Optical system, particularly for microlithographic projection illumination system, has transparent optical element during working wavelength

摘要

The optical system has a transparent optical element (100) during a working wavelength. An optical element has a crystal material with a refractive index greater than 1.7 during the working wavelength. A coating system (120) is made of two different coated materials. The coating system is embedded in the optical element, and is bordered in the crystal material. A delay caused in the coating system is partly compensated in the optical system by a birefringence. Independent claims are included for the following: (1) a method for manufacturing optical element; and (2) a microlithographic projection illumination system with an illuminating device and a projection objective.