US 6,556,612 B2 · Line narrowed laser with spatial filter

Abstract

A line narrowed laser system having a spatial filter to filter light at wavelengths greater and/or smaller than a desired range of wavelengths. The laser system is line narrowed with a line narrowing mechanism having a dispersive element which disperses laser light into wavelength dependent directions. By spatially filtering the resulting beam the bandwidth of the beam can be reduced substantially. There is also a reduction of beam energy as a result of the spatial filtering but this reduction is substantially less than some other known techniques for reducing bandwidths. A preferred spatial filter, for reducing the bandwidth of a line narrowed gas discharge laser, includes two cylindrical mirrors separated by a distance equal to their focal lengths with a slit aperture positioned at the common focal line.

Claims12

Dependent claims

A line narrowed gas discharge laser having an output beam defining a bandwidth comprising:

A) a gain medium, comprising a discharge excited laser gas, for generating a laser beam;
B) line narrowing optics comprising a diffraction grating based dispersive element defining a dispersion direction for dispersing into wavelength dependent directions laser light produced in said gain medium,
C) a spatial filter comprising an aperture positioned to define an aperture position, and at least two focusing elements each having a focus at said aperture position;
wherein said spatial filter is aligned in said laser beam so as to filter out of said laser beam light at wavelengths greater or smaller than a desired range of wavelengths,
wherein said spatial filter substantially reduces the bandwidth of the output beam, and wherein said aperture comprises two prisms transparent to said laser beam and said aperture is a rectangular slit in a material opaque to said beam.

2 more elements

Dependencies are inferred from the claim text.

Line narrowed laser with spatial filter

Life of this patent

Line narrowed laser with spatial filter

Life of this patent

Abstract

Claims12