Patent ID: 7110171

Claim:
A laser amplifier, comprising: a gain medium; a polarization rotator; a passive polarizer; a plurality of reflectors configured to define an optical path through the gain medium, the passive polarizer, and the polarization rotator; and a phase conjugator configured to receive a beam from the optical path after the beam has proceeded one or more transits through the optical path, the phase conjugator further configured to return the beam with reversed phase to the optical path to proceed an equal number of transits of the optical path in an opposite direction before exiting the optical path; and a relay telescope having a telescope focal point, between the gain medium and the passive polarizer, which is used for relaying images between the gain medium and a location in the optical path near the passive polarizer, off angle beams being generated in the optical path in addition to a desired beam, the relay telescope having a baffle near said telescope focal point to block the off angle beams while passing the desired beam, the baffle comprising a solid member having an optically transparent channel, the optically transparent channel having openings on opposite ends of the solid member, and a waist within the solid member near said telescope focal point, said waist being smaller than said openings, and said channel having sides which taper near said waist at a grazing angle in a range of about 1 to 10 degrees.