{"title":"A new multi-channel heterodyne polarimeter for plasma current and electron density measurements","authors":"John Howard","doi":"10.1016/0020-0891(93)90007-T","DOIUrl":null,"url":null,"abstract":"<div><p>A spatially-scanning phase-sensitive heterodyne far-infrared (FIR) polarimeter/interferometer for measurement of plasma current and electron densities is described. The instrument utilizes a rotating diffraction grating wheel for the dual purpose of spatially scanning the plasma cross section and providing a Doppler frequency offset for heterodyne detection purposes. Only two detectors are required to obtain accurate interferometric and polarimetric information for 15 discrete spatial chords. A novel approach to the optical processing of the initially linearly polarized probe beam allows the Faraday rotation of the vibrational ellipse to be unambiguously encoded as a phase modulation on the intermediate frequency carrier signals extracted from the two detectors. The plasma birefringence can be recovered from the corresponding amplitude modulation.</p></div>","PeriodicalId":81524,"journal":{"name":"Infrared physics","volume":"34 2","pages":"Pages 175-189"},"PeriodicalIF":0.0000,"publicationDate":"1993-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0020-0891(93)90007-T","citationCount":"12","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Infrared physics","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/002008919390007T","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 12
Abstract
A spatially-scanning phase-sensitive heterodyne far-infrared (FIR) polarimeter/interferometer for measurement of plasma current and electron densities is described. The instrument utilizes a rotating diffraction grating wheel for the dual purpose of spatially scanning the plasma cross section and providing a Doppler frequency offset for heterodyne detection purposes. Only two detectors are required to obtain accurate interferometric and polarimetric information for 15 discrete spatial chords. A novel approach to the optical processing of the initially linearly polarized probe beam allows the Faraday rotation of the vibrational ellipse to be unambiguously encoded as a phase modulation on the intermediate frequency carrier signals extracted from the two detectors. The plasma birefringence can be recovered from the corresponding amplitude modulation.