GB2189110A - Optical fibre hydrophone - Google Patents

Optical fibre hydrophone Download PDF

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Publication number
GB2189110A
GB2189110A GB08606552A GB8606552A GB2189110A GB 2189110 A GB2189110 A GB 2189110A GB 08606552 A GB08606552 A GB 08606552A GB 8606552 A GB8606552 A GB 8606552A GB 2189110 A GB2189110 A GB 2189110A
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GB
United Kingdom
Prior art keywords
optical fibre
coiled
hydrophone
fibre
ofthe
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
GB08606552A
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GB2189110B (en
Inventor
John Philip 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 GB8606552A priority Critical patent/GB2189110B/en
Publication of GB2189110A publication Critical patent/GB2189110A/en
Application granted granted Critical
Publication of GB2189110B publication Critical patent/GB2189110B/en
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
    • G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R23/00—Transducers other than those covered by groups H04R9/00 - H04R21/00
    • H04R23/008—Transducers other than those covered by groups H04R9/00 - H04R21/00 using optical signals for detecting or generating sound

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)

Abstract

An optical fibre hydrophone comprises a coiled optical fibre 1 and a cylindrical former 2 which supports the optical fibre and which has an internal or external radial flange 3 located centrally therealong for mounting the hydrophone. <IMAGE>

Description

SPECIFICATION Improvements relating to optical fibre hydrophones This invention relates to optical fibre hydrophones comprising coiled lengths of optical fibres which may, for example, be embedded within hollow cylindrical supporting structures.
The present invention seeks to reduce the sensitivity of such optical fibre hydrophonesto acceleration forces imposed upon them through their supporting structures and thereby reduce the optical phase shift which can arise in the light propagating through the optical fibre of the hydrophone due to the strain induced in the coiled optical fibre by such acceleration forces.
According to the present invention a coiled optical fibre of optical hydrophone means has at least one supporting structure comprising a hollow cylindrical formerforsupporting the coiled optical fibre and a radial mounting flange or equivalent located centrally relative to the coiled optical fibre for mounting said hydrophone.
In carrying outthe present invention the mounting flange may extend radially outwardly or inwardly from the hollow cylindrical supporting formerforthe coiled optical fibre and may, if desired, be fabricated integrally therewith.
By arranging that the hydrophone is effectively mounted at the centre ofthe coiled optical fibre it will be appreciated that in response to acceleration forces in the axial direction ofthe coiled fibre an elongation ofthe fibre in one half of the coiled optical fibre due to acceleration-induced strain will be balanced by a fibre length contraction in the other half of the coiled fibre due to acceleration-induced compressive strain. Consequently, the overail length ofthe coiled optical fibre will remain constant.
By way of example the present invention will now be described with reference to the accompanying drawings which depictvarious forms of supporting structure for coiled optical fibre hydrophones.
Referring to Figures 1 and 2,these show perspective and axial cross-sectional views of a coiled optical fibre hydrophone. A length of coiled optical fibre 1 is embedded in hollow cylindrical supporting former2 of an organicpolymerforexample.
For hydrophone mounting purposes an outwardly extending radial flange 3 is provided and may be formed integrally with the hollow coil supporting former 2. As can beseen,theflange3is located centrally relative to the coiled optical fibre 1. As a consequence, when the hydrophone which will be mounted for operation by meansoftheflange 3 is subject to acceleration forces in the direction, X, say, then the foremost half, Y, ofthe coil 1 will be subject to compressive stress which will effectively reduce the length ofthe coiled fibre whereas the rearmost half, Z, of the coiled optical fibre will be subjected to tensile stress which will elongate the coiled fibre.Overall, the length of coiled fibre twill remain constant, thereby avoiding an overall change in phase shift of light propagating therethrough. Similarly, pressure changes causing variations in refractive index of the core region of the coiled optical fibre will likewise be balanced out in the two halves ofthe coiled optical fibre.
Figure 3 shows an alternative support arrangement for the coiled hydrophone. In this embodimentthe hollow cylindrical former 2 is provided with an inwardly extending radial mounting flange 4to which a support bobbin 5 is secured. Once again it will be appreciated that when the hydrophone is subjected to acceleration forces in the general axial direction thereof the consequential contraction in length of one half ofthe coiled fibre 1 will be balanced by the elongation in length of the other half of the coiled fibre hydrophone. Pressure changes producing changes in the refractive index ofthefibrewill also be balanced out in the coil halves.
It may here be mentioned thatforthe avoidance of localised stress concentration points in the coiled optical fibre at positions adjacent the mounting flange 3 or4the density ofturns of the coiled optical fibre may, if desired, be reduced in the region ofthe mounting flange 3 or4.
For optical fibre sensing coils of greater length a plurality of mounting flanges 6 may be located at positions along its length as shown in Figure 4. In this arrangementthe hydrophone is composed of a series of balanced coiled sensors 7to 11 with conceptual but not actual joining points represented by the dotted line shown in the drawing.
Alternatively, of course, the balanced hydrophone could consist of two separately constructed hyd rophonesfastened symmetrically to the flange with eithertheirfibres spliced together to form an effectively-balanced single hydrophone, or, less advan tageoüsly, the optically processed signals from each hydrophone being subtracted after conversion to electrical signals for the purpose of acceleration balancing.
1. An optical fibre hydrophone comprising a coiled optical fibre and-at least one supporting structure therefor, said supporting structure comprising a cylindrical formerforsupporting the coiled optical fibre and a radial mounting flange or equivalent located centrally relative to the coiled optical fibre for mounting the hydrophone.
2. An optical fibre hydrophone as claimed in claim 1, in which the mounting flange extends radially outwardly from the supporting cylindrical former.
3. An optical fibre hydrophone as claimed in claim 1, in which the mounting flange extends inwardly from the cylindrical former.
4. An optical fibre hydrophone substantially as hereinbefore described and as illustrated in Figure 1 of the accompanying drawings.
5. An optical fibre hydrophone substantially as hereinbefore described and as illustrated in Figure 2 of the accompanying drawings.
The drawing(s) originally filed was (were) informal and the print here reproduced is taken from a later filed formal copy.
The claims were filed later than the filing date within the period prescribed by Rule 25(1) of the Patents Rules 1982.
**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 optical fibre hydrophones This invention relates to optical fibre hydrophones comprising coiled lengths of optical fibres which may, for example, be embedded within hollow cylindrical supporting structures. The present invention seeks to reduce the sensitivity of such optical fibre hydrophonesto acceleration forces imposed upon them through their supporting structures and thereby reduce the optical phase shift which can arise in the light propagating through the optical fibre of the hydrophone due to the strain induced in the coiled optical fibre by such acceleration forces. According to the present invention a coiled optical fibre of optical hydrophone means has at least one supporting structure comprising a hollow cylindrical formerforsupporting the coiled optical fibre and a radial mounting flange or equivalent located centrally relative to the coiled optical fibre for mounting said hydrophone. In carrying outthe present invention the mounting flange may extend radially outwardly or inwardly from the hollow cylindrical supporting formerforthe coiled optical fibre and may, if desired, be fabricated integrally therewith. By arranging that the hydrophone is effectively mounted at the centre ofthe coiled optical fibre it will be appreciated that in response to acceleration forces in the axial direction ofthe coiled fibre an elongation ofthe fibre in one half of the coiled optical fibre due to acceleration-induced strain will be balanced by a fibre length contraction in the other half of the coiled fibre due to acceleration-induced compressive strain. Consequently, the overail length ofthe coiled optical fibre will remain constant. By way of example the present invention will now be described with reference to the accompanying drawings which depictvarious forms of supporting structure for coiled optical fibre hydrophones. Referring to Figures 1 and 2,these show perspective and axial cross-sectional views of a coiled optical fibre hydrophone. A length of coiled optical fibre 1 is embedded in hollow cylindrical supporting former2 of an organicpolymerforexample. For hydrophone mounting purposes an outwardly extending radial flange 3 is provided and may be formed integrally with the hollow coil supporting former 2. As can beseen,theflange3is located centrally relative to the coiled optical fibre 1. As a consequence, when the hydrophone which will be mounted for operation by meansoftheflange 3 is subject to acceleration forces in the direction, X, say, then the foremost half, Y, ofthe coil 1 will be subject to compressive stress which will effectively reduce the length ofthe coiled fibre whereas the rearmost half, Z, of the coiled optical fibre will be subjected to tensile stress which will elongate the coiled fibre.Overall, the length of coiled fibre twill remain constant, thereby avoiding an overall change in phase shift of light propagating therethrough. Similarly, pressure changes causing variations in refractive index of the core region of the coiled optical fibre will likewise be balanced out in the two halves ofthe coiled optical fibre. Figure 3 shows an alternative support arrangement for the coiled hydrophone. In this embodimentthe hollow cylindrical former 2 is provided with an inwardly extending radial mounting flange 4to which a support bobbin 5 is secured. Once again it will be appreciated that when the hydrophone is subjected to acceleration forces in the general axial direction thereof the consequential contraction in length of one half ofthe coiled fibre 1 will be balanced by the elongation in length of the other half of the coiled fibre hydrophone. Pressure changes producing changes in the refractive index ofthefibrewill also be balanced out in the coil halves. It may here be mentioned thatforthe avoidance of localised stress concentration points in the coiled optical fibre at positions adjacent the mounting flange 3 or4the density ofturns of the coiled optical fibre may, if desired, be reduced in the region ofthe mounting flange 3 or4. For optical fibre sensing coils of greater length a plurality of mounting flanges 6 may be located at positions along its length as shown in Figure 4. In this arrangementthe hydrophone is composed of a series of balanced coiled sensors 7to 11 with conceptual but not actual joining points represented by the dotted line shown in the drawing. Alternatively, of course, the balanced hydrophone could consist of two separately constructed hyd rophonesfastened symmetrically to the flange with eithertheirfibres spliced together to form an effectively-balanced single hydrophone, or, less advan tageoüsly, the optically processed signals from each hydrophone being subtracted after conversion to electrical signals for the purpose of acceleration balancing. CLAIMS
1. An optical fibre hydrophone comprising a coiled optical fibre and-at least one supporting structure therefor, said supporting structure comprising a cylindrical formerforsupporting the coiled optical fibre and a radial mounting flange or equivalent located centrally relative to the coiled optical fibre for mounting the hydrophone.
2. An optical fibre hydrophone as claimed in claim 1, in which the mounting flange extends radially outwardly from the supporting cylindrical former.
3. An optical fibre hydrophone as claimed in claim 1, in which the mounting flange extends inwardly from the cylindrical former.
4. An optical fibre hydrophone substantially as hereinbefore described and as illustrated in Figure 1 of the accompanying drawings.
5. An optical fibre hydrophone substantially as hereinbefore described and as illustrated in Figure 2 of the accompanying drawings.
The drawing(s) originally filed was (were) informal and the print here reproduced is taken from a later filed formal copy.
The claims were filed later than the filing date within the period prescribed by Rule 25(1) of the Patents Rules 1982.
6. An optical fibre hydrophone substantially as hereinbefore described and as illustrated in Figure 3 of the accompanying drawings.
GB8606552A 1986-03-17 1986-03-17 Improvements relating to optical fibre hydrophones Expired GB2189110B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8606552A GB2189110B (en) 1986-03-17 1986-03-17 Improvements relating to optical fibre hydrophones

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8606552A GB2189110B (en) 1986-03-17 1986-03-17 Improvements relating to optical fibre hydrophones

Publications (2)

Publication Number Publication Date
GB2189110A true GB2189110A (en) 1987-10-14
GB2189110B GB2189110B (en) 1989-11-15

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Family Applications (1)

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GB8606552A Expired GB2189110B (en) 1986-03-17 1986-03-17 Improvements relating to optical fibre hydrophones

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0351990A2 (en) * 1988-07-20 1990-01-24 Gec-Marconi Limited A hydrophone
FR2748107A1 (en) * 1996-04-26 1997-10-31 Marconi Gec Ltd BALANCING WINDING ASSEMBLY AND FIBER OPTIC DETECTION SYSTEM
WO2000062021A1 (en) * 1999-04-09 2000-10-19 Qinetiq Limited An optical fibre sensor assembly
GB2386183A (en) * 2002-03-05 2003-09-10 Qinetiq Ltd Optical sensor assembly
WO2004038427A1 (en) * 2002-10-18 2004-05-06 Northrop Grumman Corporation Method and apparatus for measuring acceleration using a fiber optic accelerometer
CN107884063A (en) * 2017-12-28 2018-04-06 长沙深之瞳信息科技有限公司 A kind of modular fiber optic vector hydrophone

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1454844A (en) * 1973-03-27 1976-11-03 Inst Francais Du Petrole Pressure sensor

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1454844A (en) * 1973-03-27 1976-11-03 Inst Francais Du Petrole Pressure sensor

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0351990A2 (en) * 1988-07-20 1990-01-24 Gec-Marconi Limited A hydrophone
GB2221120A (en) * 1988-07-20 1990-01-24 Plessey Co Plc Optical fibre hydrophones
US4998226A (en) * 1988-07-20 1991-03-05 Gec-Marconi Limited Hydrophone
EP0351990A3 (en) * 1988-07-20 1991-11-06 Gec-Marconi Limited A hydrophone
AU623664B2 (en) * 1988-07-20 1992-05-21 Thomson Marconi Sonar Limited A hydrophone
GB2221120B (en) * 1988-07-20 1992-07-15 Plessey Co Plc A hydrophone
FR2748107A1 (en) * 1996-04-26 1997-10-31 Marconi Gec Ltd BALANCING WINDING ASSEMBLY AND FIBER OPTIC DETECTION SYSTEM
AU755607B2 (en) * 1999-04-09 2002-12-19 Optasense Holdings Limited An optical fibre sensor assembly
WO2000062021A1 (en) * 1999-04-09 2000-10-19 Qinetiq Limited An optical fibre sensor assembly
US8369660B1 (en) 1999-04-09 2013-02-05 Qinetiq Limited Optical fibre sensor assembly
US8666203B2 (en) 1999-04-09 2014-03-04 Optasense Holdings Limited Optical fibre sensor assembly
US8705902B2 (en) 1999-04-09 2014-04-22 Optasense Holdings Limited Optical fibre sensor assembly
GB2386183A (en) * 2002-03-05 2003-09-10 Qinetiq Ltd Optical sensor assembly
US7440644B2 (en) 2002-03-05 2008-10-21 Qinetiq Limited Optical fibre sensor assembly
WO2004038427A1 (en) * 2002-10-18 2004-05-06 Northrop Grumman Corporation Method and apparatus for measuring acceleration using a fiber optic accelerometer
US6779402B2 (en) 2002-10-18 2004-08-24 Northrop Grumman Corporation Method and apparatus for measuring acceleration using a fiber optic accelerometer
CN107884063A (en) * 2017-12-28 2018-04-06 长沙深之瞳信息科技有限公司 A kind of modular fiber optic vector hydrophone
CN107884063B (en) * 2017-12-28 2024-04-30 长沙深之瞳信息科技有限公司 Combined optical fiber vector hydrophone

Also Published As

Publication number Publication date
GB2189110B (en) 1989-11-15

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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: 19930317