High-resolution Polarimeter Research Articles

High-Resolution Polarimetric Radar for Autonomous Vehicle Research at W-Band Frequencies

High-Resolution Polarimetric Radar for Autonomous Vehicle Research at <i>W</i>-Band Frequencies

Measurement of the beam diameter at the polarimeter for quartz control plate calibration

The Knife Edge method was used to measure the diameter of a HeNe laser beam in the sample position of the high resolution polarimeter at Diopt. The acquired data profile was fitted to an equation and from the fitting parameters the diameter was calculated. The resulting laser beam diameter value obtained is a part of the polarimeter full characterization.

A high-resolution polarimeter formed from inexpensive optical parts

We describe a high resolution laser polarimeter built from commodity optical components. The optical rotation angle is determined by measuring the phase difference between two harmonically modulated polarised laser beams – an ‘object beam’ that passes through the sample under test and a ‘reference beam’ that bypasses the sample. The complete polarimeter may be assembled from low cost off-the-shelf parts for less than £300 (UK Sterling). Data acquisition and analysis are carried out on a microcontroller running an efficient algorithm based on the sliding Discrete Fourier Transform. Despite its low cost, the polarimeter is a fully automatic, research-grade instrument with an accuracy of ±0.0013° and a precision of ±0.0028° – comparable to far costlier commercial instruments. The polarimeter’s ease of use, compact size, fast measurement times and high angular resolution make it a capable and versatile tool for analytical science, while its low cost means it is ideally suited for use in resource-constrained environments and process monitoring. The polarimeter is released here as open hardware, with technical diagrams, a full parts list, and source code for its firmware included as Supplementary Information.

Calibration of Quartz Control Plates by High Resolution Polarimetry

A high resolution polarimeter is being assembled at Inmetro for calibrating quartz control plates, standards for saccharimeters and industrial polarimeters. Here is shown the first measurements by this new instrument of plates previously calibrated at the PTB.

Critical behavior of birefringence in the smectic-Aphase of chiral smectic liquid crystals

Using a high resolution polarimeter, we have measured the temperature dependence of birefringence in the vicinity of smectic-A--smectic-${C}^{*},$ smectic-A--smectic-${C}_{\ensuremath{\alpha}}^{*},$ and smectic-A--smectic-${C}_{A}^{*}$ phase transitions of chiral smectics. We have observed a large pretransitional decrease of the birefringence in materials exhibiting smectic-${C}_{\ensuremath{\alpha}}^{*}$ and smectic-${C}_{A}^{*}$ phases, indicating unusually large pretransitional fluctuations of the tilt angle. These fluctuations show a clear power-law behavior over more than two decades of temperature.

Observation of target electron momentum effects in single-arm Møller polarimetry

In 1992, L.G. Levchuk noted that the asymmetries measured in Møller scattering polarimeters could be significantly affected by the intrinsic momenta of the target electrons. This effect is largest in devices with very small acceptance or very high resolution in laboratory scattering angle. We use a high resolution polarimeter in the linac of the polarized SLAC Linear Collider to study this effect. We observe that the inclusion of the effect alters the measured beam polarization by −14% of itself and produces a result that is consistent with measurements from a Compton polarimeter. Additionally, the inclusion of the effect is necessary to correctly simulate the observed shape of the two-body elastic scattering peak.

High Resolution Polarimetric Radar Imaging and Applications

The basic principle of the generation of high resolution complex target microwave images from scattered fields is outlined, and the derivation of so-called target characteristic parameters as well as target characteristic polarizations is described. Special emphasis is given to the analysis of localized scattering centres. A fast procedure for the generation of two-dimensional microwave images under real-time conditions is explained in detail. Finally, two methods for stuying bistatic scattering effects on a monostatic measurement range are introduced.

High resolution far infrared polarimeter for plasma diagnostics

A method for the Faraday rotation angle measurement in RFX is described, which does not require an interferometric structure, resulting in a considerable simplification of the diagnostic apparatus. It incorporates the same principle of operation as is employed in a high resolution polarimeter for visible wavelengths. The test on the bench performed at the Far Infrared wavelength of interest (λ=118.8 μm) is described, the results which were obtained are presented and discussed, and the feasibility of the method has been clearly demonstrated.

Polarization transfer in the (p,p′) reaction on light nuclei

A high-efficiency, high-resolution polarimeter has been employed to measure the transverse spin-flip probability in ($p,{p}^{\ensuremath{'}}$) reactions induced by polarized protons in the energy range from 30 to 42 MeV. The spin-flip probability for central forces is shown to be uniquely related to spin transfer ($s=1$) in the eikonal approximation. More exact calculations indicate the general rule $S\ensuremath{\ge}0.5$ when $s=1$ and $S\ensuremath{\le}0.1$ when $s=0$. Antisymmetrized distorted-wave calculations give a generally poor account of spin transfer in isoscalar transitions and transitions in odd mass nuclei. Spin flip in isovector transitions is well described by the calculations.

Photoelectric method of recording an achromatic interference fringe: V. P. Koronkevich, G. A. Lenkova, N. S. Babenko and A. I. Lokhmatov, Optics & Spectrosc., 11 (1), July 1961, 58–61

In 1992, L.G. Levchuk noted that the asymmetries measured in Møller scattering polarimeters could be significantly affected by the intrinsic momenta of the target electrons. This effect is largest in devices with very small acceptance or very high resolution in laboratory scattering angle. We use a high resolution polarimeter in the linac of the polarized SLAC Linear Collider to study this effect. We observe that the inclusion of the effect alters the measured beam polarization by −14% of itself and produces a result that is consistent with measurements from a Compton polarimeter. Additionally, the inclusion of the effect is necessary to correctly simulate the observed shape of the two-body elastic scattering peak.