| （英） |
Ground-to-satellite laser communication experiments between the optical ground station located in the Koganei ward of downtown Tokyo and the low earth orbit (LEO) satellite, Optical Inter-orbit Communications Engineering Test Satellite (OICETS), also known as “Kirari”, were conducted in March and May, 2006. Optical communication links through the atmosphere are affected by the refractive index fluctuation in the atmosphere, making measurement and evaluation of atmospheric turbulence crucial issues. The Differential Image Motion Monitor (DIMM) method was used to estimate atmospheric coherence length, hence the seeing size as well, on the ground to satellite optical link. In the DIMM method, several beam spots are formed on the CCD, and the relative motions between the beam spots are calculated as the relative variance of the centers of the spots, which protects the telescope from the effects of vibrational noise and tracking error of the satellite. In contrast to stellar observation, an additional turbulence factor due to the fast movement of the telescope must be considered for ground to satellite optical links. We present the results of our measurements of atmospheric turbulence and estimate the parameters of the analytical model based on those measurements. |