The estimation of the instrumental polarization and crosstalk at the focus of the mid-infrared imaging system for the Thirty Meter Telescope

Ramya M. Anche; Chris Packham; G. C. Anupama; K. Sankarasubramanian; Maheswar Gopinathan; Manoj Puravankara

doi:10.1117/12.2312558

11 July 2018 The estimation of the instrumental polarization and crosstalk at the focus of the mid-infrared imaging system for the Thirty Meter Telescope

Ramya M. Anche, Chris Packham, G. C. Anupama, K. Sankarasubramanian, Maheswar Gopinathan, Manoj Puravankara

Author Affiliations +

Proceedings Volume 10702, Ground-based and Airborne Instrumentation for Astronomy VII; 1070298 (2018) https://doi.org/10.1117/12.2312558
Event: SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States

Abstract

The Thirty Meter Telescope (TMT) is a proposed future generation telescope which will be located on either Maunakea, Hawaii or La Palma in the Canary islands. A thermal-infrared (TIR) imager and spectrometer (MICHI) combined with an adaptive optics system is being investigated as a possible second-generation instrument for this telescope. MICHI has been designed to also have a polarimetry capability in both imaging and low dispersion spectroscopic modes. Using polarization ray tracing in Zemax, we have estimated the instrumental polarization (IP) and crosstalk introduced at the focus of the near- and mid-infrared imaging system. In our calculations, we find that the IP varies from 1.0-0.54% and 0.54-0.42%, whereas the polarization crosstalk varies between 25-4% and 4-0.7%, in the near and TIR regions respectively at the instrument port of MICHI. These values of IP and crosstalk may cause problems during the high absolute accuracy polarization observations. Here we present the polarization effects for the imaging system of MICHI and it impacts on the polarization observations.

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Ramya M. Anche, Chris Packham, G. C. Anupama, K. Sankarasubramanian, Maheswar Gopinathan, and Manoj Puravankara "The estimation of the instrumental polarization and crosstalk at the focus of the mid-infrared imaging system for the Thirty Meter Telescope", Proc. SPIE 10702, Ground-based and Airborne Instrumentation for Astronomy VII, 1070298 (11 July 2018); https://doi.org/10.1117/12.2312558

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