激光跟踪仪三维坐标转换综合优化方法

为了减少飞机等大型机械产品在安装过程中公共点测量误差的影响,提高坐标转换的精度,提出一种加权点匹配计算方法。该方法以匹配残差加权平方和最小作为解的最优性条件,根据不等精度测量时的加权原则,按照公共点的点位误差确定权重。基于广义逆矩阵理论,建立了近似的测量误差传递模型,分析了测量误差和权重对匹配结果的影响。为了指导跟踪仪位置的优选,借鉴结构力学理论提出一个公共点分布评价指标。重复测量实验表明,在相同测量条件下,与奇异值分解法相比,该匹配算法转换参数的标准差减小了约10%,稳定性较好。对某型飞机附件测量方案的优选实例表明,应用该评价指标有助于选择转换精度较高的跟踪仪站位。     

新型激光诱导荧光检测器的研制及评价

采用成本低、灵敏度高的反射式Z-型检测池,成功研制新型473nm固体激光诱导荧光检测器(LIFD)。用荧光物质异硫氰酸荧光素(FITC)标准品评价检测器性能,其灵敏度高,最低检测浓度为1×10-12mol/L(S/N=15),线性范围超过4个数量级。进一步使用FITC衍生化苯胺、对甲苯胺、对氯苯胺、联苯胺、对苯二胺等5种物质,评价该检测器,最小检测量达到pg级,重现性好,5种物质保留时间RSD值均小于1%(n=7)。说明该检测器具有灵敏度高、稳定性好、线性范围宽等特点,适用于环境与生物领域痕量物质检测。     

使用激光跟踪仪确定数控机床空间位置关系

主要是确定两台机床之间的相互位置关系，目的是使用两台机床同时加工一个工件。首先使用激光跟踪仪对两台机床进行离散化测量，然后根据测量数据建立两台机床各自的坐标系，并确定两台机床之间的相互位置关系，最后计算了由于建立新坐标系导致的坐标误差。     

Fast scanning of a pulsed terahertz signal using an oscillating optical delay line

We describe a fast measurement of a pulsed terahertz signal generated by a femtosecond laser and a photoconductive antenna using an oscillating optical delay line. The method to measure the amplitude of the retroreflector in the oscillating optical delay line is proposed and the displacement of the retroreflector is exactly calculated to acquire the optical delay time in the fast scan mode. With the different oscillation frequency and amplitude of the retroreflector, the pulsed terahertz signals are measured and analyzed. The comparison of the temporal waveform and frequency spectrum between the fast scan mode and the slow scan mode shows a good agreement with the decrease in the scanning time from 60 to 1 s at a signal to noise ratio of 430.     

Measuring workpiece dimensions using a non-contact laser detector system

Proper process control procedures are important considerations in the optimisation of any manufacturing process. Ultimately, a continuous update on the size and quality of the products being manufactured is desirable. A non-contact laser detector system was developed to measure the dimensions of wood products in a real-time operating environment, employing a two-axis lateral effect photodiode as the sensor. Computer algorithms were developed to measure the thickness, warp, and width of wood samples (pencil slats). The effect of mechanical vibration due to slat transport was identified and when possible eliminated. The system was evaluated at different transport speeds. The results indicated that, except for width measurement which is limited by the computing speed, the system can measure thickness and warp quite accurately at feed speeds of 240 feet per minute. Although the work described is specific to certain applications, the implications for use in other industrial activities where visual sensing is required is apparent.     

飞秒激光跟踪仪光轴与竖轴同轴度的标定

考虑飞秒激光跟踪仪仪器轴系的几何误差会影响仪器的指向精度并最终影响坐标测量精度,本文研究了激光光轴与竖轴的几何误差对仪器测量精度的影响。提出了激光光轴与竖轴的同轴度标定方法,以降低其不重合带来的跟踪测量误差。首先,基于几何光学原理建立了光轴与竖轴的几何误差模型,分别分析了光轴与竖轴的倾斜与平移误差对仪器测角精度的影响。然后,针对设计的仪器提出了基于旋转成像原理的光轴与竖轴同轴度的检测方法,并设计了一套同轴度检测装置。最后,基于该检测装置,通过调节两组双光楔完成了激光光轴与竖轴的倾斜与平移误差的标定。结果显示,经标定校准后激光光轴与竖轴的角度误差为3.4″;平移误差为26.1μm,得到的结果为仪器后续建立误差补偿模型奠定了基础。     

一种线性调频连续波探测抗雷达辐射源干扰方法

随着各类军用、民用辐射源频段的不断扩展以及功率的不断提升,线性调频连续波(LFMCW)探测器面对此类干扰的威胁也愈加严重。然而,目前关于LFMCW体制抗干扰技术的研究主要围绕在对抗有源干扰,鲜有针对强辐射源干扰的研究。针对上述问题,以对抗大功率雷达辐射源干扰为背景,本文对常规脉冲和线性调频脉冲信号两种典型的雷达辐射源信号进行建模,并分析其对LFMCW探测器的干扰机理。根据目标回波信号和干扰信号在时频域上的差异,提出了一种基于时频变换和边缘检测的干扰抑制算法。首先使用短时傅里叶变换(STFT)获得接收信号的时频图像,利用脉冲干扰在时间轴上的周期截断特征,在时频域进行干扰的粗滤波;然后结合边缘检测技术,沿着频率轴使用Sobel算子进行卷积,进一步滤除残留的干扰,重构滤波后的频谱,提取目标信息。仿真及实验结果表明,该算法能够有效地抑制两种典型的脉冲体制雷达辐射源信号干扰,在干扰背景下提取目标差频频率的精度优于3%。     

Plasma rotation measurement in small tokamaks using an optical spectrometer and a single photomultiplier as detector

The method for plasma rotation measurement in the tokamak TCABR is reported in this article. During a discharge, an optical spectrometer is used to scan sequentially spectral lines of plasma impurities and spectral lines of a calibration lamp. Knowing the scanning velocity of the diffraction grating of the spectrometer with adequate precision, the Doppler shifts of impurity lines are determined. The photomultiplier output voltage signals are recorded with adequate sampling rate. With this method the residual poloidal and toroidal plasma rotation velocities were determined, assuming that they are the same as those of the impurity ions. The results show reasonable agreement with the neoclassical theory and with results from similar tokamaks.     

机器人坐标系与激光跟踪仪坐标系的快速转换方法

针对机器人坐标系与激光跟踪仪坐标系的转换问题,提出一种机器人单轴旋转运动与自身读数相结合的方法。将靶标球安装在机器人末端,用激光跟踪仪实时测量球心坐标,对机器人单轴转动产生的圆弧轨迹进行空间圆拟合,由三个空间圆的单位法向量可得到旋转矩阵。再求取球心初始位置相对于机器人默认工具点的坐标偏移量,便可反推机器人坐标系原点在激光跟踪仪坐标系下的坐标,即平移向量。实验结果表明,转换后空间点X、Y、Z坐标的RMS误差分别为0.216 mm、0.111 mm、0.157 mm。     

High-accuracy displacement metrology and control using a dual Fabry-Perot cavity with an optical frequency comb generator

A displacement metrology and control system using an optical frequency comb generator and a dual Fabry-Perot cavity is developed with sub-nm accuracy. The optical frequency comb generator has expanded the displacement measurement range and the dual cavity system has suppressed the environmental fluctuation. We evaluated the absolute uncertainty of the developed displacement measurement system to be approximately 190 pm for the displacement of 14 μm and the accurate displacement control using a phase-locked loop was demonstrated with a resolution of approximately 24 pm.     

Micro laser welding of polymer microstructures using low power laser diodes

The use of laser welding for joining micro parts has experienced a substantial increase in popularity during recent years. Specifically translucent microfluidic devices are assembled using laser welding; however, a major issue is the laser beam size of commercially available laser-welding equipment and thus the resulting welding seam size, which may be orders of magnitude larger than microfluidic channels and structures. We have successfully achieved extremely small welding seams using focussed low-power laser diodes. Commercial laser welding stations for polymer assembly will typically operate in the power-region 15–50 Watts. The focussed laser beam will have a size of typically 500 μm × 500 μm and may, depending on optical configuration, be up to several mm². The resulting welding-seam will thus be in the area of 300–600 μm depending on beam energy distribution; additionally the melt will spread to unheated areas due to capillary forces. As microfluidic channels are in 20–100 μm regions, even a very limited amount of stray melt may completely fill a part of a channel and thus render it useless. We have used commercially available “single-die” laser-diodes of optical power 200–500 mW. The beam has been focussed and directed using simple optical installations, resulting in a beam-size in the area of 50 μm × 5 μm full width half maximum (FWHM) We have achieved firm welding seams of width <10 μm, with a welding speed of 15 mm/s and with virtually no noticeable spread of melt.     

激光干涉仪引力波探测器的基本光学结构

引力波是爱因斯坦广义相对论的重要预言,引力波探测是当代物理学最重要的前沿领域之一。以引力波探测为基础的引力波天文学是一门新兴的交叉科学,是对传统电磁辐射天文学的巨大拓展与补充。作为一种大型的精密光学仪器并作为引力波天文学研究的关键设备,激光干涉仪引力波探测器已在世界各地蓬勃发展起来,开辟了引力波探测的新时代。给出了激光干涉仪引力波探侧器的工作原理和基本光学结构,讨论了主要的性能参数,分析了光学镜的结构特点及测量方法。     

Phase-shifting interferometer using a frequency-tunable diode laser calibrated by an optical frequency comb

We present a phase-shifting interferometer based on a frequency-tunable diode laser calibrated by an optical frequency comb and the Carre? algorithm. By use of the frequency control strategies of locking the diode laser to different comb modes and scanning the repetition rate, an arbitrary single optical frequency synthesizer is obtained. The relative laser frequency uncertainty is 5.7 × 10(-12) for 1 s averaging time with tracing to an Rb clock and accurate phase steps are achieved by optical frequency tuning. The surface topography of a standard sphere is measured by this phase-shifting interferometer based on a flat reference. The phase measurement repeatability is λ∕200. With this technique, phase measurement uncertainties from the laser frequency and phase steps are negligible.     

基于激光跟踪仪标定五轴数控加工中心主轴

为了满足高精度加工大口径光学元件的需求,对原有的三轴机械加工中心上进行了一系列技术改造,从而实现了光学元件的五轴数控加工.介绍了三轴系统数控加工中心到五轴数控加工中心的改造过程,并提出了一种标定改造后主轴参数的方法.该方法运用高精度激光跟踪仪建立坐标系、采集数据,计算系统几何参数,由此对主轴的杆长、摆角等参数进行精确标定和精度分析.结果显示,角度量标定精度优于10.000″,长度量标定精度优于0.040 mm.实验证实提出的方法对类似的工作具有普适性.     

Automated three-dimensional analysis of particle measurements using an optical profilometer and image analysis software

The automated collection of topographic images from an optical profilometer coupled with existing image analysis software offers the unique ability to quantify three‐dimensional particle morphology. Optional software available with most optical profilers permits automated collection of adjacent topographic images of particles dispersed onto a suitable substrate. Particles are recognized in the image as a set of continuous pixels with grey‐level values above the grey level assigned to the substrate, whereas particle height or thickness is represented in the numerical differences between these grey levels. These images are loaded into remote image analysis software where macros automate image processing, and then distinguish particles for feature analysis, including standard two‐dimensional measurements (e.g. projected area, length, width, aspect ratios) and third‐dimensional measurements (e.g. maximum height, mean height). Feature measurements from each calibrated image are automatically added to cumulative databases and exported to a commercial spreadsheet or statistical program for further data processing and presentation. An example is given that demonstrates the superiority of quantitative three‐dimensional measurements by optical profilometry and image analysis in comparison with conventional two‐dimensional measurements for the characterization of pharmaceutical powders with plate‐like particles.     

激光跟踪仪的光电瞄准与定位系统

考虑激光跟踪仪的光电瞄准与定位直接影响仪器的整体测量精度和使用性能,讨论了激光跟踪仪的光电瞄准和跟踪定位控制技术并提出了光电探测瞄准、信号调理采集、数字处理及智能跟踪伺服的系统整体技术方案。对系统关键部件进行选型,利用角锥棱镜和位敏探测器(PSD)作为光电探测核心,设计了探测光路和信号处理电路。研制了系统样机,搭建了目标位移量标准测试平台,对样机光电瞄准系统探测信号进行了测试。测试结果显示:采用该设计方案设计的激光跟踪仪样机的静态定位测量精度达到6μm,随机动态跟踪测量速度大于1m/s。结果表明:提出的方法可解决激光跟踪仪定位精度低、动态跟踪效果差等常见问题,可为研制高精度、大范围、大尺寸测量仪器提供技术参考。     

衍射双波段红外光学系统设计

基于定向光栅能对不同波长的不同级光谱闪耀的原理,从一种比较新颖的角度将衍射光学元件成功地应用于双波段红外光学系统设计,使系统在衍射效率达80%的中波红外波段3.8～4.2μm和长波红外波段8.8～11.5μm同时较好地完成像差校正,会聚到共同的焦点。最后以一个f/2单透镜衍射光学系统进行了验证。设计结果表明,此双波段光学系统结构紧凑、原理简单、不需要额外的机械设备,为双波段成像、探测提供了一条新的思路。     

An evaluation of a modulated laser encoder

This paper introduces a new method of interpolation for sub-nanometer-resolution linear encoders. This method, called SPPE (scanning position probe encoder), uses high-order harmonics information obtained by a sinusoidal scanning pickup located on a periodic grating surface. The proposed encoder uses a current-modulated laser diode with diffractive grating optics. Since the electrical current changes the laser-diode wavelength, the interference light intensity is modulated as a sinusoidal scanning pickup on the scale grating. Phase-detection circuits can decode the position information in the pickup signal by using phase-locked loop techniques. The decoder achieves an interpolation rate of over 1/40,000 with interpolation errors of less than ±1 nm. A new interpolation-error measuring system was developed for the encoder. Finally, the evaluation results reveal that the presented encoder shows both high resolution and strong robustness.