CN109521246A - The current measuring method realized based on Newton's ring metal grating - Google Patents
The current measuring method realized based on Newton's ring metal grating Download PDFInfo
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- CN109521246A CN109521246A CN201811509065.3A CN201811509065A CN109521246A CN 109521246 A CN109521246 A CN 109521246A CN 201811509065 A CN201811509065 A CN 201811509065A CN 109521246 A CN109521246 A CN 109521246A
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- newton
- polarization
- metal grating
- light
- ring metal
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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
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
Abstract
The present invention relates to a kind of current measuring methods realized based on Newton's ring metal grating, belong to electric system current measurement techniques field.Light source is arranged in the side of polarizing film, and the other side is sequentially provided with magneto-optic thin film, beam expanding lens, Newton's ring metal grating and 4 quadrant detector；Light source obtains linearly polarized light by polarizing film is to the rear, and after linearly polarized light passes through magneto-optic thin film, plane of polarization is parallel to vertical direction, and the angle of plane of polarization rotation is proportional to the size in magnetic field；Beam expanding lens amplifies outgoing polarization light beam, by Newton's ring metal grating, forms the circular light spot with dark line；The direction of dark line and the plane of polarization of linearly polarized light are vertical；The direction that dark line in light spot image is detected by 4 quadrant detector obtains the rotation angle of linearly polarized light plane of polarization to obtain electric current to be measured.Measurement result is unrelated with the size of optical power, only related with the distribution of light intensity.
Description
Technical field
The present invention relates to electric system current measurement techniques fields, in particular to a kind of to be realized based on Newton's ring metal grating
Current measuring method.It is realized using Newton's ring metal grating 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 Newton's ring metal grating, solve existing
There is the above problem existing for technology.The present invention generates linear polarization light source using light source and polarizing film, and magneto-optic thin film is by magnetic field to be measured
Size is converted to the rotation angle of linearly polarized light plane of polarization, and beam expanding lens is used to amplify the section of light beam, and Newton's ring metal grating will
Linearly polarized light is converted to the circular light spot with dark line, the direction of dark line and linearly polarized light plane of polarization direction exact vertical, dark line
Rotation angle be equal to Faraday rotation angle, finally by 4 quadrant detector measurement hot spot dark line rotation angle method may be implemented
Draw the linear measurement of rotation angle.
Above-mentioned purpose of the invention is achieved through the following technical solutions:
Based on the current measuring method that Newton's ring metal grating is realized, light source 1 is arranged in the side of polarizing film 2, and the other side is set
Magneto-optic thin film 3 is set, beam expanding lens 4 is placed between magneto-optic thin film 3 and Newton's ring metal grating 5, the other side of Newton's ring metal grating 5
4 quadrant detector 6 is set；Light source 1 by polarizing film 2 rise it is to the rear obtain linearly polarized light, after linearly polarized light passes through magneto-optic thin film 3,
Plane of polarization is parallel to vertical direction, and the angle of plane of polarization rotation is proportional to the size in magnetic field；Beam expanding lens 4 puts outgoing polarization light beam
Greatly, by Newton's ring metal grating 5, the circular light spot with dark line is formed；The direction of dark line and the plane of polarization of linearly polarized light hang down
Directly；By the direction of dark line in the detection of 4 quadrant detector 6, it is to be measured to obtain to calculate the rotation angle of linearly polarized light plane of polarization
Electric current.
The grating cutting of the Newton's ring metal grating 5 is equidistant concentric circles, screen periods, that is, metal stripe
Spacing is less than lambda1-wavelength；The internal radius of concentric circles composition is 8mm, outer diameter 16mm；Screen periods are 150nm, thickness
For 100nm, duty ratio 0.5.Linearly polarized light enters Newton's ring metal grating 5, is broken down into the mutually perpendicular TM in polarization direction
Wave and TE wave, only the polarization direction TM wave vertical with metal stripe can be propagated through Newton's ring metal grating, polarization direction
For radial direction；Emergent light is the circular ring shape hot spot with dark line, and the direction of dark line and the plane of polarization of linearly polarized light are vertical, pass through four-quadrant
It limits detector 6 and detects measurement of the direction realization of dark line to larization rotation angle.
The beneficial effects of the present invention are: Faraday rotation angle is converted to the synchronous rotary of hot spot by Newton's ring, and
Spot signal is detected by 4 quadrant detector, completes the linear measurement of electric current.The present invention breaches polarization interference solution mode transfer
The limitation of formula nonlinear measurement realizes large-scale Faraday rotation angular measurement, improves the measurement range of electric current；This survey
Amount method has optical power independence, eliminates the influence of the factors such as light-intensity variation；And use magneto-optic thin film as sensing element,
Substantially linear birefrigence is solved the problems, such as.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 Newton's ring metal grating of the invention；
Fig. 3 is the angle and spacing distance schematic diagram of Newton's ring grating adjacent metal item；
Fig. 4 is light distribution coordinates computed figure；
Fig. 5 is that line polarisation passes through the light spot image formed after Newton's ring metal grating.
In figure: 1, light source；2, polarizing film；3, magneto-optic thin film；4, beam expanding lens；5, Newton's ring metal grating；6, four-quadrant is visited
Survey device.
Specific embodiment
Detailed content and its specific embodiment of the invention are further illustrated with reference to the accompanying drawing.
Referring to figs. 1 to 5, the current measuring method of the invention realized based on Newton's ring metal grating, including light
Source 1, polarizing film 2, magneto-optic thin film 3, beam expanding lens 4, Newton's ring metal grating 5,4 quadrant detector 6, the side of the polarizing film 2
Light source 1 is set, and the other side is sequentially provided with magneto-optic thin film 3, beam expanding lens 4, Newton's ring metal grating 5 and 4 quadrant detector 6；Light
Source 1 by polarizing film 2 rise it is to the rear obtain linearly polarized light, after linearly polarized light passes through magneto-optic thin film 3, plane of polarization is parallel to vertical side
To the angle of plane of polarization rotation is proportional to the size in magnetic field；Beam expanding lens 4 amplifies outgoing polarization light beam, by Newton's ring metal
Grating 5 forms the circular light spot with dark line；The direction of dark line and the plane of polarization of linearly polarized light are vertical；Pass through Quadrant detector
Device 6 detects the direction of dark line in light spot image, it can be deduced that the rotation angle of linearly polarized light plane of polarization calculates electric current to be measured.
Shown in Figure 2, linearly polarized light enters Newton's ring metal grating analyzing, and it is mutually perpendicular to be broken down into polarization direction
TM wave and TE wave.Wherein TE mode tangentially polarizes, and close to 0, the TM mode for only allowing radially to polarize penetrates transmitance.It should
The screen periods and metal line width of structure will not radially change, and extinction ratio is constant.In order to balance the polarization characteristic of grating and plus
The difficulty of work selects Grating Design parameter are as follows: period 150nm, height 100nm, duty ratio 0.5, grating circle ring area
Inside radius is 8mm, outer radius 16mm.
Shown in Figure 3, the metal wire of grating circular ring structure collapses in order to prevent, at interval of certain angle and distance,
Radial metal wire is added at adjacent rings, structure is reinforced, height is identical as annular metal cord.The radial direction of adjacent rings
Metal strip is staggered.Wherein the angle of adjacent metal item and interval are smaller, and consolidation effect is better, pitch angle α and spacing distance d
Definition it is as shown in Figure 3.But radial metal stripe pitch is too small, can generate and tangentially be polarized effect, influence the polarization characteristic of grating.Table
1 is extinction ratio of the radial metal strip of three kinds of width under different interval angle and spacing distance.Extinction ratio is closer to 1, to newton
The influence of the polarization characteristic of circular grating is smaller.As it can be seen from table 1 the width of aluminum steel is 500nm, angular interval is 0.5 degree, ring
The spacing distance of center line is 31.4 μm, and extinction ratio 1.003, the influence to grating polarization characteristic can be ignored.
The dependence of table 2 extinction ratio and metal strip angle and width
The current measuring method realized based on Newton's ring metal grating of the invention, light source 1 play to the rear obtain by polarizing film 2
To linearly polarized light, after linearly polarized light passes through magneto-optic thin film 3, linearly polarized light plane of polarization is rotated under magnetic fields, and is rotated
Angle be proportional to the size in magnetic field, plane of polarization is parallel to vertical direction；Beam expanding lens 4 amplifies outgoing polarization light beam, make its with
The size of Newton's ring grating 5 matches, and when light beam passes through Newton's ring metal grating 5, forms the circular light spot with dark line, secretly
The direction of line and the plane of polarization of linearly polarized light are vertical；The direction that dark line in light spot image is detected by 4 quadrant detector 6, obtains
The rotation angle of linearly polarized light plane of polarization is to obtain current value to be measured.Measurement result is unrelated with the size of optical power, only with light
Strong distribution is related.
Jones matrix of the Newton's ring grating under polar coordinate system be
Since the transmitance of tangential polarisation component can be ignored, i.e. TφIt is 0, then the Jones matrix under xy coordinate system is
WhereinFor the azimuth of hot spot.If the amplitude of incident polarized light is A, polarization direction and the angle of system x coordinate are
θ, as shown in Fig. 4, electric vector are represented by
When incident polarized light is after metal grating, the electric vector of output light is
Then output intensity is
WhenWhen, output intensity is maximum；When, output intensity is minimum, and emergent light spot is as shown in Figure 5.Therefore,
The position that hot spot dark line is detected by 4 quadrant detector, that is, can determineTo obtain θ.According to Faraday magnetooptical effect, to
Surveying magnetic field H and θ can be calculated by formula (6)
θ=VHl (6)
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.
4 quadrant detector testing principle of the invention:
Theoretically the positioning accuracy of 4 quadrant detector is 0.01 μm, it is assumed that hot spot dot radius r=1mm, optical power W is equal
Even to be distributed on hot spot, K is total gain amplifier of the 4 quadrant detector from optical power to voltage signal, and dr is the light in y-axis
Majorant for integral, then the signal summation that 1,2 quadrants measure in 4 quadrant detector are
Similarly, 3,4 quadrants measurement signal summation be
The then output of four-quadrant detector is
Then dr is
If the analog signal of four-quadrant detector is sampled by 16 ADC, and total voltage signal U1+U2+U3+U4It is 16 ADC
Full range voltage.Then when the signal difference between 1,2 quadrant and 3,4 quadrants is the 1/216 of full scale, drIt is that detector can be with
The least displacement of parsing
When ring-shaped light spot is radiated on the photosensitive surface of FQD, the photoelectric current that each quadrant generates and the light function received
Rate is directly proportional, i.e.,
It is by the output valve X that formula (10) and formula (12) obtain four-quadrant
Then θ is represented by
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 annulus of the Newton's ring of use
Internal diameter is 8mm, outer diameter 16mm, screen periods 150nm, with a thickness of 100nm, duty ratio 0.5；Using OSQ100-IC tetra-
Quadrant detector, wave-length coverage 400-1100nm.
Measurement is compared to the present invention by NT700 electronic transducer calibration instrument, the results are shown in Table 1, meets 0.2
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 (3)
1. a kind of current measuring method realized based on Newton's ring metal grating, it is characterised in that: the side of polarizing film (2) is arranged
Magneto-optic thin film (3) are arranged in light source (1), the other side, beam expanding lens (4) be placed in magneto-optic thin film (3) and Newton's ring metal grating (5) it
Between, 4 quadrant detector (6) are arranged in the other side of Newton's ring metal grating (5)；Light source (1) plays to the rear obtain by polarizing film (2)
To linearly polarized light, after linearly polarized light passes through magneto-optic thin film (3), plane of polarization is parallel to vertical direction, and the angle of plane of polarization rotation is just
Than in the size in magnetic field；Beam expanding lens (4) amplifies outgoing polarization light beam, and by Newton's ring metal grating (5), being formed has dark line
Circular light spot；The direction of dark line and the plane of polarization of linearly polarized light are vertical；Pass through the side of dark line in 4 quadrant detector (6) detection
To the rotation angle of calculating linearly polarized light plane of polarization is to obtain electric current to be measured.
2. the current measuring method according to claim 1 realized based on Newton's ring metal grating, it is characterised in that: described
Newton's ring metal grating (5) grating cutting be equidistant concentric circles, screen periods, that is, metal stripe spacing be less than into
Penetrate optical wavelength；The internal radius of concentric circles composition is 8mm, outer diameter 16mm；The grating internal diameter period is 150nm, with a thickness of
100nm, duty ratio 0.5.
3. the current measuring method according to claim 1 realized based on Newton's ring metal grating, it is characterised in that: line is inclined
Vibration light enters Newton's ring metal grating (5), is broken down into the mutually perpendicular TM wave in polarization direction and TE wave, only polarization direction and
The vertical TM wave of metal stripe can be propagated through Newton's ring metal grating, and polarization direction is radial；Emergent light is with dark line
Circular ring shape hot spot, the direction of dark line and the plane of polarization of linearly polarized light are vertical, pass through 4 quadrant detector (6) detect dark line side
To the measurement realized to larization rotation angle.
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| CN108008172A (en) * | 2017-11-17 | 2018-05-08 | 东北电力大学 | One kind is based on polymer optical wave guide current transformer chip |
| CN108917944A (en) * | 2018-07-13 | 2018-11-30 | 福州大学 | A kind of optical voltage transformer realized based on Newton's ring metal grating |
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2018
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| CN103675390A (en) * | 2012-09-04 | 2014-03-26 | 徐启峰 | Radial analyzer type magneto-optical film current sensor |
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| CN106706638A (en) * | 2016-12-14 | 2017-05-24 | 北京理工大学 | Phase imaging device and method based on dark stripe logic judgment |
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Application publication date: 20190326 |