Coherent lidar method and apparatus

Abstract

A coherent LIDAR method and apparatus are provided, in which two optical signals having a first frequency difference are reflected by an object. A difference in frequency between the corresponding received and reflected signals is determined. The frequency difference between the reflected signals differs from the first frequency difference due to Doppler effects. The object velocity is determined based on a comparison between the first frequency difference and the frequency difference in the reflected signals. The emitted signals can be produced by modulating a common light source. The reflected signals are inherently mixed at the receiver and further processed. Distance to the object can be determined by pulsing the emitted signals and measuring a time of flight by detecting corresponding pulse edges in the reflected signals, or by using phase sweeping. The emitter can be implemented using an optical phased array.

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