Patent ID: 6678291
Filing Date: 2004-01-13
Classification: G02B,H01S

Abstract:
A F2 laser, comprising:a discharge chamber filled with a laser gas mixture including molecular fluorine for generating a spectral emission including a plurality of closely-spaced lines in a wavelength range between 157 nm and 158 nm, said plurality of closely spaced lines including a primary line centered around 157.62 nm and a second line centered around 157.52 nm; a plurality of electrodes within the discharge chamber connected with a power supply circuit for energizing the molecular fluorine; and a laser resonator including a line selection unit located on a same side of the discharge chamber as the laser beam is outcoupled for selecting the primary line around 157.62 nm and suppressing said secondary line around 157.52 nm from an acceptance angle of said beam, such that the F2 laser emits a single wavelength laser beam having a narrow spectral bandwidth to provide a narrow band VUV beam, and wherein said line-selection unit is located on the same side of the discharge chamber as the outcoupled laser beam such that radiation emanating directly from the discharge chamber is line-selected by the line-selection unit prior to being output coupled from said resonator, said location of said line-selection unit providing increased effectiveness of the line-selection and improved spectral purity, since the F2 laser pulse duration is relatively short when compared with a pulse of a rare gas-halide excimer laser.