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US 12,645,147 B2Granted
Temperature measurement of optical elements in an optical apparatus
AssigneeASML Netherlands B.V.
InventorsKoen Martin Willem Jan Bos, Joost André Klugkist, Anirudh Anand
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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.
Claims17
An optical apparatus comprising:
- an optical element having a reflective surface for reflecting incident radiation in a beam path;
- at least one sensor configured to sense radiation corresponding to a temperature of a respective portion of a backside surface of the optical element;
- and
- at least one coating formed on the respective portion of the backside surface, the at least one coating configured to have temperature-dependent optical properties.
1 more element
Dependencies are inferred from the claim text.