CN109521249A - The current measuring method realized based on crystal birefringence - Google Patents
The current measuring method realized based on crystal birefringence Download PDFInfo
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- CN109521249A CN109521249A CN201811509754.4A CN201811509754A CN109521249A CN 109521249 A CN109521249 A CN 109521249A CN 201811509754 A CN201811509754 A CN 201811509754A CN 109521249 A CN109521249 A CN 109521249A
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- light
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
- G01R15/245—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect
- G01R15/246—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect based on the Faraday, i.e. linear magneto-optic, effect
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
Abstract
The present invention relates to a kind of current measuring methods realized based on crystal birefringence, belong to electric system current measurement techniques field.The light beam that light source issues plays generation linearly polarized light to the rear by polarizing film, magnetic field size to be measured is converted to the rotation of linearly polarized light plane of polarization into magneto-optic thin film, the linearly polarized light of outgoing is after beam expanding lens expands, the transmission and reflection of light are realized by semi-transparent semi-reflecting lens, it is focused by convex lens and enters analyzing resonant cavity, birefringece crystal in analyzing resonant cavity is spatially separated by the focus of the o light of tangential polarization and the e light of radial polarisation, plane mirror is located at the focal point of e light, make to only exist stable radial polarisation optical mode in analyzing resonant cavity, and there is the hot spot of dark line from plane mirror output；Hot spot is imaged after convex lens and semi-transparent semi-reflecting lens into ccd image sensor.The rotation angle that dark line is detected by ccd image sensor, realizes the linear measurement to faraday's magnetic rotation angle, and measurement pattern is unrelated with optical power.
Description
Technical field
The present invention relates to electric system current measurement techniques field, in particular to a kind of electricity realized based on crystal birefringence
Flow measuring method.It is realized based on crystal birefringence to faraday's magnetic rotation angle linear measurement.
Background technique
Current transformer is the important equipment for reflecting operation states of electric power system, is the important knob for connecting first and second equipment
Band, accuracy and reliability are to guarantee the important prerequisite of systematic survey accuracy and protective relaying device Reliability of Microprocessor.Mesh
The current transformer overwhelming majority used in preceding electric system is all based on electromagnetic induction principle, as voltage class and transmission are held
The continuous promotion of amount, electromagnetic current transducer exposes some defects for being difficult to ignore, the difficulty that such as insulate is big, easy magnetic saturation,
Analog signal output, service band are narrow, iron core remanent magnetism influences, response speed is slow, are not capable of measuring the problems such as DC current, serious to hinder
The development of smart grid is hindered.
With the rise of electronic technology and optical sensing technology, optical current mutual inductor receives attention both domestic and external and obtains
Quick development is arrived.Relative to traditional electromagnetic current transducer, optical transformer has the advantage that (1) is excellent
Insulation performance and cost performance.(2) without magnetic saturation and the problems such as ferromagnetic resonance.(3) it is big that bandwidth, dynamic range are measured.(4) real
The thorough isolation between high-low pressure is showed, reliability and highly-safe.(5) small in size, light-weight, good economy performance.
Faraday effect of the measuring principle of optical current mutual inductor based on magneto-optical crystal, i.e., under magnetic fields, line is inclined
Light shake by magneto-optical crystal, plane of polarization rotates, and the angle of rotation is proportional to the size in magnetic field.Generally use polarization interference
Demodulation method measures output intensity, but this measurement pattern has optical power correlation, the influence vulnerable to optical power fluctuation；It utilizes
Approximately linear transformation measurement faraday's rotation angle when SIN function low-angle, leads to range of dynamic measurement and measures the energy of harmonic wave
Power is limited；In addition, the random noise that temperature drift and linear birefrigence generate reduces the long-term running stability of mutual inductor and reliable
Property, constrain its functionization.
Summary of the invention
The purpose of the present invention is to provide a kind of current measuring methods realized based on crystal birefringence, solve existing skill
The above problem existing for art realizes the linear measurement of electric current.The present invention generates linear polarization light source, magnetic using light source and polarizing film
Magnetic field size to be measured is converted to the rotation angle of linearly polarized light plane of polarization by optical thin film, and beam expanding lens is used to amplify the section of light beam,
Linearly polarized light is converted to the circular light with dark line by the analyzing resonant cavity being made of plane mirror, birefringece crystal and spherical mirror
The rotation angle of spot, the direction of dark line and linearly polarized light plane of polarization direction exact vertical, dark line is equal to Faraday rotation angle, finally
The linear measurement at Faraday rotation angle may be implemented by ccd image sensor location spot image.
Above-mentioned purpose of the invention is achieved through the following technical solutions:
Based on the current measuring method that crystal birefringence is realized, light source 1 is located at the side of polarizing film 2, polarizing film 2 it is another
Magneto-optic thin film 3 is arranged in side, and beam expanding lens 4 is placed between magneto-optic thin film 3 and semi-transparent semi-reflecting lens 5, and semi-transparent semi-reflecting lens 5 are mounted on CCD figure
As the top of sensor 11；Convex lens 6 between plane mirror 7 and semi-transparent semi-reflecting lens 5, birefringece crystal 8 be located at plane mirror 7,
In the analyzing resonant cavity that diaphragm 9 and spherical mirror 10 form, optical direction is parallel with the c-axis of birefringece crystal 8；What light source 1 issued
Light beam plays generation linearly polarized light to the rear by polarizing film 2, and it is inclined that magnetic field size to be measured is converted to linearly polarized light into magneto-optic thin film 3
The rotation in vibration face, the rotation angle of linearly polarized light plane of polarization are proportional to the size of magnetic field H；The linearly polarized light of outgoing is through beam expanding lens 4
After expanding, the transmission and reflection of light are realized by semi-transparent semi-reflecting lens 5, is focused by convex lens 6 and enters analyzing resonant cavity, and analyzing is humorous
The birefringece crystal 8 for shaking intracavitary is spatially separated by the focus of the o light of tangential polarization and the e light of radial polarisation, and plane mirror 7
In the focal point of e light, make to only exist stable radial polarisation optical mode in analyzing resonant cavity, and has secretly from the output of plane mirror 7
The hot spot of line；Hot spot is imaged after convex lens 6 and semi-transparent semi-reflecting lens 5 into ccd image sensor 11.
Linearly polarized light is converted to the circular light spot with dark line, the direction of dark line and linear polarization by the analyzing resonant cavity
The plane of polarization of light is vertical；The measurement to faraday's magnetic rotation angle is realized by the direction that ccd image sensor 11 detects dark line.
By detecting the rotation angle of dark line, the plane of polarization rotation angle of linearly polarized light is obtained, to obtain electric current to be measured.
The birefringece crystal 8 is cylindrical lithium niobate or yttrium vanadate crystal, and light pass surface is cut along crystal c axis.
The beneficial effects of the present invention are:
Faraday rotation angle is converted to the synchronous rotary of hot spot based on crystal birefringence principle, and is passed by ccd image
Sensor detects spot signal, completes the linear measurement of electric current.The present invention breaches polarization interference demodulation modes nonlinear measurement
Limitation, realize large-scale Faraday rotation angular measurement, improve the measurement range of electric current；This measurement method has behaviour
Make simply, measurement pattern and optical power independence eliminate the influence of the factors such as light-intensity variation；And use magneto-optic thin film as quick
Sensing unit solves the problems, such as linear birefrigence substantially.The accuracy of measurement is improved, it is practical.
Detailed description of the invention
The drawings described herein are used to provide a further understanding of the present invention, constitutes part of this application, this hair
Bright illustrative example and its explanation is used to explain the present invention, and is not constituted improper limitations of the present invention.
Fig. 1 is the structural diagram of the present invention；
Fig. 2 is the structural schematic diagram of analyzing resonant cavity；
Fig. 3 is the schematic diagram of emergent light spot of the invention；
Fig. 4 is light distribution coordinates computed figure.
In figure: 1, light source；2, polarizing film；3, magneto-optic thin film；4, beam expanding lens；5, semi-transparent semi-reflecting lens；6, convex lens；7, plane
Mirror；8, birefringece crystal；9, diaphragm；10, spherical mirror；11, ccd image sensor.
Specific embodiment
Detailed content and its specific embodiment of the invention are further illustrated with reference to the accompanying drawing.
Referring to FIG. 1 to FIG. 4, the current measuring method of the invention realized based on crystal birefringence, including light source 1,
Polarizing film 2, magneto-optic thin film 3, beam expanding lens 4, semi-transparent semi-reflecting lens 5, convex lens 6, plane mirror 7, birefringece crystal 8, diaphragm 9, spherical surface
Mirror 10, ccd image sensor 11, the light source 1 are located at the side of polarizing film 2, and magneto-optic thin film 3 is arranged in the other side of polarizing film 2,
Beam expanding lens 4 is placed between magneto-optic thin film 3 and semi-transparent semi-reflecting lens 5, and semi-transparent semi-reflecting lens 5 are mounted on the top of ccd image sensor 11；
For convex lens 6 between plane mirror 7 and semi-transparent semi-reflecting lens 5, birefringece crystal 8 is located at plane mirror 7, diaphragm 9 and 10 groups of spherical mirror
At analyzing resonant cavity in, optical direction is parallel with the c-axis of birefringece crystal 8；The light beam that light source 1 issues rises by polarizing film 2
Magnetic field size to be measured is converted to the rotation of linearly polarized light plane of polarization, linear polarization into magneto-optic thin film 3 by generation linearly polarized light to the rear
The rotation angle in light polarization face is proportional to the size of magnetic field H；The linearly polarized light of outgoing passes through semi-transparent half after beam expanding lens 4 expands
Anti- mirror 5 realizes the transmission and reflection of light, is focused by convex lens 6 and enters analyzing resonant cavity, the birefringent crystalline substance in analyzing resonant cavity
Body 8 is spatially separated by the focus of the o light of tangential polarization and the e light of radial polarisation, and plane mirror 7 is located at the focal point of e light, makes
Stable radial polarisation optical mode is only existed in analyzing resonant cavity, and there is the hot spot of dark line from the output of plane mirror 7；Hot spot passes through
After convex lens 6 and semi-transparent semi-reflecting lens 5, it is imaged into ccd image sensor 11.
Linearly polarized light is converted to the circular light spot with dark line, the direction of dark line and linear polarization by the analyzing resonant cavity
The plane of polarization of light is vertical；It is realized by the direction that ccd image sensor 11 detects dark line in light spot image and faraday's mangneto is revolved
The measurement of optic angle, and measurement pattern is unrelated with optical power.
By detecting the rotation angle of dark line, the plane of polarization of available linearly polarized light rotates angle, to acquire to be measured
Electric current.
The birefringece crystal 8 is cylindrical lithium niobate or yttrium vanadate crystal, and light pass surface is cut along crystal c axis.
Analyzing principle based on crystal birefringence of the invention is:
Shown in Figure 2, birefringece crystal is located in the resonant cavity that plane mirror 7 and spherical mirror 10 form, optical direction with
The c-axis of crystal is parallel.After light is reflected into birefringece crystal 8 from spherical mirror 10, since the refractive index of o light and e light is different, the two
Focal position it is spatially separated.Plane mirror 7 is located at the focal point of e light, and e light forms stable oscillation mode intracavitary.And o
Light is blocked, or escape out cavity after intracavitary oscillation several times by diaphragm.The polarization direction of e light is radial direction, from plane mirror 7
After middle outgoing, radial polarisation light is formed.Wherein plane mirror 7 has certain transmissivity.If linearly polarized light is entered by plane mirror
Cavity has the hot spot of dark line, and the plane of polarization in dark line direction and incident polarized light from plane mirror output after resonance several times
Vertically, as shown in Figure 3.
If the plane of polarization direction P of incident polarized light, the angle with x-axis is θ；It for the azimuth of hot spot, while being also e light
The angle of (radial polarisation light) plane of polarization and x-axis, as shown in Fig. 4.Under eo coordinate system, polarised light enters birefringece crystal
Jones vector is
Since o light can not form stable mode in resonant cavity, the light exported from plane mirror contains only radial inclined
Shake component, i.e. e light, then
It is xy coordinate system by eo coordinate system transformation
Therefore the expression formula of output intensity is
Wherein, hot spot dark line position meets
When the plane of polarization of incident light rotates, hot spot dark line synchronous rotary, and the angle with incident light polarization face therewith
Remain 90 degree.
Shown in Figure 1, the light beam that light source 1 issues plays generation linearly polarized light to the rear by polarizing film 2, into magneto-optic thin film
3, magnetic field size to be measured is converted to the rotation of line polarisation plane of polarization by magneto-optic thin film 3, and the rotation of linearly polarized light plane of polarization is proportional to
The size of magnetic field H；The linearly polarized light of outgoing realizes the transmission and reflection of light by semi-transparent semi-reflecting lens 5 after beam expanding lens 4 expands,
It is focused by convex lens 6 and enters analyzing resonant cavity, analyzing resonant cavity is by plane mirror 7, birefringece crystal 8, diaphragm 9, spherical mirror 10
It forms, the birefringece crystal 8 in analyzing resonant cavity spatially divides the focus of the o light of tangential polarization and the e light of radial polarisation
It opens, plane mirror 7 is located at the focal point of e light, makes to only exist stable radial polarisation optical mode in analyzing resonant cavity, and from plane mirror
7 output faculas, hot spot are imaged after convex lens 6 and semi-transparent semi-reflecting lens 5 into ccd image sensor 11.Output facula it is dark
Line is vertical with the plane of polarization of polarised light.By detecting the rotation angle of dark line, the plane of polarization of available line polarisation rotates angle,
Acquire electric current to be measured.
The light transmission shaft of the polarizer is parallel to x-axis.The electric vector of polarised light is
Under the influence of a magnetic field, θ is had rotated by the plane of polarization of the linearly polarized light of magneto-optic thin film, under x-y coordinate system
Jones matrix is
Incident polarized light passes through magneto-optic thin film, and Jones vector is
EoutFor linearly polarized light, the angle of plane of polarization and x-axisMeet following relationship
Then
Plane of polarization angleIt can be measured by ccd image sensor, to obtain θ.It is to be measured according to Faraday magnetooptical effect
Magnetic field H and θ can be calculated by formula (11)
θ=VHl (11)
In formula: V is Fil moral (Verdet) constant of magneto-optic memory technique；H is the intensity of current field；L is light passing length.By
It is directly proportional to electric current in H, current measurement is realized by measurement θ.
According to formula (10) and (11), H withBetween relationship be
The birefringece crystal 8 is cylindrical lithium niobate or yttrium vanadate crystal, and light pass surface is cut along crystal c axis.
Embodiment:
The rated current of experimental system is 300A；Using single transverse mode LD light source, operation wavelength 808nm；Using
LPVIS050 polarizing film, wave-length coverage 550-1500nm；Using Bi-Gd-YIG magneto-optic thin film, with a thickness of 400um, Fil moral
Constant is 1.5deg/cm.Oe；Using GBE05-B beam expander, wave-length coverage 650-1050nm；The semi-permeable and semi-reflecting mirror of use
Wave-length coverage be 400nm-1100nm；Using LB4879-B convex lens, wave-length coverage 650-1050nm；It is two-fold using BD40
Crystal is penetrated, wave-length coverage is 350nm-2.3 μm；Using SM1D12C diaphragm；Using N-BK7 spherical mirror, wave-length coverage 650-
1050nm；The ccd image sensor that the DALSA of use is produced, model S3-20-02K40.
Measurement is compared to the present invention by NT700 electronic transducer calibration instrument, the results are shown in Table 1, meets 0.5
Grade electronic current mutual inductor accuracy requirement.
The basic accuracy experimental data of table 1
The foregoing is merely preferred embodiments of the invention, are not intended to restrict the invention, for the technology of this field
For personnel, the invention may be variously modified and varied.All any modification, equivalent substitution, improvement and etc. made for the present invention,
It should all be included in the protection scope of the present invention.
Claims (4)
1. a kind of current measuring method realized based on crystal birefringence, it is characterised in that: light source (1) is located at polarizing film (2)
Magneto-optic thin film (3) are arranged in the other side of side, polarizing film (2), and beam expanding lens (4) is placed in magneto-optic thin film (3) and semi-transparent semi-reflecting lens (5)
Between, semi-transparent semi-reflecting lens (5) are mounted on the top of ccd image sensor (11)；Convex lens (6) is located at plane mirror (7) and semi-transparent
Between semi-reflective mirror (5), birefringece crystal (8) is located at the analyzing resonant cavity of plane mirror (7), diaphragm (9) and spherical mirror (10) composition
Interior, optical direction is parallel with the c-axis of birefringece crystal (8)；The light beam that light source (1) issues plays generation to the rear by polarizing film (2)
Magnetic field size to be measured is converted to the rotation of linearly polarized light plane of polarization, linearly polarized light polarization into magneto-optic thin film (3) by linearly polarized light
The rotation angle in face is proportional to the size of magnetic field H；The linearly polarized light of outgoing passes through semi-transparent semi-reflecting lens after beam expanding lens (4) expands
(5) transmission and reflection for realizing light are focused by convex lens (6) and enter analyzing resonant cavity, the birefringent crystalline substance in analyzing resonant cavity
Body (8) is spatially separated by the focus of the o light of tangential polarization and the e light of radial polarisation, and plane mirror (7) is located at the focus of e light
Place, makes to only exist stable radial polarisation optical mode in analyzing resonant cavity, and has the hot spot of dark line from plane mirror (7) output；
Hot spot is imaged after convex lens (6) and semi-transparent semi-reflecting lens (5) into ccd image sensor (11).
2. the current measuring method according to claim 1 realized based on crystal birefringence, it is characterised in that: the inspection
Linearly polarized light is converted to the circular light spot with dark line by partial resonance chamber, and the direction of dark line and the plane of polarization of linearly polarized light are vertical；
The measurement to faraday's magnetic rotation angle is realized by the direction that ccd image sensor (11) detect dark line.
3. the current measuring method according to claim 1 realized based on crystal birefringence, it is characterised in that: pass through detection
The rotation angle of dark line obtains the plane of polarization rotation angle of linearly polarized light, to obtain electric current to be measured.
4. the current measuring method according to claim 1 realized based on crystal birefringence, it is characterised in that: described is double
Refracting crystal (8) is cylindrical lithium niobate or yttrium vanadate crystal, and light pass surface is cut along crystal c axis.
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Application publication date: 20190326 |