Laser beam guidance system uses ring lens so incident beam diameter, focal length and irradiation angle retain sought distant-plane distribution at maximal power transmission

摘要

The diameter of the laser beam (1) striking the first beam-forming element, the focal length realized by this same element and the irradiation angle of the ring in the first plane (7) are all so optimized as to maintain a given remote-field distribution at maximum power transmission. The beam-forming element takes the preferred form of a ring lens (3) or an axicon combined with a collimating optical system. Ring lens or axicon form an optical deflection phase element in the form of a microstructured lens surface. The beam-forming element (3) has a reflecting surface. The annular aperture in the first near-field plane (7) forms part of a Cassegrain telescope, the whole forming part of an optical satellite communications system.