METHOD OF ESTIMATING ABSOLUTE DISTANCE IN TRACKING LASER INTERFEROMETER, AND TRACKING LASER INTERFEROMETER

摘要

PROBLEM TO BE SOLVED: To properly increase/decrease a control amount of tracking control according to a distance between a device and a recursive reflector without imposing complicated operation for returning to an origin on an operator or adding expensive absolute distance sensor. SOLUTION: The tracking laser interferometer includes the recursive reflector 70 reflecting incident measurement light A in the incident direction to return it and a two-axis rotary mechanism 40 rotating an emission direction of the measurement light A so that an optical axis of the measurement light A is parallel to that of the return light B. When estimating the absolute distance L between the recursive reflector 70 and the tracking laser interferometer outputting a measurement value according to the increase/decrease in the distance between the device and the recursive reflector 70, the absolute distance L between the device and the recursive reflector 70 is estimated by calculation, according to angular position variation amountθ2of the two-axis rotary mechanism 40, wherein a displacement amount d from a prescribed position of the return light B from the recursive reflector 70 is made into a prescribed value d2. COPYRIGHT: (C)2008,JPO&INPIT