A Caltech Library Service

Full characterization of the instrumental polarization effects of the spectropolarimetric mode of SCExAO/CHARIS

't Hart, G. J. Joost and van Holstein, Rob G. and Bos, Steven P. and Ruigrok, Jasper and Snik, Frans and Lozi, Julien and Guyon, Olivier and Kudo, Tomoyuki and Zhang, Jin and Jovanovic, Nemanja and Norris, Barnaby and Martinod, Marc-Antoine and Groff, Tyler D. and Chilcote, Jeffrey and Currie, Thayne and Tamura, Motohide and Vievard, Sébastien and Sahoo, Ananya and Deo, Vincent and Ahn, Kyohoon and Martinache, Frantz and Kasdin, Jeremy (2021) Full characterization of the instrumental polarization effects of the spectropolarimetric mode of SCExAO/CHARIS. In: Polarization Science and Remote Sensing X. Proceedings of SPIE. No.11833. Society of Photo-Optical Instrumentation Engineers , Bellingham, WA, Art. No. 118330O.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Submitted Version
Creative Commons Attribution.


Use this Persistent URL to link to this item:


SCExAO at the Subaru telescope is a visible and near-infrared high-contrast imaging instrument employing extreme adaptive optics and coronagraphy. The instrument feeds the near-infrared light (JHK) to the integralfield spectrograph CHARIS. The spectropolarimetric capability of CHARIS is enabled by a Wollaston prism and is unique among high-contrast imagers. We present a detailed Mueller matrix model describing the instrumental polarization effects of the complete optical path, thus the telescope and instrument. From measurements with the internal light source, we find that the image derotator (K-mirror) produces strongly wavelength-dependent crosstalk, in the worst case converting ∼95% of the incident linear polarization to circularly polarized light that cannot be measured. Observations of an unpolarized star show that the magnitude of the instrumental polarization of the telescope varies with wavelength between 0.5% and 1%, and that its angle is exactly equal to the altitude angle of the telescope. Using physical models of the fold mirror of the telescope, the half-wave plate, and the derotator, we simultaneously fit the instrumental polarization effects in the 22 wavelength bins. Over the full wavelength range, our model currently reaches a total polarimetric accuracy between 0.08% and 0.24% in the degree of linear polarization. We propose additional calibration measurements to improve the polarimetric accuracy to <0.1% and plan to integrate the complete Mueller matrix model into the existing CHARIS post-processing pipeline. Our calibrations of CHARIS’ spectropolarimetric mode will enable unique quantitative polarimetric studies of circumstellar disks and planetary and brown dwarf companions.

Item Type:Book Section
Related URLs:
URLURL TypeDescription Paper
van Holstein, Rob G.0000-0003-1520-8405
Snik, Frans0000-0003-1946-7009
Lozi, Julien0000-0002-3047-1845
Guyon, Olivier0000-0002-1097-9908
Kudo, Tomoyuki0000-0002-9294-1793
Jovanovic, Nemanja0000-0001-5213-6207
Norris, Barnaby0000-0002-8352-7515
Martinod, Marc-Antoine0000-0002-0989-9302
Groff, Tyler D.0000-0001-5978-3247
Chilcote, Jeffrey0000-0001-6305-7272
Currie, Thayne0000-0002-7405-3119
Tamura, Motohide0000-0002-6510-0681
Vievard, Sébastien0000-0003-4018-2569
Sahoo, Ananya0000-0003-2806-1254
Deo, Vincent0000-0003-4514-7906
Ahn, Kyohoon0000-0002-1094-852X
Martinache, Frantz0000-0003-1180-4138
Kasdin, Jeremy0000-0002-6963-7486
Alternate Title:Full characterization of the instrumental polarization effects of the spectropolarimetric mode of SCExAO-CHARIS
Additional Information:© 2021 Society of Photo-Optical Instrumentation Engineers (SPIE). Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are very fortunate to have the opportunity to conduct observations from this mountain. The research of S.P. Bos and F. Snik leading to these results has received funding from the European Research Council under ERC Starting Grant agreement 678194 (FALCONER). The development of SCExAO was supported by the Japan Society for the Promotion of Science (Grant-in-Aid for Research #23340051, #26220704, #23103002, #19H00703 & #19H00695), the Astrobiology Center of the National Institutes of Natural Sciences, Japan, the Mt Cuba Foundation and the director's contingency fund at Subaru Telescope.
Funding AgencyGrant Number
European Research Council (ERC)678194
Japan Society for the Promotion of Science (JSPS)23340051
Japan Society for the Promotion of Science (JSPS)26220704
Japan Society for the Promotion of Science (JSPS)23103002
Japan Society for the Promotion of Science (JSPS)19H00703
Japan Society for the Promotion of Science (JSPS)19H00695
National Institutes of Natural Sciences of JapanUNSPECIFIED
Mt. Cuba Astronomical FoundationUNSPECIFIED
Subaru TelescopeUNSPECIFIED
Subject Keywords:SCExAO-CHARIS, spectropolarimetry, high-contrast imaging, near-infrared, instrumental polarization, crosstalk, Mueller matrix model, polarimetric accuracy
Series Name:Proceedings of SPIE
Issue or Number:11833
Record Number:CaltechAUTHORS:20210820-225225188
Persistent URL:
Official Citation:Joost G. J. 't Hart, Rob G. van Holstein, Steven P. Bos, Jasper Ruigrok, Frans Snik, Julien Lozi, Olivier Guyon, Tomoyuki Kudo, Jin Zhang, Nemanja Jovanovic, Barnaby Norris, Marc-Antoine Martinod, Tyler D. Groff, Jeffrey Chilcote, Thayne Currie, Motohide Tamura, Sébastien Vievard, Ananya Sahoo, Vincent Deo, Kyohoon Ahn, Frantz Martinache, and Jeremy Kasdin "Full characterization of the instrumental polarization effects of the spectropolarimetric mode of SCExAO/CHARIS", Proc. SPIE 11833, Polarization Science and Remote Sensing X, 118330O (9 August 2021);
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110335
Deposited By: Tony Diaz
Deposited On:21 Aug 2021 18:22
Last Modified:15 Sep 2021 21:08

Repository Staff Only: item control page