| 摘要 |
A method for exposing a surface of a target in a system comprising a set of sensors (30) for measuring distance to the target. The method comprises clamping the target to a moveable table (134), moving the target to a plurality of positions in which one or more of the sensors are positioned above the target, receiving signals from one or more of the sensors positioned above the target, calculating one or more tilt correction values (Rx, Ry) based on the signals received from the sensors, adjusting the tilt of the table based on the one or more tilt correction values, and exposing the target.
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