Patent ID: 6466598
Filing Date: 2002-10-15
Classification: H01S

Abstract:
A molecular fluorine laser system emitting a narrow bandwidth laser beam and having efficient line-selection of a main line &lgr;1 of a plurality of closely-spaced lines around 157 nm, comprising:a discharge chamber filled with a laser gas including molecular fluorine and a buffer gas; a plurality of electrodes within the discharge chamber and connected to a discharge circuit for energizing the molecular fluorine; and a resonator including the discharge chamber for generating a laser beam, said resonator further including: a solid element comprising a birefringent bulk material including an extraordinary refractive index and an ordinary refractive index, and said solid element generating a interference response spectrum along an optical path of said beam and having an intensity maximum at or near said main line &lgr;1 and an intensity minimum at or near a secondary line &lgr;2 of said plurality of closely-spaced lines to suppress said secondary line, wherein said response spectrum includes a periodic function having an argument which includes a geometric path length of the beam within the solid element (z), the wavelength of the beam (&lgr;), and a difference between a first multiplier times the extraordinary refractive index (nc) and a second multiplier times the ordinary refractive index (no), and wherein when the polarization direction of the beam is at 45Â° to each of the orthogonal directions of its ordinary and extraordinary components and the solid element is configured in transmissive mode, then a transmission spectrum of the beam through the solid element is substantially given by: T(&lgr;)=cos2[&pgr;(ncâˆ’no)z/&lgr;]; andwherein the path length for the ordinary ray is approximately given by: z=d/(1-no2sind2&agr;)1/2; where d is the thickness of the solid element and &agr; is the incidence angle.