种基于偏心抑制的 激光差动共焦焦距高精度测量方法,通过驱动工作台旋转测得透镜偏心误差的大小及方向,实现了对被测透镜的误差采集;通 过分析误差大小及方向驱动姿态调整电机,消除了测量过程中由于存在偏心误差对焦距测量精度产生的影响;通过构建系统, 优化系统参数,实现了激光差动共焦焦距高精度测量;最终实现基于偏心抑制的焦距高精度测量,解决了焦距测量时测量光轴 与透镜实际轴线不重合从而对测量结果产生影响的问题。 基于该系统进行了焦距测量实验,实验表明:测量焦距为 100 mm 透 镜时,该方法相对重复测量精度(RMS)可达到 0. 000 503% 。 该方法显著提高了焦距测量的精度及重复测量精度,为焦距的精 密测量提供了一种有效的途径。 同时,该方法可应用到镜组加工与装配中,提高镜组的成像质量与测量精度。     

激光聚变靶丸内表面轮廓测量系统的研制

针对激光聚变靶丸内表面轮廓高精度无损测量的迫切需求,研制了一套激光聚变靶丸内表面轮廓测量系统。该系统通过最小二乘算法(LSC)计算出靶丸回转偏心量,并利用偏心调整台对靶丸偏心进行自动快速调整;然后,系统软件控制气浮回转轴承驱动靶丸旋转,利用激光差动共焦传感器(LDCS)轴向响应曲线过零点及光线追迹算法精确计算出靶丸内表面轮廓上每个采样点的几何位置;最后,对靶丸内轮廓测量数据进行LSC评定得到其圆度信息。实验证明,靶丸回转偏心的自动调整时间可达22s,当采样点分别为1 024,2 048及4 096时,靶丸内轮廓测量时间分别可达10,20及40s,且圆度测量标准差可达19nm(1 024点)。该系统实现了靶丸回转偏心的自动快速调整及其内轮廓的高精度、无损、快速、自动测量。     

单光源双光路激光并行共焦测量系统设计

针对传统激光并行共焦测量过程中存在的泰伯效应,提出将数字微镜器件（DMD）引入激光并行共焦测量系统来正确辨识正焦面的位置。采用了DMD作为光分束器件,从理论上验证了它是一种投影式的阵列光源,对激光分束后不会在光路方向上产生泰伯像;同时,考虑DMD不能对分束后的光线产生会聚作用,并非高效的并行光源分束器件,本文将DMD与微透镜阵列(MLA)结合构建了单光源双光路并行共焦测量系统。该系统利用DMD光路探测正焦面位置,利用微透镜阵列光路进行精确的共焦测量。实验结果表明,两种光路下的正焦面位置仅相差2 μm,在一个泰伯间距范围之内,可以较好地克服泰伯效应对激光并行共焦测量的影响,进而保证较高精度的并行共焦测量。     

High-precision radius measurement of ball indenter

To solve the problem of calibrating the radius of a ball indenter in a hardness tester, a laser confocal radius measurement and calibration method for the ball indenter is proposed without separating the ball from the body of the indenter. The laser confocal radius measurement and calibration method uses the maximum of the confocal axial intensity curve to precisely identify the cat’s eye and confocal position of the test ball indenter. The distance between these two positions is then measured to achieve high-precision radius measurement. The theoretical analyses and experimental results indicate that the radius measurement uncertainty of the ball indenter with a diameter of 1.5875 mm is within 0.12 μm.     

宽范围大曲率半径数字化非接触测量系统

本文提出了一种新颖的利用激光偏振干涉体系产生非接触的牛顿环并与CCD图像处理技术相结合的测量方法。可测量的曲率半径为1～25m，具有很宽的测量范围；非接触测量不会损坏高精度表面；并可测试任意反向率的凹、凸球面，而测试体系结构却非常紧凑。干涉条纹经计算机数据处理可自动、快速获得测量结果。经误差分析，测量的相对误差△R/R优于0.3%。     

Development of a measuring method for several types of programmed tool paths for NC machine tools using a laser displacement interferometer and a rotary encoder

Many circular motion measuring methods for NC machine tools have been proposed, however, the drawback common to many of these methods is the restriction on the radius size due to the short measuring range of the displacement transducers used. Moreover, most of these measurement tools are specialized, and can only perform circular test path measurements. A circularity test method using a laser displacement interferometer and a rotary encoder has been developed. The measuring method features a much longer range of motion than ordinal circular test methods such as the double ball bar (DBB) method and, therefore, the radius restriction on these measurements is greatly reduced. Moreover, this measuring system can also be used for the evaluation of positioning accuracy and other more complex test paths.

The proposed device consists primarily of a laser displacement interferometer and a rotary encoder. The holders for the interferometer head and the retroreflector are connected with a stainless steel rod. The retroreflector holder has a synthetic resin linear bearing allowing it to move relative to the interferometer head so that both optical components are always facing each other. The laser interferometer measures the change in distance between the interferometer head and the retroreflector, and the rotary encoder measures the rotation angle of the stainless steel rod.

In this paper, the background, measuring principle and apparatus structure are briefly described. The experimental setup is also presented. The apparatus was employed in several measuring experiments, including circularity tests for a vertical machining center. The results from these experiments support the validity of this measurement apparatus.     

A new vacuum interferometric comparator for calibrating the fine linear encoders and scales

A new one-dimensional laser interferometric comparator has been developed for the calibration of the fine linear encoders and scales up to 1600 mm. In the comparator, the interferometer is fully arranged in vacuum and the calibration objects are mounted under atmospheric conditions. The Abbe’s principle on the alignment of workpiece with the measuring beam is satisfied in the structure of a long measuring range. A travelling slide table, on which the calibration objects are mounted, is supported on guide rails by the air bearing and is driven through a recirculating ballscrew. The exhaust of the air bearing is guided to the exterior of the booth in which the comparator is placed. The travel of the table is measured by a reference interferometer with a beam path in vacuum shielded by an evacuated metal bellow, so that the effect of refractive index is eliminated. The laser beam is led by a polarization plane maintaining glass fiber from a self-designed stabilised He–Ne laser, which is placed in an adjacency room, to the beam inlet of the main unit. The measurement system can input the interferometer signal by the encoder signal or the scale signal, and input the encoder or scale data by the interferometer signal. The system resolution is approximately 0.8 nm and maximum travelling measurement speed is 20 mm/s at continuous measurement. The uncertainly (k=2) of measurement is approximately 30 nm in linear encoders of 500 mm length and, approximately 40 nm in scales of 500 mm, although it depends on the length and the characteristics of encoders and scales. It is successful such a high accuracy that the uncertainty of measurement system is smaller than 40 nm in encoders of 1 m length.     

球型惯性元件配合间隙差动共焦精密测量方法

配合间隙是决定球型惯性器件精度和可靠性的关键参数之一,针对球型惯性器球面元件表面有缺口且未完全抛光导致曲率半径难以精确测量,进而难以准确控制球碗、球冠配合间隙瓶颈问题,提出了一种球面惯性元件配合间隙激光差动共焦高精度方法。该方法利用抗散射的激光差动共焦曲率半径测量方法分别对球碗、球冠的曲率半径进行测量,然后利用差动共焦曲率半径测量系统测得的球碗和球冠的半径差来控制球型惯性器球面的配合间隙。理论分析与实验验证表明:该方法测量球冠和球碗配合间隙的相对扩展不确定度优于20×10~(-6),其为惯性器件球冠和球碗配合间隙的高精度测量与控制提供了一种全新的技术手段。     

Application of a diffraction grating and position sensitive detectors to the measurement of error motion and angular indexing of an indexing table

In this paper, two systems for the measurement of the error motion and angular indexing of a rotary indexing table have been developed. A laser diode, a laser holder and a position sensitive detector (PSD) are integrated as a simple measuring device for the measurement of the rotary error without using a precision reference artifact (a cylinder or a sphere), multiple probes or error separation methods. The laser diode is assembled in the laser holder and fixed on the rotary table. The PSD is set up above the laser holder to detect the position of an incident laser beam from the laser diode. When the rotary table rotates, the rotary error changes the direction of the incident beam and also the position of the spot on the PSD. For the measurement of the angular indexing, a reflective diffraction grating and two PSDs are integrated as a high-resolution angle measuring device without using an autocollimator or a laser interferometer system. The diffraction grating is set at the center of the rotary table and reflects an incident laser beam into several diffractive rays. Two PSDs were set up for detecting the positions of ±1st-order diffraction rays. A simple algebraic method is used to solve the angular indexing through an optical analysis. The experimental results showed the feasibility of the proposed test devices.     

基于并行共聚焦显微系统的物方差动轴向测量

差动共聚焦显微成像技术可以获得很高的轴向测量精度,然而已有的差动共聚焦测量技术主要适用于激光扫描共聚焦,还不能满足微纳加工过程中对工件进行非接触式的在线、在位测量的要求。本文在分析差动共聚焦显微成像系统能够实现轴向测量原理的基础上,提出了适用于并行共聚焦技术的轴向测量方法。该方法利用均匀白光照明,在像方只需要使用一台相机做探测器,在物方通过移动载物台分别对样品在焦前和焦后两次成像,根据预先刻度好的差动曲线就可以得出物体表面的高度。理论模拟与实验结果均表明,该方法可以实现高精度的轴向测量,对500nm的台阶样品测量的平均误差为2.9nm,相对误差为0.58%。该方法简单、廉价、测量精度高,可以用于普通显微镜,易于实现样品的三维快速形貌还原与测量。