CN105823995A - Optical fiber sensor applicable to magnetic fields in any directions in plane - Google Patents

Optical fiber sensor applicable to magnetic fields in any directions in plane Download PDF

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Publication number
CN105823995A
CN105823995A CN201610266184.5A CN201610266184A CN105823995A CN 105823995 A CN105823995 A CN 105823995A CN 201610266184 A CN201610266184 A CN 201610266184A CN 105823995 A CN105823995 A CN 105823995A
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China
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optical fiber
magnetic field
sensing head
modulation
pzt device
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CN201610266184.5A
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CN105823995B (en
Inventor
魏兵
李宇波
周柯江
楼历月
郝寅雷
周强
杨建义
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Zhejiang University ZJU
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Zhejiang University ZJU
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/032—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect

Abstract

The invention discloses an optical fiber sensor applicable to magnetic fields in any directions in a plane. The optical fiber sensor includes a wide spectrum light source, an optical fiber circulator, an optical fiber polarizer, a 45-degree optical fiber melting point, a 1*2 polarization-maintaining optical fiber coupler, two piezoelectric ceramic modulators, two optical fiber delay loops, two quarter wave plates, two sensing heads, a photoelectric detector, two phase-locked amplifiers and a signal processing unit. The optical fiber sensor is composed of two paths of reflective type optical fiber interference structures; the included angle of the two sensing heads is 60 degrees; based on a phase-sensitive detection principle, phase difference information of an upper interferometer and a lower interferometer which is caused by a magnetic field can be demodulated through the two phase-locked amplifiers; the output of the two phase-locked amplifiers is inputted into the signal processing unit so as to be subjected to addition operation and subtraction operation; the two sensing heads are rotated, the output of the subtraction operation in the signal processing unit is zero, and the output of the addition operation in the signal processing unit is the magnitude of the magnetic field; and the direction of the magnetic field can be determined according to the rotation angle of the two sensing heads. The optical fiber sensor of the invention can be used to test the magnitudes of the magnetic field in any directions in the plane.

Description

A kind of plane any direction Magnetic Field Optical Fiber Sensor
Technical field
The present invention relates to Magnetic Field Optical Fiber Sensor, especially relate to a kind of plane any direction Magnetic Field Optical Fiber Sensor.
Background technology
Optical fiber sensing technology has the advantages such as good insulating, precision is high, volume is little, it is developed rapidly, also magnetic field sensing field it is widely used in, currently used optical fiber carries out magnetic field sensing mainly following three kinds of forms, being full fiber type respectively, fiber grating combines magnetostriction materials type and magneto-optic glass type.The magnetic field sensing of three of the above mode can realize magnetic-field measurement, but require that sensing element becomes certain degree with magnetic direction, during measurement of magnetic field, the mounting means to sensor requires higher, it is difficult to realize the most accurately measurement to any direction or variation magnetic field, direction.
Summary of the invention
In order to overcome the deficiency of background technology, it is an object of the invention to provide a kind of plane any direction Magnetic Field Optical Fiber Sensor.
The technical solution used in the present invention is as follows:
The present invention includes: wide spectrum light source, optical fiber circulator, the optical fiber polarizer, 45 ° of optical fiber fusing points, 1x2 polarization-maintaining fiber coupler, the first modulation with PZT device, the first optical fibre delay loop, the first quarter-wave plate, the first sensing head, the second modulation with PZT device, the second optical fibre delay loop, the second quarter-wave plate, the second sensing head, sensing head angle, photodetector, the first lock-in amplifier, the second lock-in amplifier, signal processing units.The light sent from wide spectrum light source is transferred to the optical fiber polarizer through optical fiber circulator and becomes line polarized light, after 45 ° of optical fiber fusing points, described line polarized light becomes the orthogonal two bunch polarized light in polarization direction, then through 1x2 polarization-maintaining fiber coupler, light beam is divided into two, wherein go up light beam successively through the first modulation with PZT device, after first optical fibre delay loop arrives the first quarter-wave plate, two line polarized lights are converted to circularly polarized light, then two circularly polarized lights arrive the first sensing head, Magnetic Field is converted to the phase information of two circularly polarized lights, carry two polarized light of phase information to be reflected tailing edge original optical path at the first sensing head end and be back to optical fiber polarizer location conflicts；After lower light beam sequentially passes through the second modulation with PZT device, the second optical fibre delay loop arrives the second quarter-wave plate, two line polarized lights are converted to circularly polarized light, then two circularly polarized lights arrive the second sensing head, Magnetic Field is converted to the phase information of two circularly polarized lights, carries two polarized light of phase information and reflected tailing edge original optical path at the second sensing head end and be back at the optical fiber polarizer interfere；Two-way interference signal the most all becomes the signal of telecommunication by optical fiber circulator to photodetector, producing modulated signal respectively by the first lock-in amplifier, the second lock-in amplifier and be respectively applied to the first modulation with PZT device and the second modulation with PZT device and the two-way interference signal that detects photodetector is demodulated, the output signal after demodulation sends into signal processing unit.
Described first sensing head and the second transducing head structure and characteristic unanimously, and are formed by single-mode fiber, magneto-optic glass and reflecting mirror.
Described first sensing head and the second sensing head are fixed together with the sensing head angle of 60 °.
The eigenfrequency that eigenfrequency is f1 and the second modulation with PZT device of described first modulation with PZT device is that f2 differs.
The eigenfrequency that described first lock-in amplifier produces is consistent with the eigenfrequency of the first modulation with PZT device；The eigenfrequency that second lock-in amplifier produces is consistent with the eigenfrequency of the second modulation with PZT device.
The invention have the advantages that:
The light path part of inventive sensor is made up of two-way reflection type optical fiber interference structure, fixes two sensing heads and to design its angle be 60 °；Utilize phase-sensitive detection principle, demodulated the phase information caused due to magnetic field in upper and lower two-way interferometer by two lock-in amplifiers respectively；Signal processing unit is sent in two phase-locked outputs, signal processing unit carries out " addition " and " subtracting each other " operation respectively to the output signal that two-way is phase-locked, rotate two sensing heads, and make signal processing unit " subtracts each other " to be output as 0, now " addition " output of signal processing unit is magnetic field size, can determine that magnetic direction according to the anglec of rotation of sensing head simultaneously.The present invention provides plane any direction Magnetic Field Optical Fiber Sensor, can test any direction magnetic field size in plane.
Accompanying drawing explanation
Fig. 1 is the structural representation of the present invention.
Fig. 2 is the design drawing of sensing head of the present invention.
In figure: 1, wide spectrum light source, 2, optical fiber circulator, 3, the optical fiber polarizer, 4, 45 ° of optical fiber fusing points, 5, 1x2 polarization-maintaining fiber coupler, 6, first modulation with PZT device, 7, first optical fibre delay loop, 8, first quarter-wave plate, 9, first sensing head, 10, second modulation with PZT device, 11, second optical fibre delay loop, 12, second quarter-wave plate, 13, second sensing head, 14, sensing head angle, 15, photodetector, 16, first lock-in amplifier, 17, second lock-in amplifier, 18, signal processing unit, 19, single-mode fiber, 20, magneto-optic glass, 21, metallic reflective coating.
Detailed description of the invention
The present invention will be further described with embodiment below in conjunction with the accompanying drawings.
As it is shown in figure 1, the present invention includes: wide spectrum light source 1, optical fiber circulator 2,3,45 ° of optical fiber fusing points 4 of the optical fiber polarizer, 1x2 polarization-maintaining fiber coupler the 5, first modulation with PZT device the 6, first optical fibre delay loop the 7, first quarter-wave plate the 8, first sensing head the 9, second modulation with PZT device the 10, second optical fibre delay loop the 11, second quarter-wave plate the 12, second sensing head 13, sensing head angle 14, photodetector the 15, first lock-in amplifier the 16, second lock-in amplifier 17, signal processing unit 18.The light sent from wide spectrum light source 1 is transferred to the optical fiber polarizer 3 through optical fiber circulator 2 and becomes line polarized light, after 45 ° of optical fiber fusing points 4, described line polarized light becomes the orthogonal two bunch polarized light in polarization direction, then through 1x2 polarization-maintaining fiber coupler 5, light beam is divided into two, wherein go up light beam successively through the first modulation with PZT device 6, after first optical fibre delay loop 7 arrives the first quarter-wave plate 8, two line polarized lights are converted to circularly polarized light, then two circularly polarized lights arrive the first sensing head 9, Magnetic Field is converted to the phase information of two circularly polarized lights, carry two polarized light of phase information to be reflected tailing edge original optical path at the first sensing head 9 end and be back to the optical fiber polarizer 3 location conflicts；Lower light beam sequentially passes through after second modulation with PZT device the 10, second optical fibre delay loop 11 arrives the second quarter-wave plate 12, two line polarized lights are converted to circularly polarized light, then two circularly polarized lights arrive the second sensing head 13, Magnetic Field is converted to the phase information of two circularly polarized lights, carries two polarized light of phase information and reflected tailing edge original optical path at the second sensing head 13 end and be back at the optical fiber polarizer 3 interfere；Two-way interference signal the most all becomes the signal of telecommunication by optical fiber circulator 2 to photodetector 15, producing modulated signal respectively by first lock-in amplifier the 16, second lock-in amplifier 17 and be respectively applied to the first modulation with PZT device 6 and the second modulation with PZT device 10 and the two-way interference signal that detects photodetector 15 is demodulated, the output signal after demodulation sends into signal processing unit 18.
Described first sensing head 9 is consistent with the second sensing head 13 structure and characteristic, and is formed by single-mode fiber 19, magneto-optic glass 20 and reflecting mirror 21.Single-mode fiber 19 is bonded by ultra-violet curing mode with magneto-optic glass 20, and metallic reflective coating 21 is realized by electron beam evaporation process, magneto-optic glass 20 a size of 10mm × 5mm × 5mm, and the thickness of metallic reflective coating 21 is 300nm.
Described first sensing head 9 and the second sensing head 13 are fixed together with the sensing head angle 14 of 60 °.
The eigenfrequency that eigenfrequency is f1 and the second modulation with PZT device 10 of described first modulation with PZT device 6 is that f2 differs.
The eigenfrequency that described first lock-in amplifier 16 produces is consistent with the eigenfrequency of the first modulation with PZT device 6；The eigenfrequency that second lock-in amplifier 17 produces is consistent with the eigenfrequency of the second modulation with PZT device 10.
The operation principle of the present invention:
Two sensors that plane any direction Magnetic Field Optical Fiber Sensor is considered as by sensing head angle is 60 ° form, and two sensors share wide spectrum light source 1, optical fiber circulator 2,3,45 ° of optical fiber fusing points 4 of the optical fiber polarizer, polarization-maintaining fiber coupler 5, photodetector 15 and signal processing unit 18.
The sensing head of two sensors of composition plane any direction Magnetic Field Optical Fiber Sensor becomes angle to be 60 °, and Magnetic Field is converted into the phase information of light by sensing head and final lock-in amplifier of crossing demodulates.Two modulation with PZT utensils used have different intrinsic modulating frequencies, two delay fiber optic loop used to have different length.
First modulation with PZT device 6, its eigenfrequency is f1, modulated signal is applied in the first modulation with PZT device 6 by the first lock-in amplifier 16, when magnetic direction is along optical propagation direction, the first harmonic signal in output signal and second harmonic signal can be extracted by the first lock-in amplifier 16, the signal entering signal processing unit 18 extracted by the first lock-in amplifier 16, can obtain magnetic field size after computing can be expressed as:
H _ 1 = a r c t a n [ V o u t 1 _ 1 V o u t 1 _ 2 · J 1 ( φ m 1 ) J 2 ( φ m 1 ) ]
Wherein, Vout_1、Vout_2It is respectively and is extracted the first harmonic component and the size of second harmonic component, J obtained by the first lock-in amplifier 161(φm1) and J2(φm1) it is corresponding Bessel function coefficient.
Second modulation with PZT device 10, its eigenfrequency is f2, modulated signal is applied in the second modulation with PZT device 10 by the second lock-in amplifier 17, when magnetic direction is along optical propagation direction, the first harmonic signal in output signal and second harmonic signal can be extracted by the second lock-in amplifier 17, the signal entering signal processing unit 18 extracted by lock-in amplifier 17, can obtain magnetic field size after computing can be expressed as:
H _ 2 = a r c t a n [ V o u t 2 _ 1 V o u t 2 _ 2 · J 1 ( φ m 2 ) J 2 ( φ m 2 ) ]
Wherein, Vout2_1、Vout2_2Divide by for being extracted the first harmonic component and second harmonic component size, J obtained by the second lock-in amplifier 171(φm2) and J2(φm2) it is corresponding Bessel function coefficient.
In signal processing unit, 18 carry out following two computings point two-way output
C 1 = H _ 1 - H _ 2 C 2 = H _ 1 + H _ 2
Fixing two sensing head angle theta=60o time actually used, the sensing head of two sensors of composition plane any direction Magnetic Field Optical Fiber Sensor synthesizes a new sensing head, as shown in Figure 2.H direction, magnetic field to be measured is unknown, the sensing head that during test, rotating synthesizing is new, the two-way output of observation signal processing unit simultaneously, when rotating to position as shown in Figure 2, the angle of magnetic direction and two sensing heads is consistent (being 30 °), and it is identical along the parallel component in two sensing head directions.Now, the C of signal processing unit 181It is output as 0, C2It is output asTherefore, when reality is applied, the first direction of rotating synthesizing sensing head, when the output 1 of signal processing unit is 0, by by the numerical value of output channel 2 divided byBeing the size in magnetic field to be measured, the direction in magnetic field can be according to the direction determining of synthesis sensing head, and the digital signal processing chip model that signal processing unit is commercially available is TMS320VC5410A.

Claims (5)

1. a plane any direction Magnetic Field Optical Fiber Sensor, it is characterized in that, including: wide spectrum light source (1), optical fiber circulator (2), the optical fiber polarizer (3), 45 ° of optical fiber fusing points (4), 1x2 polarization-maintaining fiber coupler (5), first modulation with PZT device (6), first optical fibre delay loop (7), first quarter-wave plate (8), first sensing head (9), second modulation with PZT device (10), second optical fibre delay loop (11), second quarter-wave plate (12), second sensing head (13), photodetector (15), first lock-in amplifier (16), second lock-in amplifier (17) and signal processing unit (18)；The light sent from wide spectrum light source (1) is transferred to the optical fiber polarizer (3) through optical fiber circulator (2) and becomes line polarized light, after 45 ° of optical fiber fusing points (4), described line polarized light becomes the orthogonal two bunch polarized light in polarization direction, then through 1x2 polarization-maintaining fiber coupler (5), light beam is divided into two, wherein go up light beam successively through the first modulation with PZT device (6), after first optical fibre delay loop (7) arrives the first quarter-wave plate (8), two line polarized lights are converted to circularly polarized light, then two circularly polarized lights arrive the first sensing head (9), Magnetic Field is converted to the phase information of two circularly polarized lights, carry two polarized light of phase information to be reflected tailing edge original optical path at the first sensing head (9) end and be back to the optical fiber polarizer (3) location conflicts；After lower light beam sequentially passes through the second modulation with PZT device (10), the second optical fibre delay loop (11) arrives the second quarter-wave plate (12), two line polarized lights are converted to circularly polarized light, then two circularly polarized lights arrive the second sensing head (13), Magnetic Field is converted to the phase information of two circularly polarized lights, carries two polarized light of phase information and reflected tailing edge original optical path at the second sensing head (13) end and be back to the optical fiber polarizer (3) place and interfere；Two-way interference signal all becomes the signal of telecommunication by optical fiber circulator (2) to photodetector (15), producing modulated signal respectively by the first lock-in amplifier (16), the second lock-in amplifier (17) and be respectively applied to the first modulation with PZT device (6) and the second modulation with PZT device (10) and the two-way interference signal that detects photodetector (15) is demodulated, the output signal after demodulation sends into signal processing unit (18).
A kind of plane any direction Magnetic Field Optical Fiber Sensor the most according to claim 1, it is characterized in that: described first sensing head (9) is consistent with the second sensing head (13) structure and characteristic, and formed by single-mode fiber (19), magneto-optic glass (20) and reflecting mirror (21).
A kind of plane any direction Magnetic Field Optical Fiber Sensor the most according to claim 1, it is characterised in that: described first sensing head (9) and the second sensing head (13) are fixed together with the sensing head angle (14) of 60 °.
A kind of plane any direction Magnetic Field Optical Fiber Sensor the most according to claim 1, it is characterised in that: the eigenfrequency of described first modulation with PZT device (6) is that the eigenfrequency with the second modulation with PZT device (10) is for differing.
A kind of plane any direction Magnetic Field Optical Fiber Sensor the most according to claim 1, it is characterised in that: the eigenfrequency that described first lock-in amplifier (16) produces is consistent with the eigenfrequency of the first modulation with PZT device (6)；The eigenfrequency that second lock-in amplifier (17) produces is consistent with the eigenfrequency of the second modulation with PZT device (10).
CN201610266184.5A 2016-04-26 2016-04-26 A kind of plane any direction Magnetic Field Optical Fiber Sensor Expired - Fee Related CN105823995B (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113009384A (en) * 2020-12-28 2021-06-22 国网江西省电力有限公司信息通信分公司 Vector magnetic field sensor, preparation method and detection system
CN113534022A (en) * 2021-09-17 2021-10-22 中国工程物理研究院流体物理研究所 High-precision magnetic field measuring system
CN115113339A (en) * 2022-07-26 2022-09-27 浙江大学湖州研究院 Polarization-independent low-loss optical switch

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CN102508177A (en) * 2011-11-29 2012-06-20 北京航空航天大学 Optical fibre magnetic field sensor employing reflecting reciprocal light path
CN103344925A (en) * 2013-07-05 2013-10-09 上海大学 Slow light Sagnac nonreciprocal interference optical fiber magnetic field sensor
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US5243403A (en) * 1991-09-30 1993-09-07 The United States Of America As Represented By The Secretary Of The Navy Three-axis fiber optic vector magnetometer
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113009384A (en) * 2020-12-28 2021-06-22 国网江西省电力有限公司信息通信分公司 Vector magnetic field sensor, preparation method and detection system
CN113009384B (en) * 2020-12-28 2023-12-29 国网江西省电力有限公司信息通信分公司 Vector magnetic field sensor, preparation method and detection system
CN113534022A (en) * 2021-09-17 2021-10-22 中国工程物理研究院流体物理研究所 High-precision magnetic field measuring system
CN115113339A (en) * 2022-07-26 2022-09-27 浙江大学湖州研究院 Polarization-independent low-loss optical switch
CN115113339B (en) * 2022-07-26 2024-02-13 浙江大学湖州研究院 Polarization-independent low-loss optical switch

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