共查询到20条相似文献,搜索用时 31 毫秒
1.
A one-shot method for measuring birefringence dispersion has been proposed that utilizes two retarders having different high-order birefringences. The intensity distribution of a channeled spectrum changes with different frequencies as a function of wavenumber. An intensity distribution is sufficient to determine the birefringence dispersion using the amplitude and phase components obtained by applying the fast Fourier transform. Experimental results demonstrate that this technique can measure the wavelength dependences of both the azimuthal angle and the retardation. 相似文献
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On the basis of a general Rapini and Papoular equation and the unified surface-anchoring energy, surface-anchoring strength is newly defined theoretically as a function of the azimuthal deviation angle of the surface liquid-crystal directors and the statistical distribution of polyimide chains in a typical twisted nematic liquid-crystal cell. Then these are determined experimentally by the surface second-harmonic generation method, which is nonlinear optics, and the optical phase retardation method. We assume that the anisotropy distribution of polyimide chains induced by the rubbing strength is dominated by a Gaussian distribution around the rubbing direction. 相似文献
4.
A spiral wave front source produces an acoustic field that has a phase that is proportional to the azimuthal angle about the source. The concept of a spiral wave front beacon is developed by combining this source with a reference source that has a phase that is constant with the angle. The phase difference between these sources contains information about the receiver's azimuthal angle relative to the beacon and can be used for underwater navigation. To produce the spiral wave front, two sources are considered: a "physical-spiral" source, which produces the appropriate phase by physically deforming the active element of the source into a spiral, and a "phased-spiral" source, which uses an array of active elements, each driven with the appropriate phase, to produce the spiral wave front. Using finite element techniques, the fields produced by these sources are examined in the context of the spiral wave front beacon, and the advantages of each source are discussed. 相似文献
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Dong Yan Xiaoguang Wang Lijun Song Zhanguo Zong 《Central European Journal of Physics》2007,5(3):367-376
We consider the mean spin direction (MSD) of superpositions of two spin coherent states (SCS) | ± μ〉, and superpositions of | μ〉 and | μ*〉 with a relative phase. We find that the azimuthal angle exhibits a π transition for both states when we vary the relative phase. The spin squeezing of the states, and the bosonic counterpart
of the mean spin direction are also discussed.
相似文献
6.
The passage of a linearly polarized beam through a chiral material and a phase retarder will induce a phase difference between the s and p polarizations of the beam. In this study, a phase quadrature interferometer is designed to measure the phase difference variation proportional to the optical rotation. The proportionality constant (or measurement sensitivity) can be greatly enhanced by setting the retardation of the phase retarder close to 0° or 180°. The experimental results demonstrate that with our system we can obtain a measurement resolution for the rotational angle of better than 3.5° × 10−4. This method has several advantages such as a simple optical setup, easier operation in real time, and low cost. In addition, due to the common-path arrangement, surrounding noise can be eliminated. 相似文献
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This paper presents an electro-optic modulated circular heterodyne modified Mach–Zehnder interferometer and a convenient two-phase signal-processing algorithm for the measurement of variations in the magnitude of phase retardation and the angle of principal axis in optical materials. The developed method solves the problems of normalized intensity jump and limited phase retardation measurement range associated with the circular heterodyne interferometer proposed previously. The present method uses a saw-tooth wave signal to drive an electro-optic (EO) modulator, and employs a lock-in amplifier to demodulate the principal axis angle and the phase retardation. Specifically, this paper considers two main sources of measurement errors, namely the misorientation of the EO modulator and the reflection phase retardation of the beam splitter. Furthermore, the study develops calibration procedures and identifies a means to minimize measurement errors induced by the reflection phase retardation of the beam splitter. 相似文献
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蒙特卡罗模拟是放射性测井一种重要的数值模拟方法,利用通用程序MCNP可方便地建立各种地层模型,为放射性测井研究提供了简便有效的方法。借助于蒙特卡罗方法建立随钻条件下地层模型,正演模拟随钻方位伽马成像特征。结果表明,随钻方位伽马成像图呈现正弦线特征,利用成像图可准确反演井眼相对倾角和放射性地层厚度;井眼相对倾角越大,放射性地层厚度越厚,成像图的正弦线高度值及在井轴方向上的展布高度值越大;井眼尺寸对利用成像图求取井眼相对倾角没有影响,但对计算放射性地层厚度有影响,仪器偏心对利用成像图求取井眼相对倾角和放射性地层厚度都有较大影响,若伽马计数满足测井计数统计性,可忽略井眼流体对成像图的影响。 相似文献
9.
Some years ago we developed an automatized reflectometric method to measure the surface azimuthal anchoring energy of nematic
liquid crystals on an optically isotropic substrate. This method provides a high accuracy and sensitivity but requires the
use of wedge glass plates and a sufficiently high anisotropy of the intensity reflectivity coefficients. This latter condition
restricts greatly the number of possible substrates that can be investigated with this technique. Here we develop a new reflectometric
method which offers comparable or better accuracy and sensitivity but does not require wedge plates and high anisotropy of
the reflectivity coefficients. The method is fully automated and provides a direct measurement of the azimuthal director angle.
The experimental procedure exploits the dependence of the reflectivity tensor on the surface director orientation. The measurement
of the azimuthal angle does not require any knowledge of the optical parameters of the nematic material and of the optically
isotropic substrate, and provides an absolute accuracy better than 0.2° in the whole range 0-360° and a sensitivity better than 0.1°. This reflectometric method can be also used with weakly anisotropic substrates as well as thin rubbed polymeric layers.
In this latter case, the effective uncertainty in the measurement of the director azimuthal angle depends on the substrate
anisotropy. A simple and direct experimental procedure to estimate this uncertainty is proposed.
Received 8 January 2002 and Received in final form 27 February 2003 / Published online: 15 April 2003
RID="a"
ID="a"e-mail: faetti@df.unipi.it 相似文献
10.
Accurate heterodyne interferometric ellipsometer 总被引:1,自引:0,他引:1
We describe a heterodyne interferometric ellipsometer which requires only a single reflection from the sample surface. A simple arrangement is described that enables a reference beam to be created in one arm of a modified Mach–Zehnder interferometer such that the p- and s-polarisations in this arm have a common phase and fixed relative amplitude, irrespective of the sample. When this beam is recombined interferometrically with the measurement beam, the spatially separated p and s fringes have an amplitude ratio and relative phase that are directly proportional to tanψ and Δ, respectively. Adjusting the azimuthal angle of the input linear polarisation allows both ψ-tracking to be implemented and error reduction through averaging. Measurements made with this instrument of a native oxide layer on a silicon substrate are in excellent agreement with those obtained using a commercial ellipsometer. 相似文献
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We present a new circular heterodyne interferometer with electro-optic modulation for measurement of the optical linear birefringence. It enables the measurement of not only the phase retardation but also the principal angle. The measurement procedure is carried out in two steps. In the first step of measurements, we use the electro-optic modulated circular heterodyne interferometer and the phase-lock technique to precisely measure the principal axis angle. After rotating the analyzer in the setup, the phase retardation is determined also by the phase-lock technique. The compact configuration requires only a photodetector and two simple phase-lock extractions to determine the principal axis angle and the phase retardation. The validity of the proposed design is demonstrated by measurement of the principal axis angle and phase retardation of a quarter-wave plate sample. The root-mean-square resolutions for the principal axis angle and phase retardation are found to be 0.0396° and 0.0796°, respectively, with corresponding dynamic ranges of 0–180° and 0–180°. 相似文献
14.
《The European Physical Journal C - Particles and Fields》2007,51(2):289-299
The distribution of the azimuthal angle of charged and neutral hadrons relative to the lepton plane has been studied for neutral
current deep inelastic ep scattering using an integrated luminosity of 45 pb-1 taken with the ZEUS detector. The kinematic range is 100<Q2<8000 GeV2, 0.2<y<0.8 and 0.01<x<0.1 where Q2 is the virtuality of the exchanged boson, y is the inelasticity and x is the Bjorken variable. The measurements were made
in the hadronic centre-of-mass system. The analysis exploits the energy-flow method, which allows the measurement to be made
over a larger range of pseudorapidity compared to previous results. The dependence of the moments of the azimuthal distributions
on the pseudorapidity and minimum transverse energy of the final-state hadrons are presented. Although the predictions from
next-to-leading-order QCD describe the data better than do the Monte Carlo models incorporating leading-logarithm parton showers,
they still fail to describe the magnitude of the asymmetries. This suggests that higher-order calculations may be necessary
to describe these data. 相似文献
15.
It is shown that electromagnetic surface waves propagating along the azimuthal angle can be excited efficiently by an annular
electron beam in a cylindrical metal waveguide partially filled with a magnetoactive plasma. A self-consistent system of differential
equations is obtained to describe the nonlinear interaction between the beam particles and an azimuthal surface wave in the
single-mode regime. This system of equations is analyzed numerically and the influence of the parameters of this waveguide
structure on the development of the resonant beam instability is determined.
Zh. Tekh. Fiz. 69, 84–88 (July 1999) 相似文献
16.
菱体型相位延迟器是高度消色差的λ/4相位延迟器.由于材料折射率色散的影响,在可见光范围内,仍存在2°的延迟偏差.为满足精确应用和测量的需求,从相位延迟的全反射相变理论出发,阐述了斜入射相位延迟原理,以菲涅耳菱体为例,分析了菱体型相位延迟器相位延迟随其入射角变化的规律性,结果表明:当光线非严格准直时,光的入射角对相位延迟量有明显的影响,延迟量不但对入射角变化敏感,而且还与入射光线的入射方位密切相关,呈不对称形式.当入射光的波长改变时,只需改变菱体延迟器的方位,让光线在菱体的前端面上斜入射,适当选取入射角,就可以补偿相位延迟的色散偏差,使同一菱体达到对不同波长都满足λ/4相位延迟.当角度调整精度Δi=±0.01°时,引入的延迟偏差不超过±0.009°,这一精度是其它石英波片或云母波片所不能比的. 相似文献
17.
Arthur Jabs 《Foundations of Physics》2010,40(7):776-792
The spin-statistics connection is derived in a simple manner under the postulates that the original and the exchange wave functions are simply added, and that the azimuthal phase angle, which defines the orientation of the spin part of each single-particle spin-component eigenfunction in the plane normal to the spin-quantization axis, is exchanged along with the other parameters. The spin factor (?1)2s belongs to the exchange wave function when this function is constructed so as to get the spinor ambiguity under control. This is achieved by effecting the exchange of the azimuthal angle by means of rotations and admitting only rotations in one sense. The procedure works in Galilean as well as in Lorentz-invariant quantum mechanics. Relativistic quantum field theory is not required. 相似文献
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We present a polarization-controlled terahertz (THz) wave spectroscopic imaging modality to investigate the anisotropy of the detected materials. The polarization of the emitted THz wave is controlled by changing the relative phase between the fundamental and second-harmonic waves in the two-color laser-induced air plasma THz generation configuration. The THz wave polarization direction is extracted by measuring the two electric field amplitudes when the polarization of the incident wave is controlled to be horizontal and vertical. The anisotropy of the industrial Sprayed-On-Foam-Insulation (SOFI) is characterized by measuring its azimuthal angle dependent THz polarization response. This work demonstrates that THz wave polarization-controlled imaging technique can be used for highly sensitive industrial nondestructive inspection and biological related characterization. 相似文献
19.
The azimuthal angle dependence and the temperature dependence of terahertz (THz) radiation generated from n-type (111) InSb and n-type (111) InAs surfaces irradiated with ∼80 fs near-infrared laser pulses are investigated. The azimuthal angle dependence
shows that the contribution of the difference-frequency mixing (DFM) is not dominant for both materials at the excitation
density of ∼1 GW/cm2. At an appropriate azimuthal angle, the radiation due to DFM is excluded from the total THz radiation and the temperature
dependence of THz radiation due to the surge current is observed. The increase of THz radiation with decrease of the temperature
is found to be much more pronounced for InSb than for InAs. The different temperature dependence can be attributed to the
different radiation mechanisms dominant for both materials. Especially, the temperature dependence of the THz radiation from
InSb is well explained by the photo-Dember effect.
Received: 9 May 2000 / Revised version: 17 August 2000 / Published online: 5 October 2000 相似文献