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981.
982.
In this paper we use a superluminescent diode (SLD) as the light source of an interferometer and extract a narrow spectrum from a wide spectrum of the SLD with a Fabry-Perot Etalone (FPE). By varying sinusoidally the distance between the two mirrors of FPE, the central wavelength of the narrow spectrum is scanned sinusoidally. The distance between the mirrors is exactly set by a feedback control system, and sinusoidal phase-modulated SLD light that has a large scanning width of about 10 nm can be obtained with high stability and spatial uniformity. The phase of the interference signal has two different components. One is amplitude Zb of sinusoidal phase modulation, which is proportional to the optical path difference (OPD) and the scanning width. The other is conventional phase α, which provides a fractional value of the OPD in the range of the wavelength. By combining the two values of the OPD obtained from Zb and α, an exact OPD larger than the wavelength can be measure with ment accuracy in α. Characteristics of the interferometer are made clearly through step-profile measurements. 相似文献
983.
Kenichi Hibino 《Optical Review》1999,6(6):529-538
In phase-shifting Fizeau interferometers, nonlinear motion of the phase shifter and multiple-beam interference are the most common sources of systematic errors affecting high-precision phase measurement. A new class of algorithms with extended compensating capability for these errors is proposed. Measurement errors for the new algorithms and two groups of conventional algorithms: discrete Fourier algorithms and the Schwider-Larkin-Hibino algorithms are estimated as a function of the number of sampled images when these systematic error sources are equally dominant. It is shown that the conventional phase-measuring algorithms produce significant errors when the reflectivity of the testing surface exceeds ten percent. Also, these algorithms have an optimum number of samples at around seven with which the residual errors become minimum. The new class of algorithms shows a substantial reduction of the residual errors when the number of samples exceeds ten. There is no optimum number of samples for the new algorithms. For fewer than six samples, discrete Fourier algorithms which have no error-compensating capability for the nonlinearity of phase modulation give a minimum error. 相似文献
984.
O. A. Bondarenko A. A. Korneev Yu. N. Onishchuk A. V. Berezhnoy P. B. Aryasov D. Antonyuk A. V. Dmitrienko 《Radiation measurements》1999,30(6):709-714
Object “Shelter” (known world-wide as the Sarcophagus) is a source of very high radiological and nuclear hazard. Transfer of the Sarcophagus into an ecologically safe site is a task not only for Ukraine but also for the world community. A composite approach to maintenance of radiation and nuclear safety of the Sarcophagus applying spectrometric methods using solid state nuclear track detectors (SSNTD) is suggested in this paper. The aspects are: (1) monitoring of transuranium element inhalation intake to a human body of nuclear workers; (2) neutron flux evaluation in some premises of the Sarcophagus; (3) fuel hot particle detection in air of working zones; (4) radon and thoron simultaneous measurements. 相似文献
985.
J. des Cloizeaux 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,8(3):439-443
Dirac equation is reformulated in terms of real local observables, which are mean values of the wave function . The quadrivector current is shown to be a function of the potential vector and of other local observables. The equations
describe the evolution of a four dimensional system T, X, Y, Z, and of two scalars, in the coordinate system ct, x, y, z. The current is proportional to the T vector. The Z vector is associated with the spin of the electron. Energy and gauge transformations correspond to rotations in the plane
(X, Y). In the presence of a static field, the (real) solutions of the equations appear as eigenfunctions associated with energy
eigenvalues.
Received 7 September 1998 相似文献
986.
Song Wang Xiao-hu Yan Rong-shi Cheng Department of Polymer Science Engineering Nanjing University Nanjing China 《高分子科学》1999,(2):135-140
~(13)C-NMR ~1H-decoupled spectra of styrene polymers were assigned by comparison with modelcompounds, then used in measurements of number average molecular weights. The higher limit of an exactdetermination of the end group signal is less than a molecular weight of 10~4. For polymer samples withM_n<10~3, the results obtained from ~(13)C-NMR spectra of saturated carbon region are in excellent agreementwith the values determined by ~1H-NMR, SEC, and VPO methods, while the results from ~(13)C-NMR spectra ofphenyl C-1 carbon region are somewhat higher than the values determined by other methods. 相似文献
987.
湍流运动本身的不规则性使得湍流测量中得到信号的可靠性成为一个较难检查的问题,使用天津大学流体力学实验室编的湍流测量软件对一些标准信号进行分析,由所得结果可以检查出软件的可靠性. 相似文献
988.
989.
The steady state of temperature modulated power compensation DSC has been theoretically investigated for measurements of complex
heat capacity, taking accounts of heat capacities of heat paths, heat loss to the environment, and mutual heat exchange between
the sample and the reference material. Thermal contact between the sample cell and the cell holder is also taken into accounts.
Rigorous and general solutions are obtained. From these solutions application of the technique to heat capacity measurements
is discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
990.
An experimental technique based on image analysis is proposed for the measurement of the strain field in tubes subjected to lateral collapse. Data are numerically treated to reduce the experimental error, and a correction to account for the curvature of the profile is introduced. The results, also compared with others obtained with electrical strain gages, confirm the validity of an existing model for strain and crushing force prediction. 相似文献