Profiling on a Slant Path with a Dual-Beacon Hartmann Turbulence Sensor

A dual-beacon Hartmann Turbulence Sensor (HTS) was used to estimate atmospheric turbulence profiles along a 1.8 km long slant path. This HTS uses a 16“ telescope and has 700 active subapertures. Its camera can take frames as fast as 8 kHz. The laser beacons were placed near the top of a 12 story high tower while the HTS telescope was located in a field 1848 meters away. While the field where the HTS was located was mostly flat for the first few hundred meters in the direction of the tower the ground then sloped up gradually gaining 60 meters by the time the path reached the tower. The terrain beneath the beam path was quite variegated with grassy fields, roads, forested areas and buildings giving the potential for changing turbulence along the path. The experiment was also conducted at different times of day and night and in different weather conditions to further vary the turbulence encountered. The techniques used to profile turbulence with this dual-beacon HTS will be reviewed and the results from this experimental campaign will be presented. Several other turbulence measurement systems were operating at locations near and along this path providing some other measurements for comparison.