Patent ID: 6747741
Filing Date: 2004-06-08
Classification: G01J

Abstract:
An apparatus for measuring a spectral distribution of a narrow-band laser beam generated by a line-narrowed excimer laser or a molecular fluorine laser system, comprising:an interferometric device disposed along an optical path of an output beam of the laser system such that the beam traverses the interferometric device on a first pass; a retro-reflector disposed after the interferometric device along said optical path for retro-reflecting the beam back through the interferometric device on a second pass; and a detector for measuring an intensity of the beam after the second pass through the interferometric device, and wherein the interferometric device is tunable to any of a plurality of free spectral ranges, such that the beam traversing the interferometric device is tuned over one of the plurality of free spectral ranges, and wherein spectral information is determined by using the detector to measure the intensity of the beam at each of the plurality of free spectral ranges.