Patent ID: 6421365
Filing Date: 2002-07-16
Classification: H01S

Abstract:
An excimer or molecular fluorine laser, comprising:a discharge chamber filled with a gas mixture; a plurality of electrodes within the discharge chamber connected to a power supply circuit for energizing the gas mixture; and a resonator including said discharge chamber and first and second resonator reflecting optical elements for generating an output laser beam, wherein the first resonator reflecting optical element is an output coupling interferometer including a pair of opposing reflecting surfaces configured so that the interferometer is tuned to have a reflectvity maximum at a selected wavelength around approximately an intensity maximum of the beam incident upon the interferometer, and at least one sideband of the reflectivity spectrum of the interferometer is also within the intensity spectrum of the beam incident upon the interferometer, and wherein at least a first of said pair of opposing reflecting surfaces is configured such that said first and second opposing reflecting surfaces have a varying optical distance therebetween over said incident beam cross-section which serves to suppress said at least one sideband around said reflectivity maximum to improve spectral purity such that the interferometer with non-parallel opposing reflecting surfaces has a reflectivity spectrum including a narrow reflectivity maximum and at least one sideband which is substantially suppressed to provide high spectral purity.