Patent ID: 6807205
Filing Date: 2004-10-19
Classification: H01S

Abstract:
A method for compensating optical drift of a wavelength measurement system used for relative wavelength tuning of an output beam of an excimer or molecular fluorine laser system, comprising the steps of:(a) operating the laser system including generating a laser beam and directing a beam portion through the wavelength measurement system; (b) calibrating the wavelength measurement system to an absolute reference; (c) tuning the output beam to a target wavelength using the wavelength measurement system; (d) detecting a measured wavelength of the output beam using the wavelength measurement system after a predetermined period of laser operation; (e) calculating a compensated wavelength by figuring in a previously determined measurement system drift compensation value; and (f) adjusting the wavelength of the laser beam to the target wavelength when the compensated wavelength differs from the target wavelength.