CN105842636A - Room temperature calibration-based gradiometer equivalent error area correction method and system - Google Patents
Room temperature calibration-based gradiometer equivalent error area correction method and system Download PDFInfo
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- CN105842636A CN105842636A CN201610164966.8A CN201610164966A CN105842636A CN 105842636 A CN105842636 A CN 105842636A CN 201610164966 A CN201610164966 A CN 201610164966A CN 105842636 A CN105842636 A CN 105842636A
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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
- G01R33/0052—Manufacturing aspects; Manufacturing of single devices, i.e. of semiconductor magnetic sensor chips
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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
- G01R33/0023—Electronic aspects, e.g. circuits for stimulation, evaluation, control; Treating the measured signals; calibration
- G01R33/0035—Calibration of single magnetic sensors, e.g. integrated calibration
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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
- G01R33/022—Measuring gradient
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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
- G01R33/035—Measuring direction or magnitude of magnetic fields or magnetic flux using superconductive devices
- G01R33/0354—SQUIDS
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Abstract
The invention provides a room temperature calibration-based gradiometer equivalent error area correction method and system. The method includes the following steps of: step S1, winding gradient coils; step S2, performing room temperature calibration on the gradient coils to obtain equivalent error area; and step S3, adjusting the area and/or direction of an adjustable coil according to the result of the room temperature calibration of the gradient coils, and repeating the step S2 and step S3 until the error area of the gradient coils is smaller than equal to a predetermined error area threshold value. With the room temperature calibration-based gradiometer equivalent error area correction method and system of the invention adopted, effective correction of the equivalent error area of a gradiometer can be realized, and the balance of the gradiometer under room temperature can be improved, and maneuverability is high.
Description
Technical field
The present invention relates to a kind of area of error bearing calibration and system, particularly relate to the equivalence of a kind of gradiometer based on room temperature calibration
Area of error bearing calibration and system.
Background technology
As the most highly sensitive Magnetic Sensor of one, superconducting quantum interference device (Superconducting Quantum
Interference Device, SQUID) it is widely used in biological magnetic, low-field nuclear magnetic resonance, geophysics, Non-Destructive Testing etc.
Micro-weak magnetic field detection.
One of significant challenge that the faint magnetic detection of SQUID faces suppresses powerful environmental magnetic field exactly.As a example by biological magnetic signal,
The Typical strengths of heart magnetic and brain magnetic is divided into tens pT and hundred fT magnitudes, and environmental magnetic field is very strong, and the typical case such as magnetic field of the earth is strong
Degree is 30～50 μ T, and the change in urban environment magnetic field has also reached hundreds of nT.In order to effectively suppress environmental magnetic field, except high property
The magnetic shield room of energy, most currently used noise suppression proposal is gradiometer technology.Therefore, SQUID hardware gradiometer technology
It is widely used in a variety of applications, especially under unshielded environmental condition.
At present, in SQUID gradiometer, the most widely used is that line is around axial gradiometers.Wherein, two lines around magnetic strength
Meter reversely concatenation i.e. constitutes First-order Gradient meter.Generally coil nearer for distance signal source being called receiving coil, distance signal source is relatively
Remote coil is referred to as bucking coil.According to the difference of detection gradient, its exponent number has single order, second order, higher order etc..With a ladder
Degree is calculated as example, and ideally, First-order Gradient meter only produces response to the First-order Gradient in magnetic field, and two gradiometer are only to magnetic field
Second order gradient produces impact, by that analogy.But, in actual preparation engineering, due to machining, the equal error of technique for coiling,
Gradiometer is inevitably present disequilibrium, thus inevitably uniform field and low order gradient fields is produced response, greatly
Reduce the noise suppressed performance of gradiometer.
In actual environment, the maximum intensity of uniform field, its degree of unbalancedness is maximum to the contribution of gradiometer noise response.According to gradient
Meter flux transfer principle, the uniform field degree of unbalancedness of gradiometer can be equivalent to an area of error coefficient, i.e. area of error with
Search coil area ratio.Area of error is the least, and the degree of balance of gradiometer is the highest.
Owing to gradiometer works in liquid helium temperature, it is impossible to directly the most directly correct.In actual applications, generally increase
Add gaussmeter with reference to the uniform field response compensating gradiometer.Although the method is effective, but has following deficiency:
1) increase of port number brings certain complexity to detecting system；
2) in the environment of more noisy, for ensureing the normal work of gradient channel and reference channel, it is desirable to have big dynamic range,
So certainly will need increase the hardware equalizer of gradiometer and reduce the sensitivity with reference to gaussmeter, thus cause the spirit of system entirety
The reduction of sensitivity, and the hardware equalizer of gradiometer is had higher requirement.
Therefore, the hardware equalizer degree how improving gradiometer becomes a hot research problem.
Summary of the invention
The shortcoming of prior art in view of the above, it is an object of the invention to provide the equivalence of a kind of gradiometer based on room temperature calibration
Area of error bearing calibration and system, in gradiometer winding process, above last circle bucking coil along same axial around
Make an adjustable coil, by the size and direction adjusting adjustable coil, gradiometer area of error is compensated, and carry out
Room temperature calibration, is adjusted the area of adjustable coil further according to room temperature calibration result, to realize minimum demarcation output, thus
It is effectively improved the hardware equalizer degree of gradiometer.
For achieving the above object and other relevant purposes, the present invention provides a kind of gradiometer equivalent error area based on room temperature calibration
Bearing calibration, comprises the following steps: step S1, coiling gradient coil, and described gradient coil includes having same axial reception
Coil and bucking coil, and the top being positioned at last circle bucking coil is identical with described bucking coil along described receiving coil
The axially adjustable coil of coiling；Step S2, gradient coil is carried out room temperature calibration, obtain equivalent error area；Step S3, root
According to the result of gradient coil room temperature calibration, adjust area and/or the direction of adjustable coil, repeat step S2-S3, until gradient line
The area of error of circle is less than or equal to predictive error area threshold.
According to above-mentioned gradiometer equivalent error area bearing calibration based on room temperature calibration, wherein: in described step S1, coiling
Gradient coil comprises the following steps:
11) coil brace is set, and at one end coiling receiving coil of coil brace；
12) on last circle of receiving coil, extraction is perpendicular to the twisted-pair feeder on receiving coil surface；
13) at the other end coiling support coiling bucking coil of twisted-pair feeder, and bucking coil and receiving coil is the most identical,
Coiling is in opposite direction；
14) twisted-pair feeder continues the direction along being perpendicular to bucking coil draw, and edge above compensated distance coil certain distance
The same axial coiling adjustable coil of receiving coil and bucking coil；
15) twisted-pair feeder continues the direction along being perpendicular to adjustable coil surface draw.
Further, according to above-mentioned gradiometer equivalent error area bearing calibration based on room temperature calibration, wherein: step 14)
In, described certain distance is less than or equal to 10mm.
According to above-mentioned gradiometer equivalent error area bearing calibration based on room temperature calibration, wherein: described step S2 includes following
Step:
21) using solenoid as uniform magnetic field source, electromagnetic induction is utilized to carry out output signal calculating, the induction electric of gradient coil
Gesture ε is expressed as ε=ω μ0nI0ΔSe-jωt, wherein ω is the frequency of the sinusoidal signal giving certain frequency, μ0For magnetic in vacuum
Conductance, n is the solenoidal number of turn of unit length, I0For the electric current in solenoid, Δ S is gradient coil equivalent error area；
22) signal generator, drive circuit, solenoid, gradiometer, oscillograph and lock-in amplifier is utilized to build demarcation test
System, wherein oscillograph monitoring solenoid current, lock-in amplifier detection gradiometer output signal；Under certain frequency, change
Varying signal amplitude, records the voltage signal of corresponding oscillograph and lock-in amplifier；
23) according to the oscillograph monitoring solenoid branch road reference resistance R measuredmVoltage VmGradient line is detected with lock-in amplifier
The induced voltage signal V of circleL, linear fit with determine two voltages Relationship of Coefficients as VL=aVm+ b, wherein a is straight line
Slope, b is side-play amount；
Utilize the resistance R that the induction electromotive force calculated is corresponding with monitoring voltagem,
Obtaining equivalent error area is
Wherein, gradient coil is placed in solenoidal axial centre position, makes solenoid consistent with the axial direction of gradient coil, letter
Number generator is connected with drive of constant voltage source circuit, and drive of constant voltage source circuit is connected with solenoid the most respectively and oscillograph connects, defeated
Enter the voltage signal of certain frequency ω in drive of constant voltage source circuit, drive solenoid to produce corresponding uniform magnetic field.
According to above-mentioned gradiometer equivalent error area bearing calibration based on room temperature calibration, wherein: in described step S3, two
When secondary the and area of later adjustment adjustable coil and/or direction, if current equivalent error area more than room temperature calibration first obtain etc.
Effect area of error, then change behind the direction of adjustable coil further according to room temperature calibration result, increase or reduce the area of adjustable coil；
If the equivalent error area that current equivalent error area obtains less than room temperature calibration first, then directly according to room temperature calibration result, increase
Big or reduce the area of adjustable coil.
Meanwhile, the present invention also provides for a kind of gradiometer equivalent error area based on room temperature calibration correction system, including coil winding
Module, room temperature calibration module and adjusting module；
Described coil winding module is used for coiling gradient coil, and described gradient coil includes having same axial receiving coil and benefit
Repay coil, and be positioned at the top adjustable line along the same axial coiling of receiving coil and bucking coil of last circle bucking coil
Circle；
Described room temperature calibration module, for described gradient coil carries out room temperature calibration, obtains equivalent error area；
Described adjusting module, for the result according to gradient coil room temperature calibration, adjusts area and/or the direction of described adjustable coil,
Repeat described gradient coil is carried out room temperature calibration, until the area of error of described gradient coil is less than or equal to predictive error area threshold
Value.
According to above-mentioned gradiometer equivalent error area based on room temperature calibration correction system, wherein: in described coiling module, around
Gradient coil processed comprises the following steps:
11) coil brace is set, and at one end coiling receiving coil of coil brace；
12) on last circle of receiving coil, extraction is perpendicular to the twisted-pair feeder on receiving coil surface；
13) at the other end coiling support coiling bucking coil of twisted-pair feeder, and bucking coil and receiving coil is the most identical,
Coiling is in opposite direction；
14) twisted-pair feeder continues the direction along being perpendicular to bucking coil draw, and edge above compensated distance coil certain distance
The same axial coiling adjustable coil of receiving coil and bucking coil；
15) twisted-pair feeder continues the direction along being perpendicular to adjustable coil surface draw.
Further, according to above-mentioned gradiometer equivalent error area based on room temperature calibration correction system, wherein: step 14)
In, described certain distance is less than or equal to 10mm.
According to above-mentioned gradiometer equivalent error area based on room temperature calibration correction system, wherein: described room temperature calibration module is led to
Cross following steps and described gradient coil is carried out room temperature calibration, acquisition equivalent error area:
21) using solenoid as uniform magnetic field source, electromagnetic induction is utilized to carry out output signal calculating, the induction electric of gradient coil
Gesture ε is expressed as ε=ω μ0nI0ΔSe-jωt, wherein ω is the frequency of the sinusoidal signal giving certain frequency,μ0For magnetic in vacuum
Conductance, n is the solenoidal number of turn of unit length, I0For the electric current in solenoid, Δ S is gradient coil equivalent error area；
22) signal generator, drive circuit, solenoid, gradiometer, oscillograph and lock-in amplifier is utilized to build demarcation test
System, wherein oscillograph monitoring solenoid current, lock-in amplifier detection gradiometer output signal；Under certain frequency, change
Varying signal amplitude, records the voltage signal of corresponding oscillograph and lock-in amplifier；
23) according to the oscillograph monitoring solenoid branch road reference resistance R measuredmVoltage VmGradient line is detected with lock-in amplifier
The induced voltage signal V of circleL, linear fit with determine two voltages Relationship of Coefficients as VL=aVm+ b, wherein a is straight line
Slope, b is side-play amount；
Utilize the resistance R that the induction electromotive force calculated is corresponding with monitoring voltagem,
Obtaining equivalent error area is
Wherein, gradient coil is placed in solenoidal axial centre position, makes solenoid consistent with the axial direction of gradient coil, letter
Number generator is connected with drive of constant voltage source circuit, and drive of constant voltage source circuit is connected with solenoid the most respectively and oscillograph connects, defeated
Enter the voltage signal of certain frequency ω in drive of constant voltage source circuit, drive solenoid to produce corresponding uniform magnetic field.
According to above-mentioned gradiometer equivalent error area based on room temperature calibration correction system, wherein: in described adjusting module, exist
When the area of secondary and later adjustment adjustable coil and/or direction, if what current equivalent error area obtained more than room temperature calibration first
Equivalent error area, then change behind the direction of adjustable coil further according to room temperature calibration result, increase or reduce the area of adjustable coil；
If the equivalent error area that current equivalent error area obtains less than room temperature calibration first, then directly according to room temperature calibration result, increase
Big or reduce the area of adjustable coil.
As it has been described above, the gradiometer equivalent error area bearing calibration based on room temperature calibration of the present invention and system, having following has
Benefit effect:
(1) the effective correction to gradiometer equivalent error area is achieved；
(2) degree of balance of gradiometer can at room temperature be improved；
(3) controllable property is high.
Accompanying drawing explanation
Fig. 1 is shown as the flow chart of the gradiometer equivalent error area bearing calibration based on room temperature calibration of the present invention；
Fig. 2 is shown as the structural representation of the gradient coil of the present invention；
Fig. 3 is shown as the structural representation of gradiometer equivalent error area based on the room temperature calibration correction system of the present invention.
Element numbers explanation
1 coil brace
2 receiving coils
3 bucking coils
4 adjustable coils
5 twisted-pair feeders
31 coil winding modules
32 room temperature calibration modules
33 adjusting modules
Detailed description of the invention
Below by way of specific instantiation, embodiments of the present invention being described, those skilled in the art can be by disclosed by this specification
Content understand other advantages and effect of the present invention easily.The present invention can also be added by the most different detailed description of the invention
To implement or application, the every details in this specification can also be based on different viewpoints and application, in the essence without departing from the present invention
Various modification or change is carried out under god.It should be noted that, the feature in the case of not conflicting, in following example and embodiment
Can be mutually combined.
It should be noted that the diagram provided in following example illustrates the basic conception of the present invention the most in a schematic way, then scheme
Component count, shape and size when only showing the assembly relevant with the present invention rather than implement according to reality in formula are drawn, in fact
When border is implemented, the kenel of each assembly, quantity and ratio can be a kind of random change, and its assembly layout kenel is likely to the most multiple
Miscellaneous.
In the gradiometer equivalent error area bearing calibration based on room temperature calibration of the present invention and system, in gradiometer winding process,
Along one adjustable coil of same axial coiling above last circle bucking coil, by adjust adjustable coil size and
Gradiometer area of error is compensated by direction, and carries out room temperature calibration, further according to the room temperature calibration result area to adjustable coil
It is adjusted, until obtaining predictive error area threshold.
With reference to Fig. 1, the gradiometer equivalent error area bearing calibration based on room temperature calibration of the present invention comprises the following steps:
Step S1, coiling gradient coil, this gradient coil includes having same axial receiving coil and bucking coil, Yi Jiwei
In the top of last circle bucking coil along the adjustable coil of same axial coiling of receiving coil and bucking coil.
During coiling gradient coil, during tradition gradient coil technique for coiling, need one adjustable coil of extra coiling.This can
The direction of modulation coil is the most consistent with gradient coil, is in the surface of a gradient coil circle bucking coil topmost, in coil to
The centre of upper output twisted-pair feeder is reserved.During initial reservation, little coil aperture keeps flat, the own area of reduction as far as possible.
As in figure 2 it is shown, coiling gradient coil comprises the following steps:
11) coil brace 1 is set, and at one end coiling receiving coil 2 of coil brace 1.
12) on last circle of receiving coil 2, extraction is perpendicular to the twisted-pair feeder 5 on receiving coil 2 surface.
13) at the other end coiling support coiling bucking coil 3 of twisted-pair feeder 5, and the axle of bucking coil 3 and receiving coil 2
To identical, coiling is in opposite direction.
14) twisted-pair feeder 5 continues the direction along being perpendicular to bucking coil 3 draw, and at compensated distance coil 3 certain distance
Top is along the same axial coiling adjustable coil 4 of receiving coil 2 and bucking coil 3.
In this step, the coiling direction of adjustable coil 4 can be identical with receiving coil 2, it is also possible to identical with bucking coil 3.
It is said that in general, certain distance is the best closer to bucking coil 3.Preferably, certain distance is less than or equal to 10mm.
15) twisted-pair feeder 5 continues the direction along being perpendicular to adjustable coil 4 surface draw.
Step S2, gradient coil is carried out room temperature calibration, obtain equivalent error area.
Wherein, when gradient coil is carried out room temperature calibration, solenoid is at room temperature utilized to produce the uniform magnetic field of certain frequency, should
Uniform magnetic field produces the voltage signal of certain frequency in gradient coil, utilizes phase-locking and amplification principle to carry out the extraction of small-signal,
To realize the demarcation of area error coefficient.
Specifically, step S2 comprises the following steps:
21) gradient coil induction electromotive force Theoretical Calculation.
Wherein, using solenoid as uniform magnetic field source, electromagnetic induction is utilized to carry out output signal calculating, the faradism of gradient coil
Kinetic potential ε is expressed as ε=ω μ0nI0ΔSe-jωt, ω is the frequency of the sinusoidal signal of given certain frequency, μ0For magnetic conductance in vacuum
Rate, n is the solenoidal number of turn of unit length, I0For the electric current in solenoid, Δ S is gradient coil equivalent error area.
22) test system building and measurement.
Specifically, signal generator, drive circuit, solenoid, gradiometer, oscillograph and lock-in amplifier is utilized to build demarcation
Test system, wherein oscillograph monitoring solenoid current, lock-in amplifier detection gradiometer output signal；Under certain frequency,
Change signal amplitude, record the voltage signal of corresponding oscillograph and lock-in amplifier.
23) voltage linear matching and gradient coil equivalent error areal calculation.
First, according to the oscillograph monitoring solenoid branch road reference resistance R measuredmVoltage VmWith lock-in amplifier detection ladder
The induced voltage signal V of degree coilL, linear fit with determine two voltages Relationship of Coefficients as VL=aVm+ b, wherein a is
Straight slope, b is side-play amount；
Secondly, the resistance R that the induction electromotive force of Theoretical Calculation is corresponding with monitoring voltage is utilizedm,
Can obtain equivalent error area is
The area S of known gradient meter search coil, then calculating equivalent error area coefficient is
In demarcating test system, gradient coil is placed in solenoidal axial centre position, makes the axial side of solenoid and gradient coil
To unanimously, signal generator is connected with drive of constant voltage source circuit, and drive of constant voltage source circuit is connected with solenoid and oscillography the most respectively
Device connects, and in the voltage signal of input certain frequency ω to drive of constant voltage source circuit, drives solenoid to produce corresponding uniform magnetic field；
Oscillograph monitoring solenoid branch road reference resistance RmVoltage Vm；Ginseng with signal generator output signal as lock-in amplifier
Examine signal, use the induced voltage signal V of lock-in amplifier detection gradient coilL；During measurement, under certain frequency,
Change the voltage of signal generator, measure one group of monitoring voltage VmAnd the induced voltage signal of lock-in amplifier detection gradient coil
VL。
Step S3, result according to gradient coil room temperature calibration, adjust area and/or the direction of adjustable coil, repeat step S2-S3,
Until the area of error of gradient coil is less than or equal to predictive error area threshold.
Specifically, when adjusting area and/or the direction of adjustable coil first, can heuristically area and/or direction to adjustable coil
It is adjusted.When secondary and the area that adjusts adjustable coil and/or direction later, if current equivalent error area is more than room first
The equivalent error area that temperature scale obtains surely, then change behind the direction of adjustable coil further according to room temperature calibration result, and increasing or reduce can
The area of modulation coil；If the equivalent error area that current equivalent error area obtains less than room temperature calibration first, then directly according to room
Temperature calibration result, increases or reduces the area of adjustable coil.
Such as, the area of setting compensation coil is S1, the area of receiving coil is S0, the area of adjustable coil is S ', then equivalence
Area of error is represented by △ S=S1+S’-S0.In the ideal situation, it is required that △ S is infinitely close to zero.But, in reality
In the trimming process of border, need to set a predictive error area threshold, when the equivalent error area obtained after correction is less than or equal to being somebody's turn to do
During predictive error area threshold, then it represents that correction terminates.Generally, choose that predictive error area is receiving coil area ten thousand/
Less than one.
According to experimental result, the situation of the gradiometer equivalent error area bearing calibration based on room temperature calibration of the present invention not used
Under, the area ratio of gradiometer equivalent error area and receiving coil about at about 1:1000, and use the present invention based on room temperature
After the gradiometer equivalent error area bearing calibration demarcated, gradiometer equivalent error area about exists with the area ratio of receiving coil
About 1:50000, thus drastically increase the hardware equalizer degree of gradiometer.
With reference to Fig. 3, gradiometer equivalent error area based on the room temperature calibration correction system of the present invention include coil winding module 31,
Room temperature calibration module 32 and adjusting module 33.
Coil winding module 31 is for coiling gradient coil, and this gradient coil includes having same axial receiving coil and compensating line
Circle, and it is positioned at the top adjustable coil along the same axial coiling of receiving coil and bucking coil of last circle bucking coil.
During coiling gradient coil, during tradition gradient coil technique for coiling, need one adjustable coil of extra coiling.This can
The direction of modulation coil is the most consistent with gradient coil, is in the surface of a gradient coil circle bucking coil topmost, in coil to
The centre of upper output twisted-pair feeder is reserved.During initial reservation, little coil aperture keeps flat, the own area of reduction as far as possible.
As in figure 2 it is shown, coiling gradient coil comprises the following steps:
11) coil brace 1 is set, and at one end coiling receiving coil 2 of coil brace 1.
12) on last circle of receiving coil 2, extraction is perpendicular to the twisted-pair feeder 5 on receiving coil 2 surface.
13) at the other end coiling support coiling bucking coil 3 of twisted-pair feeder 5, and the axle of bucking coil 3 and receiving coil 2
To identical, coiling is in opposite direction.
14) twisted-pair feeder 5 continues the direction along being perpendicular to bucking coil 3 draw, and at compensated distance coil 3 certain distance
Top is along the same axial coiling adjustable coil 4 of receiving coil 2 and bucking coil 3.
In this step, the coiling direction of adjustable coil 4 can be identical with receiving coil 2, it is also possible to identical with bucking coil 3.
It is said that in general, certain distance is the best closer to bucking coil 3.Preferably, certain distance is less than or equal to 10mm.
15) twisted-pair feeder 5 continues the direction along being perpendicular to adjustable coil 4 surface draw.
Room temperature calibration module 32 is connected with coil winding module 31, for gradient coil carries out room temperature calibration, obtains equivalence by mistake
Difference area.
Wherein, when gradient coil is carried out room temperature calibration, solenoid is at room temperature utilized to produce the uniform magnetic field of certain frequency, should
Uniform magnetic field produces the voltage signal of certain frequency in gradient coil, utilizes phase-locking and amplification principle to carry out the extraction of small-signal,
To realize the demarcation of area error coefficient.
Specifically, room temperature calibration module 32 uses following steps that gradient coil carries out room temperature calibration, acquisition equivalent error area:
21) gradient coil induction electromotive force Theoretical Calculation.
Wherein, using solenoid as uniform magnetic field source, electromagnetic induction is utilized to carry out output signal calculating, the faradism of gradient coil
Kinetic potential ε is expressed as ε=ω μ0nI0ΔSe-jωt, ω is the frequency of the sinusoidal signal of given certain frequency, μ0For magnetic conductance in vacuum
Rate, n is the solenoidal number of turn of unit length, I0For the electric current in solenoid, Δ S is gradient coil equivalent error area.
22) test system building and measurement.
Specifically, signal generator, drive circuit, solenoid, gradiometer, oscillograph and lock-in amplifier is utilized to build demarcation
Test system, wherein oscillograph monitoring solenoid current, lock-in amplifier detection gradiometer output signal；Under certain frequency,
Change signal amplitude, record the voltage signal of corresponding oscillograph and lock-in amplifier.
23) voltage linear matching and gradient coil equivalent error areal calculation.
First, according to the oscillograph monitoring solenoid branch road reference resistance R measuredmVoltage VmWith lock-in amplifier detection ladder
The induced voltage signal V of degree coilL, linear fit with determine two voltages Relationship of Coefficients as VL=aVm+ b, wherein a is
Straight slope, b is side-play amount；
Secondly, the resistance R that the induction electromotive force of Theoretical Calculation is corresponding with monitoring voltage is utilizedm,
Can obtain equivalent error area is
The area S of known gradient meter search coil, then calculating equivalent error area coefficient is
In demarcating test system, gradient coil is placed in solenoidal axial centre position, makes the axial side of solenoid and gradient coil
To unanimously, signal generator is connected with drive of constant voltage source circuit, and drive of constant voltage source circuit is connected with solenoid and oscillography the most respectively
Device connects, and in the voltage signal of input certain frequency ω to drive of constant voltage source circuit, drives solenoid to produce corresponding uniform magnetic field；
Oscillograph monitoring solenoid branch road reference resistance RmVoltage Vm；Ginseng with signal generator output signal as lock-in amplifier
Examine signal, use the induced voltage signal V of lock-in amplifier detection gradient coilL；During measurement, under certain frequency,
Change the voltage of signal generator, measure one group of monitoring voltage VmAnd the induced voltage signal of lock-in amplifier detection gradient coil
VL。
Adjusting module 33 is connected with room temperature calibration module 32, for the result according to gradient coil room temperature calibration, adjusts adjustable line
The area of circle and/or direction, repeat gradient coil is carried out room temperature calibration, until the area of error of gradient coil is less than or equal to predetermined
Area of error threshold value.
Specifically, when adjusting area and/or the direction of adjustable coil first, can heuristically area and/or direction to adjustable coil
It is adjusted.When secondary and the area that adjusts adjustable coil and/or direction later, if current equivalent error area is more than room first
The equivalent error area that temperature scale obtains surely, then change behind the direction of adjustable coil further according to room temperature calibration result, and increasing or reduce can
The area of modulation coil；If the equivalent error area that current equivalent error area obtains less than room temperature calibration first, then directly according to room
Temperature calibration result, increases or reduces the area of adjustable coil.
In sum, gradiometer equivalent error area bearing calibration based on room temperature calibration and the system of the present invention achieves gradient
Effective correction of meter equivalent error area；Can at room temperature improve the degree of balance of gradiometer, controllable property is high.So, this
Bright effectively overcome various shortcoming of the prior art and have high industrial utilization.
The principle of above-described embodiment only illustrative present invention and effect thereof, not for limiting the present invention.Any it is familiar with this skill
Above-described embodiment all can be modified under the spirit and the scope of the present invention or change by the personage of art.Therefore, such as
All that in art, tool usually intellectual is completed under without departing from disclosed spirit and technological thought etc.
Effect is modified or changes, and must be contained by the claim of the present invention.
Claims (10)
1. a gradiometer equivalent error area bearing calibration based on room temperature calibration, it is characterised in that: comprise the following steps:
Step S1, coiling gradient coil, described gradient coil includes having same axial receiving coil and bucking coil,
And be positioned at the top of last circle bucking coil along described receiving coil and described bucking coil same axial coiling can
Modulation coil；
Step S2, gradient coil is carried out room temperature calibration, obtain equivalent error area；
Step S3, result according to gradient coil room temperature calibration, adjust area and/or the direction of adjustable coil, repeat step
S2-S3, until the area of error of gradient coil is less than or equal to predictive error area threshold.
Gradiometer equivalent error area bearing calibration based on room temperature calibration the most according to claim 1, it is characterised in that: described
In step S1, coiling gradient coil comprises the following steps:
11) coil brace is set, and at one end coiling receiving coil of coil brace；
12) on last circle of receiving coil, extraction is perpendicular to the twisted-pair feeder on receiving coil surface；
13) at the other end coiling support coiling bucking coil of twisted-pair feeder, and bucking coil and receiving coil is the most identical,
Coiling is in opposite direction；
14) twisted-pair feeder continues the direction along being perpendicular to bucking coil draw, and above compensated distance coil certain distance
Same axial coiling adjustable coil along receiving coil and bucking coil；
15) twisted-pair feeder continues the direction along being perpendicular to adjustable coil surface draw.
Gradiometer equivalent error area bearing calibration based on room temperature calibration the most according to claim 2, it is characterised in that: step
14), in, described certain distance is less than or equal to 10mm.
Gradiometer equivalent error area bearing calibration based on room temperature calibration the most according to claim 1, it is characterised in that: described
Step S2 comprises the following steps:
21) using solenoid as uniform magnetic field source, electromagnetic induction is utilized to carry out output signal calculating, the faradism of gradient coil
Kinetic potential ε is expressed asWherein ω is the frequency of the sinusoidal signal giving certain frequency, μ0For vacuum
Middle pcrmeability, n is the solenoidal number of turn of unit length, I0For the electric current in solenoid, Δ S is gradient coil equivalent error
Area；
22) utilize signal generator, drive circuit, solenoid, gradiometer, oscillograph and lock-in amplifier to build demarcation to survey
Test system, wherein oscillograph monitoring solenoid current, lock-in amplifier detection gradiometer output signal；Under certain frequency,
Change signal amplitude, record the voltage signal of corresponding oscillograph and lock-in amplifier；
23) according to the oscillograph monitoring solenoid branch road reference resistance R measuredmVoltage VmWith lock-in amplifier detection ladder
The induced voltage signal V of degree coilL, linear fit with determine two voltages Relationship of Coefficients as VL=aVm+ b, wherein a
For straight slope, b is side-play amount；
Utilize the resistance R that the induction electromotive force calculated is corresponding with monitoring voltagem,
Obtaining equivalent error area is
Wherein, gradient coil is placed in solenoidal axial centre position, makes solenoid consistent with the axial direction of gradient coil,
Signal generator is connected with drive of constant voltage source circuit, and drive of constant voltage source circuit is connected with solenoid the most respectively and oscillograph connects
Connect, in the voltage signal of input certain frequency ω to drive of constant voltage source circuit, drive solenoid to produce corresponding uniform magnetic field.
Gradiometer equivalent error area bearing calibration based on room temperature calibration the most according to claim 1, it is characterised in that: described
In step S3, when secondary and the area that adjusts adjustable coil and/or direction later, if current equivalent error area is more than head
The equivalent error area that secondary room temperature calibration obtains, then change further according to room temperature calibration result behind the direction of adjustable coil, increase or
Reduce the area of adjustable coil；If the equivalent error area that current equivalent error area obtains less than room temperature calibration first, the most directly
Connect according to room temperature calibration result, increase or reduce the area of adjustable coil.
6. gradiometer equivalent error area based on a room temperature calibration correction system, it is characterised in that: include coil winding module, room
Temperature demarcating module and adjusting module；
Described coil winding module is used for coiling gradient coil, described gradient coil include having same axial receiving coil and
Bucking coil, and be positioned at the top of last circle bucking coil along receiving coil and bucking coil same axial coiling can
Modulation coil；
Described room temperature calibration module, for described gradient coil carries out room temperature calibration, obtains equivalent error area；
Described adjusting module, for the result according to gradient coil room temperature calibration, adjusts area and/or the side of described adjustable coil
To, repeat described gradient coil is carried out room temperature calibration, until the area of error of described gradient coil is less than or equal to predictive error
Area threshold.
Gradiometer equivalent error area based on room temperature calibration the most according to claim 6 correction system, it is characterised in that: described
In coiling module, coiling gradient coil comprises the following steps:
11) coil brace is set, and at one end coiling receiving coil of coil brace；
12) on last circle of receiving coil, extraction is perpendicular to the twisted-pair feeder on receiving coil surface；
13) at the other end coiling support coiling bucking coil of twisted-pair feeder, and bucking coil and receiving coil is the most identical,
Coiling is in opposite direction；
14) twisted-pair feeder continues the direction along being perpendicular to bucking coil draw, and above compensated distance coil certain distance
Same axial coiling adjustable coil along receiving coil and bucking coil；
15) twisted-pair feeder continues the direction along being perpendicular to adjustable coil surface draw.
Gradiometer equivalent error area based on room temperature calibration the most according to claim 7 correction system, it is characterised in that: step
14), in, described certain distance is less than or equal to 10mm.
Gradiometer equivalent error area based on room temperature calibration the most according to claim 6 correction system, it is characterised in that: described
Room temperature calibration module carries out room temperature calibration by following steps to described gradient coil, obtains equivalent error area:
21) using solenoid as uniform magnetic field source, electromagnetic induction is utilized to carry out output signal calculating, the faradism of gradient coil
Kinetic potential ε is expressed asWherein ω is the frequency of the sinusoidal signal giving certain frequency, μ0For vacuum
Middle pcrmeability, n is the solenoidal number of turn of unit length, I0For the electric current in solenoid, Δ S is gradient coil equivalent error
Area；
22) utilize signal generator, drive circuit, solenoid, gradiometer, oscillograph and lock-in amplifier to build demarcation to survey
Test system, wherein oscillograph monitoring solenoid current, lock-in amplifier detection gradiometer output signal；Under certain frequency,
Change signal amplitude, record the voltage signal of corresponding oscillograph and lock-in amplifier；
23) according to the oscillograph monitoring solenoid branch road reference resistance R measuredmVoltage VmWith lock-in amplifier detection ladder
The induced voltage signal V of degree coilL, linear fit with determine two voltages Relationship of Coefficients as VL=aVm+ b, wherein a
For straight slope, b is side-play amount；
Utilize the resistance R that the induction electromotive force calculated is corresponding with monitoring voltagem,
Obtaining equivalent error area is
Wherein, gradient coil is placed in solenoidal axial centre position, makes solenoid consistent with the axial direction of gradient coil,
Signal generator is connected with drive of constant voltage source circuit, and drive of constant voltage source circuit is connected with solenoid the most respectively and oscillograph connects
Connect, in the voltage signal of input certain frequency ω to drive of constant voltage source circuit, drive solenoid to produce corresponding uniform magnetic field.
Gradiometer equivalent error area based on room temperature calibration the most according to claim 6 correction system, it is characterised in that: institute
State in adjusting module, when secondary and the area that adjusts adjustable coil and/or direction later, if current equivalent error area is big
In the equivalent error area that room temperature calibration first obtains, then change further according to room temperature calibration result behind the direction of adjustable coil, increase
Big or reduce the area of adjustable coil；If the equivalent error area that current equivalent error area obtains less than room temperature calibration first,
Then directly according to room temperature calibration result, increase or reduce the area of adjustable coil.
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