Wafer exposure means and methods

Wafer exposure means (1), comprising: - a wafer holder (2), - an optical exposure system (20) for exposing a wafer (5) on the wafer holder (2) and having a sensor arrangement (15) for measuring a distance to an on the wafer holder (2) arranged wafer (5), wherein the sensor arrangement (5) has a plurality of height level sensors (M0, ..., M8 M;; Mi) - wherein each height level sensor (M; Mi; M0, ..., M8) measures height level values ​​(Hi), and outputs, - wherein the wafer exposure means (1) measured height level values ​​(Hi) obtained by the respective height level sensors (Mi) are output, compares with each other, - wherein the wafer exposure means (1), individual values ​​(Ci) of the sensor position offset, the individual height level sensors (Mi) are allocated, calculated - wherein the wafer exposure means (1) from the respective height level sensors (Mi) output, measured height level values ​​(Hi) using the calculated values ​​(Ci) of the sensor positional offset of the respective height level sensor (Mi) corrected.