| 摘要 |
A level sensor configured to measure a height level of a substrate arranged in a measurement position is disclosed. The level sensor comprises a projection unit to project multiple measurement beams on multiple measurement locations on the substrate, a detection unit to receive the measurement beams after reflection on the substrate, and a processing unit to calculate a height level on the basis of the reflected measurement beams received by the detection unit, wherein the projection unit and the detection unit are arranged next to the substrate, when the substrate is arranged in the measurement position. |
