共查询到20条相似文献,搜索用时 0 毫秒
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L. S. Babadzhanov 《Measurement Techniques》1994,37(8):887-889
A study is presented on the existing test scheme for means of measuring coating thickness in the range 1–20,000 gmm, from which it is shown that it does not meet contemporary requirements, and improvement suggestions are made. A special standard is needed for the unit of length in measuring coating thicknesses, together with a reference standard and natural tubular measures for copper coating thickness of insulators, as well as methods and means of comparing and checking the tubular measures.Translated from Izmeritel'naya Tekhnika, No. 8, pp. 22–23, August, 1994. 相似文献
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Servagent N. Bosch T. Lescure M. 《IEEE transactions on instrumentation and measurement》1997,46(4):847-850
A low-cost, simple, noncontact displacement sensor using the self-mixing effect inside a cw single-mode laser diode has been developed for modal analysis and defect detection. The resonance frequencies of thin clamped metallic plates have been determined with a resolution of 0.2 Hz. With such targets, classic spectrum analyzers generate a measurement error up to 10% because of the weight of the accelerometer. The frequency-shift of the fundamental resonance frequency between a standard plate and the same one with a known defect can also be measured, the modal vector associated to this frequency being distorted at the place of the defect 相似文献
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The current delivered by the photodiode in a self-mixing frequency modulated continuous wave or optical frequency domain reflectometry system consists of a dc-current resulting from the local oscillator, the reflected signal, dark current in the photodiode, and current generated from background light. The current also contains the useful harmonic signal with a beat frequency corresponding to the range and radial velocity of a target. To avoid saturation and clipping due to the dc current generated in the photodiode, it is desirable to minimize the gain at dc while maintaining a high gain in the beat frequency region. We have investigated some different solutions and present a modified current-to-voltage converter using bootstrapping and added voltage gain, which addresses this problem using only one OP-amp and no dc shorting inductors. 相似文献
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Calibration of an adaptive data-acquisition system by the use of standard measures is considered when there are destabilizing
factors. Methods are considered for reducing the errors and lessening the computational costs in the measurements.
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Translated from Izmeritel'naya Tekhnika, No. 1, pp. 7–11, January, 2006. 相似文献
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高精度光栅位移测量系统具有纳米级重复精度、环境适应性强、维度易于扩展等优点,可以满足精密制造行业对米级测量量程、亚微米级精度与多维测量能力融合的测量技术要求,在高端制造、精密仪器等领域有重要应用。通过对测量光栅的各项参数进行研究,提升了测量光栅的尺寸与制作精度;提出高精度锥面衍射光栅位移测量、高倍细分转向干涉光栅位移测量、“品”字形拼接大量程光栅位移测量等技术,实现了数百毫米测量量程亚微米级测量精度。从光栅制作到测量系统研制对提升精度、分辨力及量程提供了理论分析与技术验证。 相似文献
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An integrated optic sensor head was proposed for sensing a two-dimensional displacement of a scale consisting of crossed gratings. Two interferometers, crossing each other, are constructed by the integration of two pairs of linearly focusing grating couplers (LFGC's) and two pairs of photodiodes (PD's) on a Si substrate. Four beams radiated by the LFGC's from the sensor head overlap on the grating scale, and the beams are diffracted by the grating scale and interfere on the PD's. The period of the interference signal variation is just half of the scale grating period. The device was designed and fabricated with a grating scale of 3.2-μm period, and the sensing principle was experimentally confirmed. 相似文献
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The effects of periodic nonlinearity, intermodulation distortion, phase detection uncertainty and electrical cross-talk in a three-longitudinal-mode laser heterodyne Doppler interferometer (TLMI) displacement measurement system are presented. A frequency-path model consisting of three frequency components and two paths is also designed. As a result, there will be six frequency-path elements and 21 distinct interference terms. The periodic nonlinearity in the TLMI is mathematically modelled and simulated. Simulation results are compared with the typical two-mode heterodyne interferometer to confirm the designed model performance. The authors demonstrate that the nonlinearity of TLMI can be greatly reduced using the same compensation method as used in a two-frequency interferometer proposed by Hou et al. 相似文献
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Very lightweight, thin liquid hydrogen/deuterium heat pipe-target systems are used in the Time Of Flight (TOF) spectrometer at the COSY accelerator facility. The proton beam impinges upon LH2/LD2 targets thereby heating the target. The stability of the liquid targets depends on the thermal capacity of the whole system, the energy losses from the proton beam and heat losses from the surrounding of the heat pipe-target system. The radiation heat load has been reduced by a factor of 4.5 by reducing the length of the gas tube from 180 cm (long tube) to 40 cm (short tube). Furthermore, the 40 cm long gas tube was coated with a thin polished gold layer, thereby reducing the heat load by an additional factor 22. The thermal capacity is improved by reducing the mass of the gas tube from 23 g to 5 g. The cool down time of the 7 mm diameter gold coated heat pipe with the gold coated 40 cm gas tube is reduced by 12 min. 相似文献
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Krężel J Kujawińska M Mohr J Guttmann M Wissmann M Tonchev S Parriaux O 《Applied optics》2010,49(32):6243-6252
We present an integrated sensor based on a grating interferometer (GI) for in-plane displacement measurement in microregions of large engineering structures. The system concept and design, based on a monolithic version of Czarnek's GI, is discussed in detail. The technology chain of the GI measurement head (MH), including the master fabrication and further replication by means of hot embossing, is described. The numerical analyses of the MH by means of geometric ray tracing and scalar wave propagation are provided. They allow us to determine geometrical tolerance values as well as refractive index homogeneity and nonflatness of MH working surfaces, which provide proper beam guiding. Finally the demonstrative measurement performed with a model of the sensor is presented. 相似文献
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N. V. Myasishchev 《Measurement Techniques》2011,54(3):265-268
A quantitative measure of the performance of a technical system is proposed. Mathematical models that establish the dependence
of system performance on the probabilities of incorrect decisions in control of a technical system are obtained. 相似文献
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Measurement Techniques - 相似文献
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A. Asundi 《International Journal of Fracture》1989,40(3):R43-R48
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Surface point displacements can be measured by using standard phase-stepping speckle interferometry, but the measured data are vulnerable to disturbances during the interferogram recordings. To overcome this an interferometer with a computational system has been developed to record three phase-stepped interferograms simultaneously and to calculate displacements. This system is evaluated by measurements of the out-of-plane rotation of a flat surface. The surface displacement is calculated at a rate of 25 times/s. If one reduces noise by filtering, hardware limitations decrease the speed to 12.5 displacement calculations/s. With this system displacements can be measured with an accuracy exceeding λ/55 if filtering is applied. 相似文献
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Simultaneous measurement of out-of-plane displacement and slope using a multiaperture DSPI system and fast Fourier transform 总被引:1,自引:0,他引:1
The simultaneous quantitative measurement of out-of-plane displacement and slope using the fast Fourier transform method with a single three-aperture digital speckle pattern interferometry (DSPI) arrangement is demonstrated. The method coherently combines two sheared object waves with a smooth reference wave at the CCD placed at the image plane of an imaging lens with a three-aperture mask placed in front of it. The apertures also introduce multiple spatial carrier fringes within the speckle. A fast Fourier transform of the image generates seven distinct diffraction halos in the spectrum. By selecting the appropriate halos, one can directly obtain two independent out-of-plane displacement phase maps and a slope phase map from the two speckle images, one before and the second after loading the object. It is also demonstrated that by subtracting the out-of-plane displacement phase maps one can generate the same slope phase map. Experimental results are presented for a circular diaphragm clamped along the edges and loaded at the center. 相似文献