DISTANCE MEASUREMENT APPARATUS

PROBLEM TO BE SOLVED: To provide a distance measurement apparatus capable of preventing changes in measurement accuracy due to temperature change of a light emitting element.SOLUTION: A light projection means 1 comprises a light emitting element 11 that projects a light beam into a target space. A light receiving means 2 comprises a light receiving element 21 that receives the light from the target space. A control means 3 provides a modulation signal to the light projection means 1 to cause the light emitting element 11 to emit a modulation light, the brightness of which changes as the time passes, and provides a demodulation signal, which is synchronous with the modulation signal, to the light receiving means 2 to extract components of the modulation light from the output of the light receiving element 21. A calculation means 4 measures the time from a point when the modulation light is emitted by the light projection means 1 into the target space up to a point when the same is received by the light receiving means 2 to calculate the distance to an object in the target space. A temperature measurement means 6 measures the temperature of the light emitting element 11. An accuracy maintaining means 7 controls the drive current to the light emitting element 11 so as to be larger in proportion to the temperature measured by the temperature measurement means 6; to thereby prevent the modulation light received by the light receiving element 21 from changing irrespective of the temperature change of the light emitting element 11.