Optical interference range sensor

An optical interference ranging sensor comprising:

• a light source configured to project a light beam while continuously varying a wavelength thereof;
• an interferometer comprising a splitting unit including a coupler configured to split the light beam projected from the light source into light beams radiated toward a plurality of spots on a measurement target, the interferometer being configured to generate interference beams with the light beams split in correspondence with the plurality of spots, each of the interference beams being generated by interference between a measurement beam radiated toward the measurement target and reflected at the measurement target and a reference beam passing through an optical path that is at least partially different from an optical path of the measurement beam;
• a light-receiving unit comprising a photodetector configured to receive the interference beams from the interferometer;
• and
• a processor configured to perform operations comprising detecting a peak of the received interference beams, and calculating a distance to the measurement target by associating the detected peak with one of the plurality of spots in accordance with a mirror surface mode or a rough surface mode, which are modes for measuring the measurement target, wherein
• an optical path length difference between the measurement beam and the reference beam is made different among the light beams split in correspondence with the plurality of spots, and
• in the mirror surface mode, the processor uses, as a result of measuring the distance to the measurement target, a distance calculated based on a peak corresponding to a spot for which the optical path length difference is shortest, out of a plurality of the detected peaks.