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Showing papers on "Circular polarization published in 1976"


Journal ArticleDOI
TL;DR: In this article, the wavelength dependence of interstellar linear polarization [p(λ) was investigated using the usual Serkowski relation with three parameters: p max, λ max, and K. Optical and infrared measurements were obtained simultaneously in eight photometric passbands between U and K, giving a coherent data set for a total of 105 reddened stars.
Abstract: New observations of the wavelength dependence of interstellar linear polarization [p(λ)] made to investigate the influence of the environment on the effective size distribution of the aligned polarizing particles are presented. Optical and infrared measurements were obtained simultaneously in eight photometric passbands between U and K, giving a coherent data set for a total of 105 reddened stars. The p(λ) data were modeled using the usual Serkowski relation with three parameters: p max , λ max , and K

249 citations


Patent
21 Jun 1976
TL;DR: In this paper, the authors proposed an array of closely clustered waveguide elements each of which converts respective linearly polarized signals to left-hand and right-hand circularly polarized signals and vice versa.
Abstract: An antenna for use in propagating or receiving microwave radiation having both left-hand and right-hand circular polarization. The left-hand and right-hand circularly polarized radiation may be transmitted or received simultaneously without interference with one another, that is, they are isolated from one another by 27 dB or more. The preferred antenna comprises an array of closely clustered waveguide elements each of which converts respective linearly polarized signals to left-hand and right-hand circularly polarized signals and vice versa. Isolation means also are provided in each of the waveguide elements for preventing radiation either propagated or received by a waveguide element from being coupled into the radiation being propagated or received by other waveguide elements in the array. Preferably, square waveguide is utilized for the array elements and the isolation is provided by a plurality of conductive elements mounted on each of the open ends of the waveguide elements. The cluster array of waveguide elements may include dummy elements, may be fed with electromagnetic signals having various phase and power differences to produce desired radiation transmission or reception patterns and may be used to illuminate a parabolic reflector having a secondary radiation pattern. A single waveguide element or an array of them may be used in communications satellites and the like or may be used in radar or other applications.

133 citations


Journal ArticleDOI
TL;DR: In this paper, linear and circular polarization measurements of 31P-21S (501.6 nm) photons detected in delayed coincidence with electrons inelastically scattered from the 31P level of helium are presented.
Abstract: We present linear and circular polarization measurements of 31P-- 21S (501.6 nm) photons detected in delayed coincidence with electrons inelastically scattered from the 31P level of helium. Vector polarization and coherence parameters of the coincident radiation provide direct experimental evidence of the coherent nature of the excitation process. Atomic orientation is obtained directly from the circular polarization measurements. Analysis of the data also yields lambda and chi parameters for 31P excitations, which are compared with previous data and theory.

122 citations


Journal ArticleDOI
TL;DR: In this paper, the frequency distribution of fluorescent light induced by monochromatic dye laser radiation was investigated by means of a piezoelectrically tunable spherical Fabry Perot.
Abstract: The frequency distribution of the fluorescent light induced by monochromatic dye laser radiation was investigated. To exclude the influence of the Doppler width a strongly collimated atomic beam was used. The spectrum was measured by means of a piezoelectrically tunable spherical Fabry Perot. The interaction region between the laser light and the atomic beam was placed into the center of the interferometer. Thus the observed fluorescence spectrum was considerably more intense than in the case where the interferometer is used separately from the beam. The fluorescence spectrum was observed for different directions of polarization of the incident laser beam. In the case of weak excitation the spectrum consists of a sharp component essentially due to elastically scattered light. At high intensities a structure of three components is observed which is in agreement with theoretical predictions when circularly polarized light is used for excitation.

119 citations


Journal ArticleDOI
TL;DR: In this article, electron capture by protons in the tail of the electron density at a metal surface is investigated, and the ion velocity is assumed to be large compared to the velocity of an electron in the lowest orbit of hydrogen.
Abstract: Electron capture by protons in the tail of the electron density at a metal surface is investigated. The ion velocity is assumed to be large compared to the velocity of an electron in the lowest orbit of hydrogen. Electron transition probabilities into the 2p states of hydrogen are calculated, analogous to the first Born approximation by extending a model of Trubnikov and Yavlinskii [1] to tilted foils and nonzero angular momentum of the captured electron. From the density matrix the Stokes parameters are calculated. The results give partial agreement with experimental data, especially for the sinusoidal dependence of circular polarization on foil tilt angle.

76 citations


Journal ArticleDOI
TL;DR: In this paper, a dispersion relation for a magnetized plasma in which a large amplitude circularly polarized wave propagates along the external magnetic field is derived, and it is shown that new modes which appear due to relativistic effects, can be unstable.
Abstract: A dispersion relation is derived for a magnetized plasma in which a large amplitude circularly polarized wave propagates along the external magnetic field. It is shown that new modes, which appear due to relativistic effects, can be unstable.

75 citations


Patent
05 May 1976
TL;DR: In this paper, the authors disclosed a circularly polarized light source including a circular light polarizer using cholesteric liquid crystal material in an arrangement such that substantially 100% of the unpolarized light input may be utilized in either a narrow band or wide band configuration.
Abstract: There is disclosed a circularly polarized light source including a circular light polarizer using cholesteric liquid crystal material in an arrangement such that substantially 100% of the unpolarized light input may be utilized in a circularly polarized output in either a narrow band or wide band configuration. The circular polarizer itself comprises one or a plurality of liquid crystal cells having liquid crystal material of a predetermined ratio by weight of cholesteric to nematic liquid crystal type in each cell. The ratio of the types of materials determines a central wavelength to which each cell is tuned in its polarizing action. If a single cell is used, light of a predetermined bandwidth around its central wavelength is polarized. If a plurality of cells are stacked in a sandwich arrangement wherein each cell is tuned to a different wavelength selected in such a sequentially stepped fashion that the bandwidths for the cells form a continuous spectrum, then there is formed a wideband polarizer which can readily encompass the entire visible wavelength region of the spectrum.

69 citations


Journal ArticleDOI
TL;DR: In this paper, the vacuum polarization tensor in the presence of a static homogeneous magnetic field is calculated exactly as a function of both the magnetic field and the wave vector, and is regularized explicitly by using Shabad's diagonalization with respect to tensor indices.
Abstract: The vacuum polarization tensor in the presence of a static homogeneous magnetic field is calculated exactly as a function of both the magnetic field and the wave vector, and is regularized explicitly by using Shabad’s diagonalization with respect to tensor indices The wave properties for the two electromagnetic modes in the birefringent vacuum are calculated exactly using a technique from plasma physics The strongfield limit is considered explicitly and it is shown that the two modes reduce to forms equivalent to the magnetoacoustic and shear Alfven modes in a plasma with Alfven speed much greater than the speed of light

54 citations


Patent
02 Jan 1976
TL;DR: In this article, an electromagnetic wave ring resonator is described, including means to spatially rotate the electromagnetic field distribution of waves resonant therein about the direction of propagation of such waves to enable the waves to resonate with opposite senses of circular polarization, and means, including a laser amplifier medium, to provide different indices of refraction to resonant waves of the same sense of polarities as they pass through such laser amplifiers in different directions.
Abstract: An electromagnetic wave ring resonator is disclosed including means to spatially rotate the electromagnetic field distribution of waves resonant therein about the direction of propagation of such waves to enable such waves to resonate with opposite senses of circular polarization, and means, including a laser amplifier medium, to provide different indices of refraction to resonant waves of the same sense of circular polarization as they pass through such laser amplifier medium in different directions. With such arrangement the two mentioned means enable the waves to resonate with four different frequencies. In a laser gyroscope using such ring resonator the electromagnetic field distribution rotating means includes a catoptric arrangement which, together with the last-mentioned means, reduces the loss, scatter and linear birefringence associated with the ring resonator included in such gyroscope. The last-mentioned means produces the Zeeman effect in the laser medium and efficiently provides different optical pathlengths for waves passing through such medium because the magnetic field vector of such waves interacts with the processing atomic magnetic dipoles of the amplifier medium at the emission frequency of such amplifier medium.

48 citations


Journal ArticleDOI
TL;DR: Theoretical and experimental results for the line shape of Raman-induced Kerr effect resonances observed with elliptical pump polarization were presented in this paper, showing that the electronic contribution to the Kerr constant of benzene is 12%.
Abstract: Theoretical and experimental results are presented for the line shape of Raman-induced Kerr effect resonances observed with elliptical pump polarization. The line shape is sensitive to the ratio of the Kerr constant to the Raman tensor. Comparison of these results to those obtained by three-wave mixing reveals that the electronic contribution to the Kerr constant of benzene is 12%.

48 citations


Journal ArticleDOI
01 Jan 1976
TL;DR: This review describes the recent development of vacuum ultraviolet circular dichroism (VUCD) spectrometers and the results that have been obtained with them.
Abstract: This review describes the recent development of vacuum ultraviolet circular dichroism (VUCD) spectrometers and the results that have been obtained with them. Optical activity is a property of material that can be displayed phenomenologi­ cally in either of two forms. Optical rotatory dispersion (ORD) refers to the rotation of the polarization plane of plane polarized light when the light is passed through material, that rotation being measured as a function of the radiation wave­ length. Circular dichroism (CD) is the difference between the absorption of left and right circularly polarized radiation. Equivalently, CD is the ellipticity induced in originally plane polarized radiation. An ellipticity of 0.001 degree corresponds to an absorbancc diffcrcncc bctwccn left and right circularly polarized light of 3 x 105 units of absorbance. Optical activity can be expressed mathematically in terms of a complex, frequency dependent function-the molecular susceptibility, in which the real (dispersive) part determines the optical rotatory dispersion and the imaginary (absorptive) part determines the circular dichroism. The nature of the susceptibility is such that these real and imaginary parts are related to one another through a Kronig­ Kramers transform. Each excited state of an optically active molecule contributes to the optical activity and, in principle, both the ORD and the CD at any wavelength should be resolvable into components arising from the various contributing optical transitions. In practice it is difficult to resolve the ORD since, being a dispersive function, it can be significantly large far from the region of absorption. Since CD is nonzero only in the region of absorption and is more easily resolved into components assignable to individual optical transitions, it has come to be the preferred technique by many people. Although one's introduction to molecular optical activity is.often in connection with the asymmetric carbon atom of elementary organic chemistry, Pasteur himself noted the possibility of helical arrangements also resulting in optical activity. In recent times helicity as a source of optical activity has received a great deal of

Journal ArticleDOI
TL;DR: In this article, the results of an experiment which measured the circular-polarization correlation of photons emitted in the 91P1→73S1→63P0 cascade of atomic mercury were reported.
Abstract: The results of an experiment are reported which measured the circular-polarization correlation of photons emitted in the 91P1→73S1→63P0 cascade of atomic mercury. The results appear to be in general agreement with the predictions of quantum theory. They are compared with the predictions by several inequalities derived for various alternatives to quantum theory.

Journal ArticleDOI
TL;DR: In this paper, it was shown that cyclotron resonance lineshape distortions arise from multiple interference effects in plane parallel sample substrates and from partial circular polarization of long wavelength coherent radiation owing to the light pipe optics.

Journal ArticleDOI
TL;DR: In this article, the phase difference introduced by nitrobenzene in the electric field volume was measured and the position displacement of the fringes was observed in time using a continuous laser and a streak camera to yield the time behavior of the field or in space using a pulsed laser and photographic film.
Abstract: Electric fields are determined by interferometrically measuring the phase difference introduced between light polarized parallel and perpendicular to the electric field. The phase difference is introduced by nitrobenzene in the electric-field volume. Magnetic fields are determined by interferometrically measuring the phase difference introduced between left and right circularly polarized light by Faraday rotational glass placed in the magnetic field. The result of either measurement is a finite fringe interference pattern. The position displacement of the fringes is observed in time using a continuous laser and a streak camera to yield the time behavior of the field or in space using a pulsed laser and photographic film to yield the spatial behavior of the field.

Journal ArticleDOI
TL;DR: Averages and distributions of the rain parameters, cancellation and degree of orientation, were determined from observations of power and correlation with a polarization diversity radar using circular polarization at 16.5 GHz during the period 1971-1974 as mentioned in this paper.
Abstract: Averages and distributions of the rain parameters, cancellation and degree of orientation, are presented. The quantities were determined from observations of power and correlation with a polarization diversity radar using circular polarization at 16.5 GHz during the period 1971–1974. Data are given for a related quantity, “maximum cancellation.” The fact that this quantity is not invariant with range is shown to be evidence for the occurrence of incoherent transmission processes at 16.5 GHz.

Journal ArticleDOI
TL;DR: In this paper, the polarization of emission lines in the nucleus of NGC 1068 has been measured with a digicon, a single-channel scanner, and interference filters, and it was found that the permitted lines of H and probably also He II are polarized at nearly the same position angle and by the same amount as the neighboring continuum.
Abstract: The polarization of emission lines in the nucleus of NGC 1068 has been measured with a digicon, a single-channel scanner, and interference filters. It is found that the permitted lines of H and probably also He II are polarized at nearly the same position angle and by the same amount as the neighboring continuum. This argues strongly that a common dust scattering mechanism is responsible for all the polarization. The forbidden lines are weakly polarized at a position angle quite different from the continuum, indicating an origin outside the nuclear scattering region. The continuum radiation has been found to be circularly polarized with ellipticity of the order of 5 percent in the red. Such high ellipticity is very unlikely to be of nonthermal origin. We take it as evidence that the nuclear dust is in the form of clouds in an asymmetric skew geometry; the polarization then arises from multiple scattering within these clouds.

Journal ArticleDOI
TL;DR: In this article, the theoretical basis of a method of measuring the radial distribution of electron density and poloidal magnetic field in a Tokamak from the polarization changes occurring in a test wave propagating across a series of chords of the discharge is described.
Abstract: Describes the theoretical basis of a method of measuring the radial distribution of electron density and poloidal magnetic field in a Tokamak from the polarization changes occurring in a test wave propagating across a series of chords of the discharge. When the test wave is linearly polarized at an angle of 45 degrees to the toroidal direction the power transferred to a direction perpendicular to the initial polarization is related to electron density only. When the initial polarization is directed along the toroidal direction the power transferred to the perpendicular direction is related to both electron density and poloidal field. The optimum wavelength to obtain maximum power transfer to the direction perpendicular to the initial polarization is lambda approximately 1 mm. An experimental multi-channel system using a far infrared laser source is suggested.

Journal ArticleDOI
TL;DR: In this article, the authors reported the circular polarization of two of the resonance fluorescence series from excited molecular iodine, prepared by excitation with the 5145 A and 5017 A lines of an argon laser.
Abstract: We report the circular polarization of two of the resonance fluorescence series from excited molecular iodine, prepared by excitation with the 5145 A and 5017 A lines of an argon laser. The sign of the circular polarization of the rotationally resolved features is used to assign the spectrum. In addition, the circular polarization measures the populations of the MJ states in the excited molecule and we describe experiments to investigate the dependence of this polarization on foreign gas pressure and laser power. Results suggest that there is a strong persistence of the initially selected distribution of MJ states throughout elastic and rotationally inelastic collisions.

Journal ArticleDOI
TL;DR: In this article, it was shown that Cooper-type minima of the photoionization cross section should also exist for $l √ √ n − 1$ transitions for photoelectrons ejecting from thallium atoms.
Abstract: It has recently been predicted that Cooper-type minima of the photoionization cross section should also exist for $l\ensuremath{\rightarrow}l\ensuremath{-}1$ transitions. This theoretical conclusion is supported by measurements of the spin polarization of photoelectrons that have been ejected from thallium atoms by circularly polarized light.

Journal ArticleDOI
TL;DR: In this paper, the Power-Zienau-Woolley transformation in molecular quantum electrodynamics is carried out for a molecule in an external static magnetic field, and the Einstein B coefficients for the absorption of left and right circularly polarized photons by an oriented molecule in a uniform magnetic field are evaluated.
Abstract: The Power–Zienau–Woolley transformation in molecular quantum electrodynamics is carried out for a molecule in an external static magnetic field. From the gauge‐independent multipole Hamiltonian thus obtained the Einstein B coefficients for the absorption of left and right circularly polarized photons by an oriented molecule in a uniform magnetic field are evaluated. The B coefficients are related to the macroscopic absorption coefficients by treating the line shapes phenomenologically and by introducing a Boltzmann factor. A familiar expression for magnetic circular dichroism in a dilute medium is thereby recovered; the calculation is extended beyond the electric dipole approximation so as to include the leading contribution of natural circular dichroism. A simple use of the appropriate Kramers–Kronig dispersion relation leads to the deduction of the optical rotatory dispersion, both natural and magnetic, in spectral regions far removed from absorption bands.

Journal ArticleDOI
TL;DR: Theoretical expressions for the photoelectron spin polarization Pz and the ion count-rate 'asymmetry Ai (ratio of ion rates for right or left circular polarization in the second step), based on the hyperfine-coupling scheme for the first step, are presented in this paper.
Abstract: The authors have investigated the two-step process 62S1/2 to 62P3/2 to (epsilon 2S1/2, epsilon 2D3/2, epsilon 2D5/2) in Cs for circular polarization of the radiation in both steps. Theoretical expressions are presented for the photoelectron spin polarization Pz and the ion count-rate 'asymmetry' Ai (ratio of ion rates for right or left circular polarization in the second step), based on the hyperfine-coupling scheme for the first step. These expressions contain ratios of the three radial matrix elements involved in the ionizing step. The experimental determination of Pz and Ai, for different groups of hyperfine transitions, permits an evaluation of these ratios. The experiment was performed on a Cs atomic beam using a pulsed GaAs laser at 8521 AA for the first step and a pulsed Ar-ion laser at 5017-4545 AA for the second step. Effects of saturation in the first transition are studied and optimal conditions for use of the process in a spin-polarized electron source are discussed.

Journal ArticleDOI
TL;DR: In this article, the results of the recent observations of interstellar circular polarization are applied to a study of the galactic magnetic field, and the results are compared with what has already been learned from linear polarization observations.
Abstract: Recent observations of interstellar circular polarization are applied to a study of the galactic magnetic field. The results are compared with what has already been learned from linear polarization observations.

Journal ArticleDOI
TL;DR: In this paper, the Stokes parameters of radiation scattered by anisotropic particles (cosmic dust grains or molecules) are calculated and the effective mechanisms of transformation of the linear polarization into the circular one by free-oriented anisotropes are proposed.
Abstract: The Stokes parameters of radiation scattered by anisotropic particles (cosmic dust grains or molecules) are calculated. The effective mechanisms of transformation of the linear polarization into the circular one by free-oriented anisotropic particles are proposed. The optical activity of the irregular-shaped particles is shown to be rather large even though they consist of isotropic inactive material.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a model in which classical cyclotron emission from a hot corona can account for much of the continuum linear and circular polarization which has been observed at optical frequencies for several white dwarfs.
Abstract: We propose a model in which classical cyclotron emission from a hot corona can account for much of the continuum linear and circular polarization which has been observed at optical frequencies for several white dwarfs. Important features of our model are: (1) The degree of linear polarization (p) approx. = degree of circular polarization (q) for a variety of magnetic field configurations; (2) continuum polarization occurs in the optical only for surface magnetic field strengths B> or =10/sup 8/ gauss; (3) changes with wavelength in the handedness of circular polarization and in the position angle of the linear polarization occur naturally; and (4) the strong fields required imply severe shifting and smearing of sectral lines, for which there is evidence in some white dwarfs. Possible energy sources for and structures of such coronae are discussed. Observational tests of the model are suggested. (AIP)

Journal ArticleDOI
TL;DR: In this article, the co-polar and crosspolar fields in the focal plane of paraboloidal reflectors when excited by a plane wave are derived for linear and circular polarization, respectively.
Abstract: Equations for the co-polar and cross-polar fields in the focal plane of paraboloidal reflectors when excited by a plane wave are derived for linear and circular polarization, it is shown that for linear polarization the co-polar diffraction image consists of an elliptically shaped bright region followed by dark and bright zones. On the other hand, the cross-polar image consists essentially of four bright spots separated by a dark cross. These theoretical findings were confirmed by measurements. With circular polarization the co-polar diffraction image comprises a bright central circle followed by dark and bright rings, whereas the cross-polar image consists of a dark central circle followed by bright and dark rings. It is also shown that the field distribution in the image space is affected to a great extent by the angular semiaperture \psi '. Graphs of the variation of the image characteristics with \psi are also given.

Journal ArticleDOI
TL;DR: Asymmetric photocyclization of N-methyl N-aryl enamines by circularly polarized light gives several optically active 2-phenyl dihydroindoles.
Abstract: Asymmetric photocyclization of N-methyl N-aryl enamines by circularly polarized light gives several optically active N-methyl dihydroindoles. In the synthesis of N-methyl 2-phenyl dihydroindole, the optical yield was evaluated to be 0.20%, which is the same order of magnitude as in the asymmetric synthesis of helicenes. The mechanisms of these reactions are discussed.

Journal ArticleDOI
TL;DR: In this paper, an experiment on two-step photoionization of Cs via the 6P3/2 intermediate state using circularly polarized radiation from a GaAs laser for the first step (8521 AA) and from an Ar-ion laser (Ar-ION) for the second step (821 AA).
Abstract: An experiment is reported on two-step photoionization of Cs via the 6P3/2 intermediate state using circularly polarized radiation from a GaAs laser for the first step (8521 AA) and from an Ar-ion laser for the second step. Values for the ratio of ion production rates for right- and left-handed circular polarization in the second step and for the spin polarization of the photoelectrons are presented. The measurements are interpreted on the basis of a calculation which takes into account the hyperfine splitting of the levels involved in the first transition. A description in terms of fine-structure splitting of the 6P state is shown to be totally inadequate, even when allowing for possibly large spin-orbit effects in the continuum. The process is evaluated as a possible source of a spin-polarized electron beam.

01 Jan 1976
TL;DR: In this article, the authors made accurate calculations of the circular polarization for multiple scattering by an atmosphere with spherical aerosols, as a function of particle size and refractive index as well as the mixing ratio of aerosols and gas.
Abstract: Circular-polarization observations of Jupiter are described, and the circular polarization of other planets is discussed to the extent that it aids interpretation of the Jupiter data. The evidence strongly supports the interpretation that the circular polarization arises from scattering by aerosols in a gaseous atmosphere. Accurate calculations of the circular polarization are made for multiple scattering by an atmosphere with spherical aerosols, as a function of particle size and refractive index as well as the mixing ratio of aerosols and gas. The calculations for spheres and the few available circular-polarization observations of Jupiter permit only very limited constraints to be placed on the haze and cloud properties of the atmosphere of Jupiter. However, multispectral circular-polarization observations, combined with measurements of linear polarization and intensity, would permit detailed analysis of atmospheric aerosol properties.

Journal ArticleDOI
TL;DR: In this article, a mathematical procedure is presented for the determination of the transmission properties (instrumental operator) of an instrument with respect to the polarization state of any arbitrarily polarized radiation.
Abstract: A mathematical procedure is presented for the determination of the transmission properties (instrumental operator) of an instrument with respect to the polarization state of any arbitrarily polarized radiation. This method is applied to a complete polarimeter system in order to find the systematic error of the polarization measurements. If the operator of the polarimeter is known, the systematic error can be removed. However, inaccuracy of determination of it produces errors that are in addition to the random errors. With the cumulative effects of errors taken into account, the over-all accuracy of the polarization measurements can be calculated.

Journal ArticleDOI
01 Oct 1976-Icarus
TL;DR: In this article, a brief survey of observations of the circulr polarization of Jupiter is given, followed by a description of new observations of brightness and circularly polarized flux made over part of the planetary disc.