三坐标测量机用压电式触发测头的分析

三坐标测量机用测头对整机性能的影响较大。采用压电式触发测头能改善机械触发式测头的性能。本文就常用的几种压电式触发测头的典型结构原理及性能作一简单分析。     

复杂型面测量中测头中心的轨迹曲面及测头半径的三维补偿

根据球形测头的中心轨迹与被测曲面互为等距曲面的关系，采用双三次Ｂ样条曲面建立了描述测头中心轨迹的数学模型，并提出了一种新的三维测头半径补偿方法。     

求解凸轮当量转角-升程的方法

本文针对采用非设计要求测头 (与凸轮机构从动件 (挺柱 )不同形式和形状的测头 )进行凸轮测量所引发的当量转角—升程的求解方法问题进行了分析。并强调指出 ,在进行凸轮测量时 ,不能因为采用了非设计测头而改变凸轮设计受检点的位置 ,即测头切换应遵守凸轮受检点位置不变原则。     

杠杆表球形测头的配制

杠杆百(千)分表的球形测头在使用中很容易磨损而失掉原有形状。球形测头磨损后就影响示值误差。所以配换球形测头是杆杠表修理中经常碰到的修理项目。测头磨损后,若全部调换测头杆杠不但费工费料,还不易制造准确。我厂采用锡焊钻孔的钢球方法修复球形测头,经多年的实践证明,只要采用合理的配制、修理工艺,焊接强度及修复精度完全可以满足杠杆表使用的要求。且测头杠杆经过改装后便于多次修复。钻孔钢球制备一批备用,以后修理时只要换焊钢球就行。此法操作简便、工效高、修理质量好。现将具体的修理工艺介绍如下。(1)将已磨损的球形测头去掉,把杠杆部分修成如图(1)所示的形状。     

一种用于纳米计量的原子力显微镜测头的设计

介绍了我们研制的一种高精度、具有计量学意义的原子力显微镜测头.该显微测头与其它部件协同工作在50 mm×50 mm×2 mm的测量范围内实现纳米级精度的测量.测头采用光束偏转法检测探针悬臂的微小偏移,由单模保偏光纤引入半导体激光作为光源.该测头安装有3个立体反射镜作为激光干涉仪的参考镜.样品与原子力显微镜测头的相对位置可以由激光干涉仪直接读数,可溯源到米国际定义及国家基准上.激光干涉仪的布置无阿贝误差.测头采用立体光路设计,结构紧凑.测头厚度小于20 mm,质量约200 g,却实现了100 mm的反射光程.使用该测头测得与量块表面的力-距离曲线,还测得标称高度300 nm SiO2台阶样板的图像,分辨率优于0.05 nm.     

对发展坐标测量机测头的新思考

本文从历史发展角度评价坐标测量机各类测头优缺点，从几何量测量发展角度分析坐标测量机测头的发展方向战略，认为应当将发展扫描或测微测头作为主攻方向，在具体研制中要采用发散型思维方式，冲破原有的思维框框另辟踩途，否则不能有突破性进展。     

压电式触发测头复零机构的分析

介绍一种新颖的三坐标测量机用压电式触发测头，由于采用三对滑轮加中间环的机械复零机构，从而改善了触测性能，扩大了测头的应用范围，提高了测试精度。     

小型自感应原子力显微镜测头及其标定

设计了一种小型轻敲式自感应原子力显微镜(AFM)测头以实现微/纳尺度下的几何量测量.轻敲式测头采用石英音叉式自感应探针,通过自身的电信号输出检测悬臂梁的振幅变化,无需额外的光学传感器.设计了测头的微弱自感应信号放大电路,并补偿音叉寄生电容对测量的干扰.机械结构紧凑便于将测头固定于光学显微镜下观察测量情况,同时屏蔽外界的干扰.利用显微激光多普勒测振系统,标定了测头机电耦合系数为145 nm/V,由此可以计算测头工作频率下悬臂梁的振幅.搭建了以纳米测量机(NMM)为高精度定位平台的测试系统,利用该系统对测头进行进/退针实验,标定测头的灵敏度为0.47 nm/mV,NMM内置的干涉仪保证标定直接溯源至"米"定义.实验表明测头的非线性误差小于1%,测量范围在百纳米级.     

坐标测头技术及应用

测头系统是测头及其附件组成的系统．测头是测量机触测被测零件的发讯机构，它可以输出开关信号，亦可以输出比例模拟信号，它是坐标测量机的关键部件，测头精度的高低很大程度上决定了测量机的测量重复性及精度。坐标测头技术近几年发展很快．尤其是扫描测头和非接触测头。     

微孔光纤测头的研制及应用

基于微孔测量中测头不能做得足够小的技术难题,文中提出采用标准多模通信光纤,按特定的工艺技术方法烧熔光纤测球,再进行封装制成测头,应用在微孔测量中.重点介绍了这种测头的技术参数和成形方法、原理,并对研制的φ0.1 mm光纤测头几何形貌进行实际测量,应用于φ0.6 mm小孔孔径的测量分析,标准偏差不超过0.5μm,取得了很好应用效果.     

一种高灵敏度传感器：—四棱镜光点检测器

本文介绍一种用于激光准直高精度直线度测量的高灵敏度光电信号检测器,该检测器根据激光束腰处聚焦光斑点小的特点,采用一种四棱镜光点会聚式检测器来接收激光束信息,它的检测灵敏度比传统的四棱镜式四象限位敏传感器高出一个数量级以上;该检测器对激光束平行漂移与角漂移表现出不同的检出特征,因而尤适合于做为激光束漂移补偿检测和直线度误差检测;该检测器还具有结构简单、使用方便等优点。     

一维光电位置敏感器的应用研究

简要叙述了一维光电位置敏感器（ＰＳＤ）的工作原理,以及采用光学三解法测量构成的尺寸测量传感器,重点介绍光电位置敏感器、半导体激光器实现睡钢轨磨耗自动检测的方法。     

Shear-sensitive magnetoresistive robotic tactile sensor

We have developed a tactile sensor for robotic applications that is sensitive to pressure and, unlike most other tactile sensors, also responds to shear components of the vector force. We consider this an important advantage for robotic manipulation. In our design a magnetoresistive detector senses variation in the magnetic field of a miniature magnetic joystick. This joystick is mechanically mounted by attaching it to a metal foil, which provides elasticity without hysteresis. The detector chip is fabricated using IC technology, and an array of joystick mechanisms can potentially be made by batch processing. We have designed and partially tested a 2 × 2 array prototype, demonstrating the viability of this approach.     

海水盐度检测技术的最新进展

本文首先介绍了海水盐度检测的传统方法电导率法,给出了电导率法盐度测量的优缺点和测量特性;详细论述了该领域的最新技术进展,包括微波遥感技术、裸露光纤法、表面等离子共振法、基于PSD的光学法、基于盐度敏感材料的测量法。具体分析了各种技术的原理、发展现状、存在的问题,并对比了它们的优缺点。最后,对海水盐度测量技术的发展进行了展望,并提出了今后有待进一步解决的关键问题。     

Displacement sensing resolution of position-sensitive detectors inatmospheric turbulence using retroreflected beam

The position sensing resolution of a lateral-effect photodiode (LEP) and a four-quadrant (4Q) photodetector used as the position sensitive detector (PSD) in a sensor which measures the lateral displacement of a corner cube reflector (CCR) by illuminating it and detecting the position of the reflected light spot with the PSD is studied. An LEP is much noisier than a 4Q detector, but in an outdoor environment the sensitivity of the 4Q detector to atmospheric turbulence due to defocusing makes its resolution worse than that of an LEP. Submillimeter resolutions at the target distances of several hundreds of meters are electrically achievable with an LEP. Outdoors, however, its resolution is also bounded by the atmospheric turbulence. In turbulent measurement conditions, standard deviations of better than 1 cm were typically achievable up to the distance of 300 m and about 10 cm up to half a kilometer     

SENTIRAD—An innovative personal radiation detector based on a scintillation detector and a silicon photomultiplier

The alarming personal radiation detector (PRD) is a device intended for Homeland Security (HLS) applications. This portable device is designed to be worn or carried by security personnel to detect photon-emitting radioactive materials for the purpose of crime prevention. PRD is required to meet the scope of specifications defined by various HLS standards for radiation detection. It is mandatory that the device be sensitive and simultaneously small, pocket-sized, of robust mechanical design and carriable on the user's body. To serve these specialized purposes and requirements, we developed the SENTIRAD, a new radiation detector designed to meet the performance criteria established for counterterrorist applications. SENTIRAD is the first commercially available PRD based on a CsI(Tl) scintillation crystal that is optically coupled with a silicon photomultiplier (SiPM) serving as a light sensor. The rapidly developing technology of SiPM, a multipixel semiconductor photodiode that operates in Geiger mode, has been thoroughly investigated in previous studies. This paper presents the design considerations, constraints and radiological performance relating to the SENTIRAD radiation sensor.     

Chemical sensing systems using xerogel-based sensor elements and CMOS photodetectors

We present the first example of an integrated complementary metal-oxide-semiconductor (CMOS) photodetector coupled with a solid-state xerogel-based thin-film sensor to produce a compact chemical sensor system. We compare results using two different CMOS-based detector systems to results obtained by using a standard photomultiplier tube (PMT) or charge-coupled device (CCD) detector. Because the chemical sensor elements are governed by a Stern-Volmer relationship, the Stern-Volmer quenching constant is used as the primary comparator between the different detectors. All of the systems yielded Stern-Volmer constants from 0.042 to 0.049 O/sub 2/%/sup -1/. The results show that the CMOS detector system yields analytical data that are comparable to the CCD- and PMT-based systems. The disparity between the data obtained from each detector is primarily associated with the difference in how the signals are obtained by each detector as they presently exist. We have also observed satisfactory reversibility in the operation of the sensor system. The CMOS-based system exhibits a response time that is faster than the chemical sensor element's intrinsic response time, making the CMOS suitable for time-dependent measurements. The CMOS array detector also uses less than 0.1% the power in comparison to a standard PMT or CCD. The combined xerogel/CMOS system represents an important step toward the development of a portable, efficient sensor system.     

Shack-Hartmann sensor improvement using optical binning

We present a design improvement for a recently proposed type of Shack-Hartmann wavefront sensor that uses a cylindrical (lenticular) lenslet array. The improved sensor design uses optical binning and requires significantly fewer detector pixels than the corresponding conventional or cylindrical Shack-Hartmann sensor, and so detector readout noise causes less signal degradation. Additionally, detector readout time is significantly reduced, which reduces the latency for closed loop systems and data processing requirements. We provide simple analytical noise considerations and Monte Carlo simulations, we show that the optically binned Shack-Hartmann sensor can offer better performance than the conventional counterpart in most practical situations, and our design is particularly suited for use with astronomical adaptive optics systems.     

Liquid-crystal Hartmann wave-front scanner

The liquid-crystal wave-front scanner (LCWS) is a highly sensitive wave-front sensor suited to the measurement of aberrations in optical systems and, more generally, of static wave fronts, and it is based on the Hartmann test. In the LCWS an incoming wave front is scanned sequentially by a programmable moving aperture that is implemented by use of a liquid-crystal display. The position of the diffraction spot is recorded behind an observation lens with a CCD detector and provides an estimation of the local slopes in two orthogonal directions at the aperture position. The wave front is then reconstructed from slope data by use of a least-squares method. Experiments are reported for nearly planar wave fronts as well as for strongly aberrated wave fronts, demonstrating both the large dynamic range and the great sensitivity of the LCWS. The LCWS is compared with the Shack-Hartmann wave-front sensor in terms of dynamic range and sensitivity.     

Improved electrodeposited iridium oxide pH sensor fabricated on etched titanium substrates

In the present paper, the preparation and characterization of an improved solid-state pH sensor are described. The sensor is based on anodically electrodeposited iridium oxide film, as a pH-sensing layer. Merits of the present sensor include (i) excellent adhesion of the pH sensitive layer to the substrate, (ii) excellent reproducibility of sensor fabrication, (iii) faster preparation procedure, and (iv) low cost of the titanium substrate. These advantages are realized by combining acid-etched titanium as the electrode substrate with an optimized electrodeposition solution consisting of IrCl4 as an iridium source, hydrogen peroxide, potassium oxalate, and potassium carbonate. Heating the electrodeposition solution to 90 degrees C reduced the time required for solution development from approximately 3 days to 10 min. The pH-sensing layer is protected with a layer of Nafion and a microporous polyester membrane. The improved sensor showed a super-Nernstian response (-73.7 +/- 1.2 mV/pH unit) in the pH range of 1.5-11.5. The present pH sensor, fabricated in a tubular form, is used as a detector in a flow injection analysis (FIA) system for pH measurements. Optimization of the FIA experimental parameters resulted in a linear dependence of peak heights on the pH of the injected samples in the pH range of 2-11.