PURPOSE: To enable distance measurement in a wide range from a long distance of several meters and more to a short distance of several cm.

CONSTITUTION: An optical/electronic circuit including a laser oscillator 1, a chopper 2, a half mirror 3, a fixed mirror 4, and a detector 5, which forms a photo-interferometer when photo intermittent operation due to the chopper 2 is stopped, and which forms a laser radar when the chopper 2 is operated, is put on a tracking machine 6, while a reflector 7 is put on a target plate 8. When the distance between the tracking machine 6 and the target plane 8 is not less than approximately 3m, a measurement is carried out in the laser radar mode, while if the distance is shorter, the measurement is carried out in a photo-interference mode.