公开(公告)号：US20240361590A1

公开(公告)日：2024-10-31

申请号：US18645681

申请日：2024-04-25

Applicant: Lasertec Corporation

Inventor： Ko GONDAIRA ,  Masaki INOUE ,  Haruhiko KUSUNOSE

IPC: G02B27/00 ,  G03F1/82

CPC classification number: G02B27/0006 ,  G03F1/82

Abstract: To provide an optical apparatus and a method of preventing contamination of the optical apparatus that can more effectively prevent contamination. An optical apparatus according to an embodiment includes a light source configured to generate irradiation light including EUV light, an optical system chamber in which a target object to be irradiated with the irradiation light is disposed, a drop-in mirror provided in the optical system chamber in order to guide the irradiation light, an introducing unit configured to introduce argon into the optical system chamber, a power supply configured to apply a negative voltage to the drop-in mirror in the optical system chamber, an ammeter configured to measure an ion current flowing to the drop-in mirror, and a control unit configured to control an introduction amount of the argon according to a measurement result of the ammeter.