Showing papers on "Polarimetry published in 1981"
TL;DR: Spectrophotopolarimetric capability can be added to a laboratory interferometer-spectrometer by use of a specially designed module described in this article, where high-resolution spectra can be obtained of the Stokes parameters of the reference beam and the beams diffusely reflected or transmitted by a sample medium of interest.
Abstract: Spectrophotopolarimetric capability can be added to a laboratory interferometer-spectrometer by use of a specially designed module described herein. With the instrument so augmented, high-resolution spectra can be obtained of the Stokes parameters of the reference beam and the beams diffusely reflected or transmitted by a sample medium of interest. For any such beam, the exponential Fourier transforms of the two interferograms obtained with a polarizer-analyzer oriented along the 0 deg and the 90 deg directions provide the spectra of I and Q, separately. Within experimental (and numerical) noise, this I spectrum should be the same as the one obtained with the polarizer removed. The remaining Stokes parameters U and V are obtained with a third interferogram recorded with the polarizer along the 45 deg direction. The complete theory of this instrument is described including the detailed analysis of the polarization-interferograms it provides.
77 citations
38 citations
TL;DR: In this paper, the use of photoelastic polarimeters in astronomy is briefly reviewed, and a visible and near-UV photo-elastic modulation polarimeter is described which has been in continuous service on the 61-cm telescope of Pine Mountain Observatory for 6 years.
Abstract: The use of photoelastic polarimeters in astronomy is briefly reviewed, and a visible and near-UV photoelastic modulation polarimeter is described which has been in continuous service on the 61-cm telescope of Pine Mountain Observatory for 6 years. The polarimeter is used primarily for linear polarization measurements, but is easily adaptable to circular polarimetry. The instrument has produced data at a sensitivity level of 0.01%, with long-term absolute reproducibility.
32 citations
TL;DR: In this article, four narrowband filters covering the 440-850 nm wavelengths were used to measure the polarization of the continuum of Comet West 1976 VI, and it was suggested by dirty silicates with radii approaching 5 microns may be responsible for the phenomena observed.
31 citations
TL;DR: The theory of Bragg crystal x-ray polarimeters is presented to-gether with an analysis of the statistics of photon-limited polarimeters as discussed by the authors, and the focusing Bragg laser polarimeter is described and a number of results obtained at 2.6 keV and 5.2 keV are presented.
Abstract: The theory of Bragg crystal x-ray polarimeters is presented to-gether with an analysis of the statistics of photon-limited polarimeters. The focusing Bragg crystal polarimeter flown on the OSO-8 Satellite is described and a number of results obtained at 2.6 keV and 5.2 keV are presented. A polarimeter of this type with at least ten times the area is needed to answer a number of astrophysically interesting questions. A discussion is given of a Compton scattering polarimeter that is expected to be useful of energies above 40 keV. It is shown how this polarimeter may be used to test for the presence of a black hole in Cyg X-1. A solar flare x-ray polarimeter that is scheduled to be flown on an early space shuttle mission is described and an estimate is given of its sensitivity.
20 citations
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TL;DR: In this article, the peak noise level of a Faraday-effect polarimeter with a He-Ne laser source has been found to be as low as ± 0.05 second of arc.
Abstract: Factors limiting the sensitivity of measurement obtainable with polarimetric instrumentation are discussed, with particular emphasis on modulation methods and the special problems associated with a coherent light source. Under optimum conditions the peak noise level of a Faraday-effect polarimeter with a He-Ne laser source has been found to be as low as ± 0.05 second of arc. The addition of quartz wedge units enables lateral displacements and departures from straightness to be measured and a system is described that possesses low sensitivity to laser beam direction changes and air turbulence. Profile measurements on a silica bar using this polarimetric system and measurements by precise Fizeau interferometry have agreed to better than 0.2 um over the 300 mm length of the bar.
13 citations
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TL;DR: In this paper, the authors describe the instruments and techniques used to measure this polarization and indicate the solar physical processes illuminated by these measure-ments, including broadband observa-tions of Thomson scattering in the solar corona; for observations of resonance polarization in prominence and coronal emission lines; and for narrowband, spectrally resolved polarimetry in Fraunhofer lines formed in the photosphere and chromosphere.
Abstract: A variety of physical processes and conditions in the solar at-mosphere produce polarized light, a useful diagnostic tool. We describe the instruments and techniques used to measure this polarization and indicate the solar physical processes illuminated by these measure-ments. Included are descriptions of instruments for broadband observa-tions of Thomson scattering in the solar corona; for observations of resonance polarization in prominence and coronal emission lines; and for narrowband, spectrally resolved polarimetry in Fraunhofer lines formed in the photosphere and chromosphere.
TL;DR: The Ultraviolet Spectrometer and Polarimeter on the Solar Maximum Mission spacecraft is described in this article, which has a spatial resolution of 2-3 arcsec and a spectral resolution of 0.02 A FWHM in second order.
Journal Article•
01 Jan 1981
TL;DR: In this paper, a low light level CCD imaging system is described in which the polarization as well as the intensity for each pixel in the image is measured and displayed on a color display.
Abstract: A low light level CCD imaging system is described in which the polarization as well as the intensity for each pixel in the image is measured and displayed on a color display. Overall performance is good, and the availability of quick-reduced Stokes images makes CCD polarimagery attractive for astronomy. We show polarization images of two objects recently studied.
Journal Article•
TL;DR: A design of this type is described in which the speed of rotation of a quarter-wave retarder is made to appear different for the incident and backscattered beams by use of Faraday cells with appropriate excitations.
Abstract: To measure all 16 elements of a backscattering Mueller matrix, a polarimeter of the return-path configuration must be used with nonreciprocal polarizing-analyzing optics. Nonreciprocity is essential to make the same optics behave differently for the forward and backward waves. A design of this type is described in which the speed of rotation of a quarter-wave retarder is made to appear different for the incident and backscattered beams by use of Faraday cells with appropriate excitations. The same performance as of a previously described single-path polarimeter [Opt. Lett. 2, 148 (1978)] is realized. Applications are anticipated in polarization lidar studies and also to extend perpendicular-incidence ellipsometry to the characterization of depolarizing (e.g., rough) anisotropic surfaces.
01 Jan 1981
01 Jan 1981
TL;DR: The accuracy and precision of polarimetric analyses, as with many optical methods of analysis, can be significantly enhanced through the use of lasers as sources of illumination as discussed by the authors, such as high brightness, stable intensity, spatial coherence, and monochromaticity.
Abstract: The accuracy and precision of polarimetric analyses, as with many optical methods of analysis, can be significantly enhanced through the use of lasers as sources of illumination. The properties that give lasers advantage over conventional sources for polarimetry are high brightness, stable intensity, spatial coherence, and monochromaticity. In order to appreciate the advantages to both visual and photoelectric polarimetry we will first briefly discuss typical methods of measurement, then present experimental comparisons of lasers and conventional lamps.