Method and apparatus for concentrating and combining the energy of

Abstract

Methods and apparatus are disclosed for concentrating the energy of a laser diode beam by imaging a first numerical aperture of the beam in one beam plane to a reduced numerical aperture at a focal plane, and by guiding the beam between reflective boundaries to maintain the value of a lesser second numerical aperture in another beam plane at the focal plane. The reduced numerical aperture in the first plane optimally matches the second numerical aperture in the second plane so that the energy can be received into the entrance end of an optical fiber whose numerical aperture also matches the second numerical aperture. The area of this fiber preferably matches that of the image at the focal plane. A coupler that guides the beam to its focal plane preferably utilizes an imaging element, e.g., a cylindrical lens or a cylindrical elliptical mirror, and a pair of spaced reflective walls. The exit ends of a plurality of fibers that are illuminated by respective beams can be closely packed into any desired pattern which can be fractionally magnified by a relay lens into a very concentrated energy pattern. If desired, this final image may be fed into a single optical fiber for passage through remote or convoluted optical paths.