Abstract: The invention relates to the determination of the carrier-to-noise ratio for optical transmissions when a noise-affected optical signal containing a message signal is transmitted along an optical signal transmission path, whereby the optical signal together with the optical noise transmitted therewith is fed to an optical filter (OF). The optical output signal from the above is converted into a corresponding electrical signal in a detector device (Det) and either the mid-frequency of the optical filter (OF), or the detector device (Det) is periodically modulated with a modulation signal (Um). The received total light power (Pges) is determined from a direct current component of the electrical signal and the signal power (Pse) of said message signal is determined from a time-dependent modulation component. The carrier-to-noise ratio is determined from the above parameters.

Abstract: An arrangement for optically coupling an electro-optical transducer module to a light waveguide uses two lenses wherein the first lens is arranged in front of the electro-optical transducer module axially offset relative to the axis of the transducer module and a second lens is arranged in front of the light waveguide axially offset relative to the optical axis thereof. The optical axes of the two lenses are also axially offset relative to one another so that disturbing back-reflections are drastically reduced without diminishing the coupling efficiency of the arrangement.

Abstract: With a light waveguide feedthrough for optoelectronic modules a light waveguide fiber (1) is guided hermetically tight and mechanically stable, in particular long-term stable, directly through a module housing wall. The light waveguide fiber (1) is compression glazed in the housing-side front portion of a relatively thick-walled metal tubule (2) without external coating (5) and affixed by adhesion in its rear portion. An application of the light waveguide feedthrough according to the invention is in optoelectronic transducer modules.