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[18.01] Design and Calibration of a Near IR Adaptive Optics Imaging Polarimeter for Lick Observatory

M. Perrin, J. Lloyd, P. Kalas, J. R. Graham (UC Berkeley Astronomy Department)

We have modified IRCAL, the near-IR science camera used with the Lick Observatory adaptive optics system, to add an imaging polarimetry mode. This mode uses an optically contacted YLF (LiYF₄) Wollaston prism to provide dual, simultaneous images of perpendicular polarizations. This system is intended for high resolution, high dynamic range polarimetry in the near infrared, particularly for studies of star forming regions and circumstellar disks. We describe the design, construction, and calibration of the polarimeter and present the results of initial astronomical observations taken during spring and summer 2002.

Initial results are promising, with the YLF Wollaston prism delivering excellent polarizing efficiency without compromising image quality. An instrumental polarization of about 2% in all three NIR bands arises predominantly from the dichroic in the AO system, but appears to be constant over time and should not negatively affect system performance. For several previously studied polarized sources, our data have good agreement with prior work, validating our techniques, but have generally higher spatial resolution, providing new insight into detailed structure.

This work was supported by the NSF Center for Adaptive Optics, managed by UC Santa Cruz under AST-9876783.

The author(s) of this abstract have provided an email address for comments about the abstract: mperrin@astro.berkeley.edu

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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.