公开(公告)号：US20160231241A1

公开(公告)日：2016-08-11

申请号：US15013348

申请日：2016-02-02

Applicant: ASML Netherlands B.V.

Inventor： Nitesh PANDEY

IPC: G01N21/47

CPC classification number: G01N21/4788 ,  G03F7/70625 ,  G03F7/70633 ,  G03F7/70641 ,  G03F7/70941

Abstract: An optical system (10) includes an arrangement for splitting a source beam into a measurement beam and a reference beam. The reference beam is reflected off a reflective element (42) which mounted on a delay line (44). A target (35) scatters the radiation from the measurement beam. The scattered radiation and the reference beam are brought to interfere on a detector (40) by calibrating the delay line (44). The detected interference pattern is Fourier-transformed and filtered to select a region of interest around a side-band of the Fourier-transformed interference pattern in order to remove noise caused by stray radiation that hits the detector.

Abstract translation: 光学系统（10）包括用于将源光束分成测量光束和参考光束的装置。 参考光束从安装在延迟线（44）上的反射元件（42）反射。 目标（35）散射来自测量光束的辐射。 通过校准延迟线（44）使分散的辐射和参考光束在检测器（40）上产生干涉。 检测到的干涉图案被傅立叶变换和滤波，以选择傅立叶变换干涉图案的边带周围的感兴趣区域，以便消除由检测器引起的杂散辐射引起的噪声。