Novel satellite positioning system using acousto-optic deflector

Space gravitational wave detector in Japan named DECIGO is equilateral triangle-shaped laser interferometer with the arm length of 1000 km. For initial alignment and keeping formation of DECIGO, we propose novel satellite positioning system. Our system consists of a single-mode laser, acousto-optic deflectors (AOD) and a frequency counter. The diffraction beam from AOD deflects with the deflection angle which is proportional to the modulation frequency of AOD. The modulation frequency is swept to scan the angle of the deflected beam, and, at the remote end, a photo detector derives its position from the detected modulation frequency of the scanned deflected beam. Compared with the conventional optical method, our system is compact and has no moving elements, and the angle resolution of our system depends on not the optical diffraction limit but the resolution of frequency counting. In the current paper, we present the principle and the preliminary results of our system.