Patent ID: 7260134

Claim:
A laser comprising: first and second elongated electrodes, said first and second electrodes each having a stepped cross-section including a thick portion and a thin portion, said thin portion of said first electrode being wider than said thick portion of said second electrode, said electrodes having a step height defined by the difference in thickness between said thick and thin portions thereof; said electrodes being arranged spaced apart and face-to-face with said thin and thick portions of said first electrode facing respectively said thick and thin portions of said second electrode, where the spacing between said electrodes being arranged such that an elongated discharge gap is formed between said thin portion of said first electrode and said thick portion of said second electrode, said discharge gap having a height and a width, said discharge gap width being about equal to the width of said thick portion of said second electrode and said discharge gap being filled with a lasing gas; a solid dielectric insert extending longitudinally along the length of said electrodes, said insert having a height less than said step height and being located between said thick portion of said first electrode and said thin portion of said second electrode and in contact therewith; a pair of mirrors configured and arranged to define a laser resonant cavity extending through said elongated discharge gap; means for exciting said lasing gas to create a gas discharge in said discharge gap, thereby causing laser radiation to circulate in said resonant cavity; and wherein the height of said discharge gap is selected such that said gap forms a waveguide for said laser radiation in the height direction, and the width of said gap is selected such that said laser radiation is allowed to propagate in free space in the width direction of said gap in a manner controlled by said configuration and arrangement of said mirrors.