Remote sensing of the Earth´s surface with an airborne polarized laser

A new remote sensing instrument, the Airborne Laser Polarization Sensor (ALPS), is making the first multispectral radiometric and polarization measurements of the Earth´s surface using a polarized laser light source. Results from data flights taken over boreal forests in Maine at 1060 and 532 nm, using a Nd:YAG laser source, showing depolarization signatures for three broadleaf and five coniferous tree species, are discussed. Measurements made over nonforest ground cover had a large dynamic range in depolarization values at both wavelengths. The ALPS system use twelve photomultiplier tube detectors configurable to measure desired parameters such as the total backscatter and the polarization state, including the azimuthal angle and ellipticity, at different ultraviolet to near-infrared wavelengths simultaneously. Measurements of the azimuth and ellipticity of the backscatter polarization were variable and no specific conclusions have yet been drawn