共查询到20条相似文献,搜索用时 187 毫秒
1.
Ping Yang Manfred Wendisch George Kattawar Yongxiang Hu 《Journal of Quantitative Spectroscopy & Radiative Transfer》2011,112(12):2035-2039
This note reports on the effects of the polarization state of an incident quasi-monochromatic parallel beam of radiation and the orientation of a hexagonal ice particle with respect to the incident direction on the extinction process. When the incident beam is aligned with the six-fold rotational symmetry axis, the extinction is independent of the polarization state of the incident light. For other orientations, the extinction cross-section for linearly polarized light can be either larger or smaller than its counterpart for an unpolarized incident beam. Therefore, the attenuation of a quasi-monochromatic radiation beam by an ice cloud depends on the polarization state of the beam if ice crystals within the cloud are not randomly oriented. Furthermore, a case study of the extinction of light by a quartz particle is also presented to illustrate the dependence of the extinction cross-section on the polarization state of the incident light. 相似文献
2.
A variable beam attenuator for 3.39 μm radiation consists of two yttrium orthovanadate crystal plane-parallel plates and one λ/2 MgF2 waveplate. The attenuated light beam can be kept at the same states of polarization and vacuity distribution as those of the incident light beam. The attenuation ratio is independent of the state of the incident light beam and can be changed continually. 相似文献
3.
A. P. Ivanov 《Optics and Spectroscopy》2009,107(2):171-183
As light passes through scattering media, certain specific features of the polarization of radiation manifest themselves.
The paper presents materials on this problem that were obtained at the Institute of Physics of the National Academy of Sciences
of Belarus over recent decades. Results of experimental investigations of media that model real objects are described for
the case where the dimensionless optical parameters of media and objects coincide. A method for determining the position of
a diffuse light source in the atmosphere via predominant oscillations of the light vector of scattered radiation for two directions
of observation is proposed. The structure of aerosol formations (smokes, dust and liquid-droplet and crystalline clouds) is
interpreted based on the character of depolarization of laser radiation sounding atmosphere. The polarization of laser radiation
passing through a turbid medium and reflected from it is studied. Practical applications are proposed. Fundamentals of an
applied vector theory of radiation transfer, which made it possible to considerably expand notions of light scattering in
strongly turbid media, are given. Studies of light propagation in encapsulated liquid crystals, which are used for solving
of a large number of problems, are described. In these objects, ordinary and extraordinary rays that arise in crystals under
electric voltage can give rise to a wave that is attenuated to a different degree and whose phase and polarization characteristics
are varying. 相似文献
4.
Takao Nanba Yasuhito Urashima Mikihiko Ikezawa Makoto Watanabe Eiken Nakamura Kazutoshi Fukui Hiroo Inokuchi 《International Journal of Infrared and Millimeter Waves》1986,7(11):1769-1776
At the UVSOR Facility, Institute for Molecular Science, the practical use of the synchrotron radiation as a far-infrared light source has started. A spectroscopic system has been constructed at the beam line BL6A1 of UVSOR storage ring, which covers the wavenumber region from 5 to 250 cm–1. The cross sectional diameter of the light beam at the sample position is as small as 3 mm with the angular divergence of about 100 mrad. The system has been made mainly for the transmission and reflection measurements of small samples with small angular divergence by the use of the high brightness of the synchrotron radiation. Examples of observed transmission and reflectivity spectra are shown. 相似文献
5.
A study is made of the electron kinetics in a discharge plasma produced by a high-power beam of electromagnetic radiation
in the centimeter-wave region under conditions approaching free space, when the dimensions of the chamber are much greater
than the wavelength of the microwave radiation. Two regimes of discharge production are investigated: the regime of short
microsecond pulses at a repetition rate of 200 Hz, and a single millisecond pulse regime. It is shown that at threshold values
of the microwave energy flux density the electron density in the initial stages of discharge formation reaches the critical
value, and that the average energy of the electrons is of the order of 1.5–3 eV.
Zh. Tekh. Fiz. 67, 10–14 (June 1997) 相似文献
6.
On the basis of the beam tensor formalism proposed by F. I. Fedorov, the theory of polarization selfaction of radiation in isotropic resonant media is extended to the case of partial elliptic polarization of an electromagnetic wave. The influence of the degree of radiation polarization on the known polarization self-action effects is demonstrated and the self-polarization (depolarization) of light is predicted. 相似文献
7.
Naumenko G. A. Aleinik A. F. Aryshev A. S. Kalinin B. N. Karataev P. V. Potylitsyn A. P. Saruev G. A. Chefonov O. V. Sharafutdinov A. N. 《Russian Physics Journal》2002,45(9):895-904
A theoretical model and results of experiments on optical polarization radiation of relativistic electrons from conducting targets performed on the synchrotron and microtron of Nuclear Physics Institute at Tomsk Polytechnic University are reported. The measurements of spectral characteristics of resonance polarization radiation in periodic targets over a wide range of electron energies (both in the Smyth–Purcell geometry and for different angles between the targets and the direction of the electron beam) show reasonable agreement with theoretical estimates. 相似文献
8.
G. Baum C. D. Caldwell W. Schröder 《Applied Physics A: Materials Science & Processing》1980,21(2):121-126
A lithium-6 atomic beam is spin-polarized by means of optical pumping with a single-mode dye laser operating on the resonance
transition. Simultaneous pumping of both hyperfine substates is achieved by frequency-splitting the laser light with an acousto-optic
modulator. A polarization dependent signal, obtained by probing the optical activity of the beam with linearly polarized light,
is utilized in a microprocessor-controlled laser stabilization scheme. The polarization is analyzed with a sextupole magnet
and its overall value is 0.70 for an intensity of 1×1014 atms s−1. By reversing the sense of circular polarization of the pumping light the atomic beam polarization is easily reversed in
direction. 相似文献
9.
The beam propagation factor, M2 of the master-oscillator power-amplifier (MOPA) CuBr laser emission compliant with ISO 11146 is studied methodically. Statistical
parameters of 2D intensity profile of the near and far fields of MOPA laser radiation are measured by a beam analyzing technique
as functions of timing delay between MO and PA. For first time the influence of the gas buffer (causing the radiation profile
to change from annular to top-hat and Gaussian-like) and light polarization on CuBr laser beam focusability (M2) was under investigation. The MOPA gain curve is found and the influence of gain on the input signal (from MO into PA) due
to the absorption/amplification in PA on the field profiles is shown. For annular radiation M2 range is from 13–14 (small delays) to 5–6 (large delays) and for filled-center radiation M2 is 6–7 (small delays) and at the end of gain curve is as much as 4. With polarized light, M2 drops to 3 at the end of gain curve. The brightness of laser emission with hydrogen goes up 3–5 times and the linearly-polarized
beam is at least 40% brighter than that of partial or non-polarized beams. 相似文献
10.
本文从偶极子辐射场的Heaviside-Feynman表达式出发, 用经典的电动力学方法推导了考虑内禀磁矩影响后的相对论电子辐射频谱分布的表达式, 并对做匀速圆周运动的极端相对论性电子的同步辐射, 计算了两个偏振方向上的考虑磁矩修正后的辐射谱. 计算结果表明对于特征频率为ωc的同步辐射, 如果ħωc≥10 keV, 内禀磁矩对辐射的修正是可观的. 通过同步辐射的内禀磁矩修正, 本文讨论了电子束极化度与辐射场偏振度的依赖关系, 并基于此关系提出一种测量电子束极化度的新方法.
关键词:
同步辐射
电子内禀磁矩
同步辐射偏振度
束流极化度 相似文献
11.
12.
A. F. Glova A. Yu. Lysikov D. D. Malyuta S. S. Nelyubin P. I. Peretyatko Yu. F. Ryzhkov 《Physics of Atomic Nuclei》2016,79(14):1663-1670
An experimental installation with a laser plasmatron based on a continuous wave CO2 laser with a radiation power of up to 3.5 kW has been created. The plasmatron design makes it possible to bring out the plasma jet into atmospheric air both along and across the laser beam direction. The spatial temperature distributions on the metal substrate surface heated by the plasma jet are measured. The threshold power for optical discharge maintenance as a function of the gas flow rate and the focal length of the focusing lens are obtained for an Ar and Ar/CH4/H2 gas mixture under atmospheric pressure; the radiation spectrum of the discharge plasma is measured. A one-dimensional model of the discharge for estimation of its geometrical parameters in a convergent laser beam with consideration of radiation refraction on the discharge is given. 相似文献
13.
14.
N.A. Shevchenko N.N. Dadoenkova I.L. Lyubchanskii F.F.L. Bentivegna Y.P. Lee Th. Rasing 《Photonics and Nanostructures》2012,10(4):400-408
Second-order nonlinear optical diffraction by standing acoustic waves in a crystalline plate is theoretically investigated. A detailed analysis of the polarization state of the second-harmonic light diffracted by both longitudinal and transversal acoustic waves is carried out. It is shown that longitudinal standing acoustic waves only allow p-polarized nonlinear optical diffraction, irrespective of the incoming state of polarization, whereas transversal standing acoustic waves allow all possible combinations of incoming and diffracted polarization states. Numerical estimates of the relative intensities of nonlinearly diffracted radiation peaks are made for a GaAs plate. 相似文献
15.
David Tzach Robert Buschauer Gregory Benford 《International Journal of Infrared and Millimeter Waves》1981,2(1):71-82
After eliminating reflections from the walls of the plasma container, we observed polarization of the coherent synchrotron radiation from a relativistic electron beam rotating in a plasma. Several features of the polarization agree well with calculations based on the single particle synchrotron radiation theory. A particular polarization ratio (Fig. 3) does not, however. We deduce from this direct diffraction of the radiation by the beam electrons. This is strong evidence for beam-particle bunches of size cm. Also, there must be some absorption of the extraordinary wave to account for the observations. We suggest a way to apply these results to measure the pitch angle of the beam.Work supported by Army Research Office. 相似文献
16.
The characteristics of a discharge and radiation in nitrogen and argon under pressures of 10–760 Torr and the discharge formation without pre-ionization of the gap from an auxiliary source are considered. A peak is detected on the pressure dependence of the radiation power of the second positive system of nitrogen for E 0/p ~ 270 V/cm Torr and nitrogen pressure p ~ 70 Torr. In the pressure range 10–760 Torr and for a voltage pulse leading front duration of ~ 10 ns, an electron beam is formed behind the grid anode with various half-amplitude pulse durations. It is shown that, under the given conditions, the electron beam is formed at the voltage pulse front both in the case of a discharge gap breakdown and in the absence of a clearly manifested breakdown, as well as for a 10-ns delay of breakdown at the leading front of a discharge current pulse. 相似文献
17.
Polarization characteristics of diffraction radiation generated by charged particles moving close to a tilted conducting half-plane or passing through a slit are studied. Unlike the linearly polarized transition radiation, the diffraction radiation is shown to possess elliptical polarization. The dependence of three Stokes parameters of diffraction radiation on the distance to the slit center is analyzed for the case of a particle passing through a slit. A method for determining the transverse beam size while measuring the diffraction radiation polarization is proposed. 相似文献
18.
N. I. Petrov 《Journal of Experimental and Theoretical Physics》1997,85(6):1085-1093
The depolarization and rotation of the polarization plane of radiation propagating in a two-dimensional graded-index medium
is investigated on the basis of the quantum-mechanical method of coherent states. It is shown that the degree of polarization
of both linearly and circularly polarized radiation decreases with increasing distance as a result of interaction between
the polarization (spin) and the path (orbital angular momentum) of the beam. The wave nature of the depolarization is emphasized.
The depolarization decreases as the radiation wavelength decreases. It is found that the degree of polarization exhibits oscillations
of pure diffraction origin during the propagation of light in a single-mode optical fiber. It is shown that the rotation of
the polarization plane is nonuniform in character and depends on the offset and the tilt angle of the incident-beam axis relative
to the fiber axis. The Berry phase is found to undergo oscillations of a wave nature during the propagation of radiation in
an inhomogeneous medium. It is shown that the spread in the angle of rotation of the polarization plane increases with distance
and can be determined from measurements of the degree of polarization of the radiation.
Zh. éksp. Teor. Fiz. 112, 1985–2000 (December 1997) 相似文献
19.
M. Ya. Agre 《Optics and Spectroscopy》2002,92(4):499-504
A compact expression for the cross section of scattering of an arbitrarily polarized light by aligned atomic systems is obtained, in which the dependence on the geometric parameters and the Stokes parameters specifying the state of partial polarization of the incident radiation is represented in explicit form. The effect of atomic alignment and the processes of dissipation of the light energy on the polarization specific features and the angular distribution of the scattered light is investigated. In particular, it is shown that, if a dissipative channel is accessible, the angular distribution and the degree of linear polarization of scattered light depend on the degree of circular polarization of the incident radiation η2. Dissipative processes also induce the circular polarization of the light scattered by aligned atoms when η2=0. 相似文献
20.
Direct observability of polarization moments of a higher order—octupole orientation of atomic angular momenta (κ=3) and their hexadecapole alignment (κ=4)—from polarization of quadrupole radiation is discussed. The case when atoms are excited through dipole absorption of light producing orientation or alignment of angular momenta with κ=1 or 2 and higher polarization moments are induced by collisions with a beam of particles is considered. It is shown that differences in the laws of transformation of polarization moments of various ranks κ in rotations of coordinate axes allow us to select the pure contribution of the higher polarization moment under study from the signal of polarization of quadrupole emission by excluding the contribution of orientation or alignment with κ=1 or 2. Optimum systems of coordinate axes for the observation of octupole orientation from circular polarization of light and for the observation of hexadecapole alignment from linear polarization of light, in which the pure contribution of the higher polarization moment under study to polarization of quadrupole emission reaches its maximum, are calculated. 相似文献