圆度误差检测方法现状与展望

介绍了目前的圆度误差检测方法的原理和特点,着重讨论了近年来出现的新型圆度误差检测手段,最后展望了圆度误差检测方法的发展趋势。     

复杂曲面测量模式与关键技术

首次提出将复杂曲面测量划分为三种模式 ,论述了各测量模式的演变及其主要测量方法 ,综合评述了复杂曲面测量涉及的数据获取、曲面重构、测头半径补偿以及误差评定等关键技术的研究现状     

多目标轨迹分离方法研究

为了实现多目标落点测量,建立了多目标测量方案,并且对大视场光电测量设备在像面坐标系下进行多目标分离的方法进行研究。该方法按目标运动方向、运动速度、运动加速度的变化,建立了相关性评价函数,根据评价函数判断像点与目标轨迹的关联程度,从而现实多目标轨迹分离工作;而且在分离过程中,考虑了同一目标像点在不同幅图像上的丢失情况,根据已有目标轨迹数据,使用卡尔曼滤波器补充丢失的像点,保证同一目标轨迹的连续性。仿真数据与实际数据结果表明,该方法有效地分离了多目标轨迹。满足多目标落点测量的设计要求。     

微机电系统（MEMS）促进测量学发展

本文从纳米、超微角位移测量、及力学、声学、医学测量诸方面说明MEMS促进测量学的发展。通过所举范例,可以看出MEMS在各方面促进测量学发展及其深远的科学意义。其中超微角位移测量的构想以往资料未见,是创新。     

Problems in the measurement of Vickers and Brinell indentations

Hardness measurements by Vickers and Brinell indentations are liable to error, even when performed by experienced operators. The authors examine the problems involved in such measurements and the standards and specifications under which they are made. They conclude that some causes of error not yet fully understood and the effects of differences in optical microscopes are not taken into account. Greater standardisation of measurement systems has become necessary.     

An optical non-contact probe

An optical non-contact probe to detect displacement, position and inclination of a work surface is presented. It uses two light beams which intersect near the surface and form spots of light on it. Images of the spots are formed on a photo-detector by a lens. Positions of the images and distance between them, which depend on the distance from the intersection to the surface, are sensed by the detector. Its output is electrically converted into a signal which represents displacement, position or inclination of the surface. An experimental probe is set up, in which laser diodes and a position-sensitive detector are used. The probe is tested on sandy, milled, lathe-turned, ground and specular surfaces and the measurements agree with predicted values.     

A fast calibration-independent method for complex permittivity determination at microwave frequencies

A transmission/reflection microwave method based on uncalibrated S-parameter measurements for complex permittivity determination of dielectric materials is presented. There are three main advantages of the proposed method. First, the measurements are performed without the need of any calibration standards. Second, it does not require any additional dielectric sample with different thickness; two uncalibrated measurements are required: (i) with a sample filled waveguide and (ii) with an empty waveguide. Third, it does not need a precise location or precise shifting distance of the sample inside the waveguide. The method is iterative needing an initial guess to start the mathematical calculations, and high measurement accuracy can be expected. The method is validated by complex uncalibrated S-parameter measurements at X-band frequencies of low-loss samples (Teflon, Celotex and Duroplex) fitted into a waveguide section.     

A VXI instrument for real-time tracking of impedances

A VXI instrument for impedance measurements, equipped with a TMS320C30 Digital Signal Processor, is presented. It implements two measurement techniques: the first, based on an image model approach, allows accurate impedance measurements, while the second, based on an amplitude-phase approach, is mainly oriented in increasing the instrument throughput. The hardware architecture and the software strategies adopted in the VXI instrument implementation are then described in detail. Experimental tests for a wide range of impedance values are then carried out for the instrument metrological characterization and throughput evaluation. Concluding remarks are finally reported.     

Novel non-contact torque measurement using the magnetomechanical effect

With the recent developments in science and technology, torque measurements have been widely used in many fields. However, present torque measurement methods have limitations for long-term applications. Therefore, a new method of non-contact torque measurement based on the magnetomachanical effect is reported that may be used in reducing fatigue for long-term measurements. The theory of the changes in magnetization with torque are analyzed to construct a model. Hence, an experiment platform was constructed that includes an excitation coils, shaft, and Gauss meter. The relationship between the magnetic induction and the torque was measured using this apparatus. The results show that the experimental measurements are in agreement with mathematical models obtained using magnetomechanical concepts. The results also show that the maximum nonlinearity error of the system is 0.6% and the maximum repetitive error is 3.125%. Additionally, this proposed method meets the requirements for long-term torque measurements and may also be used for the non-contact characterization of the torque of watercraft and airplanes.     

Non-contact measurement technique for dimensional metrology using optical comb

This paper proposes a non-contact pulsed interferometer for dimensional metrology using the repetition frequency of an optical frequency comb. A compact absolute-length measuring system is established for practical non-contact measurement based on a single-mode fiber interferometer. The stability and accuracy of the measurements are compared with those from a commercial incremental laser interferometer. The drifts of both systems have the same tendency and a maximum difference is approximately 0.1 μm. Subsequently, preliminary absolute-length measurements up to 1.5 m were measured. The signal-to-noise ratios of the small signals are improved by a frequency-selective amplifier. It is apparent that the noise is rejected, and the intensity of the interference fringes is amplified, achieving a maximum standard deviation of measurement approximately 1 μm. The proposed technique can provide sufficient accuracy for non-contact measurement in applications such as a simple laser-pulse tracking system.     

Three different attitude measurements of spinning projectile based on magnetic sensors

Micro-inertial sensors currently could not provide long-time stability attitude information for the high spinning projectile because of drift errors. Meanwhile, the method of the navigation and attitude measurement with respect to the earth’s magnetic field is still auxiliary, and the attitude angle information cannot be got only by measuring the three-axis components of the geomagnetic field. In view of the flying characteristics of high spinning projectile, three different attitude measurements only using magnetic sensors are researched. Through comparative analyses, the calculating principle, system composition, applicable condition and error range of these methods are explained. Meanwhile, the semi-physical experiments are made to prove the effectiveness of the three attitude measurements. The experiment results indicate that only scalar arithmetic operations are required for these angular measurements and they have the day/night and all weather capability. The three different measurements have same angle error range within ±1° but different attitude updating rate.     

Application of cat's-eye retroreflector in micro-displacement measurement

The performance of a cat's-eye retroreflector in interferometric micro-displacement measurements is discussed. Based on paraxial calculations, approximate equations of the wavefront distortion and the measurement error caused by the displacement itself are derived. The capability for nanometer scale error compensation is suggested.     

Reducing the uncertainty in real-time impedance measurements

This paper arises from the exigency of enhancing the performance of a VXI-based digital meter designed for real-time tracking of impedance. Specifically, the metrological characterization of the meter has put into evidence that the experienced measurement uncertainty is mostly due to wide-band noise corrupting the acquired signals. With the aim of reducing its noise susceptibility without compromising the measurement rate, two digital signal-processing solutions are proposed. The first one pre-processes the acquired signals by means of predictive digital filtering for improving zero-crossing detection and, consequently, granting more reliable phase displacement measurements. The second solution evaluates the inner product of the signals of interest in order to average noise during the course of measurement, thus limiting its effect on the overall uncertainty. Many impedance measurements are carried out to draw a proper comparison between the proposed solutions.     

Image-based measurement of the dimensions and of the axis straightness of hot forgings

Non-contact measurement of shapes and dimensions is currently quite a common issue. A lot of systems with different speeds and accuracies are in the market. Measurement of high temperature objects is, however, a very special task which ensures a specific solution. This paper presents a measurement system composed of two high resolution single-lens reflex cameras and a software application, which is designed for the fast measurement of shapes and dimensions of rotationally symmetric forgings. The software computes the length, diameter, and straightness of the axis, based on a 3D model constructed from four boundary curves of the forging captured in two images. Experimental measurements have shown an error of up to 2% for the length measurement and 1% for the diameter measurement. Results are available in a few seconds. The proposed measurement approach based on boundary curves shows a great potential for practical use in forging plants.     

Measurement optimum condition of speckle interferometry based on dual-camera technique

The speckle interferometer based on multi-camera technology using two cameras is applied to a dynamic deformation measurement of the package of an electronic device. To perform high precise measurement by this method, the optimum conditions for measurements are discussed concerning the size of speckle and the frequency of carrier signals. Under the optimum conditions, the deformation process of the package during the operation of an operational amplifier is measured. Then, the local maximum deformation can be estimated as 150 nm from experimental results. From the results, it can be also confirmed that electronic devices are deformed by the stress of a heat by an operation every second during the operating time.     

Thin thickness measurements by means of a wavelet transform-based method

A non-invasive method for thin thickness measurements of multilayer structures is presented herein. This measurement method uses the wavelet transform for the analysis and processing of the ultrasonic signal received from the structure under test. The wavelet transform also shows itself to be a powerful tool for the detection of partially overlapping echoes in a noisy environment. This paper first describes the basic idea underlying the measurement method and then a procedure, set up by the authors, and suitable for the validation of the method when a standard multilayer structure to be used as a reference is not available, is presented and discussed. Finally, measurements of the thicknesses of actual multilayer structures and, in particular, of structures in the ophthalmic and microelectronic technology field, are carried out.     

Roughness measurement by electronic speckle correlation and mechanical profilometry

A practical optical sensor for rough surface diagnostics has been developed for applications in mechanical engineering. The principle of the sensor is based on digital speckle correlation. First, the measuring principle and the optical system arrangement are described, then optical measurements on different rough surfaces are compared with mechanical stylus measurements and the results are discussed with consideration of the advantages and differences of the two methods.     

Phase-statistical method and device for high precise and high-efficiency angular measurements

A method and device for precise large-scale angular measurements in precision manufacturing is described. High accuracy of the method results from phase measurements by permanent integration over the total circle of the grating scales. According to this method, dividing errors of two of three scales are summed up to zero and the dividing error of the third scale is significantly reduced. An optoelectronic device based on this method has been developed, produced, and tested, and its design and operation are described. The device consists of optical grating scales of regular accuracy. This results in simplification of the structure of the measuring device and increases its reliability. Testing of the experimental batch shows that the accuracy of the device is ± 0.2 arcsec. Different setups of the measured equipment and examples of the real-life application are shown.     

Structural view independence: A criterion for judging the objectivity of economic parameters measured by opinion survey

Economic measurements have a great influence over all our lives, but as with other soft measurements, significant effort is needed to ensure their objectivity. This is particularly true of the process of consolidating into a single representative figure different people’s valuations of a non-market good (“views”), as measured by opinion survey. Sometimes the views are transformed and averaged before being returned to the original domain as the back-transformed mean. Examples are the geometric mean resulting from a logarithmic transformation and the root-mean-squared (r.m.s.) value from a square transformation. Such transformations are tested for objectivity using the new criterion of structural view independence. It is shown that an analyst using any general, nonlinear, increasing and differentiable transformation other than the linear transformation can know at the outset that he is giving greater weight to views of his choosing, meaning that he has no claim to objectivity. Of all such transformations, only the linear transformation possesses the desirable property of structural view independence. The resultant sample mean is objective and the only consolidated figure recommended for human views.