A coherent laser range finder based on optical phase modulation and phase shift measurement is presented. In the proposed laser range finder, the emitted laser is modulated by an electro-optic phase modulator using a 20 MHz sine signal, and the received laser is mixed with a local oscillator using a 90° optical hybrid. Compared with traditional laser phase shift range finders, the proposed laser range finder can measure the velocity and range at high precision simultaneously. An algorithm to calculate the range and velocity is deduced. Our preliminary experiments on moving targets indicate that when the measurement rate is 100 kHz, the root mean square errors of range and velocity, respectively, are 9.35 × 10 − 4 m and 4.74 × 10 − 4 m / s .

We propose a laser nutation tracking sensor for beaconless laser communication, which uses a micro-electro-mechanical system (MEMS) mirror to achieve high-efficiency and large-amplitude nutation at its resonant frequency. We derive a new formula for the case of incompletely detectable optical power in the nutation cycle. In the experiment, we measure the performance of the sensor in calculating boresight error under three different nutation radii. Combining with the proposed algorithm for the new scene, we complete the accurate boresight calculation in the range of ± 200 µ r a d , at the nutation radius of 4.9 µm. We trust that the receiving field of view (FOV) of this tracking sensor can be further expanded by increasing the nutation radius. The sensor, as proposed in this paper, will be of constructive help to simplify tracking systems in the future.

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