Laser propagation through turbulence over land and sea

摘要

This paper will describe single and double path laser link measurements over land and sea. The laser system consisted of a CO_2 laser, a pointing and tracking head, a quadrant laser receiver, a 3-5 μm IR-camera, a TV camera and a laser range finder. For the naval scenario the laser system was placed in a building 18 m above water and corner cube targets and a single path receiver were placed on islands at 2.5, 5.5 and 16.5 km. For the land scenario the laser system was placed in a building about 13 meters above ground looking at targets and a single path receiver at 2 km range. Together with the laser registrations, separate instruments such as a scintillometer and a weather station were recording the meteorological parameters. The analysis contains evaluation of temporal and amplitude signal distributions, probability and mean time of fade and tracking performance. Results from single ended and double ended paths will be compared. Different ways of using this database for turbulence simulation and laser system performance predictions also in other wavelength regions will be discussed as well as the impact on applications including laser imaging, free-space laser communications and directed infrared countermeasures.