巧用数字多用表实现精确测量

一、减少和消除仪器内部连接误差和测量引线带来的误差内部连接线引入的误差:当不同金属连接时,会构成一个热偶结,热偶结产生随温度变化的电压。这一电压虽然很低,但高精度数字多用表也能显示出来。因此在测量微小电压时,因数字多用表内部连接     

使用GCP快速测量表面粗糙度

照射在样本表面的激光束随 表面粗糙度的不同，反射光的密度分布将不同，表面粗糙度增大时，反射光的密度将被扩展。本根据这一原理，提出一种使用激光束快速测量表面粗糙度的无触点光学方法。该方法利用高斯曲线的系数，通过测量反射光的密度分布曲线的宽度，由高斯曲线系数的标准差，利用ＧＣＰ测量表面粗糙度，给出了测量结果。     

圆度测量中基于相关性分析的信号周期计算方法北大核心CSCD

论述了用单测头进行现场圆度测量时,应对圆周封闭性问题的解决方法。利用傅里叶变换分析测量信号的频域特性,得到信号的各频率分量,通过滤波的方式消除噪声影响、漂移影响。提出一种基于相关性分析的方法,准确获得测量信号周期。通过MATLAB进行仿真分析,验证了该方法的正确性和可靠性。通过改变测量信号的频率和幅值,即改变圆度测量时的转速和偏心量,得到周期计算误差随信号频率和幅值变化的关系。结果表明周期计算误差随频率的增大而减小,即频率越高,用该方法得到的周期越接近于信号的实际周期;但当频率一定时周期计算误差值不随幅值改变而产生显著变化。     

复合表面形貌测量中通道串扰和色差消除方法

为实现漫反射表面和镜面复合表面的快速测量，基于条纹投影和条纹反射的复合表面测量系统通过相机的多颜色通道快速获得绝对相位。针对复合表面形貌测量中相机、投影仪、显示屏所引入颜色通道间的串扰和色差，研究了基于矩阵的串扰消除方法和绝对相位对应像素偏差的色差消除方法。基于串扰矩阵，分别建立投影仪和显示屏的串扰矩阵，完成颜色通道间的串扰消除。通过彩色正交条纹获得各颜色通道水平和竖直方向的绝对相位，建立颜色通道间相位差和像素偏差之间的关系，实现每一像素点的像素偏差校正，消除色差的影响。实验结果证明，所提色差和串扰消除方法使复合台阶的测量均方根误差从0.479 mm降至0.030 mm，提高了测量效率和测量精度。     

基于小波包的数值积分误差分析及消除方法

在结构损伤识别的时域法研究中，数值积分的误差将直接影响反演参数结果的精度。积分初值的未知、消除数值积分引入的误差是结构损伤反演计算中信号处理的难题。针对积分初值、数值积分积累误差和数值积分引入的偏移误差进行了理论分析，得出此类误差均具有低频特性的性质，可作为信号低频噪声进行处理。根据数值计算误差的特点分析及小波包多尺度、高分辨的特性，设计了一种基于小波包的滤波器，较好地解决了消除数值积分计算引入误差的问题。通过四层剪切结构模型算例验证，结构刚度反演误差由73％-32．2％降低到0．6％-0．24％，获得了较理想的效果。该方法同样可以用于其它领域的数值处理。     

测量系统存在幅值和相位误差时准确测量频率响应函数的方法

给出了一种在测量系统存在幅值和相位误差时准确测量频率响应函数的方法，导出了频率响应函数测量系统的系统函数一般表达式；确定了测量系统误差特征函数，并以此为基础消除了测量系统误差对测量结果的影响。实验结果表明，该方法行之有效，并具有一般性。     

生物介质复介电常数的微扰法测量

由谐振腔微扰理论出发，得到复介电常数计算式，测量了不同浓度的NaCl溶液及小鼠血液、肿瘤细胞悬液等样品的复介电常数；所得结果较为精确，证明了本测量系统的可靠性；对测量的系统、方法、仪器所引入的误差做了一定分析。     

主动测量信息处理的智能化

本文提出了一种对被测变量测量值所需信息进行了智能化处理方法，在线辨识出表征传感器滞后特性的时间常数Ｔｍ，再利用校正（补偿）的方法减少或消除滞后特性的影响，以减少或消除动态误差，使测量与控制融为一体，实现主动测量技术的全盘自动化。     

电阻应变式传感器线损补偿电路设计

当二次测量仪表与传感器有一定距离时，由于桥路供电导线自身电阻的存在，且导线的阻值随环境温度而变，这将不可避免地引入测量误差。文中提出了供桥电压直接补偿法和比率补偿法。前者是将采样线反送回的实际桥压信号与供桥电压源的基准电压进行比较，通过误差放大器控制调整管，使加到传感器测量桥路上的电压保持稳定；后者是通过电路进行比率运算，消除桥压对测量结果的影响。在采用A/D变换技术的测量电路中，应用比率法不仅能有效的消除桥压变化对测量结果的影响，而且在电路上也非常简单。     

一种采用应变测力传感器补偿动态力测量误差的理论研究

本文在理论上研究了一种采用串联多自由度应测力传感器补偿动态力测量误差的方法，在数学上根据串联多自由度应变测力传感器的输入输出传递函数建立了这种传感器的状态方程，通过对传感器数学模型的分析，提出了一种消除动态力测误差的方法，在本文的假设情况下采用这种方法在理论上可以完全消除测力传感器的动态测量误差。     

基于光路折叠的室内基线场误差分析方法研究

为了有效开展长距离光电测距类仪器的室内检定工作,在50m高精度导轨上利用1组平面反射镜进行光路折叠,搭建了100m室内基线场。对基线系统的测量误差进行了分析,考虑各项误差的调整精度,将误差分析结果应用到实际光路调整过程中,分析得到对基线长度影响更显著的误差量,并对其进行了控制和调整,提高测量光路的平行性调整精度,最后选择双频激光干涉仪作为长度基准开展验证实验。实验结果表明:通过光路折叠方法可以实现2倍光程倍增,基线系统的精度较高,可进行连续测量,有效地解决了室内基线建立过程中所存在的检测效率低、可重复性差等技术问题。     

远距离高精度多普勒位移测量

通过泛函、激光散斑理论和随机过程各态遍历的研究,导出激光多普勒信号强度与聚焦光斑直径、接收透镜通光口径、光电接收器响应等参数间的关系,在此基础上设计出一种适用于远距离处面内位移测量的光路。此光路将高斯光束束腰聚焦在被测体上,实现最小聚焦光斑和平面波叠加,此外采用大口径透镜接收散射光,用响应度高的光电接收器转换光电信号等措施获得高强度高信噪比的测量信号。将此光路用于 100m 处面内位移(49.70mm)测量,其精度可达 2%。此设计方法能用于振动或地震波的高精度检测。     

Experiments with active phase matching of parallel-amplified Multiline HF laser beams by a phase-locked Mach-Zehnder interferometer

Active phase matching of multiline HF laser beams by means of a phase-locked Mach-Zehnder interferometer was demonstrated by locking the interferometer to the central interference fringe at zero optical path length difference. The central fringe could be found by varying the spectral content of the input beam. Laser amplification in one leg of the interferometer decreased fringe visibility without adversely affecting locking. Single-line fringe patterns produced by an array spectrometer (while the interferometer was operated in its scanning mode) were analyzed to show that no significant dispersion occurred in the amplifier. The techniques developed have potential for measuring dispersion mismatch between larger parallel amplifiers. These experiments demonstrated in principle that a number of multiline HF amplified beams can be recombined and phase-matched to produce a high beam quality output beam.     

A CAD/CAM system from 3D coordinate measuring data

A CAD/CAM system with some new numerical methods is presented in this paper. This system mainly consists of two stages. In stage 1, the least squares method is applied to fit a best form of parametric surface to a set of data points obtained from a 3D coordinate measuring machine, with the errors caused by the probe compensated. In stage 2, from the best form of parametric surface obtained in stage 1, a new efficient method—adaptive path planning—which has better performance than the old parametric method is developed to generate the cutter path. By application of adaptive path planning, machining time can be reduced. By transforming the cutter contact path to the cutter location path, the curvature method for detecting gouging is presented by which a tool path with gouging avoidance can be generated.     

激光束角漂移对双频激光直线度测量的影响

利用惠更斯关于波面传播的理论，分析计算了双频激光渥拉斯顿棱镜直线度测量系统中激光束角漂移以及渥拉斯顿棱镜和双面反射镜倾角对测量精度的影响，得到了相应的结论。     

分光光度测色仪中双光路d/0结构的改进

在分光光度测色仪的双光路d/0结构设计中,通常采用积分球内壁作为参考点来消除光源波动对仪器重复性产生的影响.但是在这种情况下,参考信号在一定程度上会受到测试样品的漫反射光的干扰,仪器的重复性和准确性也随之降低.本文设计了一种改进的d/0测量结构,采用LED复合光源作为测试光源,在参考光路设置单独的参考白壁,而不再将积分球内壁作为参考点,并建立实验进行验证.实验结果表明,改进的光路结构可以有效的消除被测试样品的漫反射光对参考光路信号的影响.     

Geometric phase lens

The design of a lens that modulates the geometric phase of an optical beam by manipulating its polarization is presented. To produce such a geometric phase element with a spatially varying phase function, one needs a wave plate with varying orientation. One can use subwavelength grooves to produce form birefringence, but the variation in orientation generally leads to branch points in the groove pattern. These branch points do not affect the phase of the traversing beam directly because the grooves are subwavelength. However, they do produce errors in the groove orientation, which indirectly leads to errors in the geometric phase function that is implemented. A design procedure is provided to compute the groove pattern for such a rotationally symmetric geometric phase element; and, with the aid of a numerical simulation, the effect of the branch points in the groove pattern on its performance is investigated.     

一种共路补偿激光漂移的直线度测量方法

在激光基准长距离、高精度直线度测量中,空气扰动是影响其测量精度的一个主要因素。提出了一种简单的共路补偿空气扰动造成激光漂移的方法。角锥棱镜作为位置敏感器,四象限探测器探测角锥棱镜逆向反射光所携带的直线度误差,二维PSD和透镜用来监测空气扰动所带来的角度漂移。实验结果表明,通过补偿后,空气扰动所带来附加位置误差可以减少大约75%。     

Liquid lens using acoustic radiation force

A liquid lens is proposed that uses acoustic radiation force with no mechanical moving parts. It consists of a cylindrical acrylic cell filled with two immiscible liquids (degassed water and silicone oil) and a concave ultrasound transducer. The focal point of the transducer is located on the oil-water interface, which functions as a lens. The acoustic radiation force is generated when there is a difference in the acoustic energy densities of different media. An acoustic standing wave was generated in the axial direction of the lens and the variation of the shape of the oil-water interface was observed by optical coherence tomography (OCT). The lens profile can be rapidly changed by varying the acoustic radiation force from the transducer. The kinematic viscosity of silicone oil was optimized to minimize the response times of the lens. Response times of 40 and 80 ms when switching ultrasonic radiation on and off were obtained with a kinematic viscosity of 200 cSt. The path of a laser beam transmitted through the lens was calculated by ray-tracing simulations based on the experimental results obtained by OCT. The transmitted laser beam could be focused by applying an input voltage. The liquid lens could be operated as a variable-focus lens by varying the input voltage.     

Branch-point reconstruction in laser beam projection through turbulence with finite-degree-of-freedom phase-only wave-front correction

Wave-front sensing and deformable mirror control algorithms in adaptive optics systems are designed on the premise that a continuous phase function exists in the telescope pupil that can be conjugated with a deformable mirror for the purpose of projecting a laser beam. However, recent studies of coherent wave propagation through turbulence have shown that under conditions where scintillation is not negligible, a truly continuous phase function does not in general exist as a result of the presence of branch points in the complex optical field. Because of branch points and the associated branch cuts, least-squares wave-front reconstruction paradigms can have large errors. We study the improvement that can be obtained by implementing wave-front reconstructors that can sense the presence of branch points and reconstruct a discontinuous phase function in the context of a laser beam projection system. This study was conducted by fitting a finite-degree-of-freedom deformable mirror to branch-point and least-squares reconstructions of the phase of the beacon field, propagating the corrected field to the beacon plane, and evaluating performance in the beacon plane. We find that the value of implementing branch-point reconstructors with a finite-degree-of-freedom deformable mirror is significant for optical paths that cause saturated log-amplitude fluctuations.