선형이송기구의 5자유도 오차운동 측정 시스템

Abstract

A new measurement system is proposed that can detect five-degree-of-freedom (five-DOF) error motions of a linear stage with high sensitivity. The system divided into a moving target part and a stationary detection part. The moving target part, which is composed of three retro-reflectors, is mounted on a carriage of a linear stage. The stationary detection part is composed of three laser sources, ball-lenses, and PSDs, and placed on a reference table. Three parallel laser beams from laser sources is reflected at three retro-reflectors, and then arrived at the PSDs after passing through the ball-lenses. Relative position changes of the retro-reflectors by the multi-DOF motions of the moving target part shift the optical paths of the reflected beams, and the PSDs detect the displacement of the laser beam. The ball-lenses play a pivotal role in displacement magnification of the beam spot on PSDs. In this paper, the relationships between the output of the three PSDs and the five-DOF motions of the moving target pat are derived, and the system model is defined from it. Based on the ray-tracing method, simulations are performed to estimate the proposed measurement system’s performances. The results show that the proposed method is useful to precisely measure the error motions of linear stages.