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Analysis of polarization introduced due to the telescope optics of the Thirty Meter Telescope

Anche, Ramya Manjunath and Sen, Asoke Kumar and Anupama, Gadiyara Chakrapani and Sankarasubramanian, Kasiviswanathan and Skidmore, Warren (2018) Analysis of polarization introduced due to the telescope optics of the Thirty Meter Telescope. Journal of Astronomical Telescopes, Instruments, and Systems, 4 (1). Art. No. 018003. ISSN 2329-4124. doi:10.1117/1.JATIS.4.1.018003.

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An analytical model has been developed to estimate the polarization effects, such as instrumental polarization (IP), crosstalk (CT), and depolarization, due to the optics of the Thirty Meter Telescope. These are estimated for the unvignetted field-of-view and the wavelengths of interest. The model estimates an IP of 1.26% and a CT of 44% at the Nasmyth focus of the telescope at the wavelength of 0.6 μm at field angle zero with the telescope pointing to zenith. Mueller matrices have been estimated for the primary, secondary, and Nasmyth mirrors. It is found that some of the Mueller matrix elements of the primary and secondary mirrors show a fourfold azimuthal antisymmetry, which indicates that the polarization at the Cassegrain focus is negligible. At the inclined Nasmyth mirror, there is no azimuthal antisymmetry in the matrix elements, and this results in nonzero values for IP and CT, which would negatively impact the polarization measurements at the telescope focus. The averaged Mueller matrix is estimated at the Nasmyth focus at different instrument ports and various zenith angles of the telescope. The variation in the Mueller matrix elements for different coatings is also estimated. The impact of this polarization effect on the science case requirements has been discussed. This analysis will help in achieving precise requirements for future instruments with polarimetric capability.

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Additional Information:© 2018 SPIE. Paper 17025P received Jun. 10, 2017; accepted for publication Dec. 18, 2017; published online Jan. 22, 2018. Authors would like to thank the referee for useful comments. Authors would also like to thank TMT project and all the members of the TMT polarimetry modeling team.
Group:Thirty Meter Telescope
Subject Keywords:instrumental polarization; crosstalk; ray tracing; analytical method; Mueller matrix; Thirty Meter Telescope
Issue or Number:1
Record Number:CaltechAUTHORS:20180425-165415146
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Official Citation:Ramya Manjunath Anche, Asoke Kumar Sen, Gadiyara Chakrapani Anupama, Kasiviswanathan Sankarasubramanian, Warren Skidmore, "Analysis of polarization introduced due to the telescope optics of the Thirty Meter Telescope," J. Astron. Telesc. Instrum. Syst. 4(1) 018003 (22 January 2018)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86049
Deposited By: George Porter
Deposited On:27 Apr 2018 15:25
Last Modified:15 Nov 2021 20:34

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