GB2208945A - Optical cable suitable for non intrusive taps - Google Patents
Optical cable suitable for non intrusive taps Download PDFInfo
- Publication number
- GB2208945A GB2208945A GB8719692A GB8719692A GB2208945A GB 2208945 A GB2208945 A GB 2208945A GB 8719692 A GB8719692 A GB 8719692A GB 8719692 A GB8719692 A GB 8719692A GB 2208945 A GB2208945 A GB 2208945A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cable
- sheath
- sections
- preformed
- optical fibre
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
- G02B6/4401—Optical cables
- G02B6/4429—Means specially adapted for strengthening or protecting the cables
- G02B6/443—Protective covering
- G02B6/4431—Protective covering with provision in the protective covering, e.g. weak line, for gaining access to one or more fibres, e.g. for branching or tapping
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/2804—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
- G02B6/2852—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers using tapping light guides arranged sidewardly, e.g. in a non-parallel relationship with respect to the bus light guides (light extraction or launching through cladding, with or without surface discontinuities, bent structures)
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4219—Mechanical fixtures for holding or positioning the elements relative to each other in the couplings; Alignment methods for the elements, e.g. measuring or observing methods especially used therefor
- G02B6/4236—Fixing or mounting methods of the aligned elements
- G02B6/424—Mounting of the optical light guide
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/42—Coupling light guides with opto-electronic elements
- G02B6/4201—Packages, e.g. shape, construction, internal or external details
- G02B6/4287—Optical modules with tapping or launching means through the surface of the waveguide
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
- G02B6/4401—Optical cables
- G02B6/4403—Optical cables with ribbon structure
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
- G02B6/4401—Optical cables
- G02B6/4407—Optical cables with internal fluted support member
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Light Guides In General And Applications Therefor (AREA)
Abstract
An optical fibre cable is manufactured by preforming elongate sheath sections (2) and bringing the sections together whilst feeding cable elements such as strength members (3) and coated optical fibres (4) into channels provided in the sheath sections. The sheath sections may be secured together by impact or hot melt adhesive. To enable easy access to the fibres, such as for the application of non-intrusive taps, easy knock-out panels (2a) are provided at intervals along the length of one or both sheath sections before they are joined by, for example, die-stamping. if a mechanical grating is required for a tap it may be embossed or engraved in one sheath section, the other sheath section having knock-out panels aligned with the grating. <IMAGE>
Description
COMMUNICATIONS CABLE
This invention relates to commurications cable and in particular to an optical cable construction for use in a system in which a non-intrusive tap is needed, such as in optical fibre communication systems and In particular a local area network (LAh'!, and a method of manufacturing cable.
A known method of tapping enter into and out of a single-mode optical fibre waveguide WithOUt interrupting the main flow of energy is to introduce a micro-bend perturbation to the fibre axis of such a mechanical wavelength and amplitude that resonance coupling occurs between the bound dominant mode in the fibre core and the first radiating mode within the cladding. The radiating energy can be removed from the cladding using an index-matching mediu With or without a gentle fibre bend.
In our earlier patent Application No. 8716360 (Serial No. )(M.M. Ramsay - D.L. Waters 31-2) there is described an optical cable construction that could lead to increased efficiency for non-intrusive taps. This previously suggested construction involves a corrugated reflective surface, for example a corrugated aluminium plastics laminate, against which a coated, for example acrylate coated, single mode optical fibre may be pressed by collecting optics, to provide the microbends for mode coupling and to reflect radiation back to the collecting optics. This corrugated reflective surface is bonded to two longitudinal strength members of the cable optical fibres located adJacent the surface, and a sheath provided thereover.
there a tap is required to be inserted part of the sheath is cut away on the opposite side to the corrugated reflective surface to expose the fibre and the surface so that the fibres can be pressed against the corrugated reflective surface by the collecting optics.
An alternative form of non-intrusive tap is described in our earlier patent Application No. 8716361 (Serial No. ) (M.M. Ramsay - J. bees 32-22). This type of tap does not employ part of the cable with which it is used for its tapp-g operation, rather it involves means whereby it clips on to the fibre, has integral microbend inducing corrgations and has integral radiation collecting means. One form of optical cable with which such a non-intrusive tap may be employed is described in our earlier patent Application
No. 8716362 (Serial No. ) (M.M. Ramsay - J.G.
Titchmarsh 33-10). That cable comprises 2 sheath containing an optical fibre supported in an elastomeric filler. Strength members may be provide in the sheath. Ere elastomeric filler has a longitudinal and radial split whereby the fibre may be exposed, following exposure of the elastomer split such as by cutting the sheath, when it is required to insert a tap
It is an object of the present invention to provide an alternative cable construction and a method of manufacturing an optical cable with which non-intrusive taps can be employed.
According to one aspect of the present invention there is provided a cable including a sheath comprised of substantially identical preformed elongate sections provided with channels for the reception of cable elements and such that when the sheath sections are united the cable elements are retained within cavities of the sheath.
According to another aspect of the present invention there is provided a method of manufacturing a cable including the steps of taking substantialiy identical preformed elongate sheath sections provided with channels for the reception of cable elements, feeding cable elements into the channels of at least one sheath section, bringing the sheath sections together, with the cable elements therebetween, and securing them together, the cable elements being retained within cavities internal of the sheath formed by the sheath sections.
Embodiments of the invention will no be described with reference to the accompanying drawings, in which:
Fig. 1 illustrates a possible cable sneath element cross-section;
Fig. 2 illustrates a section through an optical cable including two cable sheath elements o Ic. 1 and taken at a positiOn along the length of the cable where a tap is not required;
Fig. 3 illustrates a section through an optical cable including two cable sheath elements of Fig. 1 and taken at a position along the length of the cable where a tap may be provided;
Fig. 4 illustrates a section through an alternative embodiment of optical cable to that shown in
Fig. 3 but employing two cable sheath elements of Fig.
1, and
Fig. 5 illustrates a section through the cable of Fig. 3 with a non-intrusive tap associated with one fibre thereof.
The conventional methods of cable manufacture generally involve assembling the various elements of the cable together, the configuration of which assembly may take a wide variety of forms, and then extruding a sheath around these elements to complete the cable.
Such a method is used to provide the cable construction of the above referred to patent Application No. 8716360 (MM. Ramsay - D.L. Waters 31-2).
In the method of cable manufacture proposed by the present invention extrusion of a sheath element forms one of the early steps in manufacture. As is apparent from the cable cross-section shown in Fig. > , the cable 1 includes two identical cable sheath elements 2, two strength members 3 and four coated optical fibres 4 contained within a thixotropic gel(5)-filled cavity 6. The sheath elements or sections 2 are preformed, for example, extruded, to the cross-section illustrated in
Fig. 1, although this is not the only possible cross-section, with channels for the reception of cable elements.Since half the sheath is extruded at a tiine in the illustrated embodiment the cable design has mu-h more flexibility, particularly with regard to the "internal" shape of the extrusion, i.e. the shapIng a- the entire face 7 which is internal of the completed cable. The coated fibres 4 may be conventional since mode core/cladding structure fibres with a plastics coating of, for example, acrylate. Wnereas four fibres 4 are illustrated this is not the only possibility, there may be one or more fibres. The cavity 6 is filled with the thixotropic gel 5, for example Rheogel 21G as supplied by Messrs. Syntec. The sheath may be of polyethylene and the strength members of steel. When the sheath sections are united the cable elements are retained within cavities internal of the sheath.
As the sheath elements are pre-extruded -sections it is possible to employ conventional die stamping techniques on them, either or both, before assembly of the cable to produce easy knock-out sections or panels 2a in the finished cable sheath. Fig. 3 shows an embodiment with one such section in one side only whereas Fig. 4 shows an embodiment with such sectior,s on both sides. Die-stamping to produce easy knock-out sections, a technique which is employed extensively in the metal stamping industry, involves stamping wlth a metal die into which grooves have been cut. The stamping operation is performed against a resilient pad and the stamped section is then partially cut out but held in place by uncut elements corresponding te the grooves in the die.By altering the size and number of the grooves the easy knock-out panel can be tailored to give a required ease of knock-out. Such panels may be space at intervals along the length of the cable, or even substantially continuously along its length. Kner, there are such panels in both sheath elements and the employed tap (not shown) is of a form which requires access from both sides of the fibre, the knock-out panels will need to be substantially opposIte one another.
Fig. 5 illustrates a cable as in Fig. 3 but with the easy knock-out panel In the sheath element removed and a non-intrusive tap 8 applied to one of the coated fibres. The tap & comprises two similarly shaped transparent members 9 and 9a typically formed of polymethylmethacrylate and generally triangular in cross-section. The surfaces 10 may be metallised to enhance their reflectivity. Around the members 9 and 9z is a surface coating 11 of a low refractive index, typically this coating is of fluorinated ethylene propylene. Ene coating is split at 12.The apices of the members 9 and 9a have generally part circular cross-sectional surfaces and the internal surfaces of the coating 11 adjacent the split are also part circular, so that the various surfaces together define a generally cylindrical cavity 13 into which a fibre may be inserted. The surfaces of the apices are also provided with radial protrusions or corrugations (not shown in detail) which when the tap is in position on a fibre cause microbending, inducing coupling between the core and cladding modes and resulting in coupling between the fibre and the tap. The coupled-out radiation is directed axially of the tap towards a tap outlet face (not shown) by reflection from the part-spherical or part-parabolic surface 14 of the tap.
The tap has two basic axial sections, that having the coating and being engageable with the fibre and an adjacent section at whose end the coupled out radiation is available. See earlier referred to Application No.
8716361 (M.M. Ramsay - J. Lees 32-22). To apply the tap to a fibre, the coated apex section of the tap is pushed radially against the fibre with the split 12 aligned therewith. The surface coating 11 acts as a hinge at 15, and the pushing action in the radial direction causes the members 9 and 9a to be separated slightly and the fibre to pop into cylindrical cavity 13.
As a result of the inside surface of a sheath element being accessible initially, it is possible to emboss or engrave a grating thereat, which can be used to induce microbend coupling, which gratings should preferably only be disposed at positions which will be opposite the easy knock-out sections where taps may be disposed, since otherwise bending of the fibre may result in undesired losses due to coupling out of radiation at the bends. The grating sections may be aluminised to obtain enhanced reflectivity.
Alternatively, an intermittently corrugated aluminium plastics laminate as referred to above may be incorporated into the complete cable, the corrugated sections being at spacings equal to the spacing between the easy knock-out panels.
All of the required cable elements are premanufactured and in the final stage of cable manufacture the two sheath elements are brought together enclosing all the cable elements which are fed in concurrently, i.e. strength members, fibres, fillings, reflecting elements etc, and are joined using, for example, an impact or hot melt adhesive.
Thus an optical fibre cable is constructed from two substantially identical extruded sections. Strength members, fibres, fillers etc are added at the same time as the sections are brought together and joined. This enables complex cross-sections to be obtained quite easily and easy knock-out panels to be incorporated into the sheath during the manufacturing process. In this way complex cables can be assembled that are quite impossible with normal sheath extrusion techniques.
Claims (18)
1. A cable including a sheath comprises o substantially identical preformed elongate sections provided with channels for the reception of cable
elements and such that when the sheath sections are
united the cable elements are retained within cavities
of- the sheath.
2. A cable as claimed in claim 1 and comprising
two said preformed sections each having a channel for
the reception of a strength member and a channel for the
reception of at least one optical fibre.
3. A cable as claimed in claim 2, each preformed
section including a further channel for the receptIon of
a further strength member, the optical fibre channel
being disposed between the strength member ch2nrzels.
4. A cable as claimed in claim 3 wherei
intervals along its length at least one of the preformed
sections is provided with removable panels adjacent the
optical fibre channels.
5. A cable as claimed in claim 4 wherein te removable panels have been provided by die-stat ping.
6. A cable as claimed in claim 4 or claim 5,
wherein one preformed section is provided with said
removable panels at intervals along its length and the
other preformed section is provided with mechanic;
gratings, at intervals along its length and aligned with the removable panels, for use in producing optical fibre
microbending.
7. A method of manufacturing a cable including the steps of taking substantially identical preformed
elongate sheath sections provided with channels for the
reception of cable elements, feeding cable elements into
the channels of at least one sheath section, bringing
the sheath sections together, with the cable elements
therebetween, and securing them together, the cable
elements being retained within cavities internal of the
sheath formed by the sheath sections.
8. A method as claimed in claim 7 wherein there are two said preformed sect ions and wherein the cable elements include at least one strength member and at least one optical fibre.
9. A method as claimed in clai 8 further including the step of injecting a filler material into the optical fibre cavity.
10. A method as claimed in claim 9 wherein the filler material is a thixotropic gel.
11. A method as claimed in claim 8 wherein there are two strength members, the respective channels therefor being disposed on different sides of the optical fibre channel.
12. A method as claimed in claim ii, including the step of providing at least one of the preformed sections with removable panels adjacent the optical fIbre charnel prior to said feeding step.
13. A method as claimed in claim 12, whereIn the removable panels are provided by stamping wit grooved dies against a resilient material whereby the panels are partly cut out.
14. A method as claimed in claim 12 or clalm 13 wherein one preformed section is provided with said removable panels at intervals along its length and the other preformed section is provided with mechanical gratings, at the same intervals along its length for use in producing optical fibre microbending, and including the step of aligning the removable panels with the mechanical gratings whilst bringing the sheath sections together.
15.. A method as claimed in claim 14, wherein the mechanical gratings are embossed or engraved in the other preformed section prior to said feeding step.
16. A method as claimed in any one of claims 7 to 15 wherein the sheath sections are received together by an impact or hot melt adhesive.
17. A method of manufacturing a cabe substantially as herein described with reference to and as illustrated in the accompanying drawings.
18. A cable manufactured by a method as claimed in any one of the preceding claims.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8719692A GB2208945B (en) | 1987-08-20 | 1987-08-20 | Communications cable |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8719692A GB2208945B (en) | 1987-08-20 | 1987-08-20 | Communications cable |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8719692D0 GB8719692D0 (en) | 1987-09-30 |
| GB2208945A true GB2208945A (en) | 1989-04-19 |
| GB2208945B GB2208945B (en) | 1991-03-06 |
Family
ID=10622560
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8719692A Expired - Fee Related GB2208945B (en) | 1987-08-20 | 1987-08-20 | Communications cable |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2208945B (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2255836A (en) * | 1991-05-11 | 1992-11-18 | Northern Telecom Ltd | Fibre optic cable |
| GB2319351A (en) * | 1996-03-12 | 1998-05-20 | Nippon Telegraph & Telephone | Flat optical cable with round edged sheath |
| EP1031862A2 (en) * | 1999-02-18 | 2000-08-30 | Alcatel | Method for accessing optical fibers in the midspan region of an optical fiber cable |
| WO2006061370A1 (en) | 2004-12-09 | 2006-06-15 | Siemens Aktiengesellschaft | Fibre optic ribbon with several individual optical fibres and method for production thereof |
| WO2006097540A1 (en) * | 2005-03-18 | 2006-09-21 | Siemens Aktiengesellschaft | Strip device |
| WO2006097541A1 (en) * | 2005-03-18 | 2006-09-21 | Siemens Aktiengesellschaft | Method for producing a light wave guide strip |
| EP1891475A1 (en) * | 2005-06-15 | 2008-02-27 | Siemens Aktiengesellschaft | Method for producing an optical fibre strip comprising several individual optical fibres |
| WO2013070993A1 (en) * | 2011-11-10 | 2013-05-16 | Commscope, Inc. Of North Carolina | Miniaturized optical fiber drop cable |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1473818A (en) * | 1975-02-27 | 1977-05-18 | Siemens Ag | Stranded elements for optical cables |
| GB2017968A (en) * | 1978-03-31 | 1979-10-10 | Kokusai Denshin Denwa Co Ltd | Submarine optical fibre cable |
| GB1587789A (en) * | 1977-07-20 | 1981-04-08 | American Hospital Supply Corp | Light guides |
| EP0143286A2 (en) * | 1983-10-29 | 1985-06-05 | Alcatel N.V. | Optical telecommunication cable |
| GB2180665A (en) * | 1985-09-16 | 1987-04-01 | Telephone Cables Ltd | Optical cables and the manufacture thereof |
-
1987
- 1987-08-20 GB GB8719692A patent/GB2208945B/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1473818A (en) * | 1975-02-27 | 1977-05-18 | Siemens Ag | Stranded elements for optical cables |
| GB1587789A (en) * | 1977-07-20 | 1981-04-08 | American Hospital Supply Corp | Light guides |
| GB2017968A (en) * | 1978-03-31 | 1979-10-10 | Kokusai Denshin Denwa Co Ltd | Submarine optical fibre cable |
| EP0143286A2 (en) * | 1983-10-29 | 1985-06-05 | Alcatel N.V. | Optical telecommunication cable |
| GB2180665A (en) * | 1985-09-16 | 1987-04-01 | Telephone Cables Ltd | Optical cables and the manufacture thereof |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2255836A (en) * | 1991-05-11 | 1992-11-18 | Northern Telecom Ltd | Fibre optic cable |
| GB2255836B (en) * | 1991-05-11 | 1995-11-08 | Northern Telecom Ltd | Fibre optic cable |
| GB2319351A (en) * | 1996-03-12 | 1998-05-20 | Nippon Telegraph & Telephone | Flat optical cable with round edged sheath |
| GB2319351B (en) * | 1996-03-12 | 2001-05-02 | Nippon Telegraph & Telephone | Flat optical fibre cable with round edged sheath |
| EP1031862A2 (en) * | 1999-02-18 | 2000-08-30 | Alcatel | Method for accessing optical fibers in the midspan region of an optical fiber cable |
| EP1031862A3 (en) * | 1999-02-18 | 2004-06-16 | Alcatel | Method for accessing optical fibers in the midspan region of an optical fiber cable |
| WO2006061370A1 (en) | 2004-12-09 | 2006-06-15 | Siemens Aktiengesellschaft | Fibre optic ribbon with several individual optical fibres and method for production thereof |
| JP2008523428A (en) * | 2004-12-09 | 2008-07-03 | シーメンス アクチエンゲゼルシヤフト | Strip light guide with a plurality of optical individual fibers and method for producing the same |
| WO2006097540A1 (en) * | 2005-03-18 | 2006-09-21 | Siemens Aktiengesellschaft | Strip device |
| WO2006097541A1 (en) * | 2005-03-18 | 2006-09-21 | Siemens Aktiengesellschaft | Method for producing a light wave guide strip |
| EP1891475A1 (en) * | 2005-06-15 | 2008-02-27 | Siemens Aktiengesellschaft | Method for producing an optical fibre strip comprising several individual optical fibres |
| WO2013070993A1 (en) * | 2011-11-10 | 2013-05-16 | Commscope, Inc. Of North Carolina | Miniaturized optical fiber drop cable |
| US8942526B2 (en) | 2011-11-10 | 2015-01-27 | Commscope, Inc. Of North Carolina | Miniaturized optical fiber drop cable |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2208945B (en) | 1991-03-06 |
| GB8719692D0 (en) | 1987-09-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19930820 |