Backscattering from the littoral air medium in an airborne diode laser system

摘要

During the recent nighttime testing of the Airborne Laser Diode Array Illuminator (ALDAI) system in a humid and aerosol-rich environment, it was found that the laser backscatter competed with the ground-reflected signal at higher altitudes. Such an effect was stronger in the polarization channel parallel to the outgoing illumination. Theoretical calculations indicated that most of the scattering was taking place in the first few feet of overlap between the outgoing illumination and the field of regard. To test this, the laser was pointed into a geometry which had no target field, that scattered solely into the air. Backscattered returns were reduced and plotted versus source-receiver separation distance.