GB2133737A - Improvements relating to the manufacture of magnetic sensing optical devices - Google Patents

Improvements relating to the manufacture of magnetic sensing optical devices Download PDF

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Publication number
GB2133737A
GB2133737A GB08301112A GB8301112A GB2133737A GB 2133737 A GB2133737 A GB 2133737A GB 08301112 A GB08301112 A GB 08301112A GB 8301112 A GB8301112 A GB 8301112A GB 2133737 A GB2133737 A GB 2133737A
Authority
GB
United Kingdom
Prior art keywords
magnetic
optical fibre
fibre
optical
layer
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
Application number
GB08301112A
Other versions
GB2133737B (en
Inventor
John Phillip Dakin
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Plessey Co Ltd
Original Assignee
Plessey Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Plessey Co Ltd filed Critical Plessey Co Ltd
Priority to GB08301112A priority Critical patent/GB2133737B/en
Priority to AU26462/84A priority patent/AU564488B2/en
Publication of GB2133737A publication Critical patent/GB2133737A/en
Application granted granted Critical
Publication of GB2133737B publication Critical patent/GB2133737B/en
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/0128—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects
    • G02F1/0131—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects based on photo-elastic effects, e.g. mechanically induced birefringence
    • G02F1/0134—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on electro-mechanical, magneto-mechanical, elasto-optic effects based on photo-elastic effects, e.g. mechanically induced birefringence in optical waveguides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/15—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor incorporating preformed parts or layers, e.g. extrusion moulding around inserts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/05—Filamentary, e.g. strands
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
    • B29K2105/16—Fillers

Abstract

The improvement comprises the step of extruding on to the outer surface of an optical fibre, a layer of flexible rubber or plastics material containing magnetic dust or particles, for producing straining of the optical fibre due to the magneto-strictive effect when the optical fibre is subjected to magnetic fields. The magneto-strictive effect may be enhanced by subjecting the magnetic material to a magnetic field whilst it is still viscous, as it is being applied to the fibre. The magnetic particles can thereby be aligned coaxially, or radially, depending on the applied field. The extended layer may be of 300 mu m to 2 m.m. thickness, applied to a fibre of 130 mu m outside diameter.

Description

SPECIFICATION Improvements relating to magnetic sensing optical devices This invention relates to optical devices for sensing magnetic fields.
More specifically, the present invention relates to such optical sensing devices of the form comprising an optical fibre (usually single-mode) coated with a strongly adherent film of magnetic material (e.g.
nickel) so that when the magnetic film is subject to a magnetic field and it undergoes a change in length due to the magnetic-strictive effect the optical fibre also undergoes a corresponding change in length which varies the optical characteristics of the fibre.
Such variations in optical characteristics produce phase modulation of light being transmitted through the fibre and this phase modulation may readily be detected by a Mach-Zender interferometer.
In the manufacture of these metal coated optical fibre sensing devices the following difficulties are experienced:- (1) It is difficult to coat the optical fibre with nickle or other suitable magnetic material without accidentally scratching or etching the surface of the bare fibre which causes weakening of the fibre glass by the formation of stress concentration points; (2) It is difficult to metal coat long lengths of optical fibre by electro-chemical, sputtering or evaporation coating techniques and; (3) It is difficult to achieve the degree of adherence of metal film to the optical fibre which will withstand fairly wide temperature cycling.
According to the present invention the above difficulties in the manufacture of optical fibre sensing devices are avoided by extruding on to the optical fibre a layer of flexible material containing magnetic dust or particles for producing variable longitudinal straining of the optical fibre due to the magneto-strictive effect when the device is subjected to magnetic fields.
In carrying out the present invention the extruded material may comprise plastics material, or rubber, filled with magnetic particles or dust and the layer may be applied by a standard extruder on to the usual plastics sheathing of the optical fibre.
With this method of fabrication according the the present invention it is very easy to extrude the magnetic material over long lengths of fibre.
Moreover, the magneto-strictive properties can be tailored by suitable choice of magnetic particle material, particle size, proportion of magnetic material to plastics or rubber extrusion material and the particular plastics material or rubber utilised for the layer.
It is contemplated that the extruded magnetic layer will be applied over the usual plastic sheathing for the optical fibre so that the optical sensor will have good mechanical strength and the layer could be electrically insulating and/or provide a degree of acoustic isolation (i.e. isolation of internal fibre from deformation and consequent change of characteristics due to impingement of acoustic waves on the sensor).
It is further contemplated that the magnetostrictive effect could be enhanced by subjecting the magnetic material to a magnetic field whilst it is still in a fluid viscous state as it is applied to the optical fibre. In this way the magnetic particles can be pre-aligned in the axial or radial direction of the optical fibre according to the applied field.
As regards the thickness of the extruded layer of magnetic material the layer may have an outside diameter of approximately 300 Am to 2mm when applied to the plastics sheathing of optical fibre with an outside diameter of approximately 130 Fm.
CLAIMS (Filed on 13/1/84) 1. A method of manufacturing a magnetically responsive optical fibre comprising the step of extruding on to the outer surface of an optical fibre a layer of flexible material containing magnetic dust or particles for producing straining of the optical fibre due to the magneto-strictive effect when the optical fibre is subjected to magnetic fields.
2. A method as claimed in claim 1, in which the flexible material is of rubber of plastics material.
3. A method as claimed in claim 1 or claim 2, in which the flexible material is extruded over the usual plastics sheathing of the optical fibre.
4. A method as claimed in any preceding claim, in which the extruded flexible material containing the magnetic dust or particles is subjected to a magnetic field to pre-align the particles according to requirements whilst the extruded material is still in a viscous state.
5. A magnetically responsive optical fibre manufactured by the method claimed in any preceding
claim.
6. An optical sensing device incorporating a magnetically responsive optical fibre as claimed in claim 5.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements relating to magnetic sensing optical devices This invention relates to optical devices for sensing magnetic fields. More specifically, the present invention relates to such optical sensing devices of the form comprising an optical fibre (usually single-mode) coated with a strongly adherent film of magnetic material (e.g. nickel) so that when the magnetic film is subject to a magnetic field and it undergoes a change in length due to the magnetic-strictive effect the optical fibre also undergoes a corresponding change in length which varies the optical characteristics of the fibre. Such variations in optical characteristics produce phase modulation of light being transmitted through the fibre and this phase modulation may readily be detected by a Mach-Zender interferometer. In the manufacture of these metal coated optical fibre sensing devices the following difficulties are experienced:- (1) It is difficult to coat the optical fibre with nickle or other suitable magnetic material without accidentally scratching or etching the surface of the bare fibre which causes weakening of the fibre glass by the formation of stress concentration points; (2) It is difficult to metal coat long lengths of optical fibre by electro-chemical, sputtering or evaporation coating techniques and; (3) It is difficult to achieve the degree of adherence of metal film to the optical fibre which will withstand fairly wide temperature cycling. According to the present invention the above difficulties in the manufacture of optical fibre sensing devices are avoided by extruding on to the optical fibre a layer of flexible material containing magnetic dust or particles for producing variable longitudinal straining of the optical fibre due to the magneto-strictive effect when the device is subjected to magnetic fields. In carrying out the present invention the extruded material may comprise plastics material, or rubber, filled with magnetic particles or dust and the layer may be applied by a standard extruder on to the usual plastics sheathing of the optical fibre. With this method of fabrication according the the present invention it is very easy to extrude the magnetic material over long lengths of fibre. Moreover, the magneto-strictive properties can be tailored by suitable choice of magnetic particle material, particle size, proportion of magnetic material to plastics or rubber extrusion material and the particular plastics material or rubber utilised for the layer. It is contemplated that the extruded magnetic layer will be applied over the usual plastic sheathing for the optical fibre so that the optical sensor will have good mechanical strength and the layer could be electrically insulating and/or provide a degree of acoustic isolation (i.e. isolation of internal fibre from deformation and consequent change of characteristics due to impingement of acoustic waves on the sensor). It is further contemplated that the magnetostrictive effect could be enhanced by subjecting the magnetic material to a magnetic field whilst it is still in a fluid viscous state as it is applied to the optical fibre. In this way the magnetic particles can be pre-aligned in the axial or radial direction of the optical fibre according to the applied field. As regards the thickness of the extruded layer of magnetic material the layer may have an outside diameter of approximately 300 Am to 2mm when applied to the plastics sheathing of optical fibre with an outside diameter of approximately 130 Fm. CLAIMS (Filed on 13/1/84)
1. A method of manufacturing a magnetically responsive optical fibre comprising the step of extruding on to the outer surface of an optical fibre a layer of flexible material containing magnetic dust or particles for producing straining of the optical fibre due to the magneto-strictive effect when the optical fibre is subjected to magnetic fields.
2. A method as claimed in claim 1, in which the flexible material is of rubber of plastics material.
3. A method as claimed in claim 1 or claim 2, in which the flexible material is extruded over the usual plastics sheathing of the optical fibre.
4. A method as claimed in any preceding claim, in which the extruded flexible material containing the magnetic dust or particles is subjected to a magnetic field to pre-align the particles according to requirements whilst the extruded material is still in a viscous state.
5. A magnetically responsive optical fibre manufactured by the method claimed in any preceding
claim.
6. An optical sensing device incorporating a magnetically responsive optical fibre as claimed in claim 5.
GB08301112A 1983-01-15 1983-01-15 Improvements relating to the manufacture of magnetic sensing optical devices Expired GB2133737B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB08301112A GB2133737B (en) 1983-01-15 1983-01-15 Improvements relating to the manufacture of magnetic sensing optical devices
AU26462/84A AU564488B2 (en) 1983-01-15 1984-04-05 Magnetic sensing optical fibre

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08301112A GB2133737B (en) 1983-01-15 1983-01-15 Improvements relating to the manufacture of magnetic sensing optical devices

Publications (2)

Publication Number Publication Date
GB2133737A true GB2133737A (en) 1984-08-01
GB2133737B GB2133737B (en) 1986-10-15

Family

ID=10536408

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08301112A Expired GB2133737B (en) 1983-01-15 1983-01-15 Improvements relating to the manufacture of magnetic sensing optical devices

Country Status (2)

Country Link
AU (1) AU564488B2 (en)
GB (1) GB2133737B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0131404A2 (en) * 1983-07-07 1985-01-16 Stc Plc Fibre optic sensors
US20110031431A1 (en) * 2009-08-04 2011-02-10 The Boeing Company Magnetic composite structures with high mechanical strength
US8111584B1 (en) * 1987-06-11 2012-02-07 Plessey Overseas Limited Optical sensing arrangements

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB479721A (en) * 1937-04-27 1938-02-10 James Sims Reid Process of coating metal with a plastic composition
GB531464A (en) * 1939-03-29 1941-01-06 Distillers Co Yeast Ltd Improvements in the manufacture of multi-strand fibrous articles
GB860220A (en) * 1958-07-15 1961-02-01 Leyman Corp Mechanical orientation of magnetically anisotropic particles
GB934473A (en) * 1961-06-22 1963-08-21 Gen Motors Corp Articulated magnets
GB1128995A (en) * 1966-06-17 1968-10-02 Flexigrip Ltd Improvement relating to bags
GB1166234A (en) * 1967-01-13 1969-10-08 Ibm Coating Methods.
GB1371740A (en) * 1973-03-29 1974-10-23 Standard Telephones Cables Ltd Coating optical fibres
GB1448130A (en) * 1973-12-18 1976-09-02 Standard Telephones Cables Ltd Providing an optical fibre with a thermoplastic sheath
GB1498228A (en) * 1975-06-26 1978-01-18 Standard Telephones Cables Ltd Coated glass optical fibres
GB1584644A (en) * 1976-07-01 1981-02-18 Maillefer Sa Method for manufacturing electric wire having wireenamel-type insulation

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB479721A (en) * 1937-04-27 1938-02-10 James Sims Reid Process of coating metal with a plastic composition
GB531464A (en) * 1939-03-29 1941-01-06 Distillers Co Yeast Ltd Improvements in the manufacture of multi-strand fibrous articles
GB860220A (en) * 1958-07-15 1961-02-01 Leyman Corp Mechanical orientation of magnetically anisotropic particles
GB934473A (en) * 1961-06-22 1963-08-21 Gen Motors Corp Articulated magnets
GB1128995A (en) * 1966-06-17 1968-10-02 Flexigrip Ltd Improvement relating to bags
GB1166234A (en) * 1967-01-13 1969-10-08 Ibm Coating Methods.
GB1371740A (en) * 1973-03-29 1974-10-23 Standard Telephones Cables Ltd Coating optical fibres
GB1448130A (en) * 1973-12-18 1976-09-02 Standard Telephones Cables Ltd Providing an optical fibre with a thermoplastic sheath
GB1498228A (en) * 1975-06-26 1978-01-18 Standard Telephones Cables Ltd Coated glass optical fibres
GB1584644A (en) * 1976-07-01 1981-02-18 Maillefer Sa Method for manufacturing electric wire having wireenamel-type insulation

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0131404A2 (en) * 1983-07-07 1985-01-16 Stc Plc Fibre optic sensors
EP0131404A3 (en) * 1983-07-07 1987-07-01 Stc Plc Fibre optic sensors
US8111584B1 (en) * 1987-06-11 2012-02-07 Plessey Overseas Limited Optical sensing arrangements
US20110031431A1 (en) * 2009-08-04 2011-02-10 The Boeing Company Magnetic composite structures with high mechanical strength
US9362036B2 (en) * 2009-08-04 2016-06-07 The Boeing Company Magnetic composite structures with high mechanical strength
US10692652B2 (en) 2009-08-04 2020-06-23 The Boeing Company Methods for manufacturing magnetic composite structures with high mechanical strength

Also Published As

Publication number Publication date
AU2646284A (en) 1985-10-10
GB2133737B (en) 1986-10-15
AU564488B2 (en) 1987-08-13

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19940115