A light source includes a plurality of light-emitting units arranged in a two-dimensional array. An optical element changes divergence angles of laser beams from the light-emitting units. A splitting element splits a part of each of the laser beams passing through the optical element. A compensating element compensates for a fluctuation in the divergence angle of each of the laser beams incident on the splitting element due to a change of temperature. A light-receiving element receives laser beams split by the splitting element. The light source, the optical element, the splitting element, the compensating element, and the light-receiving element are integrally supported.