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arXiv · 2602.03233

SQUIDPOL: Seoul National University QUadruple Imaging Device for POLarimetry

Sunho Jin·Jooyeon Geem·Masateru Ishiguro·Woojin Park·Heeyoung Oh·Chan Park·Seungwon Choi·Yoonsoo P. Bach·Hyeonwoo Ju·Jinguk Seo·Bumhoo Lim·Myungshin Im
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Abstract

We present SQUIDPOL, a low-cost, multi-channel optical imaging polarimeter that performs simultaneous linear polarization measurements using a rotating half-wave plate, a non-polarizing beam splitter, and four wire-grid filters. We show that the off-the-shelf non-polarizing beam splitter introduces measurable polarization-dependent systematics, which can bias polarimetric measurements if left uncorrected. We quantify this effect for both transmitted and reflected beams and incorporate a correction scheme into the data-analysis pipeline. On-sky validation demonstrates stable and reproducible performance, achieving a polarization accuracy of about 0.15 percent for bright polarized standard stars. Mounted on the 60-cm Ritchey-Chretien telescope (focal length 4200 mm, f/7) at the Pyeongchang Observatory of Seoul National University, SQUIDPOL provides an effective common field of view of 13.5 by 8.2 arcminutes with a pixel scale of 0.45 arcseconds per pixel and supports standard B, V, R_C, and I_C filters.

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Sunho Jin, Jooyeon Geem, Masateru Ishiguro, Woojin Park, Heeyoung Oh, Chan Park, Seungwon Choi, Yoonsoo P. Bach, Hyeonwoo Ju, Jinguk Seo, Bumhoo Lim, Myungshin Im. 2026-02-03. SQUIDPOL: Seoul National University QUadruple Imaging Device for POLarimetry. https://arxiv.org/abs/2602.03233

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