Optical fibre cable

Claim 2

An aerial optical fibre cable suitable for long spans comprising an elongate core member having a central longitudinal axis and defining .[.a surfacial.]. .Iadd.an open .Iaddend.slot extending parallel to said axis .Iadd.and located to one side of said axis, .Iaddend.said member being the .[.main.]. tensile strength member of the cable and .[.wholly consisting of.]. .Iadd.comprising .Iaddend.high tensile strength material, at least one optical fiber located in said slot, and means closing the slot, said core member also being the .[.main.]. crush-resistant armouring around the optical fiber, there being an excess length of fiber in the slot, said means providing a weak line of access to said optical fibre.

Claim 3

A cable as claimed in claim 1 wherein the core member is made of a pultruded glass-reinforced-plastics material.

Claim 4

A cable as claimed in claim 1, comprising a tubular member within said slot and containing the fibres, there being an excess length of the fibres within said tube and an excess length of tubular member within said cable.

Claim 5

A cable as claimed in claim 1, said slot containing loose optical fibres.

Claim 6

An optical fibre cable as claimed in claim 1 and having a ribbon element containing optical fibres side-by-side in said slot.

Claim 7

A cable as claimed in claim 1 wherein the excess length of element within the cable lies in the range 0.2 to 0.8%.

Claim 8

A cable as claimed in claim 1 wherein the diameter of the core member is approximately 10 mm.

Claim 9

A cable as claimed in claim 1, wherein the slot is of substantially rectangular shape.

Claim 10

An optical fibre cable as claimed in claim 1, wherein the core member is made wholly of a nonelectrically-conducting material.

Claim 13

A method of making a cable as claimed in claim 10 wherein the core member is bent around a capstan to provide excess fibre in the cable when straightened.

Claim 14

A method as claimed in claim 10, wherein the fibres are housed in a tube and there is an excess length of fibres within the tube prior to introducing the tubed fibres into the slot.

Claim 17

A method as claimed in claim 13, comprising after the element has been introduced into the slot in the core, applying a binder to the core to retain the element in the slot, and bending the core around the capstan such that over-feedin of the element in to the core is induced to produce said excess.

Claim 18

A method as claimed in claim 14 comprising encasing the bound core in a tape and encasing the taped core in an extruded plastics material.

Claim 19

A method as claimed in claim 13 comprising filling the slot with a viscous water blocking material at a position in which the cable core contains the excess length of element. .Iadd.

Claim 20

A core member for an aerial optical fibre cable suitable for long spans, said core member having a central longitudinal axis and defining at least one longitudinally-extending slot extending parallel to and located to one side of said axis, said core member being made of a non-metallic material having a high elastic modulus of at least 40,000 n/mm 2 . .Iaddend. .Iadd.18. A core member as claimed in claim 17, made of a pultruded glass-reinforced-plastics material. .Iaddend. .Iadd.19. A core member as claimed in claim 18, having a circular cross-section, and wherein the slot is of substantially rectangular cross-sectional shape. .Iaddend. .Iadd.20. A method of making a fibre optic cable suitable for long spans comprising providing an elongate core member having a central longitudinal axis and defining a longitudinally-extending slot extending parallel to and located wholly to one side of said axis, feeding at least one optical fibre into the slot, and bending the core member around a curved surface to cause excess length of fibre to be fed into the slot while the member is bent and so that when the member is straightened said excess length of fibre will remain in said slot. .Iaddend.