Near space demonstration of a compact LWIR spectro-polarimeter for ice cloud measurements

An InfraRed Channeled Spectro-Polarimeter (IRCSP) was demonstrated in the near space environment as a piggyback out of NASA Columbia Scientific Ballooning Facility. The compact IRCSP is sensitive to linearly polarized long-wave infrared (LWIR) light between 7-12 microns and targets cloud micro-physical properties. Post landing the instrument was retrieved with no damage to the optical payload and collected over 150 minutes of flight data at altitudes above 30 km. The results collected both demonstrate the operation of uncooled microbolometers in the low pressure environment and are the first know high-altitude observations of a polarized signal from cloud tops in the LWIR. During deployment, the IRCSP reported brightness temperatures between 250-285K with uncertainty of < 1:5K. In addition, statistically significant polarization modulation with degrees of linear polarization (DoLP) between 1 - 20% and preferential angle of linear polarization (AoLP) trends were detected. These results support the hypothesis that the LWIR polarimetry has the potential to add new sensitivity to existing remote sensing platforms.