公开(公告)号：US11719529B2

公开(公告)日：2023-08-08

申请号：US17613124

申请日：2020-05-11

Applicant: ASML NETHERLANDS B.V.

Inventor： Maarten Jozef Jansen ,  Manoj Kumar Mridha ,  Engelbertus Antonius Fransiscus Van der Pasch

IPC: G01B9/02002 ,  G01B9/02055 ,  G01J9/02 ,  G03F7/20 ,  G03F7/00

CPC classification number: G01B9/02002 ,  G01B9/0207 ,  G01J9/02 ,  G03F7/70775 ,  G01B2290/60

Abstract: An interferometer system including: an optical system arranged to split a radiation beam from a laser source into a first beam along a first optical path and a second beam along a second optical path, and recombine the first beam and the second beam to a recombined beam, a detector to receive the recombined beam and to provide a detector signal based on the received recombined beam, and a processing unit, wherein a first optical path length of the first optical path and a second optical path length of the second optical path have an optical path length difference, and wherein the processing unit is arranged to determine a mode hop of the laser source on the basis of a phase shift in the detector signal.