Multi- And Hyperspectral Polarimetric Imaging Of The Ocean Surface

A novel polarization camera (Teledyne DALSA) based on the Sony first polarization imaging sensor provides a high resolution broadband image of the object in 400-900 nm spectral range, where each pixel contains four subpixels bearing built-in linear polarizers oriented at the 0, 45, 90 and -45 degrees. With an additional lens it has a field of view (FOV) of about 40 degrees degrees. The camera was equipped with a filter wheel containing five band-pass filters, thus providing multi-spectral, multi-angular high quality polarimetric data with high spatial resolution. The camera has undergone radiometric calibration and was used in various illumination conditions and water environments in NYC area. Spatial and temporal distribution of water and sky Stokes vector components were characterized at various wind speeds. Polarization images were also used for the estimation of wave slope statistics from the ocean surface.Results are compared with concurrent measurements of total and polarized radiances by a state-of-the-art snapshot hyperspectral imager, which simultaneously acquires spectra with 4 nm spectral resolution in the wavelength range of 450-750nm, also with a 40 degrees FOV for 20 - 60 degrees viewing angles. A computer-controlled filter wheel was installed in front of the imager, allowing division-of-time Stokes vector images from the ocean surface.The combination of these two instruments allows to observe spectral and polarization properties of the wind-roughened ocean at high spatial and temporal resolution, with the goal of advancing our understanding of the air-water interface and in-water light propagation.