Abstract: A fluid cooled laser mirror includes a body defining internal chamber means made up of inner and outer chambers generally separated by a wall defined by the body. An inlet port communicates with the inner chamber, and outlet ports communicate with the outer chamber. The wall defines a plurality of passages therethrough, allowing communication between the inner and outer chambers, so that cooling fluid may flow into the center of the body in the inner chamber, through the passages of the wall, into the outer chamber, and from the outlet ports. Vanes are appropriately placed to properly direct and guide cooling fluid so that it cools in a highly efficient manner.

Abstract: A method of focussing a laser beam having a ring-shaped cross-section to provide a depth of focus for use in cutting and the like, in which the laser beam is converged to and through a focus by reflection from a concave mirror, and in which the diverging laser beam emanating from the focus is passed into an axicon having a substantially cylindrical inner reflective surface for reflecting the diverging laser beams back to an elongated focus. In its apparatus form, focussing means is provided together with a substantially cylindrical axicon positioned to intercept said diverging laser beam and to bring it back to a focus along an extended axis. The cylindrical axicon is preferably formed from a pair of telescoped tubular members having a closed annular space therein for receiving a cooling fluid, with the inner cylinder having its inner surface highly polished and/or coated with some material to minimize the absorption of the incident laser beam.