The IRCAL Polarimeter: Design, Calibration, and Data Reduction for an Adaptive Optics Imaging Polarimeter

Abstract

We have upgraded IRCAL, the near-infrared science camera of the Lick Observatory adaptive optics system, to add a dual-channel imaging polarimetry mode. This mode uses an optically contacted YLF (LiYF_4) Wollaston prism to provide simultaneous images in perpendicular linear polarizations, providing high resolution, high dynamic range polarimetry in the near infrared. We describe the design and construction of the polarimeter, discuss in detail the data reduction algorithms adopted, and evaluate the instrument's on-the-sky performance. The IRCAL polarimeter is capable of reducing the stellar PSF halo by about two orders of magnitude, thereby increasing contrast for studies of faint circumstellar dust-scattered light. We discuss the various factors that limit the achieved contrast, and present lessons applicable to future high contrast imaging polarimeters.

15 pages; accepted to PASP

References in corpus (7)

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Cited by in corpus (2)

• Speckle Suppression Through Dual Imaging Polarimetry, and a Ground-Based Image of the HR 4796A Circumstellar Disk
• Evidence for an Edge-On Disk around the Young Star MWC 778 from Infrared Imaging and Polarimetry