Astronomical Polarimetry with the RIT Polarization Imaging Camera

TL;DR

This paper evaluates the RIT Polarization Imaging Camera, a micropolarizer-based sensor, for astronomical use, demonstrating its ability to detect very low polarization signals and its potential as a compact, robust tool for astronomy.

Contribution

The study develops calibration and demodulation procedures for the RITPIC camera, assessing its performance for astronomical polarimetry in low signal-to-noise conditions.

Findings

Capable of detecting polarization signals as small as 0.3%

Characterized pixel throughput, efficiency, and orientation across wavelengths

Demonstrated suitability for astronomical targets with easy calibration

Abstract

In the last decade, imaging polarimeters based on micropolarizer arrays have been developed for use in terrestrial remote sensing and metrology applications. Micropolarizer-based sensors are dramatically smaller and more mechanically robust than other polarimeters with similar spectral response and snapshot capability. To determine the suitability of these new polarimeters for astronomical applications, we developed the RIT Polarization Imaging Camera to investigate the performance of these devices, with a special attention to the low signal-to-noise regime. We characterized the device performance in the lab, by determining the relative throughput, efficiency, and orientation of every pixel, as a function of wavelength. Using the resulting pixel response model, we developed demodulation procedures for aperture photometry and imaging polarimetry observing modes. We found that, using the current calibration, RITPIC is capable of detecting polarization signals as small as $\sim0.3\%$. The relative ease of data collection, calibration, and analysis provided by these sensors suggest than they may become an important tool for a number of astronomical targets.