Abstract: Optical fiber joint loss is determined by launching an optical signal in an upstream fiber and measuring the launched signal at an end of the upstream fiber which is to be joined to a downstream fiber, joining the upstream fiber to the downstream fiber and disposing the joint in a transparent medium, the transparent medium having a refractive index substantially equal to or greater than a refractive index of a cladding of the downstream fiber, measuring a fixed proportion of optical power coupled at a predetermined angle with respect to a longitudinal axis of the downstream fiber immediately adjacent the joint, and estimating the optical fiber joint loss as L=1-k(P.sub.o /P.sub.i), where L is the estimated joint loss, P.sub.i is the optical power measured before making the joint, P.sub.o is the optical power measured after making the joint, and k is an empirically determined proportionality constant.

Abstract: An optical fiber prooftester for exerting a controlled tensile force on spliced optical fibers includes a base member, a first optical fiber clamp in the form of a coil spring attached to the base and a sliding member mounted for movement on the base member. A second optical fiber clamp also in the form of a coil spring is fixed to the sliding member. A spliced optical fiber is mounted in the first and second clamps with the splice located between the clamps. A constant force wound spring acting between the base member and the movable member urges the movable member away from the first optical fiber clamp thereby applying a predetermined tensile force upon the splice.