Abstract: An optical fiber assembly is described exhibiting antistatic behavior comprising at least one optical fibre and having an external organic polymer-based coating which contains a non-aqueous, or substantially non-aqueous, antistatic composition comprising (a) an antistatic agent(s), and (b) an organic liquid(s) having a dielectric constant of .gtoreq.15 and a boiling point of .gtoreq.100.degree. C.

Abstract: Simple and inexpensive optical fibre splicing apparatus comprises a splicing station comprising a fibre support table and a pair of electrodes; high voltage circuitry for striking an arc; clamp assemblies at opposite ends of the table for holding end parts of aligned fibres on the table with their end faces spaced a predetermined distance apart between the electrodes, a part of at least one of the clamp assemblies being constrained to move towards and away from the other; mechanical means for controlling movement of the part of the movable clamp assembly; and a firing button for actuating the high voltage circuitry and mechanical control means. Preferably, a low voltage power source is housed in a casing separately formed with respect to the casing of the splicing station and is connected to the high voltage circuitry of the splicing station by a flexible cable.

Abstract: A termination system is provided for use with optical fibre members installed in tubular passageways using a flow of air or other gas. The system comprises a chamber defined by a body having an opening provided with a removable cover. An end of at least one passageway in which a first optical fibre member may be installed is terminated on the body so that the passageway communicates with the interior of the chamber. Means are mounted on the cover for terminating an end of at least one second optical fibre member. Preferably the passageway carries a plurality of first optical fibre members and the cover has means for terminating the ends of an equal plurality of the second optical fibre members.

Abstract: Optical connecting means for effecting disconnectable optical connections between multiplicities of optical fibres comprises a two-part mechanical connector and a plurality of two-part optical fibre connectors mounted in the body parts, of the mechanical connector. One body part of each optical fibre connector is slidably mounted in and with respect to the body part of the mechanical connector with their axes parallel to one another and is urged by a spring housed in the body part in a rectilinear direction towards the mating end of the body part. One body part of each optical fibre connector is fixedly secured in and with respect to the body part of the mechanical connector with their axes parallel to one another. Preferably, the body parts of the optical fibre connectors in each body part of the mechanical connector 1 are mounted one above another.

Abstract: A duct is provided for receiving an optical fibre member by blowing. The duct is formed at least in part of a plastics material which is electrically conductive or has electrically conductive material such as carbon black held therein or has an electrically conductive material applied thereto preferably the duct has a radially inner layer defining an inside wall of the duct and at least one further layer positioned outwardly of the inner layer, the inner layer being formed of the plastics material which is electrically conductive or has electrically conductive material held therein or had an electrically conductive material applied thereto.

Abstract: An optical fibre connector-part comprises a body of moulded plastics material having two oppositely disposed ends, at least one of which ends is adapted to make a plug and socket connection with an end of another optical fibre connector-part. At least one optical conductor is disposed within and extends between the two oppositely disposed ends of the plastics body and has permanently optically connected therein at least one discrete passive integrated optical chip for effecting at least one passive fibre optic function. At least one permanent optical connection between the optical conductor and the optical chip is wholly encapsulated within the moulded plastics material of the body so that an optical signal is accurately transmittable between the optical conductor and the optical chip.

Abstract: A device for continuously monitoring the difference in pressure of fluid in two closed spaces and separated by a dividing wall comprises an open-ended tubular housing which is secured to a rigid tube passing through and rotatably mounted in a horizontal passage in the wall with their axes inclined at an angle to one another. By rotably adjusting the housing with respect to the wall, the housing can be arranged to lie at a desired angle to the horizontal. The housing has a length three times its internal diameter and is transparent in end parts and opaque in a central part, each part being equal to a third of the total length of the housing. Two balls, each of a diameter slightly less than the internal diameter of the housing, are retained and free to roll within the housing, the ball remote from the wall being green and the other red.

Abstract: Composite apparatus for preparing and positioning tails of two optical fibers for fusion splicing and for effecting a fusion splice between prepared and appropriately positioned tails comprises optical fiber cleaving apparatus mechanically controlled fusion splicing apparatus optical fiber holding devices and associated transfer arms and a low voltage power source, the cleaving and splicing apparatus, holding devices and associated transfer arms being housed in a casing and the low voltage power source being housed in a casing which is separately formed with respect to the casing. The low voltage power source is electrically connected to the high voltage circuitry of the splicing apparatus by a flexible electric cable.

Abstract: Signal attenuation caused by a coating on an optical fibre is measured by feeding a length of the coated optical fibre into an integrating sphere assembly, forming within that part of the fibre within the sphere a loop of such a diameter that there is no risk of macrobending of the fibre and feeding the optical fibre out of the sphere to a detector. Light from a source is transmitted through the fibre and the power of the transmitted signal is continuously detected. The diameter of the loop is gradually decreased to cause macrobending of the fibre F and the strength of the light radiated through the coating by the macrobend in the fibre and collected and integrated by the sphere is monitored. The attenuation by the coating of the transmitted signal is determined from the discrepancy between the reduction of power of the transmitted signal and the increase in strength of the light radiated through the coating by the macrobend.

Abstract: Means for effecting a disconnectable optical connection between an optical guide carried by a circuit board and an optical guide carried by or associated with a backplane comprises in combination a two-part plug and socket mechanical connector and a two-part plug and socket optical fibre connector. One part of the mechanical connector is movable to a limited extent with respect to the backplane or circuit board on which it is carried and the other part of the mechanical connector is fixedly secured to a circuit board or to the backplane. One part of the optical fibre connector is housed in and fixedly secured with respect to the fixed part of the mechanical connector and the other part of the optical fibre connector is slidably mounted in and with respect to the movable part of the mechanical connector and is urged by a spring towards the mating end of the movable part of the mechanical connector.

Abstract: In the manufacture of a cable core comprising a moisture-impermeable multi-wire conductor, the conductor is stranded in a conventional manner and, after a fluid-impermeable layer of plastics material has been extruded over the conductor to form the core, the core is wound around the hub of a cable drum in such a way that each end of the wound core is exposed and accessible. One exposed end of the wound core is sealed and air is evacuated from the conductor interstices by a vacuum pump cemented to the other exposed end of the wound core. A source of semi-conductive moisture-impermeable compound in a liquid or semi-liquid state is then connected to the exposed end of the wound core and moisture-impermeable compound is drawn into and flows along the evacuated conductor interstices until the interstices are filled throughout the length of the core. The moisture-impermeable compound in the interstices is then permitted to solidify or thicken to such an extent that it will not readily flow from the conductor.

Abstract: The rubber sealing cap of a mineral insulated cable termination has embedded in the circumferential wall of the cap effecting a circumferentially continuous, fluid-tight fit around the cut-back sheath of the cable, a resilient metal sleeve which protrudes from the end face of the tube and which has at its free end an inwardly extending flange which mechanically engages with the cable sheath and which is so inclined with respect to the cable sheath as to restrain the cap against removal from the cable. The protruding flange preferably has at its free end a plurality of circumferentially spaced teeth which engage with the cable sheath.

Abstract: When effecting a fusion splice between two optical fibres, end parts of the two fibres are introduced transversely into opposite ends of an open-ended channel in a surface of a rigid elongate support member having at a position intermediate of its ends and in the surface a transversely extending open-ended slot for temporarily accommodating the electrodes by which fusion splicing is to be effected. After fusion splicing of the fibres and withdrawal of the electrodes, any space in the channel not occupied by the fushion spliced fibres and the transversely extending slot are filled with a curable material which is permitted or caused to set. A preformed elongate lid is secured to the surface of the support member 1 and the support member and lid provide permanent protection for the fusion splice.

Abstract: In a "Futurebus+" backplane, at each end of the backplane the signal lines are each electrically connected to a power bus on a face of the board or to a power plane encapsulated in the board via a discrete resistor mounted on the face of the board and separately formed with respect to the other resistors and the ground lines are each electrically connected to the power bus or power plane via a discrete capacitor mounted on the face of the board and separately formed with respect to the other capacitors. Preferably, at each end of the backplane the discrete resistors and capacitors are mounted on both faces of the board, the number on one face being approximately the same as the number on the other face. In the event that a resistor or capacitor should be faulty, only the signal or ground line to which the faulty resistor or capacitor is connected will be out of service until the faulty resistor or capacitor is replaced.

Abstract: In a method of stringing an overhead conductor incorporating an optical fibre ribbon, at least two lengths of overhead conductor, each having a bore within and extending along the length of the conductor, are electrically and mechanically connected end to end in such a way that the bores of interconnected conductor lengths are smoothly continuous and the conductor consisting of the interconnected conductor lengths is strung between a plurality of towers. After the conductor has been strung, the optical fibre ribbon is introduced into and propelled along the bore of the suspended conductor by fluid drag of a gaseous medium.

Abstract: An optical measurement system is disclosed which enables rapid and repeatable measurement of insertion and return loss of each fiber in sequence of a multi-fiber connector 15 connected to an optical fiber ribbon 16 to be obtained without disturbing either the light source 17, 18 or detector components 19, 20 of the system. The system comprises a multi-channel optical switch 1 for connection to a light source 17, 18; 1.times.

Abstract: A method is described for introducing one or more optical fibre members (1) into a tubular passageway (2). The method involves passing a current of fluid, preferably air, into and through a venturi (6) the downstream side of which communicates with the passageway (2). The optical fibre member (1) is introduced into the venturi (6) via a hypodermic tube (7) and then into the passageway (2). Apparatus for carrying out the method are described.

Abstract: An optical fibre cable comprises an inner sheath containing at least one optical fibre member, and an outer sheath containing the inner sheath. The inner sheath is of a material which is soft and has a low modulus of elasticity. The outer sheath of a material having bulk properties, such as density and stiffness, and surface properties, such as surface texture and friction such that the cable can be propelled along a duct by a flow of air travelling along the duct. An intermediate sheath may be provided between the inner and outer sheaths.

Abstract: An optical fibre cable comprises a plurality of optical fibre structures each of which comprises an optical fibre surrounded by at least one sheath layer. The optical fibre structures are separably held together side-by-side. The optical fibre cable is propellable along a tubular pathway by fluid drag of a gaseous medium passing over the cable, and each of the individual optical fibre structures is preferably also so propellable when the said structures are separated from one another.

Abstract: A flame-retardant cross-linkable polymer composition for extrusion which is capable of producing non-porous products comprises: at least one flame-retardant filler of the class that evolve substantial amounts of bound water on heating at temperatures above a value T.sub.d that lies in the range 120.degree.-250.degree. C.; a compatible ethyelene copolymer base in which the filler is dispersed; a hydrolysable unsaturated silane; and a free-radical grafting initiator having a half-life of less than 10 minutes at a temperature 25.degree. C. below T.sub.d.