Remote detection of a rotator based on rotational Doppler effect

Based on the rotational Doppler effect arising from optical orbital angular momentum, we proposed the detection system of a rotator over a distance, by probing the object with a Laguerre-Gauss beam and a Kepler telescope. The angular velocities in tens of meters detection distances can be detected by analyzing the returned beating signals. Different probe beams with various topological charges from l = +/- 25 to l = +/- 45 are employed. The biggest measurement error is 1.15 Hz. This scheme proves the feasibility of a practical sensor to detect a rotator remotely. (C) 2020 The Japan Society of Applied Physics.