Abstract: A transparent molded article for optical applications made from silicon nitride and a coating thereon of oxidic silicon nitride formed by chemical reaction of the silicon nitride with oxygen. The moldings can be shaped, depending on the area of application, to give various articles, for example optical waveguides, prisms, sensor elements or lenses, and are used in all areas where high optical demands are made.

Abstract: A process for the preparation of optical materials from silicon nitride by pyrolysis of polymeric silazanes, by pressing the pulverulent polymeric silazanes to give moldings before the pyrolysis or first dissolving the polymeric silazanes in an organic solvent, drawing fibers from this solution and pyrolyzing these fibers after evaporation of the solvent, or by melting polymeric silazanes, casting, injection-molding or extruding this melt to give moldings and subsequently pyrolyzing the moldings. An oxidic coating is produced on the silicon nitride molding in an oxygen-containing atmosphere during or after the pyrolysis. The pyrolysis can be carried out at 800.degree.-1000.degree. C. in an atmosphere containing ammonia or an ammonia/inert gas mixture.

Abstract: In a process for the production of an optical coupler for polymeric optical fibers using ultrasound welding, the fibers are warmed, before the welding, to a temperature of from 50.degree. to 250.degree. C. for from 0.2 to 3 hours. The polymeric optical fibers are introduced into a plastic tube which melts with the fibers during the welding operation to form a unit. In another embodiment, a connector bar which has the same refractive index as the core material of the polymeric optical fibers can be inserted into the plastic tube, the polymeric optical fibers are brought into contact with the connector, and the plastic tube, the connector bar and the fibers are welded to one another under the action of ultrasound.

Abstract: A thermoplastic molding compound consisting of units of 2,3-difluoroacrylic acid esters or their deuterated derivatives, or containing units of these esters, is distinguished by a high glass transition temperature and a high transparency. It is therefore suitable for the manufacture of beam waveguides for long transmission distances and high continuous use temperatures.

Abstract: A detector for detecting invisible radiation and charged particles is composed of at least one radiation-absorbing panel and at least one optical waveguide arranged parallel to the surface of said panel and containing a fluorescent dyestuff. The luminescent light produced in the panel by the absorbed radiation is converted into a fluorescent radiation in the optical waveguide conducted to a photosensitive semiconductor component by total reflection and measured at that point.

Abstract: A process for the production of optical couplers from polymers in which the coupler structure is produced by injection molding and the polymers employed are preferably amorphous polymers, in particular PMMA, polystyrenes, polycarbonates, polyolefins, polyesters, polysulfones, polyether sulfones, polyether imides, polyarylates, polyamides or polyester carbonates. The coupler element is solid and may be coated with a polymer which has a lower refractive index than the coupler, so that the light propagation takes place in the coupler itself.

Abstract: Process for producing an optical coupler for polymer optical waveguides by arranging the optical waveguides in the same sense and bundling them by means of a plastic shrink-on sleeve. In this process, two to 10.sup.5 polymer optical waveguides are arranged in the same sense and bundled and a plastic tube is put over the mixing region. Then a piece of plastic shrink-on sleeve is pushed over the plastic tube and the shrink-on sleeve is heated to a temperature at which it contracts. The shrinkage temperature of the shrink-on sleeve is inside the thermoelastic temperature range of the plastic tube. The optical waveguide bundle may be stretched during or after heating.

Abstract: Transparent thermoplastic molding compound made of 2,3-difluoroacrylic acid esters. A thermoplastic molding compound consisting of units of 2,3-difluoroacrylic acid esters or their deuterated derivatives, or containing units of these esters, is distinguished by a high glass transition temperature and a high transparency. It is therefore suitable for the manufacture of beam waveguides for long transmission distances and high continuous use temperatures.

Abstract: A light detector consists of a plate-like light-absorbing body and at least one optical waveguide connected thereto. Both parts of the light detector contain a fluorescent dye, whereby the irradiated light is converted into a fluorescence radiation. This radiation is guided by total reflection to a light-sensitive semiconductor element and is measured there. The light detector is suitable as light barrier, fiber-optic revolution counter or UV detector.

Abstract: Mechanically robust star couplers of polymer optical waveguides having low insertion losses and small fluctuations between the individual output fibers are obtained if polymer optical waveguides are arranged in parallel in the middle region of an apparatus and fused with one another under pressure and with the supply of heat. The optical cladding of the polymer optical waveguides has been previously removed. The method is easy and cost-effective. The apparatus is composed of a lower part with a channel recessed therein and an upper part with a male die located therein, which male die corresponds in its shape to the shape of the channel.

Abstract: Channels in which polymeric optical waveguides can be laid can be milled in surfaces of plastic sheets by means of an excimer laser. The free space between the optical waveguides is filled up with a transparent casting resin.The channels produced by means of the laser are distinguished by high dimensional accuracy and low surface roughness.

Abstract: An optical waveguide having a core/sheath structure whose sheath comprises a polysiloxane or a terpolymer based on vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene is suitable for transmission paths of ca. 10 to 100 m and can also be used at a temperature above 100.degree. C. without significant reduction of the transmission path.

Abstract: High-efficiency optical couplers for polymer optical waveguides are obtained when optical waveguides are bundled and fused by means of a piece of plastic shrink sleeve, the plastic shrink sleeve being heated above the shrinkage temperature. The process is simple and cost-advantageous.