Polarimetric optical imaging of scattering surfaces

A polarimetric optical specular event detector (OSED) has been developed to provide spatially and temporally resolved polarimetric data of backscattering in the visible from water wave surfaces. The OSED acquires simultaneous, two-dimensionally resolved images of the remote target in two orthogonal planes of polarization. With the use of plane-polarized illumination the OSED presently can measure, in an ensemble of breaking waves, the equivalent four-element polarization matrix common to polarimetric radars. Upgrade to full Stokes parameter state of polarization measurements is straightforward with the use of present single-aperture, multi-imager CCD camera technology. The OSED is used in conjunction with a coherent pulse-chirped radar (PCR), which also measures the four-element polarization matrix, to provide direct time-correlated identification of backscattering mechanisms operative during wave-breaking events which heretofore have not been described theoretically. We describe the instrument and its implementation, and examples of spatially resolved polarimetric data are displayed as correlated with the PCR backscatter cross section and polarization ratio records.