A high precision straight-motion system

Abstract In this system, a steel block is completely floated by air pads mounted on a mechanical sliding table. When the table moves, the vertical and horizontal positions and the pitch, roll and yaw angles of the block change because of the misalignment of the sliding table. These changes are detected against references by optical and electronic devices and the positions and angels of the block controlled by changing the supply pressure to each pad. Straight-edge masters and a laser straightness interferometer are used as the references for vertical and horizontal straightnesses, and autocollimators are used to detect the change in pitch and yaw angle attitudes. As a reference to the roll angle attitude, the two straight-edge masters are used. The working length of the system is 1 m. The positional errors of the block motion with respect to the references are less than 0.1 and 0.4 μm and the angular changes are less than 0.2 s of arc.