Design and Performance Analysis of a Highly Efficient Polychromatic Full-Stokes Polarization Modulator for the CRISP Imaging Spectrometer

Abstract

We present the design and performance of a polychromatic polarization modulator for the CRisp Imaging SpectroPolarimeter (CRISP) Fabry-Perot tunable narrow-band imaging spectropolarimer at the Swedish 1-m Solar Telescope (SST). We discuss the design process in depth, compare two possible modulator designs through a tolerance analysis, and investigate thermal sensitivity of the selected design. The trade-offs and procedures described in this paper are generally applicable in the development of broadband polarization modulators. The modulator was built and has been operational since 2015. Its measured performance is close to optimal between 500 and 900~nm, and differences between the design and as-built modulator are largely understood. We show some example data, and briefly review scientific work that used data from SST/CRISP and this modulator.

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Cited by in corpus (7)

• SSTRED: Data- and metadata-processing pipeline for CHROMIS and CRISP
• DeSIRe: Departure coefficient aided Stokes Inversion based on Response functions
• High flow speeds and transition-region like temperatures in the solar chromosphere during flux emergence
• Improved reconstruction of solar magnetic fields from imaging spectropolarimetry through spatio-temporal regularisation
• A reconnection driven magnetic flux cancellation and a quiet Sun Ellerman bomb
• The making of robust and highly performing imaging spectropolarimeters for large solar telescopes
• Decay of a photospheric transient filament at the boundary of a pore and the chromospheric response