Abstract: In a device for performing measurements on at least partly transparent objects such as optical fibres a radiation beam is directed on the object. The radiation deflected by the object is imaged by means of a lens system (321, 322) on a radiation-sensitive detection system (330). As a result of refraction on interfaces between areas having a different refractive index (311, 312) in the object and between the object and the surroundings (315), dark or light bands corresponding to the projection of the interfaces are produced on the radiation-sensitive detection system (330). Thus measurements can be performed on the internal structure of the object.

Abstract: The invention relates to an optical glass fibre 1 having a synthetic resin coating which consists of at least two layers 2 and 3 in which the first layer 2 is formed from an elastomer forming material which can be cured by exposure to actinic radiation, and in which the optical glass fibre exhibits a great tensile strength, a small risk of static fatigue fracture and a low ageing rate, owing to the fact that the synthetic resin composition comprises between 0.1 and 5% by weight of one or more phosphorus compounds of the following structural formula: ##STR1## wherein n has a value of 1 or 2 and wherein R represents an organic group, preferably an organic group which co-reacts during curing of the elastomer forming material and is built into the polymeric network thus formed.

Abstract: A method of and a device for manufacturing an optical fiber with a protective coating. A cooling device cools the fiber after drawing from a preform. The cooling device comprises a forced-cooled double-walled tube. In the space enclosed by the inner tube through which the fiber to be cooled is passed, a gas is present which has good heat-transporting properties. The gas may be, for example, helium. Cooling of the fiber takes place by heat dissipation via the helium to the forced-cooled tube wall.

Abstract: An optical fiber provided with a synthetic resin coating, comprising a glass fibre, a first enveloping layer of a synthetic rubber having a modulus of elasticity from 0.1 to 10 MPa and a subsequent enveloping layer of a synthetic resin having a larger modulus of elasticity than the first layer, obtains a large mechanical resistance and a high insensitivity to temperature variations within the range from -60.degree. C. to +80.degree. C., in that the thickness of the first layer is from 5 to 20 .mu.m and in that the modulus of elasticity of the second layer is more than 1000 MPa.

Abstract: The invention provides an optical fibre having a synthetic resin cladding, comprising a glass fibre, a first cladding layer of a synthetic rubber and a subsequent cladding layer of a synthetic resin the molecules of which are oriented substantially in the longitudinal direction of the glass fibre, in which a low application temperature, a low pressure and a high cladding rate can be used in that the oriented synthetic resin is formed from a curable synthetic resin composition which comprises one or more oligomeric compounds the molecules of which comprise reactive groups and the molecular weight of which is smaller than 5000.The invention further relates to a method of manufacturing such an optical fibre and a device for cladding a glass fibre with a curable synthetic resin composition in which an elongation flow in the curable synthetic resin composition is produced to effect the orientation in the curable synthetic resin composition.

Abstract: A method of and an apparatus for providing a bubble-free coating on a fibre, more particularly on an optical fibre. A fibre to be coated is fed into a pressure chamber (61) via an inlet duct (56) with a restricted inlet opening (57) and leaves the pressure chamber (61) through an outlet opening (41) of a nozzle (40). Liquid coating material is supplied to the pressure chamber (61) at such a pressure that the coating material rises in the inlet duct (56) up to a certain level to form a convex meniscus (D). By flushing the surroundings of the inlet opening (57) with a gas having a kinematic viscosity which is lower than that of air, the drawing speed at which the applied coating is still bubble-free can be considerably increased.

Abstract: The invention relates to a transmission projection screen having a high light output and a suitable contrast, for example, for use in a projection-television system, and a method of manufacturing such a screen.The projection screen comprises a transparent substrate having a front surface which is provided with mutually parallel ribs. Light-absorbing glass fibers 10 are provided at the bottom of the grooves 24 between the ribs 22, and they are fixed by means of a hot-melt adhesive layer 11.

Abstract: An arrangement for coating a fibre, more particularly an optical fibre, comprising a housing (31) with a pressure chamber (61) which is in communication with a connection (63) for the supply of liquid coating material. A fibre to be coated is supplied via a guide duct (59) in a tubular guide member (55), traverses the pressure chamber (61) and leaves the device (11) via an outlet opening (41) in a nozzle (40). The tubular guide member (55) is made of an elastically deformable material. By means of two spindles (79), the end of the tubular guide member (55) can be adjusted so that the coating is centered with respect to the fibre and a coaxial location of fibre and coating is obtained.

Abstract: A method of manufacturing a fiber-optical coupling element by fusion of two monomode fibers. The fiber cores are made of a core glass, the American softening temperature of which is at least 80.degree. C. higher than that of the cladding glass. The fibers are heated to a temperature between 520.degree. and 560.degree. C. By the method, fibers can be fused to form a coupling element without undesirable deformation of the fiber cores.

Abstract: An optical fiber having a circular outer cross-section and having a core which has a noncircular cross-section is produced by using a double crucible. The outer crucible is provided with a ring-shaped channel of which at least one of the boundary walls has a noncircular cross-section. The glass of the outer crucible is passed through this channel before it is contacted with the glass of the inner crucible.

Abstract: A coupling element for coupling a laser radiation source to a monomode optical transmission fiber. The end of the fiber is monotonically flattened at a temperature at which the fiber core has a viscosity of between 10.sup.7 to 10.sup.8.5 poises. The fiber has a cladding glass chosen to have a viscosity of between 10.sup.10 -10.sup.11 poises at the flattening temperature. This causes the core glass to emerge in the form of a semi-ellipsoidal lens, when the fiber is flattened.

Abstract: Method of producing a coupling element for coupling a laser radiation source to a monomode optical transmission fiber. The end of the fiber is monotonically flattened at a temperature at which the fiber's core has a viscosity of between 10.sup.7 to 10.sup.8.5 poises. The fiber has a cladding glass chosen to have a viscosity of between 10.sup.10 -10.sup.11 poises at the flattening temperature. This causes the core glass to emerge in the form of a semi-ellipsoidal lens, when the fiber is flattened.