Method and system for laser phase tracking for internal reflection subtraction in phase-encoded LIDAR

A system comprising:

• a laser that provides a plurality of optical signals;
• a modulator that modulates the plurality of optical signals from the laser to generate a plurality of modulated optical signals;
• an optical coupler that generates a plurality of reference optical signals, each associated with a respective optical signal of the plurality of optical signals from the laser, transmits the plurality of modulated optical signals into free space, and receives a plurality of returned optical signals responsive to transmitting the plurality of modulated optical signals into the free space;
• an optical mixer that mixes each of the plurality of returned optical signals with a respective reference optical signal of the plurality of reference optical signals to generate a respective mixed optical signal of a plurality of mixed optical signals;
• an optical detector that detects each mixed optical signal of the plurality of mixed optical signals to generate a respective electrical signal of a plurality of electrical signals;
• and
• a processor that:
• determines a first signal by adjusting a parameter of a first electrical signal of the plurality of electrical signals;
• determines a second signal by adjusting a parameter of a second electrical signal of the plurality of electrical signals;
• determines an internal reflection signal indicative of an internal reflection of one or more optical components based on the first signal and the second signal;
• determines a third signal by adjusting a third electrical signal of the plurality of electrical signals using the internal reflection signal;
• and
• operates a vehicle based on the third signal.