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Design, construction and calibration of the Galway Astronomical Stokes Polarimeter (GASP)

  • Andrew Shearer

Research output: Chapter in Book or Conference Publication/ProceedingConference Publicationpeer-review

Abstract

The Galway Astronomical Stokes Polarimeter (GASP) is an ultra-high-speed, full Stokes, astronomical imaging polarimeter based upon a Division of Amplitude Polarimeter. It has been developed to resolve extremely rapid (similar to microsecond) variations in objects such as optical pulsars and magnetic CVs. The polarimeter has no moving parts or modulated components, so the complete Stokes vector can be measured from just one exposure - making it unique to astronomy - and the time required for the complete determination of the Stokes vector is limited only by detectors and photon fluxes. The polarimeter utilizes a modified Fresnel rhomb, which acts as a highly achromatic quarter wave plate and a beamsplitter (referred to as an RBS). We present a detailed description of the design process for the RBS and other optics of the polarimeter, and give a theoretical analysis of its expected performance. Calibration is an important, and difficult, issue with all polarimeters, but particularly in astronomical polarimeters. We give a detailed description of calibration techniques appropriate to this type of polarimeter - particularly a version of the Eigenvalue Calibration Method of Compain Drevillon.
Original languageEnglish (Ireland)
Title of host publicationUNIVERSE AT SUB-SECOND TIMESCALES: HIGH TIME RESOLUTION ASTROPHYSICS
Publication statusPublished - 1 Aug 2008

Authors (Note for portal: view the doc link for the full list of authors)

  • Authors
  • Collins, P,Redfern, RM,Sheehan, B,Phelan, D,Ryan, O,Shearer, A

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