{"title":"Polarimetric 360° absolute rotary encoder","authors":"Mark J. Johnson","doi":"10.1515/aot-2021-0056","DOIUrl":null,"url":null,"abstract":"Abstract Encoders of angle based on rotating polarizers suffer from 180° ambiguity due to their inherent twofold rotational symmetry. This restricts their applications in motor and machine controls. We show that the ambiguity can be resolved through a geometrical mapping from a plane to a conical surface. Seen from the local surface normal, one full rotation of the cone gives one half rotation of the polarizer axis. With appropriate transmission or reflective optics and multiphase detection, we build high resolution, moderate accuracy, absolute-angle encoders without 180° ambiguity. Polymer birefringent retarders can be used similarly.","PeriodicalId":46010,"journal":{"name":"Advanced Optical Technologies","volume":null,"pages":null},"PeriodicalIF":2.3000,"publicationDate":"2022-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Advanced Optical Technologies","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1515/aot-2021-0056","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"OPTICS","Score":null,"Total":0}
引用次数: 1
Abstract
Abstract Encoders of angle based on rotating polarizers suffer from 180° ambiguity due to their inherent twofold rotational symmetry. This restricts their applications in motor and machine controls. We show that the ambiguity can be resolved through a geometrical mapping from a plane to a conical surface. Seen from the local surface normal, one full rotation of the cone gives one half rotation of the polarizer axis. With appropriate transmission or reflective optics and multiphase detection, we build high resolution, moderate accuracy, absolute-angle encoders without 180° ambiguity. Polymer birefringent retarders can be used similarly.
期刊介绍：
Advanced Optical Technologies is a strictly peer-reviewed scientific journal. The major aim of Advanced Optical Technologies is to publish recent progress in the fields of optical design, optical engineering, and optical manufacturing. Advanced Optical Technologies has a main focus on applied research and addresses scientists as well as experts in industrial research and development. Advanced Optical Technologies partners with the European Optical Society (EOS). All its 4.500+ members have free online access to the journal through their EOS member account. Topics: Optical design, Lithography, Opto-mechanical engineering, Illumination and lighting technology, Precision fabrication, Image sensor devices, Optical materials (polymer based, inorganic, crystalline/amorphous), Optical instruments in life science (biology, medicine, laboratories), Optical metrology, Optics in aerospace/defense, Simulation, interdisciplinary, Optics for astronomy, Standards, Consumer optics, Optical coatings.
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