OPTICAL SYSTEM AND EXTREME ULTRAVIOLET (EUV) LIGHT GENERATION SYSTEM INCLUDING THE OPTICAL SYSTEM

摘要

An optical system used with a laser apparatus may include a focusing optical system, a beam splitter, and an optical sensor. The focusing optical system has one or more focus, for focusing a laser beam outputted from the laser apparatus. The beam splitter is disposed between the focusing optical system and the one or more focus of the focusing optical system. The optical sensor is disposed on a beam path of a laser beam split by the beam splitter.