Abstract: Method of determining the position of the optical axis of an optical waveguidde relative to a nominal axis, in which method the position of a light spot formed on a detector surface by a light beam leaving the optical waveguide is determined relative to the nominal position. A simple determination of the spatial position of an optical waveguide with respect to the angular and lateral position is possible in that the light beam is guided onto detector surfaces arranged at two different distances from the end face of the optical waveguide and in that the deviations of the light spots formed on the detector surfaces from their nominal positions are evaluated as criteria for the relative values of the angular and lateral positions of the optical waveguide.

Abstract: The invention relates to a method of measuring the eccentricity of a waveguide embedded in a cylindrical connector pin. The optical center of the end face of the waveguide is introduced into the mechanical axis of rotation of a distance sensor scanning the outer surface of the connector pin. Subsequently, the eccentricity of the waveguide is determined from the measuring values obtained during the relative rotation of the distance sensor along the outer surface of the connector pin.

Abstract: The invention relates to a method of measuring the optical radiation energy reflected by a reflection place as a relative fraction of energy supplied by an optical transmitter via an optical line. Using few components, reliable and constantly exact measuring values can be obtained in that the optical line (12,25) is connected to a backscattering measuring device (1) (OTDR) which transmits radiation in known manner via an optical connector (5) and which comprises a reception and evaluation device (6 and 7, respectively) for forming a measuring value which is proportional to the optical power backscattered in the optical connector (5) of the backscattering measuring device (1) and in that a reflection element (17, 19) having known reflection factor R.sub.N is arranged in the optical path between the connector (5) of the OTDR (1) and the end of an optical path comprising the reflection area (9) to be examined.