Patent ID: 9594306
Date: 2017-03-14
CPC Classifications: B82Y,G02B,G03F,G21K,H05G

Claim:
1. A lithographic apparatus configured to pattern a beam of radiation and project the beam of radiation onto a substrate, comprising: a first spectral purity filter configured to reduce the intensity of radiation in the beam of radiation in at least one first undesirable range of radiation wavelengths; and a second spectral purity filter configured to reduce the intensity of radiation in the beam of radiation in at least one second undesirable range of radiation wavelengths that is different than the at least one first undesirable range of radiation wavelengths; wherein the first spectral purity filter and the second spectral purity filter are provided with different radiation filtering structures from each other; wherein the first spectral purity filter is a grating spectral purity filter, comprising: wherein the second spectral purity filter is a second grating spectral purity filter comprising: