TW376446B - Six-degree-of-freedom measurement apparatus and method - Google Patents

Abstract

A precision six-degree-of-freedom measurement apparatus which has the capability to measure simultaneously six motion errors of an X-Y stage, including two linear positioning errors, a vertical straightness error, a yaw error, a pitch error, and a roll error. The pitch and yaw measurements are adopted with a new apparatus, and the roll and vertical straightness measurement are based on a new measuring method. The apparatus uses an optical reflection device with one set of long right-angle reflector to eliminate the nonlinear effect of pitch rotation versus the distance measurement. The apparatus utilizes the optical reflection device and a pair of quadrant photo detectors to make the roll and vertical straightness measurement possible. This invention uses four laser sources to measure four distances to obtain positioning, horizontal straightness, yaw and pitch errors, and uses two quadrant photo detectors to detect vertical straightness and roll errors. This invention can break the bottleneck of conventional technique which can't precisely measure all six degree of errors at same time.