A method for operating an excimer or molecular fluorine laser system at a
stabilized wavelength includes generating a laser beam and directing a
beam portion through a wavelength measurement system, calibrating the
wavelength measurement system to an absolute reference, determining the
wavelength of the laser beam including figuring in a drift compensation
value of the wavelength, and tuning the wavelength to a target wavelength
when the determined wavelength differs from the target wavelength.
