| 摘要 |
A lithographic apparatus having a plurality of individually controllable radiation source units each providing a portion of a patterned beam of radiation, a control system configured to monitor a parameter of performance of each of the individually controllable radiation source units, and a replacement mechanism configured to replace one of the individually controllable radiation source units with a replacement unit responsive to the control system determining that a criterion has been met based on the monitored parameter of performance. |
