Reflection-Polarization Pattern of the Flat Water Surface Measured by 180° Field-of-View Imaging Polarimetry

Abstract

Using 180° field-of-view imaging polarimetry, Gál et al. (2001b) recorded the reflection-polarization pattern of the flat water surface under a clear sky at sunset (Figs. 12.1, 12.2). Due to this technique, they could experimentally test and prove the validity of the theoretical predictions of Schwind and Horváth (1993) and Horváth (1995). Comparing the theoretical (Fig. 12.2B-D), semiempirical (Fig. 12.2E-G) and measured (Fig. 12.2H-J) reflection-polarization patterns of the flat water surface, a remarkable resemblance can be established between them. The reason for this close similarity is that the strong repolarization ability of the water surface overwhelms the slight differences between the polarization of the single-scattered Rayleigh skylight (Figs. 12.1A,B) and the real skylight (Figs. 12.1C,D). There are small, irrelevant differences between the measured (Figs. 12.2H-J) and predicted (Figs. 12.2E-G) reflection-polarization patterns, because the water surface was slightly undulating, and some light was scattered inside the water, then returned (this reemitted radiation from the water was not taken into consideration in the prediction).