Ray-path equalizer for signal transmission via multimode optical waveguides

Claim 1

In an optical signal-transmitting system, in combination: two aligned light guides with confronting ends respectively emitting and collecting bundles of light rays whose limiting rays include a critical angle with a common centerline of said light guides in at least one longitudinal plane of symmetry thereof; and an equalizer between said light guides comprising two identical transparent bodies of positive refractivity spaced apart from each other and from said confronting ends along said centerline, each of said bodies having a cross-section in said plane of symmetry consisting of two symmetrical truncated lens profiles with a boundary lying on said common centerline and with optical axes lying on opposite sides of said boundary, each of said lens profiles extending from said boundary to at least a point of interception of a limiting ray of a ray bundle converging at the closer light-guide end, the path of a limiting ray extending from said point of interception at a lens profile of one of said bodies to the geometrical center of the other of said bodies and thence substantially along said centerline to the more distant light-guide end; the distance w of said point of interception from said centerline, the spacing c of said optical axes from said boundary, the focal length f of each lens profile and the separation d of the geometrical centers of said bodies substantially satisfying the relationship w/c = d/f.