公开(公告)号：US20240280502A1

公开(公告)日：2024-08-22

申请号：US18581794

申请日：2024-02-20

Applicant: Lasertec Corporation

Inventor： Minoru HOSOMI

IPC: G01N21/88

CPC classification number: G01N21/8806 ,  G01N21/8851 ,  G01N2201/06113 ,  G01N2201/0636 ,  G01N2201/12753

Abstract: An optical apparatus according to the present embodiment includes a detector for detecting detection light of illumination light reflected by a sample, an optical system for illuminating the sample with the illumination light and guiding the detection light reflected by the sample to the detector, a displacement measurement unit for measuring a displacement drift indicating the amount of drift in the position of an optical element included in the optical system, a storage unit for storing the correlation between the displacement drift and a focus drift indicating the amount of drift in the distance between the sample and the optical system when the detection light detected by the detector is brought into focus, and a prediction unit for predicting a focus drift from the measured displacement drift by using the correlation.