Abstract: A digital optical switch with two input terminals and two output terminals to satisfy the extensive uses of optical switches. The conditions for adiabatic mode evolution can be flexibly adjusted depending on the planned use for said switch, the technological production thereof still being simple. In the digital optical switch according to the invention, the first incoming waveguide, with regard to the second incoming waveguide in the input section and the third outgoing waveguide with regard to the fourth outgoing waveguide in the output section are symmetrical with each other in cross-section, index of refraction and arrangement in relation to the direction in which the light spreads. Structural electrodes have a tapering effect on the wave guides and are adjusted thereto, and an electrode arranged in the output section is electrically driven.

Abstract: A measurement method is presented for the determination of low levels of optical absorption in any material, with at least a quasi-simultaneous detection of the transmission intensities of a measurement light beam and a reference light beam, the wavelengths of which are different, such that, essentially, the measurement light is absorbed by the material to be tested, and with a joint analog acquisition of the detected measurement and reference signals, taking into consideration the natural difference in intensities between the measurement light beam and the reference light beam.

Abstract: An electronic projector system having a fluid, preferably an oligo (phenylenemethylene) resorcinol, having optical and improved hydromechanical, hydrodynamic, electrical and other physical and chemical properties oriented to HDTV requirements, and thus to provide measures suitable for widespread application regarding resistance to radiation damage.

Abstract: A system for videoconferencing saves travel time and money. To enable participants to see each other continually and simultaneously, and to show documents and objects, equipment is needed, the costs of which vary with the number of locations to be interconnected, and with measures taken for reducing the needed transmission capacity and the outfit of each terminal. As in known videoconference systems, such as studio, or working place systems, the video and audio signals are switched and/or mixed in the inventive system. The necessary equipment, however, is no longer needed at the respective locations, if a central station for videoconferencing is provided which includes this equipment only in a volume actually necessary for the conference. Each of the connected participant locations only comprises terminal units, the same which are needed for a picture telephone system. In addition, both the video and the audio reception can individually be controlled from each location.

Abstract: User stations for digital time multiplex communications networks with decentralized exchange which are provided with basic equipment, independent of the structure of the network, composed of modular units which are used according to the requirements of the user, the service to be performed and the structurally given conditions are further provided with an additional equipment performing features including call transfer, call diversion, automatic call transfer, etc.

Abstract: An interactive cable television system for serving a plurality of user locations in a service area divided into a plurality of service regions, including a central office and a service network having a portion composed of parallel cables arranged in a tree pattern possessing a plurality of nodes remote from the user locations and, in the vicinity of the users, a further portion representing the lowermost plane of the network and composed of transmission cables connected to groups of user locations, the transmission cables being connected to each group in a star pattern, the system presenting a plurality of transmission paths and permitting multiple utilization of the paths, the parallel cables of the first mentioned portion of the network being connected in each service region in a tree structure extending from one node toward the user locations and being constituted by two parallel autonomous sets of cables, thus representing medium planes of the network, the network further including, in each service region