Abstract: Optical performance characteristics of fiber optical cable components and assemblies are tested for quality in an accurate, consistent, and stable manner by the method and apparatus of this invention. The novel apparatus enables acceptability testing of a supplier's fiber optic component/assembly by comparing its optical transmission level with the level of a similar known acceptance cable or a calibration cable, the latter two cables being incorporated in the invention apparatus. Other optical parameters can be tested by this invention to determine additional line losses, such as insertion losses, optical continuity, signal modulation, etc. Stability in the test method is assured by utilizing a variable, calibrated power source.

Abstract: The transmission efficiency of radiant energy through terminated fiber op cables depends substantially on the packing fraction of the specific fiber optic cable being employed. The invention method and apparatus enables any given length of sample fiber cable to be tested, at the installation site if necessary, to obtain a direct reading in terms of packing fraction. The method compares the light level of the energy transmission through a calibrated, solid core calibration rod of known diameter with the energy transmission through the sample terminated cable.

Abstract: A coupler for connecting a radiant energy transmitting element to a radiant nergy receiving element which utilizes a specially designed lens for each element, said lenses having spherical convex segments positioned in close face-to-face relationship so that the radiant energy emerging from the transmitting element is treated as a point source which is sequentially defocused and focused by means of the lenses onto the receiving element to minimize refraction and other losses and to insure maximum coupling efficiency.

Abstract: A coupling device is provided for a multi optical-fiber cable in which the bared free ends of the individual fibers to be coupled or terminated are geometrically oriented in a substantially focusing relation to each other to enable the propagated light beam patterns being transmitted through each fiber end to be concentrated by being superimposed substantially at a common focal plane thereby enhancing the intensity of light being available for transmission across the coupling.