Rotary joint for optical fibers

Claim 1

A rotary joint for two optical fibers, each optical fiber having a tip and center axis, rod lenses fixed to the tips of the fibers, said rod lenses each having an optical axis and a refractive index which varies in the radial direction, normal to a central axis of the lens, with a variation proportional to the square of the radius and proportional to a constant "a" wherein the length of the lens is equal to π/(2√a); two rotary members respectively having connected thereto said two rod lenses, a mechanism for imparting pressure to said rotary members to maintain said optical axes of said two rod lenses in alignment, and a mechanism for finely setting the angle between said two rod lenses, said mechanism being provided on at least one of said rotary members in order to cause parallel rays to be transmitted from one rod lens to the other rod lens such that one said rays coincides with the rotary axis of the respective rotary member and maintains angular settings of end faces of said lenses relative to said parallel rays during relative rotation between said two rotary members, thereby decreasing sensitivity of optical transmission to any displacement of the lenses from said axis.