基于线阵CCD的测隙装置设计

在工业现场，传统的测量方式不能快速准确地测量微小尺寸。基于工业上小尺寸测量的需要，设计了一种可用于测量间隙的光电检测装置。用线阵CCD(Charge Coupled Device)作光电接收传感装置，单片机作主控处理器，对齿轮和高频淬火感应器之间的间隙进行在线非接触测量，取得了较好的测量效果。该方案适用于成本低但测量精度相对要求较高的场合。     

频差偏差对全视场外差测量精度的影响

根据全视场外差测量的相关理论,推导了频差偏差与仪器测量精度的相互关系.分析了频差大小、频差偏差、采集初始时间、初始相位、采样频率和采样周期数等相关参数对测量精度的影响.研究结果可以作为全视场外差测量设备设计、参数选取的理论依据;并给出了通过合理选择采样时间和采样帧数提高测量精度的一种方法.     

Application of pressure sensitive paint measurement to a low-solidity cascade diffuser of a transonic centrifugal compressor

A pressure sensitive paint (PSP) measurement has been known as a pressure field measurement technique based on the oxygen quenching phenomenon of luminescence of specific luminophores. A PSP measurement was applied for pressure field measurement in a low-solidity circular cascade diffuser of a single-stage transonic centrifugal compressor with 5 in pressure ratio for HFC134a gas. The oxygen concentration was about 500 ppm. Ru (bath-phen) was adsorbed on a silica-gel thinlayer chromatography sheet, and the sheet was pasted onto the side-wall between the cascade vanes. A drastic change in luminescent intensity was recognized during a surge condition. Also the pressure variations based on luminescent intensity agreed well with the pressure fluctuations measured using a semiconductor pressure sensor with high-frequency-response. It was shown that a PSP measurement worked well to investigate the unsteady pressure fields in a circular cascade diffuser of a transonic centrifugal compressor. Moreover, the time response of PSP becomes clear as a problem to be overcome for the present.     

Accuracy analysis of parallel plate interferometer for angular displacement measurement

The measurement accuracy of a parallel-plate interferometer for angular displacement measurement is analyzed. The measurement accuracy of angular displacement is not only related to the accuracy of phase extraction, but also related to initial incident angle, refraction index and thickness of plane-parallel plate as well as wavelength's stability of laser diode, etc. Theoretical analysis and computer simulation show that the measurement error of the angular displacement bears a minimum value when choosing an optimal initial incident angle in a large range. These analytical results serve as a guide in practical measurement. In this interferometer, reducing the refraction index or increasing the thickness of the parallel plate can improve the measurement accuracy; and the relative error of the phase measurement is 3.0×10⁻⁴ corresponding to 1 °C temperature variation. Based on these theoretical and experimental results, the measurement accuracy of the parallel-plate interferometer is up to an order of 10⁻⁸ rad.     

Applications of Fiber Optic Grating Technology to Multi-Parameter Measurement

In this article, approaches reported in the literature for multi-parameter measurement relying on fiber grating technology are reviewed. Due to its importance, the particular case of temperature/strain simultaneous measurement is addressed in further detail, as well as the techniques and sensing heads for temperature-independent strain measurement. Specific criteria are also proposed for sensing head classification in the context of multi-parameter measurement.     

Laser Alignment Techniques for Simultaneously Measuring Five Degree of freedom Deviations of the Object

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红外热像仪参数的双黑体测量装置

对红外热像仪参数双黑体测量装置的工作原理进行了介绍。装置采用双黑体及反射型靶标为温差辐射源，可实现黑体温度温差准直辐射的定期校准和红外热像仪参数测量量值的溯源，也可实现红外热像仪参数的可控性，以及对它进行稳定的、可复现的精确测量。推导出利用红外热像仪参数双黑体测量装置测量信号传递函数SiTF数学模型，分析了红外热像仪参数测量装置的客观因素——仪器常数，针对仪器常数对SiTF测量的影响进行了试验。试验结果表明，仪器常数对红外热像仪SiTF参数测量精度影响较大，并同时影响时域与空域NETD及3D噪声的准确测量。     

一种小型光谱色彩分析仪的设计

为解决目前颜色测量仪器测速慢、体积大的问题，采用先进的颜色测量方法——光电摄谱法，建立了一个测色的数学模型，设计了一种全自动测色的小型光谱色彩分析仪。仪 器由照明系统、光电摄谱仪、信号采集与处理电路、测色软件四部分组成。详细阐述了照明系统和光电摄谱仪的设计。光电摄谱仪采用平场凹面光栅分光，线阵CCD接收，缩小了仪 器体积。利用此仪器测量7块标准色板，色品坐标测量不确定度小于0.01，测试周期为1秒。结果表明，此仪器不仅精度高，还满足了工业生产中对测色的速度和准确度要求。     

影像测量技术在叶尖间隙测量中的应用

针对航空涡轮发动机叶尖间隙测量难度大、精确度不高的问题,提出利用影像测量技术对装配过程中的叶尖间隙进行高精度测量,采用自定义标定、改进的边缘检测和Hough变换、图像超分辨率复原技术,通过运动控制机构、工业CCD摄像机、计算机视觉库,设计了独特的图像测量体系,实现了叶尖间隙的高精度非接触测量。实验结果表明,测量精度达到了15 m,与其他叶尖间隙测量以及影像测量系统相比,该方法不仅精确度有所提高,而且移植性好、成本低。     

Proposed Test of Relative Phase as Hidden Variable in Quantum Mechanics

We consider the possibility that the relative phase in quantum mechanics plays a role in determining measurement outcome and could therefore serve as a “hidden” variable. The Born rule for measurement equates the probability for a given outcome with the absolute square of the coefficient of the basis state, which by design removes the relative phase from the formulation. The value of this phase at the moment of measurement naturally averages out in an ensemble, which would prevent any dependence from being observed, and we show that conventional frequency-spectroscopy measurements on discrete quantum systems cannot be imposed at a specific phase due to a straightforward uncertainty relation. We lay out general conditions for imposing measurements at a specific value of the relative phase so that the possibility of its role as a hidden variable can be tested, and we discuss implementation for the specific case of an atomic two-state system with laser-induced fluorescence for measurement.     

Laser Alignment Techniques for Simultaneously Measuring Five Degree-of-freedom Deviations of the Object

An optical measurement system has been developed for the simultaneous detection for five degree-of-freedom (DOF) deviations of the object. The measuring system designed bases on laser holographic technique, laser alignment technique, laser drift compensation technique and magneto-optic modulating technique where a single laser beam is used as datum line. This measuring system is applied to multiple degree-of-freedom alignment and measurement of fine deviation, and it carries out the automatic testing in a deformation of machine tool, or the loaded axon in a strain wind tunnel balance. Through actual calibration and measurement, the resolution of the system is estimated to be 4 μm for linear displacement error measurement and better than 2″ for angular error measurement with a 1 m offset between laser and a photoelectric receiving target.     

Applications of Fiber Optic Grating Technology to Multi-Parameter Measurement

Abstract

In this article, approaches reported in the literature for multi-parameter measurement relying on fiber grating technology are reviewed. Due to its importance, the particular case of temperature/strain simultaneous measurement is addressed in further detail, as well as the techniques and sensing heads for temperature-independent strain measurement. Specific criteria are also proposed for sensing head classification in the context of multi-parameter measurement.     

应用多传感器技术测量微孔几何参量

基于多传感器技术,提出了一种将接触式和非接触式传感器集成到坐标测量机上研究微孔几何参量测量的理论和方法,可对喷墨打印机喷嘴、生物医学仪器孔、燃气涡轮叶片的致冷喷口和柴油机喷油器喷孔等微孔进行实时测量。介绍了系统的组成和测量原理,讨论了微孔测量步骤。实验中,以直径0．16mm、深0．9mm的三个柴油机喷油嘴喷孔做测试,根据测量结果,分析了微孔的圆柱度、直径、圆度、直线度和锥度五个特征参量,并对测量系统的重复性和再现性进行了分析,对于微孔加工过程中的质量控制具有指导作用。     

Calibration and evaluation of optical systems for full-field strain measurement

The design and testing of a reference material for the calibration of optical systems for strain measurement is described, together with the design and testing of a standardized test material that allows the evaluation and assessment of fitness for purpose of the most sophisticated optical system for strain measurement. A classification system for the steps in the measurement process is also proposed and allows the development of a unified approach to diagnostic testing of components or sub-systems in an optical system for strain measurement based on any optical technique. The results described arise from a European study known as SPOTS whose objectives were to begin to fill the gap caused by a lack of standards.     

窄带高功率微波效应测试中功率密度测量不确定度评估

针对窄带高功率微波（HPM）效应试验的辐射场准确测试需求,分析补充了功率密度参数的测量不确定度主要分量,提出了一个参数更为全面的乘式测量不确定度评估模型。采用B类评估方法,根据相关标准和信息对各分量进行了一组赋值,计算得到了相对形式的分量标准不确定度。给出了评估测试环境影响、位置偏差等分量不确定度半宽度的实验方法,为HPM效应功率密度参数测量不确定度的合理评定提供了参考,为实现其全部分量基于实测数据客观评估测量不确定度提供了操作方法。     

空间点目标光谱探测与特征识别研究进展

光学观测是空间目标识别的重要手段,由于探测距离远,视场中的空间目标多呈现为非分辨的点目标。相比于传统的定轨测量和光度测量,光谱探测提供了波长维的可分辨信息,极大的提升了目标表面材质判别能力,并为目标状态反演提供了更可靠的依据,极具应用潜力。介绍了近年来国内外学者在空间点目标光谱探测及特征识别方面的典型研究进展,依据主要研究方法,分为多通道测光探测、高光谱探测、实验室光谱特性测量、目标特性建模仿真四个方向。其中,多通道测光获得了低光谱分辨率的测量数据,是常用的广域空间目标分类判别手段;高光谱探测研究反射能量在波长维的精细分布,有助于反演重点目标的材质组成;实验室光谱特性测量可在受控条件下模拟目标探测的物理过程,提供材质光谱特性数据库;目标特性建模仿真则对物理属性抽象特征化,研究目标光谱变化过程。通过分析国内外研究成果,总结当前研究的能力与不足,提出几点研究思路,为后续研究开展提供参考。     

光束指向稳定性高精度检测方法研究北大核心CSCD

光束指向稳定性是高能激光应用研究中的一项关键指标,光束指向稳定性的检测是高能激光系统性能实现的重要环节。以长焦距聚焦反射镜与高分辨率CCD(charge coupled device)为主要元件,构建高精度的光束指向检测装置。采用灰度重心法定位光斑中心,并以理想光斑与实测光斑为例进行验证,误差小于1个像元。利用CCD高频采样,统计单位时间内光斑中心位移,获得光束指向稳定性指标,检测实例精度可达1.25μrad。该方法简便易行,测量精度高,适用于各种波长的激光光束指向检测以及其他相关参数的测量。     

Reduction methods of the reconstruction error for large-scale implementation of near-field acoustical holography.

New extrapolation methods in real and wave number spaces are proposed to extend near-field acoustical holography (NAH) toward a more quantitative technique applicable to the vibration measurement of actual large-scale structures. The finiteness of the measurement aperture is a serious impediment to such large-scale implementation of NAH because the measurement aperture sufficiently larger than the vibrating structure of interest is usually needed. We should thus investigate how to reduce the reconstruction error when the measurement aperture is restricted to a fraction of the vibrating structure. The following practical suggestions are derived from simulations and underwater experiments: (1) A wave number-space extrapolation method can reduce the reconstruction error to about 25% for the measurement aperture corresponding to 1/16th of the vibrating structure when 10,000 iterations of the extrapolation process are applied. (2) A real-space extrapolation method can reduce the reconstruction error to negligible degree (10(-10)%) for the measurement aperture corresponding to four times as large as the vibration structure when ten iterations of the extrapolation process are applied. (3) The former method may be widely and safely applied, but many iterations are necessary; the latter method can reduce the reconstruction error very quickly, but a wider measurement aperture than that in the former is needed. Therefore, when the measurement aperture cannot be larger than the vibrating structure, the former method is recommended, while when the measurement aperture is larger than the structure, the latter method is recommended. Summing up, the accuracy of our proposed methods, which is attributed to the property of data extrapolation method that the data inside the measurement aperture is conserved after adequately extrapolating the data outside the aperture, will be relevant to a more quantitative measurement and analysis of real large-scale structures.     

Stable isotopic analysis of pyrogenic organic matter in soils by liquid chromatography-isotope-ratio mass spectrometry of benzene polycarboxylic acids

Pyrogenic organic matter (PyOM), the incomplete combustion product of organic materials, is considered stable in soils and represents a potentially important terrestrial sink for atmospheric carbon dioxide. One well-established method of measuring PyOM in the environment is as benzene polycarboxylic acids (BPCAs), a compound-specific method, which allows both qualitative and quantitative estimation of PyOM. Until now, stable isotope measurement of PyOM carbon involved measurement of the trimethylsilyl (TMS) or methyl (Me) polycarboxylic acid derivatives by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). However, BPCA derivatives can contain as much as 150% derivative carbon, necessitating post-analysis correction for the accurate measurement of δ13C values, leading to increased measurement error. Here, we describe a method for δ13C isotope ratio measurement and quantification of BPCAs from soil-derived PyOM, based on ion-exchange chromatography (IEC-IRMS). The reproducibility of the δ13C measurement of individual BPCAs by IEC-IRMS was better than 0.35‰ (1σ). The δ13C-BPCA analysis of PyOM in soils, including at natural and artificially enriched 13C-abundance, produced accurate and precise δ13C measurements. Analysis of samples that differed in δ13C by as much as 900‰ revealed carryover of <1‰ between samples. The weighted sum of individual δ13C-BPCA measurements was correlated with previous isotopic measurements of whole PyOM, providing complementary information for bulk isotopic measurements. We discuss potential applications of δ13C-BPCA measurements, including the study of turnover rates of PyOM in soils and the partitioning of PyOM sources based on photosynthetic pathways.     

双参量偏振调制光纤传感器输出信号的分离与线性化

分析了用一个传感头实现双参量测量的偏振调制光纤传感器的工作原理，表明该传感器能同时输出两路信号，其中一路利用泡克耳斯效应测电压或利用光弹效应测压力，另一种利用旋光效应测温度。但其输出的两个测量参量之间存在交叉敏感现象，并且其输出呈明显的非线性。因此提出一种基于人工神经网络的双参量偏振调制光纤传感器输出信号分离与线性化方法。以传感器输出作为输入样本，测量参量的实际值作为输出样本，通过训练使神经网络建立传感器输出与其实际感受的测量值之间的复杂非线性关系。计算机仿真与实验结果表明，该方法不仅能在较宽的测量范围内有效地分离两个测量参量，而且能在神经网络的输出端得到理想的线性输出。