Optical branching element

Claim 1

An optical branching element which comprises a central optical transmission line, said central optical transmission line having a circular cross section and a predetermined diameter and a straight end portion, said straight end portion including a flat end surface which is perpendicular to an imaginary center line which extends through said straight end portion, said flat end surface defining an imaginary plane, a plurality of peripheral optical transmission lines, each peripheral optical transmission line having a circular cross section and a diameter which is about the same as said predetermined diameter of said central optical transmission line, each peripheral optical transmission line having a straight end portion which defines a flat end surface which is perpendicular to an imaginary center line which extends through the associated straight end portion, the straight end portion of each peripheral optical transmission line being positioned with respect to the straight end portion of said central optical transmission line such that they are in contact with the straight end portion of said central optical transmission line and such that the flat end surfaces thereof are positioned in said imaginary plane, the flat end surfaces of said peripheral optical transmission lines contacting the flat end surface of said central optical transmission line at respective contact points, a holder in which the straight end portions of said central optical transmission line and said plurality of peripheral optical transmission lines extend, said holder maintaining contact between said central optical transmission line and said peripheral optical transmission lines and maintaining the flat end surfaces thereof in said imaginary plane, said holder including a flat contacting surface which is located in said imaginary plane, and a reflector which is in contact with the flat contacting surface of said holder and which includes means forming a concave reflecting surface therein which faces said end surfaces of the straight end portions of said central optical transmission line and said peripheral optical transmission lines, said concave reflecting surface being symmetrical about a center point which is located on said imaginary center line which extends through said straight end portion of said central optical transmission line, said concave reflecting surface being formed of a plurality of reflective surface portions, the number of reflective surface portions equalling the number of peripheral optical transmission lines, each reflective surface portion having a semi-spherical surface which is defined by a predetermined radius from a respective said contact point, said predetermined radius being larger than the diameter of the peripheral optical transmission line with which the reflective surface portion is associated.