公开(公告)号：WO2022233500A1

公开(公告)日：2022-11-10

申请号：PCT/EP2022/058246

申请日：2022-03-29

Applicant: ASML NETHERLANDS B.V.

Inventor： BOS, Koen, Martin, Willem, Jan ,  KLUGKIST, Joost, André ,  ANAND, Anirudh

IPC: G03F7/20 ,  G01J5/00 ,  G02B7/18

Abstract: An optical apparatus is disclosed, the apparatus comprising an optical element having a reflective surface for reflecting incident radiation in a beam path, and at least one sensor configured to sense radiation corresponding to a temperature of a respective portion of a backside surface of the optical element. Also disclosed is a method of controlling a temperature of a reflective surface of an optical element in a lithographic apparatus.