Ultraviolet vs. Visible Skylight Polarization Measurements

Concerning autonomous navigation in GNSS-denied environments, insects like bees, ants, locusts and butterflies are certainly the cup winners. Bees and some ants are known to be sensitive to polarized light, both in ultraviolet (UV) and visible spectra, and to use it for their outside moving heading calculation. Therefore, we chose to compare UV and visible skylight polarization measurements in order to understand how UV could be used to improve heading estimation by processing the skylight's angle of polarization patterns. We then used a commercial polarimetric camera sensitive to visible polarized light and a UV-sensitive camera enhanced with polarized light measurement ability.