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

Abstract

Abstract. 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.

Polarization aberrations in next-generation giant segmented mirror telescopes (GSMTs)

“…The ELT coating has 60Å thick NiCrN x on the Zerodor substrate followed by 1100Å of silver, 3Å of NiCrN x , and finally 55Å thick aluminum-doped Si 3 N 4 (Schotsaert et al 2020). The TMT will have 65Å thick NiCrN x on the Zerodor substrate followed by 1100Å of silver, 6Å of NiCrN x , and finally 85Å thick Si 3 N 4 as the top layer (Anche et al 2018c). The GMT mirrors will be coated with bare aluminum.…”

“…In the case of ELT, de Juan Ovelar et al ( 2014) estimated an instrumental polarization (IP) of 6% and crosstalk (CT) of 30% at a wavelength of 0.55 µm with the primary mirror of ELT considered as a monolith. For the TMT with primary mirror as a monolith, Anche et al (2018c) estimates an IP of 4.5% to 0.6% and CT of 73% to 11% in the wavelength range of 0.4 µm to 2.583 µm for field angle and zenith angle equal to zero. Although these results indicate the source and magnitude of polarization introduced by the telescope optics, they focus more on the polarimetric instruments for these telescopes rather than the high-contrast imaging instruments.…”

Simulations of polarimetric observations of debris disks through the Roman Coronagraph Instrument

“…where, I 0 Any optical component in the system can either introduce or modify the incoming source polarization causing instrumental polarization, or polarization crosstalk. 22,23 These effects can be accounted for using the 4×4 Mueller matrix of the system, as explained in the next section.…”

Review on Complete Mueller Matrix Optical Scanning Microscopy Imaging

“…Over the last few decades, it has shown its efficiency in multiple areas showcasing its particular sensitivity to the medium structure and orientation [2]. As follows, it has been referred to a wide range of experimental applications from astrophysics [3,4], remote target detection [5][6][7][8], and micro/nanoparticles in a turbid or highly scattering medium [9][10][11][12][13][14]. Especially, Mueller matrix polarimetry is the most comprehensive method as it provides the full polarimetric response of a sample through its 4 × 4 Mueller matrix (MM).…”