Abstract: For short-distance communication systems, particularly for optical-waveguide links in the subscriber area, it is proposed to operate the standard single-mode optical waveguide for long-distance applications, which is optimized for the wavelength range from 1300 nm to 1600 nm, with optical transmitters and optical receivers whose operating wavelengths lie clearly below the cutoff wavelength of the optical waveguide. By means of a suitable stable laser-waveguide coupling, it is ensured that single-mode operation is achieved, which is necessary to transmit digital signals at high bit rates. The increased loss of the optical waveguide at 800 nm can be accepted because of the relatively short length of subscriber lines. Both unidirectional and bidirectional transmission over a single optical waveguide using wavelength-division or modal multiplexing is possible.

Abstract: The device comprises a transducer (3) comprising a row of photoelectric elements (27), and a coupling member (7) with an entrance (11) which is to be directed towards the document (1) and an exit (13) which is coupled to the transducer. The coupling member is constructed as an integrated optical waveguide circuit comprising a glass substrate (17) in which there are provided grooves (19) which, in order to form optical conductors (21), are filled with a glass having a refractive index which is higher than that of the glass of the substrate. The width of each groove gradually decreases from the entrance of the coupling member towards the exit and over the entire length of the grooves the distance between every two adjacent grooves is substantially constant and substantially smaller than the width of the grooves, so that substantially all light originating from a scanned line of the document is supplied to the transducer.

Abstract: Optical waveguide circuits, such as signal splitters, can be produced by etching grooves in a transparent, glass substrate and by filling the grooves with glass having a higher refractive index than the material of the substrate. The grooves have a semicircular cross-section and the filling glass is produced by a low temperature plasma-activated chemical vapor deposition process. Two substrates can be placed on top of each other, with the surfaces in which the filled grooves have been provided in contact, to form an integrated optical circuit.

Abstract: Doped silica glass is deposited by means of reactive deposition from the gas phase by the action of a nonisothermal plasma, on the inside of a quartz glass tube. The coated tube is collapsed and the preform thus obtained is drawn into an optical fiber.During the deposition procedure the tube inside diameter between 6 and 30 mm must satisfy the formula(M/A.sub.I) 1/3.58.times.1 mm.ltoreq.dwherein M is the deposition rate of doped quartz glass in grams per minute and A.sub.I has the value 1.42.times.10.sup.-4 g/min. At the end of the deposition, prior to collapsing, the inside diameter must satisfy the equation(M/A.sub.II) 1/3.04.times.1 mm.gtoreq.dA.sub.II having the value 6.63.times.10.sup.-5 g/min.

Abstract: Microlenses which are easy to handle are produced by providing rotation-symmetrical recesses in a glass plate, depositing vitreous layers by means of a vapor deposition process onto the plate, until the recesses are fully filled up, whereafter the thickness of the coated glass plate is reduced to the original value or to a smaller value. Two lenses produced in this manner are then combined to one lens by placing the embedded lenses on top of one another by means of their flat sides.

Abstract: In the reactive deposition of the core material from a gas which is passed through the tube onto the inner wall of the tube by means of a plasma zone, while a relative motion is effected in the axial direction between the tube and a plasma-producing device, the rate of precipitation is increased without impairing the quality of the core material coat, the reactive deposition being effected at a pressure of from 1 to 100 Torr and a temperature zone being superimposed on the plasma zone.

Abstract: The change in the refractive index across the radius which is important for self-focussing fibre optic light conductors is obtained because in the plasma-activated CVD-method the oxygen content of the gas mixture and/or the temperature of the tube wall is continuously reduced during the coating procedure.

Abstract: In the reactive deposition of the core material from a gas which is passed through the tube onto the inner wall of the tube by means of a plasma zone, while a relative motion is effected in the axial direction between the tube and a plasma-producing device, the rate of precipitation is increased without impairing the quality of the core material coat, the reactive deposition being effected at a pressure of from 1 to 100 Torr and a temperature zone being superimposed on the plasma zone.