Abstract: A cuspate lens is disclosed having a slope magnitude which decreases from a maximum at a central cusp to a minimum at the periphery. A radially symmetric version of the lens can focus light into a ring, or produce an annular beam. Also disclosed are a fiber optic coupler and an optical slip ring using the cuspated lenses or other refractive devices capable of producing an annular beam of light, such as axicons or eccentric lenses.

Abstract: This invention comprises a method by which a carbon based film is deposited by ion beam deposition upon and chemically bonded to a substrate article. The carbon based film deposited by the method of this invention comprises an atomic initial layer, adjacent to and chemically bonded by carbide bonding to the substrate surface, which is overgrown by a carbon layer that assumes the true diamond microstructure or, alternatively, a carbon structure which more closely approximates the microstructure and physical, chemical and electrical properties of true diamond than has heretofore been attained by prior diamond-like films.The method by which the chemically bonded diamond or diamond-like film is deposited upon a substrate comprises: positioning an electrically grounded substrate having an atomically clean surface within a deposition chamber maintained at a pressure of 1.times.10.sup.-9 torr or less and impinging upon the atomically clean substrate surface a .sup.12 C.sup.