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14 February 2003 Characterization of polarising beamsplitters by ray tracing
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Four different designs for a polarising beamsplitter (BS) are compared under the aspect of their suitability for high resolution solar spectropolarimetry. The four designs are: A solution based on a Savart-plate, two air-spaced Wollaston prisms, and a glass beamsplitter cube with polarisation sensitive dielectric coating, and a single Wollaston prism inside a focal reducer. Using ray-tracing algorithms these beamsplitters are characterised with the help of spot diagrams for the two light paths of orthogonal polarisation. It is shown that with the current spectrographs employed in solar research, the differential optical aberrations introduced by the beamsplitter are negligible, thanks to the slow F/#-ratio of existing solar telescopes and the limited field of view of currently used array detectors. It will, however, be demonstrated that with the new generation of large solar telescopes care must be exercised on the design of the beamsplitter. This will be shown using an example spectrograph, as could be used in a new 1.5 m class solar telescope.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Thomas Bluemchen and Achim M. Gandorfer "Characterization of polarising beamsplitters by ray tracing", Proc. SPIE 4843, Polarimetry in Astronomy, (14 February 2003);

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