System and Methods Utilizing Optical Feedback for Zero-Range Measurement

A light detection and ranging (lidar) device, comprising:

• a rotatable mirror configured to rotate about a mirror rotation axis with a period of rotation;
• a transmitter configured to transmit, during the period of rotation of the rotatable mirror, a plurality of light pulses toward the rotatable mirror, wherein the rotatable mirror (i) reflects at least a first light pulse of the plurality of light pulses into an environment of the lidar device and (ii) reflects at least a second light pulse of the plurality of light pulses into an internal optical path;
• a receiver, wherein the receiver comprises a detector configured to (i) detect a reflected light pulse comprising a reflection of the first light pulse caused by an object in the environment and (ii) detect the second light pulse received via the internal optical path, wherein the internal optical path is defined at least in part by one or more internal reflectors that reflect the second light pulse toward the rotatable mirror such that the rotatable mirror reflects the second light pulse toward the receiver;
• and
• a controller configured to determine a distance to the object in the environment based on a time when the first light pulse is transmitted by the transmitter, a time when the reflected light pulse is detected by the detector, and a time when the second light pulse is detected by the detector.