CN1163665A - Process and arrangement for measuring magnetic field-using faraday effect with compensations in intensity and temperature effects - Google Patents
Process and arrangement for measuring magnetic field-using faraday effect with compensations in intensity and temperature effects Download PDFInfo
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- CN1163665A CN1163665A CN 95196247 CN95196247A CN1163665A CN 1163665 A CN1163665 A CN 1163665A CN 95196247 CN95196247 CN 95196247 CN 95196247 A CN95196247 A CN 95196247A CN 1163665 A CN1163665 A CN 1163665A
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Abstract
Process and arrangement for measuring a magnetic field using the faraday effect with compensation of variations in intensity and temperature effects. Two light signals (L1', L1, L2', L2) pass through a series circuit comprising a first multimode waveguide (4), a first polarizer (5), a Faraday sensor device (3), a second polarizer (6) and a second multimode waveguide (7) in mutually opposite senses of passage. The polarization axes of the two polarizers (5, 6) are set according to cos(2 eta +2 theta )=-2/3, in each case at a polarization angle eta and theta relative to the linear double-refraction axis in the sensor device (3). The measuring signal (M) obtained is the quotient of two linear functions of the light intensities (I1, I2) of the two light signals (L1, L2) after passing through the series circuit.
Description
The present invention relates to a kind of method and apparatus of measuring magnetic field.
Known optical measuring device and the measuring method of utilizing magneto-optic faraday effect measurement magnetic field.So-called Faraday effect means that rectilinearly polarized light its plane of polarization affected by magnetic fields produces rotation.Rotation angle and light in magnetic field total distance of process proportional, with so-called Fil moral (Verdet) constant as proportionality constant.Verdet constant depends on material, temperature and wavelength usually.In magnetic field, be provided for measuring magnetic field by faraday-sniffer of making such as light transmissive materials such as glass.Magnetic field impels the rectilinearly polarized light that is sent by faraday-sniffer to do the deflection of an anglec of rotation, this anglec of rotation be can be used as measuring-signal calculated.Known this magneto-optic measuring method and measurement mechanism are applied in current measurement.For this reason, faraday's sniffer is set near the lead and to the magnetic field that is produced by the electric current in the lead and examines and determine.Usually faraday's sniffer ring encloses lead, thus make measuring light in the path of closure around lead.In this case, rotation angle is directly proportional with the amplitude of electric current to be measured very approx.Faraday's sniffer can be for around the solid glass ring structure of lead or also can be the light transmitting fiber coil that has a circle at least around lead.
Compare with traditional inductance type current transformer, the advantage of this magneto-optic measurement mechanism and measuring method is current potential separation and insensitive to electromagnetic interference (EMI).But what mechanical vibration will cause recording to the influence of sniffer and light feeder line when adopting magneto-opitcal current transducer is false Strength Changes, and especially the influence of temperature variation in the sniffer all can be brought problem.
For reducing the influence of vibration to measuring, mutual reverse by two of faraday's sniffer transmissions, promptly the light signal that direction is opposite is well known.These disclosed technical measures are based on such design, and promptly the linear birefrigence and the non-reversible Faraday effect that can be subjected to two light signals that cause owing to vibration as reversible effect on its common light path by corresponding signal process distinguishes.
In first known form of implementation, by send two mutual reverse, rectilinearly polarized light signals as the fiber optic coils of faraday's sniffer, this fiber optic coils is around current lead.The optical fiber of fiber optic coils is mechanical pair twist optical fiber (to turning round optical fiber) or the optical fiber that has the stretching pair twist of high linear birefrigence.Optical fiber also has the llogyric birefringence that is higher than Faraday effect except Faraday effect.In two light signals each is resolved into the component of two mutual vertical polarizations by a polarizing beam splitter after passing sniffer.The signal Processing part produces the measuring-signal of electric current in the current lead with four light components altogether, and this measuring-signal is basic to conform to the merchant of the llogyric birefringence of optical fiber with faraday's measured angular and thereby have nothing to do with linear birefrigence in the optical fiber.Though adopt the linear birefrigence in the sniffer that measuring-signal that the method obtains causes with temperature to a great extent irrelevant, because the llogyric birefringence of optical fiber and the relation of temperature, so measuring-signal still is subjected to Temperature Influence.In this known form of implementation, two mutual reverse light signals only pass faraday's sniffer and separated (WO92/13280) again by photo-coupler mutually when leaving faraday's sniffer on a common light path.
In two other known forms of implementation, two light signals pass the light series circuit that is made of first light transmitting fiber, first polarizer, faraday's sniffer, second polarizer and second light transmitting fiber in the mutual oppositely mode of curling up.Two light signals are converted to an electric strength signal respectively by corresponding photoelectric commutator after passing the light series circuit.
In the form of implementation of having carried in first US4916387, a solid glass ring as faraday's sniffer is arranged, this glass ring is around current lead.The polarization axle of two polarizers is with 45 ° of deflections of mutual angle.Be the Strength Changes of not wishing in the compensated optical fiber feeder line to occur, the precondition of this measuring system of putting down in writing in US4916387 is, do not wish the Strength Changes (noise) that occurs and because the different sign stack in the Strength Changes that Faraday effect produces and two the electric strength signals and so can separating mutually.But the conclusion that draws through more accurate physical observation is that two fibre-optic machineries of two light signals of transmission move the attenuation factor of the transient change of the light intensity that plays a part two light signals substantially.Also undeclared with regard to how these different attenuation factor being compensated in US4916387.
At the lightwave technology magazine, the 12nd volume, in October, 1994, in second form of implementation of 1882 to 1890 pages of records, has a low fiber optic coils of birefringence that is made of single-mode fiber as faraday's sniffer at the 10th phase.The polarization axle of two polarizers forms one mutually greater than 0 ° various polarizers angle, and this angle is preferably 45 °.The light of a unique light source is divided into two light signals, and in these two light signals light transmitting fiber of attaching troops to a unit by photo-coupler input respectively.By two electric strength signals, this electric strength signal conforms to light intensity after the light signal of being attached troops to a unit passes series circuit, derives a measuring-signal, the difference of this measuring-signal and two strength signals with the merchant conform to.Therefore can the attenuation factor in two light transmitting fibers be compensated substantially.Certainly its light intensity must be adjusted to identical in the time of in two light signal input series circuits.
At US4916387 or lightwave technology magazine, the 12nd volume, the 10th phase, in October, 1994, the compensation in the measuring-signal influence is not illustrated to temperature action in 1882 to 1890 pages.Exactly, adopted the temperature-sensitive fiber optic coils as sniffer.But make the corresponding comparatively difficulty of this fiber optic coils.
The objective of the invention is to propose a kind of magnetic field of measuring, especially by the measurement in magnetic field being measured the measuring method and the measurement mechanism of electric current, wherein can actually eliminate Strength Changes and influence of temperature variation on the optical transmission line of two mutual reverse light signals.
Purpose of the present invention is achieved by the feature of claim 1 and claim 6, and two light signals oppositely pass the light series circuit that is made of first optical transmission line, first polarizer, faraday's sniffer, second polarizer and second optical transmission line around ground mutually.Obtain the merchant of two linear functions of the light intensity of two light signals that pass optical transmission line respectively by calculating device as the measuring-signal in magnetic field.This measuring-signal basically with two optical transmission lines on Strength Changes irrelevant, but usually still with temperature, especially sniffer in temperature relevant.Be the influence of compensation temperature, the first polarizer angle η of the intrinsic axle (main shaft) of the linear birefrigence in the polarization axle (axis of homology) of at this moment regulating first polarizer and the faraday's sniffer and regulate the polarization axle of second polarizer and this second polarizer angle θ of intrinsic of sniffer to measuring-signal.The selection of two polarizer angle η and θ should be similar at least to be satisfied
cos(2η+2θ)＝-2/3 (1)
About the useful design of the inventive method and device and further design, see also dependent claims.
The present invention is described in further detail by accompanying drawing below, in the accompanying drawing:
Fig. 1 measures the measurement mechanism of magnetic field or electric current for adopting faraday's sniffer,
Fig. 2 measures the measurement mechanism of electric current for adopting faraday's sniffer and special calculating device,
Fig. 3 is the polarization axle and the birefringent intrinsic axle of sniffer neutral line of two polarizers.Parts identical among the figure are indicated with same Reference numeral.
In Fig. 1 and 2 to faraday's sniffer with 3, to two optical transmission lines with 4 and 7, to two polarizers with 5 and 6, to light source with 10, to three photo-couplers with 11,12 and 13 and calculating device indicated with 20.
Faraday's sniffer 3 is made of the material that has magneto-optic faraday performance characteristic at least.Under the influence of the magnetic field H of partial penetration sniffer 3 at least, because Faraday effect, the polarization polarisation of light that passes sniffer 3 is changed.Sniffer 3 is in known manner by the solid of one or more the most handy glass, or at least one optical fiber constitutes.
Sniffer 3 has two optical interface 3A and 3B, thereby makes the light in interface 3A or 3B input pass sniffer 3 also respectively in another interface 3B or the output of 3A place.First interface 3A of sniffer 3 is by the end optically-coupled of first polarizer 5 with article one optical transmission line 4.The second interface 3B of sniffer 3 is by the end optically-coupled of second polarizer 6 with second optical transmission line 7.Article one transmission line 4 with the opposing other end of sniffer 3 by photo-coupler 12 both with photo-coupler 11, carry out light with calculating device 20 again and be connected.Second transmission line 7 with the opposing other end of sniffer 3 by photo-coupler 13 equally both with photo-coupler 11, carry out light with calculating device 20 again and be connected.Photo-coupler 11 and light source 10 carry out light and are connected and the light L of light source 10 is divided into two light signal L1 ' and L2 ', and these two light signals are fed to coupling mechanism 12 and 13 and be imported into then in first and second transmission line 4 and 7.Two light signal L1 ' and L2 ' are mutually oppositely around passing the light series circuit that is made of first transmission line, 4, the first polarizers 5, sniffer 3, second polarizer 6 and second transmission line 7 and being exported by series circuit again as the light signal that indicates with L1 and L2.Therefore light source 10 and three photo- couplers 11,12 and 13 constitute and send two the mutual reverse light signal L1 of series circuit and devices of L2 of passing.
Can substitute by optical splitter to small part coupling mechanism 11,12 and 13.Also can substitute coupling mechanism 11 and a light source 10 with two light sources in addition, these two light sources send a light signal L1 or L2 respectively.The device that is used to send two mutual reverse light signal L1 that pass series circuit and L2 also can alternately constitute as the photoelectric commutators of transmitter and receiver operation by two in addition, and light signal L1 and L2 that these two photoelectric commutators also play a part to pass series circuit simultaneously convert the electric strength signal to.
The first light signal L1 ' is risen inclined to one side by first polarizer, 5 straight lines after passing first transmission line 4 and is fed in the sniffer 3 at interface 3A place as rectilinearly polarized light signal L1 '.The plane of polarization of the first rectilinearly polarized light signal L1 ' is deflected faraday's measured angular ρ that depends on magnetic field H when passing sniffer 3.The direction of propagation with observed light signal is a benchmark, and positive angle value is rotated in the forward corresponding to mathematics, promptly corresponding to counterclockwise; Fu angle value is corresponding to the rotation of mathematics negative sense, promptly corresponding to clockwise direction in contrast.The first light signal L1 ' in its plane of polarization deflection be fed to second polarizer 6 behind the measured angular ρ.The first light signal L1 ' that second polarizer 6 only allows to be arrived be incident upon on its polarization axle component by and therefore the first light signal L1 ' is played a part analyzer.At this moment the first light signal L1 ' is indicated with L1 by the component of second polarizer, 6 transmissions and is transmitted to calculating device 20 by second transmission line 7 and coupling mechanism 13.
The second light signal L2 ' is at first by second transmission line 7 and then by first polarizer, 5 linear polarizations.At this moment this second rectilinearly polarized light signal L2 ' is in interface 3A place input sniffer 3.When passing sniffer 3, faraday measured angular-the ρ of magnetic field H is depended in one of the plane of polarization deflection of the second rectilinearly polarized light signal L2 ', this measured angular since the irreversible property of Faraday effect have opposite symbol with the identical value of the first light signal L1 '.The second light signal L2 ' of its plane of polarization deflection measurement-ρ at this moment is fed to second polarizer 6.The second light signal L2 ' that second polarizer 6 only allows to be arrived project on its polarization axle component by and therefore play a part analyzer for the second light signal L2 '.The second light signal L2 ' at this moment is transmitted to calculating device 20 with the L2 sign and by first transmission line 4 and coupling mechanism 12 by the component of second polarizer, 6 transmissions.
Two polarizers 5 and 6 polarization axle (transmission axle) P1 and P2 form an angle α as shown in Figure 3 each other, and angle α is a benchmark with the transmission direction of light signal L1 ' or L2 ', are not equal to the integral multiple of 180 ° or π.So the polarization axle P1 and the P2 of two polarizers 5 and 6 are not parallel mutually.
In a particularly preferred form of implementation angle α of two polarizers 5 and 6 polarization axle P1 and P2 be approximately equal at least+45 ° or-45 ° or rather+π/4 or-π/4.At this moment, the working point during H=0 has optimum linear and measures in the scope of sensitivity and regulated at one.
Before the input series circuit, connect predetermined fixing mutual ratio usually and adjust light intensity I1 ' and the I2 ' of two light signal L1 ' and L2 '.Two light intensities are preferably equal, i.e. I1 '=I2 '.In described form of implementation, the light L with light source 10 after coupling mechanism 11 is divided into two equal parts with the coupling ratio at 50%: 50%.
Two light signal L1 ' or L1 and L2 ' or L2 experienced identical Strength Changes respectively with 7 o'clock passing two transmission lines 4, and the attenuation loss that this Strength Changes especially causes because of mechanical vibration causes.This Strength Changes mainly enters light intensity I1 and I2 in the mode of attenuation coefficient.Article one, the definition of the attenuation coefficient real number of optical transmission line, general relevant with the time is the light intensity of arrival optical transmission line one end and the ratio of the input intensity of the light of the input transmission line other end.If A is that the real number attenuation coefficient and the B of first transmission line 4 is the attenuation coefficient of second transmission line 7.Then two light signal L1 passing the light series circuit and light intensity I1 and the following general formula that concerns of I2 of L2 are suitable for:
I1＝I0·A·B·cos
2(ρ+α) (2)
I2＝K·I0·B·A·cos
2(ρ-α) (3)。I0 is predetermined fixing output intensity.K is a coupling coefficient, and this coupling coefficient is drawn by the coupling ratio of coupling mechanism 11,12 and 13 in described form of implementation.When the coupling ratio of all coupling mechanisms 11,12 and 13 is respectively 50%: 50%, K=1.Cos in formula (2) and (3)
2One shows that light intensity I1 and I2 are when the predetermined angle of two polarization axles of two polarizers 5 and 6 is α and the relation of faraday's measured angular ρ.Cos in two light intensity I1 of formula (2) and (3) and the expression formula of I2
2The only difference to some extent in coupling coefficient K of coefficient before one.
M＝(a·I1+b·I2+c)/(d·I1+e·I2+f) (4)。Wherein coefficient a and e or coefficient b and d are not equal to zero at least.
This measuring-signal M of formula (4) is in fact irrelevant with the Strength Changes in the transmission line 4 or 7 that especially causes because of vibration.Therefore also can adopt the telecommunication optical fiber (multimode optical fiber) simple, that price is comparatively cheap to do transmission line 4 and 7 in all forms of implementation, this is because high relatively decay and vibration sensing degree can be compensated in measuring-signal M.But also can adopt other optic fibre wire or free radiation device as transmission line 4 and 7.
Different input intensity when coefficient a, b, c, d, e and the f of the linear function of molecule and denominator especially can import series circuits with two light signals in the formula (4) is adaptive.Coefficient a, b, c, d, e and f be preferably with suitable according to formula (2) and (3) definite light intensity I1 and I2, can not draw measuring-signal thereby do not need the linear birefringence effect in the sniffer 3 taken in promptly
M～sin (2 ρ) (5), main sinusoidal proportional with double faraday's measured angular ρ of this measuring-signal.Preferably coefficient d, e and the f to the merchant's of formula (4) denominator neutral line function d I1+eI2+f adjusts, and makes linear function dI1+eI2+f actual constant and thereby irrelevant with magnetic field H.
In a special form of implementation, the merchant who obtains by two light intensity I1 and I2
M＝I1/I2＝cos
2(ρ+α)/(K·cos
2(ρ-α)) (6a)
Or
M=I2/I1=(Kcos
2(ρ-α))/cos
2(ρ+α) (6b) is as measuring-signal.When selecting coefficient a=e=1 and b=c=d=f=0 or a=c=e=f=0 and b=d=1 for use, draw formula (6a) or merchant (6b) by the general merchant of formula (4).This measuring-signal M depends on measured angular and therefore depends on measurement field H in comparatively complicated but tangible mode.
Especially at the input intensity I1 ' of two light signal L1 ' and L2 ' and I2 ' at least when equating, in a useful form of implementation, also can adopt by the poor I1-I2 (or I2-I1) that passes two light intensity I1 behind the series circuit and I2 with and the merchant of I1+I2
M=(I1-I2)/(I1+I2) (7) is as measuring-signal.When linear birefringence effect not occurring in sniffer 3, this measuring-signal M is proportional with sin (2 ρ) again.
Calculating device 20 can be in every way derived the attenuation coefficient A that eliminated transmission line 4 and 7 and the measuring-signal of B according to two light intensity I1 of two mutual reverse light signal L1 and L2 and I2.Common two signal L1 and L2 are at first become the electric strength signal by opto-electronic conversion respectively by calculating device 20, and this electric strength signal is certain light signal L1 or the light intensity I1 of L2 or directly measuring of I2.According to these two electric strength signals, utilize numerical tabular or also can determine measuring-signal M with computing machine.For this reason, calculating device 20 contains element corresponding simulation or numeral.
In a not shown form of implementation, two electric strength signals at first utilize an A/D converter to be digitized and this digitized signal is proceeded to handle according to one among formula (4), (6a), (6b) or (7) by microprocessor or digital signal processor.
Especially calculate that according to formula (4), (6a), (6b) or (7) (when I1, I2) measuring-signal M, also can adopt analog element, the arithmetic speed of general analog element will be higher than digital element for predefined function M as two light intensity I1 and I2 at computing machine.
A measurement mechanism form of implementation shown in Figure 2, this form of implementation have the calculating device 20 of band analog element.Calculating device 20 contains two photoelectric commutators 21 and 22, subtracters 23, a totalizer 24 and a divider 25 in this form of implementation.First converter 21 is connected with coupling mechanism 13 light and the first light signal L1 that passes series circuit is converted to the first electric strength signal S1, its signal intensity and the first light signal L1 light intensity I1 conform to.Second converter 22 is connected with coupling mechanism 12 light and the second light signal L2 that passes series circuit is converted to the second electric strength signal S2 that the light intensity I2 as the second light signal L2 measures.Two electric strength signal S1 and S2 flow to the input end of subtracter 23 and totalizer 24 respectively.At the difference signal S1-S2 of subtracter 23 output terminals (or S2-S1) with flowed to the input end of divider 25 respectively with signal S1+S2 at totalizer 24 output terminals.The output signal of divider (S1-S2)/(S1+S2) will and be added on the output terminal of calculating device 20 as measuring-signal M.This measuring-signal M conforms to formula (7).
Utilize analog element in the not shown form of implementation can obtain to satisfy the measuring-signal M of formula (4) simply in the following way, the corresponding coefficient a of two linear functions in additional respectively amplification coefficient that is connected an amplifier and this amplifier and the formula (4) before the input end of subtracter 23 and totalizer 24, when bearing b-b, d and e are complementary and have and coefficient c added according to the molecule in the formula (4) in the output signal of subtracter 23 and coefficient f is added other totalizer in the output signal on totalizer 24 output terminals according to the denominator in the formula (4).The output signal of two totalizers is fed to the input end of divider 25 then in addition.As b when being positive, the most handy another totalizer substitutes subtracter 23.
Adaptive by coefficient a, b, c, d, e and f among the measuring-signal M that forms according to formula (4) especially can compensate with 22 different sensitivity two photoelectric commutators 21.
The measurement mechanism of Fig. 2 is preferably used in the electric current of measurement at least one wire 2.Faraday's sniffer 3 detect the magnetic field H that produces by this electric current I induction and with one of the plane of polarization deflection of two light signal L1 ' and L2 ' by magnetic field H and the measured angular ρ that therefore determines by electric current I or-ρ.In the useful especially form of implementation shown in Fig. 2, sniffer 3 is around electric wire 2, thereby two light signal L1 ' and L2 ' ring on an actual closed optical path enclose electric current I.When this situation, measured angular ρ and electric current I are directly proportional.Sniffer 3 can be to have the solid glass ring of the interior reflective surface of two light signal L1 ' and L2 ' guiding or the structure that realizes with other known way.Calculating device 20 is according to two light signal L1 that pass series circuit and the light intensity I1 of L2 and the measuring-signal M that I2 derives electric current I, and this measuring-signal is irrelevant fully with Strength Changes on two transmission lines 4 and 7.
When according to described a kind of measuring method or described a kind of measurement mechanism magnetic field H or electric current I being measured, the temperature effect in the sniffer 3 will be a problem.This temperature effect will cause a linear birefrigence δ as temperature T function δ (T) in the sniffer 3, and this birefringence will cause the measurement mistake to magnetic field H or electric current I.Temperature variation also can change Verdet constant and measurement sensitivity thereupon in addition.
Substantially can eliminate the influence of temperature by taking the following described measure of carrying out temperature compensation to this measuring-signal.Regulate the polarization axle P1 of first polarizer 5 and the folded polarizer angle η of intrinsic axle (main shaft, optical axis) EA of sniffer 3 neutral line birefringence δ, and regulate the second folded polarizer angle θ (see figure 3) of intrinsic axle EA of the polarization axle P2 and the sniffer 3 neutral line birefringence δ of second polarizer 6.Two polarizer angle η and θ are at least according to described formula
Cos (2 η+2 θ)=-2/3 (1) is approximate to be determined.
The intrinsic axle of linear birefrigence δ is determined that by certain polarization direction in fact the polarized light of input sniffer 3 does not have any variation ground to leave sniffer again on this direction.If what import sniffer 3 in contrast is the rectilinearly polarized light that has the plane of polarization that is not parallel to the intrinsic axle of sniffer 3, then when passing sniffer 3 since linear birefrigence δ light by elliptic polarization.Can determine two intrinsic axles of mutually orthogonal usually linear birefrigence δ in a known way.For example sniffer 3 can be arranged on a polarizer, for example a polarizer 5 and an analyzer, and for example polarizer 6, between.The polarization axle of two polarizers is vertical mutually.Two polarization axles of polarizer and analyzer are corresponding to the datum axis deflection in the same way of sniffer 3, till the light intensity by the analyzer transmission equals zero (maximum delustring) in a form of implementation.At this moment, intrinsic axle is parallel to two polarization axles of polarizer and analyzer.Two polarization axles also can be corresponding to the reference axis deflection in the same way of sniffer 3, till the light intensity maximum by the analyzer transmission (minimum delustring) in another form of implementation in addition.When this situation, by the optical circular polarizing of sniffer 3 outputs.At this moment, the intrinsic axle of linear birefrigence δ is offset 45 ° or-45 ° corresponding to the polarization axle of analyzer.
It is possible with the angle value of two polarizer angle η that satisfy formula (1) accurately and θ deviation being arranged slightly, and when especially linearity in sniffer 3 and/or circular birefringence were high, this deviation can reach about 5 ° usually.Especially draw the intrinsic axle EA that two polarizers 5 and 6 polarization axle P1 and P2 are not parallel to the linear birefrigence δ in the sniffer 3 by relational expression (1).
Regard as baseline system selected be first light signal L1's ' or the second light signal L2's ' pass direction and consider the symbol that two polarizer angle η and θ conform to the mathematics sense of rotation, the angle α of two polarizers 5 and two polarization axles of 6 equals to differ from η-θ or θ-η.The preferred adjustment of declinate α should be similar at least satisfies relational expression
sin(2α)＝sin(±2(η-θ))＝±1 (8)。The polarizer angle η that satisfies formula (8) conforms to described form of implementation with θ, and declinate α is adjusted to its preferred value+45 ° or-45 ° in this form of implementation.For example as shown in Figure 3, can select η=10.Two polarizer angle η of two formulas (1) and (8) are satisfied in 45 ° and θ=55.45 ° conduct simultaneously and the angle of θ is worth.
When the measuring-signal M that obtains with approximate at least polarizer angle η that regulates according to formula (1) and θ at this moment even temperature changes in sniffer 3, also equal at the measuring-signal M that derives according to formula (4) or (7) substantially, promptly according to the measuring-signal of the linear birefringence δ of nothing under the situation of (5) and the proportional value of sin (2 ρ).
In a special form of implementation, can adjust two polarizer angle η and θ of two polarizers 5 and 6 in simple mode according to formula (1) the best, the ratings of when calibration measurement, measuring-signal M being expected during with no linear birefringence according to the relation of itself and temperature, especially change two polarizer angle η and θ with comparing and adjust as the ratings under the situation of the predetermined polarizer angle η of parameter and θ at two, till the temperature independent ratings of actual measured signal M and reality is consistent according to relational expression (5).
The advantage of carrying out temperature compensation by adjustment polarizer angle η and θ is, measures the frequency span of magnetic field H or electric current I.That is to say, owing to taked the temperature compensation measure that the frequency spectrum of magnetic field H to be measured or electric current I can be restricted.
Claims (11)
1. measure the method in magnetic field (H) with the sniffer with Faraday effect characteristic (3) for one kind, wherein
A) first light signal (L1) passes the light series circuit that is made of first optical transmission line (4), first polarizer (5), sniffer (3), second polarizer (6) and second optical transmission line (7),
B) second light signal (L2) passes this light series circuit with the direction reverse direction that passes with first light signal (L1),
C) polarization axle (P1) of first polarizer (5) carries out the adjustment of one first polarizer angle of deflection η corresponding to the intrinsic axle (EA) of the linear birefrigence in the sniffer (3), and wherein two polarizer angle η and θ are at least near satisfying relational expression
Cos (2 η+2 θ)=-2/3 and
D) obtain the measuring-signal (M) of magnetic field (H), this measuring-signal equals to pass respectively two light signals (L1, light intensity L2) (I1, the merchant of two linear functions I2) ((aI1+bI2+c)/(dI1+eI2+f)) of light series circuit.
2. the method for claim 1, wherein measuring-signal (M) with two light intensities (I1, difference I2) with and merchant ((I1-I2)/(I1+I2)) proportional.
3. the method for claim 1, wherein (I1, merchant I2) (I1/I2 or I2/I1) is proportional with two light intensities for measuring-signal (M).
4. (P1 P2) with intrinsic axle (EA) formed two the deflector angle η and the θ of the linear birefrigence of sniffer (3), makes it approximate at least and satisfies as the described method of above-mentioned each claim, wherein to adjust the polarization axle of two polarizers (5,6) like this
sin(2θ-2η)＝±1。
5. as the described method of above-mentioned each claim, wherein the magnetic field (H) of electric current (I) is measured and measuring-signal (M) measuring as electric current (I).
6. device of measuring magnetic field (H), it has
A) one has the light series circuit that sniffer (3), second polarizer (6) and second optical transmission line (7) of Faraday effect characteristic constitute by first optical transmission line (4), first polarizer (5), one,
B) be used to send two light signals that oppositely pass series circuit mutually (L1, device L2) (10,11,12,13) and
C) be used to derive the calculating device (20) of magnetic field (H) measuring-signal (M), this measuring-signal and two light signal (L1 that pass the light series circuit respectively, L2) (I1, the merchant's light intensity of two linear functions I2) ((aI1+bI2+c)/(dI1+eI2+f)) conforms to, wherein
D) the polarizer axle (P1) of first polarizer (5) satisfies relational expression with respect to the polarization axle (P2) of birefringent intrinsic axle one first polarization angle η of (EA) deflection in the sniffer (3) and second polarizer (6) with respect to this intrinsic axle (EA) deflection one second polarizer angle θ and two polarizer angle η and θ are approximate at least
cos(2η+2θ)＝-2/3。
7. device as claimed in claim 6, wherein two optical transmission lines (4,7) are made of multimode photoconduction line.
8. as claim 6 or 7 described devices, wherein calculating device (20) is derived measuring-signal (M), this measuring-signal with two light intensities (I1, difference I2) with and the merchant ((I1-I2)/(I1+I2) is proportional.
9. as claim 6 or 7 described devices, wherein calculating device (20) is derived measuring-signal (M), and (I1, merchant I2) (I1/I2 or I2/I1) is proportional for this measuring-signal and two light intensities.
10. as each described device in the claim 6 to 9, wherein (P1 P2) is similar to according to relational expression with birefringent intrinsic axle (EA) formed polarizer angle η of sniffer (3) neutral line and θ the polarization axle of two polarizers (5,6) at least
Sin (2 θ-2 η)=± 1 adjusts.
11., sniffer (3) and calculating device (20) wherein are set in the magnetic field of electric current (I) (H) derive the measuring-signal of measuring as electric current (I) (M) as each described device in the claim 6 to 10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 95196247 CN1163665A (en) | 1994-12-23 | 1995-12-08 | Process and arrangement for measuring magnetic field-using faraday effect with compensations in intensity and temperature effects |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4446425.8 | 1994-12-23 | ||
| CN 95196247 CN1163665A (en) | 1994-12-23 | 1995-12-08 | Process and arrangement for measuring magnetic field-using faraday effect with compensations in intensity and temperature effects |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1163665A true CN1163665A (en) | 1997-10-29 |
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| CN 95196247 Pending CN1163665A (en) | 1994-12-23 | 1995-12-08 | Process and arrangement for measuring magnetic field-using faraday effect with compensations in intensity and temperature effects |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010075809A1 (en) * | 2009-01-04 | 2010-07-08 | 上海舜宇海逸光电技术有限公司 | Optical fiber magneto-optical detecting device |
| US7787728B2 (en) | 2004-03-31 | 2010-08-31 | Zolo Technologies, Inc. | Optical mode noise averaging device |
| CN102933972A (en) * | 2009-12-21 | 2013-02-13 | 株式会社日立制作所 | Single-phase optical current transformer |
| US8786857B2 (en) | 2009-08-10 | 2014-07-22 | Zolo Technologies, Inc. | Mitigation of optical signal noise using a multimode transmit fiber |
| US8786856B2 (en) | 2009-01-09 | 2014-07-22 | Zolo Technologies, Inc. | Method and apparatus for monitoring combustion properties in an interior of a boiler |
| CN1938621B (en) * | 2004-03-31 | 2015-04-01 | 佐勒技术公司 | Optical mode noise averaging device |
| US9366621B2 (en) | 2012-04-19 | 2016-06-14 | Zolo Technologies, Inc. | In-furnace retro-reflectors with steerable tunable diode laser absorption spectrometer |
| CN107918106A (en) * | 2017-11-07 | 2018-04-17 | 南京航空航天大学 | Magnetic induction intensity and the two-parameter fiber-optic monitoring method of electric current based on bending shape identification |
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1995
- 1995-12-08 CN CN 95196247 patent/CN1163665A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7787728B2 (en) | 2004-03-31 | 2010-08-31 | Zolo Technologies, Inc. | Optical mode noise averaging device |
| CN1938621B (en) * | 2004-03-31 | 2015-04-01 | 佐勒技术公司 | Optical mode noise averaging device |
| WO2010075809A1 (en) * | 2009-01-04 | 2010-07-08 | 上海舜宇海逸光电技术有限公司 | Optical fiber magneto-optical detecting device |
| US8786856B2 (en) | 2009-01-09 | 2014-07-22 | Zolo Technologies, Inc. | Method and apparatus for monitoring combustion properties in an interior of a boiler |
| US8786857B2 (en) | 2009-08-10 | 2014-07-22 | Zolo Technologies, Inc. | Mitigation of optical signal noise using a multimode transmit fiber |
| CN102933972A (en) * | 2009-12-21 | 2013-02-13 | 株式会社日立制作所 | Single-phase optical current transformer |
| CN102933972B (en) * | 2009-12-21 | 2015-11-25 | 株式会社日立制作所 | single-phase optical current transformer |
| US9366621B2 (en) | 2012-04-19 | 2016-06-14 | Zolo Technologies, Inc. | In-furnace retro-reflectors with steerable tunable diode laser absorption spectrometer |
| CN107918106A (en) * | 2017-11-07 | 2018-04-17 | 南京航空航天大学 | Magnetic induction intensity and the two-parameter fiber-optic monitoring method of electric current based on bending shape identification |
| CN107918106B (en) * | 2017-11-07 | 2019-12-06 | 南京航空航天大学 | Magnetic induction intensity and current double-parameter optical fiber monitoring method based on bending form identification |
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