Linear polarization of light by two wheat canopies measured at many view angles.

Reports research to understand how visible light is linearly polarized and reflected by wheat as a function of sun-view directions, crop development stage, and wavelength. The analysis is based on 200 spectra taken continuously in wavelength from 0.45 to 0.72 micrometer in 33 view directions using an Exotech model 20C spectroradiometer 6 meters above two wheat canopies in the boot and fully headed maturity stages. The results show that the amount of linearly polarized light from the wheat canopies is greatest in the blue spectral region and decreases gradually with increasing wavelength, and that the linearly polarized light from the canopies is generally greatest in the azimuth direct of the sun and tends toward zero as the view direction tends toward the direction of the hot spot or anti-solar point. -from Authors