The polychromatic polarization modulator

Alfred G. de Wijn; Steven Tomczyk; Roberto Casini; Peter G. Nelson

doi:10.1117/12.857745

20 July 2010 The polychromatic polarization modulator

Alfred G. de Wijn, Steven Tomczyk, Roberto Casini, Peter G. Nelson

Proceedings Volume 7735, Ground-based and Airborne Instrumentation for Astronomy III; 77354A (2010) https://doi.org/10.1117/12.857745
Event: SPIE Astronomical Telescopes + Instrumentation, 2010, San Diego, California, United States

Abstract

An increasing number of astronomical applications depend on the measurement of polarized light. For example, our knowledge of solar magnetism relies heavily on our ability to measure and interpret polarization signatures introduced by magnetic field. Many new instruments have consequently focused considerable attention on polarimetry. For solar applications, spectro-polarimeters in particular are often designed to observe the solar atmosphere in multiple spectral lines simultaneously, thus requiring that the polarization modulator employed is efficient at all wavelengths of interest. We present designs of polarization modulators that exhibit near-optimal modulation characteristics over broad spectral ranges. Our design process employs a computer code to optimize the efficiency of the modulator at specified wavelengths. We will present several examples of modulator designs based on rotating stacks of Quartz waveplates and Ferroelectric Liquid Crystals (FLCs). An FLC-based modulator of this design was recently deployed for the ProMag instrument at the Evans Solar Facility of NSO/SP. We show that this modulator behaves according to its design.

Citation Download Citation

Alfred G. de Wijn, Steven Tomczyk, Roberto Casini, and Peter G. Nelson "The polychromatic polarization modulator", Proc. SPIE 7735, Ground-based and Airborne Instrumentation for Astronomy III, 77354A (20 July 2010); https://doi.org/10.1117/12.857745

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