2007PASP..119.1126M

In this paper we present the design, calibration method, and initial results of the Dual-Beam Imaging Polarimeter (DBIP). This new instrument is designed to measure the optical polarization properties of point sources, in particular, Main Belt asteroids. This instrument interfaces between the Tek 2048x2048 camera and the University of Hawaii's 88 inch telescope and is available for facility use. Using DBIP we are able to measure linear polarization with a 1 σ Poisson signal noise of 0.03% per measurement and a systematic error of order 0.06%±0.02%. In addition, we discuss measurements of the polarization of the asteroid 16 Psyche that were taken as part of the instrument commissioning. We confirm Psyche's negative polarization of -1.037%±0.006% but find no significant modulation of the signal with rotation above the 0.05% polarization level.