GB2120398A

GB2120398A - Fibre optic bundles

Info

Publication number: GB2120398A
Application number: GB08214640A
Authority: GB
Inventors: John Sinclair Armour
Original assignee: TRANSPORT SECRETARY OF STA
Current assignee: TRANSPORT SECRETARY OF STA
Priority date: 1982-05-19
Filing date: 1982-05-19
Publication date: 1983-11-30
Also published as: GB2120398B

Abstract

The production of coherent fibre optic bundles has hereto involved either the positioning of a bundle of tubes which are then drawn together to form a coherent fibre optic bundle, or the flat parallel laying up of individual fibres which are then rolled and wrapped in such a way as to retain coherence when the fibre optic bundle is formed. The invention disclosed uses optical fibres 14 as the warp of a cloth 10 produced by weaving, the weft of the cloth 12 holding the optical fibres relative to one another so that sheets of the cloth may be folded or rolled to form coherent fibre optic bundles. An appropriate choice of weft would allow the extremities of the bundle to be fused to fix the optical fibres in position, while the weft between the extremities could be removed, for instance by the action of a solvent, to allow the extremities to be easily relatively movable. <IMAGE>

Description

SPECIFICATION Fibre optic bundles The invention concerns improvements in or relating to optical fibre bundles and particularly, but not exclusively to coherent optical fibre bundles i.e. bundles wherein the relative positions of individual optical fibre ends at one extremity of the bundle bears a known relationship to the relative positions of individual optical fibre ends at the other extremity. Conventionally the positions of the individual fibres within the bundles are the same at both extremities as, for example, in coherent bundles used in viewing aids.

A first prior art method of producing coherent fibre optic bundles uses an adaptation of the known method of producing individual fibres by drawing out a heated glass tube. The method involves collecting a bundle of tubes and heating and drawing these to form a fibre optic bundle of small diameter.

A second prior art method of producing coherent fibre optic bundles employs a rotating drum and a feeder mechanism for feeding a single optical fibre onto the drum as it rotates in order to give and evenly-wound drum. The fibres are then cutoff the drum wholst still retaining their even configuration and wrapped to give a coherent bundle.

Disadvantages of these prior art methods are that they are relatively complex and expensive and offer a limited degree of scope for variation of the cross section of the finished bundle.

Purposes of the invention include the allevation of these disadvantages.

According to the present invention there is provided a method of producing a coherent fibre optic bundle including the steps of weaving a fabric such that at least some of the woven threads of the fabric are optical fibres and folding the woven fabric to form a bundle.

The optical fibres preferably form at least some of the warp threads. The woven fabric may then be rolled into a spiral bundle to leave the warp ends at the two extremities of the bundle.

Alternatively the woven fabric may be folded concertina-fashion to leave the warp ends at the two extremities of the bundle. A further alternative is to form the fabric into a tubular construction with the warp ends at the two extremities of the tube.

Where the optical fibres form at least some of the warp, the weft may be formed of, for example, plastic fibres. After folding the fabric to form a bundle, the bundle may be subjected to local heating at each extremity in order to melt the weft fibres and then cooled so that the optical warp fibres are held in place by the melted plastic. In addition, in order to provide flexibility, the bundle, except for the two extremities, may be immersed in a solvent which dissolves the weft plastic without affecting the optical warp fibres.

An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings consisting of Fig 1 depicting in magnified form and in plan view a first stage in the fabrication of a coherent fibre optic bundle.

Fig 2 depicting in magnified form and in end elevation a second stage in the fabrication of a coherent fibre optic bundle.

In Fig 1 a fabric, a portion, 10, of which is shown in the drawing, is woven by conventional means using polyester thread as the weft, 12, and optical fibres made of optical quality plastic as the warp, 1 4. The warp additionally contains market threads, 16, which consist of warp threads made of a distinctively coloured plastic material included at regular intervals in the series of optical fibre warp threads. In Fig 1 the marker threads constitute every fifth warp thread.

When weaving of the fabric is completed it is folded concertina-fashion length-ways with the marker threads, 1 6, lying along the folds to give a coherent bundle of optical fibres. Fig. 2 illustrates in elevation a magnified view along an end of the bundle which appears as a rectangular array of optical fibre ends.

Each extremity of the coherent bundle is then subjected to local heating by radio frequency induction so as to melt the polyester weft threads.

but leave the plastic optical fibres unaffected. The heating is then removed, enabling the polyester material to solidify in order to secure the optical fibres in a rectangular array. The coherent bundle, except for its two extremities, is then immersed in a bath of solvent which dissolves the polyester weft material at the mid portion of the bundle, but leaves the plastics optical fibres intact. The removal of the weft gives the bundle an increased degree of flexibility.

The invention is not confined to the details of the above embodiment. The optical fibres may, instead of comprising a portion of the warp threads, comprise some of the weft threads. The woven fabric may then be folded width-ways instead of length-ways to form a coherent bundle.

The weft threads may, instead of comprising polyester material, be made up of an alternative material, for example nylon. Additionally, instead of dissolving away some of the weft material after forming the bundle, it may be left in place to give a more firm construction.

The woven fabric may be folded to give an array of optical fibre ends other then rectangular, for example a spiral arrangement.

1. A method of producing a coherent fibre optic bundle including the steps of weaving a fabric such that at least some of the woven threads of the fabric are optical fibres and folding the woven fabric to form a bundle.

2. A method of producing a coherent fibre optic bundle including the steps of weaving a fabric such that at least some of the woven threads of the fabric are optical fibres and rolling the woven fabric to form a bundle.

3. A method of producing a coherent fibre optic bundle as in claim 1 or claim 2 in which some of the warp threads are formed of optical fibres, the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Fibre optic bundles The invention concerns improvements in or relating to optical fibre bundles and particularly, but not exclusively to coherent optical fibre bundles i.e. bundles wherein the relative positions of individual optical fibre ends at one extremity of the bundle bears a known relationship to the relative positions of individual optical fibre ends at the other extremity. Conventionally the positions of the individual fibres within the bundles are the same at both extremities as, for example, in coherent bundles used in viewing aids. A first prior art method of producing coherent fibre optic bundles uses an adaptation of the known method of producing individual fibres by drawing out a heated glass tube. The method involves collecting a bundle of tubes and heating and drawing these to form a fibre optic bundle of small diameter. A second prior art method of producing coherent fibre optic bundles employs a rotating drum and a feeder mechanism for feeding a single optical fibre onto the drum as it rotates in order to give and evenly-wound drum. The fibres are then cutoff the drum wholst still retaining their even configuration and wrapped to give a coherent bundle. Disadvantages of these prior art methods are that they are relatively complex and expensive and offer a limited degree of scope for variation of the cross section of the finished bundle. Purposes of the invention include the allevation of these disadvantages. According to the present invention there is provided a method of producing a coherent fibre optic bundle including the steps of weaving a fabric such that at least some of the woven threads of the fabric are optical fibres and folding the woven fabric to form a bundle. The optical fibres preferably form at least some of the warp threads. The woven fabric may then be rolled into a spiral bundle to leave the warp ends at the two extremities of the bundle. Alternatively the woven fabric may be folded concertina-fashion to leave the warp ends at the two extremities of the bundle. A further alternative is to form the fabric into a tubular construction with the warp ends at the two extremities of the tube. Where the optical fibres form at least some of the warp, the weft may be formed of, for example, plastic fibres. After folding the fabric to form a bundle, the bundle may be subjected to local heating at each extremity in order to melt the weft fibres and then cooled so that the optical warp fibres are held in place by the melted plastic. In addition, in order to provide flexibility, the bundle, except for the two extremities, may be immersed in a solvent which dissolves the weft plastic without affecting the optical warp fibres. An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings consisting of Fig 1 depicting in magnified form and in plan view a first stage in the fabrication of a coherent fibre optic bundle. Fig 2 depicting in magnified form and in end elevation a second stage in the fabrication of a coherent fibre optic bundle. In Fig 1 a fabric, a portion, 10, of which is shown in the drawing, is woven by conventional means using polyester thread as the weft, 12, and optical fibres made of optical quality plastic as the warp, 1 4. The warp additionally contains market threads, 16, which consist of warp threads made of a distinctively coloured plastic material included at regular intervals in the series of optical fibre warp threads. In Fig 1 the marker threads constitute every fifth warp thread. When weaving of the fabric is completed it is folded concertina-fashion length-ways with the marker threads, 1 6, lying along the folds to give a coherent bundle of optical fibres. Fig. 2 illustrates in elevation a magnified view along an end of the bundle which appears as a rectangular array of optical fibre ends. Each extremity of the coherent bundle is then subjected to local heating by radio frequency induction so as to melt the polyester weft threads. but leave the plastic optical fibres unaffected. The heating is then removed, enabling the polyester material to solidify in order to secure the optical fibres in a rectangular array. The coherent bundle, except for its two extremities, is then immersed in a bath of solvent which dissolves the polyester weft material at the mid portion of the bundle, but leaves the plastics optical fibres intact. The removal of the weft gives the bundle an increased degree of flexibility. The invention is not confined to the details of the above embodiment. The optical fibres may, instead of comprising a portion of the warp threads, comprise some of the weft threads. The woven fabric may then be folded width-ways instead of length-ways to form a coherent bundle. The weft threads may, instead of comprising polyester material, be made up of an alternative material, for example nylon. Additionally, instead of dissolving away some of the weft material after forming the bundle, it may be left in place to give a more firm construction. The woven fabric may be folded to give an array of optical fibre ends other then rectangular, for example a spiral arrangement. CLAIMS

3. A method of producing a coherent fibre optic bundle as in claim 1 or claim 2 in which some of the warp threads are formed of optical fibres, the warp ends of the fabric being the extremities of the bundle.

4. A coherent fibre optic bundle produced as in claim 3 having the fabric weft of a thermally deformable material, such that the extremities of the bundle may be thermally treated to hold rigidly the fibre optic content of the warp.

5. A coherent fibre optic bundle produced as in claim 3 or claim 4 having the fabric weft removable to allow the extremities of the bundle to be relatively moveable.

6. A coherent fibre optic bundle substantially as hereinbefore described with reference to Figures 1 and 2.