A laser includes a light source, a scanning unit, a receiving lens, a homogenizing unit, a light detection unit, and a processing unit. The light source is configured to output a laser beam. The scanning unit is configured to guide the laser beam to a specified region. The receiving lens is configured to converge an echo light signal formed through reflection of the laser beam. The homogenizing unit is configured to uniformly emit the converged echo light signal onto a photosensitive pixel of the light detection unit, which includes a plurality of photosensitive cells. The plurality of photosensitive cells are used to convert the received echo light signal into an echo electrical signal and are controlled by a plurality of gating circuits. The processing unit is configured to analyze an echo electrical signal output by the plurality of photosensitive cells in a gating period.