Abstract:
An overhead electric conductor with optical fibres 3 loosely housed in the bore of a central core 1, which bore also contains a greasy water-impermeable medium 4, is manufactured by causing a preformed elongate metal member 2 of U-shaped transverse cross-section and the optical fibres to advance in the direction of their lengths, the rate of advance of the fibres being restrained. As the U-shaped elongate member 2 is transversely folded around the optical fibres 3, greasy water-impermeable medium 4 is injected into the bore of the elongate metal member 2 under a controlled pressure. The consistency of the greasy water-impermeable medium 4, the pressure and rate at which it is injected into the bore and the degree of restraint imparted to the optical fibres 3 is such that, in a predetermined length of the conductor, the length of the optical fibres exceeds the length of the bore by a controlled extent, preferably 1 to 3%.
Abstract:
A plastic optical fiber comprising a core and a cladding, wherein the core is made a polymer comprising units of methyl methacrylate and of a methacrylate ester the ester moiety of which has an alicyclic hydrocarbon of 8 to 20 carbon atoms, and the cladding is made of a fluorine-containing polymer comprising units of the formula: wherein R 1 and R 2 are each hydrogen or C, -C 3 alkyl, R 11 is fluorine or trifluoromethyl, and R 12 is C 2 - C 11 fluoroalkyl, which units (I) are derived from fluoroalkyl a-fluoroacrylate or trifluoromethacrylate, which has short- and long-time heat and humidity resistance as well as low attenuation of light transmission.
Abstract:
In a simple and inexpensive method of manufacturing an optical fibre ribbon structure 11, several optical fibres 1 (and if desired one or more than one flexible reinforcing element) are arranged to travel side by side and an overall coating 3 of plastics material is applied to the advancing optical fibres to form a plastics coated optical fibre array 4. This array is fed between a pair of advancing tapes 5 and the advancing taped plastics coated optical fibre array 8 is subjected to a curing operation to cure the plastics material and cause it to bond to the embedded optical fibres 1 and lightly to the tapes 5. The tapes 5 are then peeled away from the array to form an optical fibre ribbon structure 11. The plastics material of the overall coating Is preferably an acrylate or other plastics material that can be cured by ultra-violet radiation.
Abstract:
A penetration assembly for an optical fiber cable comprises a pair of axially-aligned cylindrical sleeves 13 surrounding an optical fiber cable 6. An air-tight seal is formed between the optical fiber cable and the sleeves by means of glass connectors 16 connected to the optical fiber cable and flexible metal connectors 15 connected between the glass connectors and the inside of the sleeves. Each glass connector 16 comprises a plurality of cylindrical sections each having a different coefficient of thermal expansion having a value between that of the optical fiber cable 6 and that of the flexible metal connector 15. The coefficient of thermal expansion of the glass connector 16 changes in a stepwise manner from the section connected to the optical fiber cable 6 to the section connected to the flexible metal connector 15. This step-wise change in coefficient of thermal expansion reduces the thermal stresses exerted on each section and prevents cracks due to thermal stress, a common problem with the resinous materials presently used to form air-tight seals in penetration assemblies. Since the air-tight seal between the optical fiber cable and the sleeves is formed from glass and metal, it is more resistant to radiation than presently used seals formed from resinous materials.
Abstract:
A process is disclosed for producing an infra-red light transmitting optical fiber by drawing a rod of single crystal or polycrystalline metal halide into a fiber through a die; also disclosed is a process for producing an infrared light transmitting optical fiber of step-index type by forming around a single crystal or polycrystalline fiber core, an intimate cladding crystal layer having a lower refractive index than the core by working in the temperature range that does not cause recrystallization of the core or cladding during working.
Abstract:
A cable adapted for well logging has an optical fiber core in which the optical fibers are protected from moisture and non-uniform stresses by first wrapping the fibers in a helical spiral around a solid, soft, deformable core material and then blanketing them with more of the same. Next the blanketed core is closely and tightly wound with several overlapping layers of a metallic tape jacket. The jacket buffers radial loads applied by other portions of the cable and forms a barrier against moisture penetration. The soft core and blanket have properties close to a liquid so that only uniform, essentially hydrostatic stresses are transmitted to the optical fibers.
Abstract:
An optical communication element assembled from an optical fibre bonded in a state of axial compressive stress to a metal tape. The tape may be folded-up into a tube and sealed by soldering. Such elements are strong and not sensitive to stress corrosion. Such an optical communication element may be produced by passing a metal tape and an optical fibre in contact around a drum with the optical fibre on the outside. An adhesive, which solidifies or cures during the passage around the drum is applied to the metal tape. The method is further explained by reference to Fig. 3.