Patent ID: 6476987
Filing Date: 2002-11-05
Classification: G02B,H01S

Abstract:
A line narrowing unit for use within an excimer or molecular fluorine laser resonator for generating a line-narrowed DUV/VUV laser beam, comprising:a dispersive prism including a bulk material which is substantially transparent at an emission wavelength of said laser system, said prism being arranged at a particular orientation within said resonator for dispersing the beam such that only a selected portion of the spectral bandwidth of the beam remains within an acceptance angle of said resonator and other unselected portions are dispersed outside of the acceptance angle of said resonator, wherein said prism includes an entrance surface at which a laser beam is incident and refracted into the bulk material, and an exit surface at which said beam exits and refracts out of said bulk material, and wherein said beam makes a non-symmetric pass through said prism, such that an entrance angle of said beam at said entrance surface of said prism differs from an exit angle of said beam at said exit surface of said prism, and one of said entrance and exit angles is greater than Brewster's angle and the other is at least around Brewster's angle.