| 摘要 |
Four laser positioning units are used to position and control an X-Y stage which is movable in X and Y directions. For each laser positioning unit, a mirror constantly reflects laser beam to an optical position sensor, where the mirror is integrally mounted on a rotation unit which is integrally mounted on the one side of platform of X-Y stage, where the laser diode is mounted on another rotation unit which is stationary, the optical position sensor is also stationary. Each rotation unit includes a fine rotation stage and a coarse rotation stage, the fine rotation stage has very high resolution but short rotation range, and the coarse rotation stage has a large rotation range but low resolution. When moving the X-Y stage, four fine stages constantly rotate mirror or/and laser to reflect the laser beam onto the optical position sensor, the amount of rotations and geometry of position of laser and mirror gives precisely the position of moving stage. After fine rotation stages nearly reach their rotation limit, the fine stages return to its starting position gradually when the coarse rotation stage moves to keep the laser constantly reflected onto the optical position sensor. The fine stages and coarse stages in different laser positioning units work alternatively to position the stage. In z-positioning unit, a fine rotation stage is used to rotate precisely a spring cantilever so that a stylus tip on an open end of spring cantilever can touch a surface downwardly with preset cantilever deformation which is measured by the capacitance between a capacitive sensor under a piezoelectric stacks and a capacitive film sensor on the top of spring cantilever.
|
