OPTICAL SYSTEM AND EXPOSURE SYSTEM PROVIDED WITH THE OPTICAL SYSTEM

摘要

An optical system having a good optical performance without being practically affected by double refraction even if an optical material having an intrinsic double refraction, such as fluorite, is used. The optical system comprises a fifth−group light transmitting member having a feature of practically transmitting light with a wavelength of up to 200 nm and being formed to have an optical axis aligned with a crystal axis [110] or a crystal axis practically optically equivalent to the crystal axis [110], and a sixth−group light transmitting member having a feature of practically transmitting light with a wavelength of up to 200 nm and being formed to have an optical axis aligned with a crystal axis [110] or a crystal axis practically optically equivalent to the crystal axis [110]. The fifth−group light transmitting member and the sixth−group light transmitting member are so related in position as to be rotated about 90° from each other around an optical axis.