Development of differential image motion LiDAR for profiling optical turbulence

The tropospheric profile of the atmospheric refractive index structure characteristic is required for several applications, including performance analyses of astronomical adaptive optics systems, astronomical site surveys, and validation of atmospheric turbulence prediction models. Based on the research of differential image motion detection principle and feasibility, a turbulence profile LiDAR for measuring range profiles of atmospheric optical turbulence was developed. Compared with traditional techniques, this system was insensitive to instrumental problems, such as defocus and vibrations. The profiles of the strength of refractive turbulence and differential image motion were measured initiatively and in real time by this system. In the field experiment, the turbulence in 200-8 000 m atmosphere was measured. The range resolution of this system is 200-1 000 m, altogether 13 measured positions. Each position observed 20 seconds and got 1 000 images with a 50 Hz frame rate ICCD camera, the differential image motion of each position calculated through those images, and retrieve the result to the strength of refractive turbulence profile. Preliminary data of this field experiment shows that the LiDAR is operating properly.