Patent ID: 8503068

Claim:
A radiation source apparatus for generating deep ultraviolet (DUV) radiation comprising: a first laser apparatus for generating a first laser beam of radiation having a first fundamental wavelength between approximately 1060 nm and 1080 nm; a second laser apparatus for generating a second laser beam of radiation having a second fundamental wavelength between approximately 1750 nm and 2100 nm; a third laser apparatus for generating a third laser beam of radiation having a third fundamental wavelength between approximately 1080 nm and 1120 nm; first wavelength conversion means arranged to receive the first laser beam of radiation and to generate a beam of first DUV radiation having a fourth-harmonic wavelength of the first fundamental wavelength; second wavelength conversion means arranged to receive the beam of first DUV radiation and the second laser beam of radiation and to sum-frequency mix the first DUV radiation with the second fundamental wavelength radiation to generate a beam of second DUV radiation having a wavelength between approximately 232 nm and 237 nm; and third wavelength conversion means arranged to receive the beam of second DUV radiation and the third laser beam of radiation and to sum-frequency mix the second DUV radiation with the third fundamental wavelength radiation to generate third DUV radiation having a wavelength between approximately 192.5 nm and 194.5 nm.