Polarization azimuth angle in daylight scenes

Abstract

Lord Rayleigh derived the degree of polarization for singular molecular scattering phenomena in the atmosphere as a function of the relative angular orientations of the source, scattering center, and observer. This paper extends the Rayleigh model by giving the azimuth angle for the linearly polarized scattered radiation detected by the observer. Together these two parameters give a complete Stokes vector characterization of Rayleigh scattering in the earth-horizon coordinate system. An experimental validation confirms the analytical results. The validation methodology uses a polarization axis finder attached to a commercial off-the-shelf digital camera. Each image supplies enough information to calculate the skylight polarization azimuth angle in real time. The equation for the skylight polarization azimuth angle is used to create a pictorial representation of the polarized sky by using colors to represent azimuth angles. A color scheme is used to display the degree of polarization and the polarization azimuth angle of a vehicle at several different times in daylight. An analysis of the reflected polarized light from the vehicle is included.

High-speed imaging chopper polarimetry

“…In a previous paper 9 we derive an equation for the polarization azimuth angle of skylight in the earthhorizon coordinate system, as given Eq. (23).…”