Patent ID: 6608848
Filing Date: 2003-08-19
Classification: H01S

Abstract:
A molecular fluorine laser system, comprising:a discharge chamber and a resonator and generating a narrow band output beam around 157 nm of a known absolute wavelength; a wavelength selection and tuning unit for selecting one of multiple closely-spaced characteristic molecular fluorine emission lines around 157 nm by optically suppressing non-selected lines of the multiple closely-spaced characteristic molecular fluorine emission lines, and for tuning a central wavelength of the narrow band output beam from the laser within the selected line; a wavelength calibration module permitting the wavelength of the narrow band output beam to be calibrated to a specific wavelength standard, said module coming at least one species for optically interacting with a beam portion in a region around 157 nm, for measuring effects of interaction of the beam portion with The at least one species when the narrow band output beam is scanned; a wavelength monitoring module for turning the wavelength to a desired wavelength after calibrating the wavelength monitoring module to the specific wavelength standard with the wavelength calibration module; and a processor for calibrating the wavelength of the narrow band output beam based on the measured effects of the interaction of the at least one species with the component of the output beam, and for controlling the tuning of the wavelength to the desired wavelength by controlling the wavelength selection and tuning unit according to information received from the wavelength monitoring module which is calibrated to the absolute wavelength standard, such that the wavelength is moved away from an interaction wavelength with the absolute wavelength standard based on information received from the wavelength monitoring module as the wavelength is Tuned to the desired wavelength within the selected line of the multiple closely-spaced characteristic molecular fluorine emission lines around 157 nm.