A laser ranging system (5) includes a light source (32, 34) emitting a beam (31) of collimated light. A beam splitter (12) polarizes the beam with a first type of linear polarization. A wave plate (14) receives the beam from the beam splitter (12) and polarizes the beam with a circular polarization. A movable mirror (16) scans the beam across a target (22), receives a return beam (17) from the target, and reflects the return beam toward the wave plate (14). The wave plate polarizes the return beam with a second type of linear polarization. The beam splitter (12) receives the return beam (23) from the wave plate (14). A detector (20) detects arrival of the return beam from the beam splitter (12). A circuit (18) determines a distance to the target as a function of a time interval between emission of the beam (31) of collimated light and arrival of the return beam (23).