Patent ID: 7672342

Claim:
Method of generating pulsed coherent radiation in the wavelength ranges of XUV- to X-rays, comprising the steps of: providing a laser source generating laser light pulses that have a repetition rate and an output spectrum comprising a fundamental frequency comb of frequency modes; in-coupling the laser light pulses into a resonant cavity; locking the resonant cavity and the laser source to each other so that light pulses travelling in the resonant cavity continuously are increased by coherent addition of the laser light pulses coupled into the resonant cavity; and generating high harmonic pulses by an n th harmonic generation interaction of the laser light pulses with a non-linear medium contained in the resonant cavity, wherein the non-linear medium is arranged in an environment of reduced pressure; wherein a spectrum of the high harmonic pulses contains frequency components that are the sum of n frequency modes of the fundamental frequency comb for n th harmonic generation thereby providing a frequency comb itself; and wherein the high harmonic pulses are generated at the repetition rate of the laser light pulses generated by the laser source.