THE FIRST MEASUREMENT OF A 3-DIMENSIONAL COORDINATE BY USE OF A LASERTRACKING INTERFEROMETER SYSTEM BASED ON TRILATERATION

A three-dimensional coordinate of a target position was measured using a laser tracking interferometer system based on laser trilateration. Laser interferometers, which are mounted on two-directional rotating s tages, track the motion of the target retroreflector. By applying the principle of trilateration, the position of the retroreflector is esti mated using the optical path difference caused by the motion of the ta rget. Four laser interferometers were used, which produced redundancy in the measurement. By taking advantage of the redundancy, the positio n of the interferometers and the initial position of the target is sel f-calibrated and consequently the target position was calculated. The measurement error of a preliminary experiment was about 40 mu m for a 1 m measurement.