Systems design, assembly, integration and lab testing of WALOP-South Polarimeter
Paper in proceeding, 2024
Wide-Area Linear Optical Polarimeter (WALOP)-South is the first wide-field and survey-capacity polarimeter in the optical wavelengths. On schedule for commissioning in 2024, it will be mounted on the 1 m SAAO telescope in Sutherland Observatory, South Africa to undertake the PASIPHAE sky survey. PASIPHAE program will create the first polarimetric sky map in the optical wavelengths, spanning more than 2000 square degrees of the southern Galactic region. In a single exposure, WALOP-South's innovative design will enable it to measure the linear polarization (Stokes parameters q and u) of all sources in a field of view (FoV) of 35 × 35 arc-minutes-squared in the SDSS-r broadband and narrowband filters between 500-750 nm with 0.1 % polarization accuracy. The unique goals of the instrument place very stringent systems engineering goals, including on the performance of the optical, polarimetric, optomechanical, and electronic subsystems. In particular, the major technical hurdles for the project included the development of: (a) an optical design to achieve imaging quality PSFs across the FoV, (b) an optomechanical design to obtain high accuracy optical alignment in conjugation with minimal instrument flexure and stress birefringence on optics (which can lead to variable instrumental polarization), and (c) an on-sky calibration routine to remove the strong polarimetric cross-talk induced instrumental polarization to obtain 0.1% across the FoV. All the subsystems have been designed carefully to meet the overall instrument performance goals. As of May 2024, all the instrument optical and mechanical subsystems have been assembled and are currently getting tested and integrated. The complete testing and characterization of the instrument in the lab is expected to be completed by August 2024. While the instrument was initially scheduled for commissioning in 2022, it got delayed due to various technical challenges; WALOP-South is now on schedule for commissioning in second half of 2024. In this paper, we will present (a) the design and development of the entire instrument and its major subsystems, focusing the instrument's opto-mechanical design which has not been reported before, and (b) assembly and integration of the instrument in the lab and early results from lab characterization of the instrument's optical performance.
stellar polarization
WALOP
imaging polarimetry
wide field camera
polarization
PASIPHAE
polarimetry
linear polarimetry
optical polarimeter
Author
S. Maharana
Foundation for Research and Technology Hellas (FORTH)
Inter-University Centre for Astronomy and Astrophysics
South African Astronomical Observatory
A. N. Ramaprakash
Inter-University Centre for Astronomy and Astrophysics
California Institute of Technology (Caltech)
Foundation for Research and Technology Hellas (FORTH)
Chaitanya Rajarshi
Inter-University Centre for Astronomy and Astrophysics
Pravin Khodade
Inter-University Centre for Astronomy and Astrophysics
Bhushan Joshi
Inter-University Centre for Astronomy and Astrophysics
Pravin Chordia
Inter-University Centre for Astronomy and Astrophysics
Abhay Kohok
Inter-University Centre for Astronomy and Astrophysics
R. M. Anche
Inter-University Centre for Astronomy and Astrophysics
University of Arizona
Deepa Modi
South African Astronomical Observatory
J. A. Kypriotakis
University of Crete
Foundation for Research and Technology Hellas (FORTH)
Amit Deokar
Inter-University Centre for Astronomy and Astrophysics
Aditya Kinjawadekar
Inter-University Centre for Astronomy and Astrophysics
S. B. Potter
South African Astronomical Observatory
University of Johannesburg
D. Blinov
Saint Petersburg State University - Spsu
Foundation for Research and Technology Hellas (FORTH)
University of Crete
H. K. Eriksen
University of Oslo
M. Falalaki
University of Crete
Foundation for Research and Technology Hellas (FORTH)
Hitesh Gajjar
South African Astronomical Observatory
T. Ghosh
National Institute of Science Education and Research
E. Gjerløw
University of Oslo
Sebastain Kiehlmann
Foundation for Research and Technology Hellas (FORTH)
University of Crete
I. Liodakis
Foundation for Research and Technology Hellas (FORTH)
University of Crete
N. Mandarakas
Foundation for Research and Technology Hellas (FORTH)
University of Crete
Georgia Virginia Panopoulou
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
V. Pavlidou
University of Crete
Foundation for Research and Technology Hellas (FORTH)
T. J. Pearson
California Institute of Technology (Caltech)
V. Pelgrims
University of Crete
Foundation for Research and Technology Hellas (FORTH)
Université libre de Bruxelles (ULB)
A. C.S. Readhead
California Institute of Technology (Caltech)
Foundation for Research and Technology Hellas (FORTH)
R. Skalidis
California Institute of Technology (Caltech)
Konstantinos Tassis
University of Crete
Foundation for Research and Technology Hellas (FORTH)
Namita Uppal
University of Crete
Foundation for Research and Technology Hellas (FORTH)
I. K. Wehus
University of Oslo
Proceedings of SPIE - The International Society for Optical Engineering
0277786X (ISSN) 1996756X (eISSN)
Vol. 13096 130967P9781510675155 (ISBN)
Ground-Based and Airborne Instrumentation for Astronomy X 2024
Yokohama, Japan,
Yokohama, Japan,
Subject Categories
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
DOI
10.1117/12.3016144