Patent ID: 8514405

Claim:
A tracking type laser gauge interferometer comprising: a first recursive reflector provided at a predetermined position, the first recursive reflector being configured to reflect light parallel to incident light; a second recursive reflector attached to a measurement object; a main body part configured to guide light emitted from a laser light source to the first recursive reflector and make emergent the light reflected at the first recursive reflector; a rotating mechanism configured to rotate the main body part about the first recursive reflector; a sensor configured to detect a rotational angle of the rotating mechanism; and a control unit configured to control the rotating mechanism based on the light emergent from the main body part and reflected at the second recursive reflector, so as to measure the distance between the recursive reflectors while tracking the second recursive reflector, wherein: the main body part includes: a light receiving element configured to receive the light reflected at the first recursive reflector and detect a position of the received light; and the control unit includes: an angle acquisition unit configured to acquire the rotational angle of the rotating mechanism from the sensor; a correction unit configured to correct the rotational angle of the rotating mechanism acquired by the angle acquisition unit on the basis of the position of the received light detected by the light receiving element; and a position calculation unit configured to calculate a position of the second recursive reflector based on the corrected rotational angle of the rotating mechanism corrected by the angle correcting unit and a distance between the recursive reflectors.