CN105223524A - A kind of optically pumped magnetometer - Google Patents
A kind of optically pumped magnetometer Download PDFInfo
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- CN105223524A CN105223524A CN201510750575.XA CN201510750575A CN105223524A CN 105223524 A CN105223524 A CN 105223524A CN 201510750575 A CN201510750575 A CN 201510750575A CN 105223524 A CN105223524 A CN 105223524A
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- 238000000034 method Methods 0.000 claims abstract description 12
- 230000003534 oscillatory effect Effects 0.000 claims abstract description 8
- 230000001133 acceleration Effects 0.000 claims abstract description 5
- 230000010363 phase shift Effects 0.000 claims description 20
- 238000011896 sensitive detection Methods 0.000 claims description 14
- 238000005086 pumping Methods 0.000 claims description 10
- 230000003321 amplification Effects 0.000 claims description 9
- 230000000694 effects Effects 0.000 claims description 9
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 9
- 230000003287 optical effect Effects 0.000 claims description 9
- 238000001514 detection method Methods 0.000 claims description 8
- 230000006641 stabilisation Effects 0.000 abstract description 4
- 238000011105 stabilization Methods 0.000 abstract description 4
- 238000012935 Averaging Methods 0.000 abstract description 2
- 238000013461 design Methods 0.000 description 12
- 238000005259 measurement Methods 0.000 description 8
- 230000008878 coupling Effects 0.000 description 6
- 238000010168 coupling process Methods 0.000 description 6
- 238000005859 coupling reaction Methods 0.000 description 6
- 238000001914 filtration Methods 0.000 description 4
- 229910052734 helium Inorganic materials 0.000 description 3
- 239000001307 helium Substances 0.000 description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 3
- 238000007599 discharging Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- JJWKPURADFRFRB-UHFFFAOYSA-N carbonyl sulfide Chemical compound O=C=S JJWKPURADFRFRB-UHFFFAOYSA-N 0.000 description 1
- 230000007123 defense Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000013341 scale-up Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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Abstract
The invention discloses a kind of optically pumped magnetometer, magnetometer adopts the method simultaneously applying fundamental frequency and two frequency-doubled signals, utilizes the feature of two frequency-doubled signal amplitude changes to complete acceleration integral action, thus realizes the quick tracking of external magnetic field change.Adopt the method for multiple varactor parallel connection, devise and strangle oscillatory circuit form based on west, there is the voltage controlled oscillator of enlarging function.Thus it is wide to form a kind of reference frequency output, wave band coverage coefficient is large, and has the voltage controlled oscillator of higher momentary stabilization degree.The reference frequency output of this voltage controlled oscillator is greater than 6-50MHz, in gamut, there is not local lose phenomenon of shaking, wave band coverage coefficient reaches 3.6, signal averaging value stabilization, the amplitude of output waveform all reaches more than 2.5V in whole frequency range, meets the needs of optically pumped magnetometer completely.This voltage controlled oscillator structure is simple, stable performance, can meet the survey magnetic requirement of wide range.
Description
Technical field
The present invention relates to a kind of broadband helium light pump magnetic apparatus, belong to magnetic measurement field.
Background technology
Magnetic field very early be familiar with by people, compass, compass etc. are all the devices in the measurement magnetic field of early stage people invention, As time goes on the progress of society, magnetometer arises at the historic moment, as the instrument measuring magnetic field intensity and direction, be widely used in field, the sea, land and sky such as artificial satellite, space exploration.The kind of current magnetometer gets more and more, and conventional magnetometer mainly comprises flux-gate magnetometer, proton-precession magnetometer, superconductive magnetometer and atom magnetometer etc.Flux-gate magnetometer is that the principle be directly proportional to the modulation signal that magnetic core inductive coil exports by the value of external magnetic field carries out measuring; Proton-precession magnetometer be by composition object rotary proton phenomenon principle and carry out measuring, in rotary proton, signal frequency is directly proportional to external magnetic field strength, and scale-up factor is defined as the gyromagnetic ratio of proton; Superconductive magnetometer utilizes the knot of the Joseph under superconducting state in the sub-tunneling characteristics of amount of substance to realize weak magnetic fields measurement with superconducting circuit; Atom magnetometer utilizes the combined action of Zeeman splitting and optical pumping, makes atom generation optical magnetic resonance, is measured the value of external magnetic field by the change of measuring light intensity.
Optically pumped magnetometer produces in magnetic field based on Zeeman effect by the energy level of Elements Atom, the highly sensitive magnetic survey equipment of the one utilizing optical action and mr techniques to develop, it will transform the measurement of paired frequency to the measurement in magnetic field, realize the measurement to tested magnetic field by both corresponding relations, in geophysical research, cosmic space magnetic survey, military and national defense, mineral reserve detection etc., obtain widespread use at present.
The detection control loop of helium light pump magnetic apparatus utilizes low-frequency modulation signal to realize the magnetic survey of system and the normal tracking to magnetic field.In traditional detection control loop, system is only applied fundamental frequency modulation signal and is followed the tracks of magnetic field, two frequency-doubled signals are now repressed as garbage signal in track loop, though this method simplifies loop to a certain extent, but when the change of external magnetic field exceeds the normal tracing area of magnetic resonance, fundamental frequency modulation signal will become very little and system can not normally be followed the tracks of, the requirement of this system of carrying out continuous coverage with faster rate that is difficult to satisfy the demand.In view of the feature of two frequency-doubled signals near tracking area, fundamental frequency and two frequency-doubled signals are applied in detection control loop herein simultaneously, utilize the feature of two frequency-doubled signal amplitude changes to complete acceleration integral action, thus realize the detection control loop under large external magnetic field rate of change with fast tracking capability, simultaneously in order to make optically pumped magnetometer have larger survey quantity of magnetism journey, this loop also designs that to achieve a kind of reference frequency output wide, wave band coverage coefficient is large, and there is the voltage controlled oscillator of higher momentary stabilization degree, in order to meet the requirement to entirely magnetic field range measurement.
Summary of the invention
The object of the invention is to propose the design of a kind of broadband helium light pump magnetic apparatus.The reference frequency output of voltage controlled oscillator is greater than 8-20MHz, in gamut, there is not local lose phenomenon of shaking, wave band coverage coefficient reaches 2.5, signal averaging value stabilization, the amplitude of output waveform all reaches more than 3V in whole frequency range, meets the needs of optically pumped magnetometer completely.This voltage controlled oscillator structure is simple, stable performance, can meet the survey magnetic requirement of wide range, thus provides solution for effective measurement of optically pumped magnetometer realization to entirely magnetic field range.
For reaching this object, the present invention by the following technical solutions:
A design for broadband optically pumped magnetometer, comprises the chief components such as voltage controlled oscillator, amplifying circuit, optical pumping magnet-sensitive element, low noise amplifier circuit, phase sensitive detection, phase-shift circuit and frequency selection circuit;
Adopt the method for multiple varactor parallel connection, devise and strangle oscillatory circuit form based on west, form the voltage controlled oscillator with enlarging function, provide suitable frequency to optical pumping sensitive element, and through the amplification of amplifier, pumping signal is stabilized in suitable amplitude;
Sensitive Apparatus produces very little output under the influence of a magnetic field, and this output signal can improve signal to noise ratio (S/N ratio) through the effect of low noise amplifier, reduces the impact of spurious signal;
Then form a detection control loop by the effect of phase sensitive detection, phase-shift circuit and frequency selection circuit, adopt the method simultaneously applying fundamental frequency and two frequency-doubled signals, utilize the feature of two frequency-doubled signal amplitude changes to complete acceleration integral action, thus realize the quick tracking of external magnetic field change.
Frequency selection circuit source filter UAF42 designs, and filter type is second-order bandpass filter, and centre frequency is 1kHz, and bandwidth is 75Hz.
The fundamental frequency signal frequency selection circuit utilizing UAF42 to design applies integrated transporting discharging and resistance R12, R13 of its inside, and amplify the fundamental frequency signal after extracting, amplification coefficient is Av=R12/R13.
Phase shift and phase-sensitive detection circuit, its circuit form as shown in Figure 2: in A2 part, Rz2 and C6 realizes phase shift function, and phase shift is used to the additional phase shift of compensated corpus tracker, realizes overall negative feedback, ensures the reliable and stable of system.Signal through coupling after deliver to phase-sensitive detector (PSD) A3 part, COM4 be Strobe Controller provide with the reference signal of 1kHz rate variation, signal exports to controlled integrator finally by after R34, C7 filtering.
Amplitude discriminator circuit for differentiating that the amplitude design of two frequency-doubled signals adopts bar shaped driving chip LM3914, circuit as shown in Figure 4, in order to improve reference voltage, chip outer meeting resistance R9 and R50, reference voltage design such as formula (4), and is divided into 10 grades; Selected voltage comparator 3 (i.e. LED3) is as threshold voltage end; When two frequency-doubled signal amplitudes are higher than threshold voltage, LED1 ~ LED3 output low level; When two frequency-doubled signal amplitudes are lower than threshold voltage, LED3 ~ LEDl0 exports high level; Now just remove by the exporting change of LED3 port the gating controlling Strobe Controller signal, thus realize the object of following the tracks of external magnetic field fast.
The controlled integrator of integrator circuit is the part A in circuit, and the phase sensitive detection of control end COM3 and fundamental frequency signal exports acting in conjunction in controlled integrator.
The input end that the extraction of phase shift and phase-sensitive detection circuit still adopts active filter UAF42 to come, forms proportional integral circuit as shown in the figure; A3 part is proportional amplifier, its D amplification coefficient Av=-R42/R41; In A4 part, R4 and C9 realizes phase shift function, signal through C10 coupling after deliver to phase-sensitive detector (PSD) A1 part, COMl be here Strobe Controller provide with the reference signal of 2kHz rate variation, signal exports to amplitude Discr. finally by after R43, C11 filtering.
Voltage controlled oscillator adopts the form of 2 grades of circuit to form varactor voltage controlled oscillator: l level circuit is that oscillatory circuit is strangled in west, in order to produce oscillator signal; 2nd grade of circuit is connected into common emitter form, plays the effect of amplification.
Oscillatory circuit west is strangled in west, and to strangle circuit be sprinkle on the basis of circuit at carat, a small capacitances C4 in parallel at inductance L two ends, and meet C1, C2 much larger than C3, and C4; Adopt the method for multiple varactor parallel connection in order to realize the wide variation of capacitance, thus realize the increase of voltage controlled oscillator reference frequency output.
Common emitter form circuit is, the positive pole of varactor is received on-12V power supply, thus make it be operated in reverse bias condition, in this voltage controlled oscillator, L is vibration inductance, 3 varactors VD1, VD2 and VD3, connect with electric capacity C after in parallel, and and L, C, form the perceptual branch road of oscillator together, the oscillating capacitance c. between transistor collector and emitter, the oscillating capacitance C2 between base stage and emitter are respectively two capacitive branch.C5, C6 and C7 are coupling and shunt capacitance respectively.
Accompanying drawing explanation
Fig. 1 is the general frame figure that the specific embodiment of the invention 1 provides magnetometer.
Fig. 2 is fundamental frequency signal phase shift and phase-sensitive detection circuit
Fig. 3 is controlled integrator circuit
Fig. 4 is two frequency-doubled signal phase shift and phase-sensitive detection circuits
Embodiment
Embodiment 1
A design for broadband optically pumped magnetometer, comprises the chief components such as voltage controlled oscillator, amplifying circuit, optical pumping magnet-sensitive element, low noise amplifier circuit, phase sensitive detection, phase-shift circuit and frequency selection circuit;
Adopt the method for multiple varactor parallel connection, devise and strangle oscillatory circuit form based on west, form the voltage controlled oscillator with enlarging function, provide suitable frequency to optical pumping sensitive element, and through the amplification of amplifier, pumping signal is stabilized in suitable amplitude;
Sensitive Apparatus produces very little output under the influence of a magnetic field, and this output signal can improve signal to noise ratio (S/N ratio) through the effect of low noise amplifier, reduces the impact of spurious signal;
Then form a detection control loop by the effect of phase sensitive detection, phase-shift circuit and frequency selection circuit, adopt the method simultaneously applying fundamental frequency and two frequency-doubled signals, utilize the feature of two frequency-doubled signal amplitude changes to complete acceleration integral action, thus realize the quick tracking of external magnetic field change.
Concrete exemplifying embodiment 2
Frequency selection circuit source filter UAF42 designs, and filter type is second-order bandpass filter, and centre frequency is 1kHz, and bandwidth is 75Hz.
The fundamental frequency signal frequency selection circuit utilizing UAF42 to design also applies integrated transporting discharging and resistance R12, R13 of its inside, and amplify the fundamental frequency signal after extracting, amplification coefficient is Av=R12/R13.
Phase shift and phase-sensitive detection circuit, its circuit form as shown in Figure 2: in A2 part, Rz2 and C6 realizes phase shift function, and phase shift is used to the additional phase shift of compensated corpus tracker, realizes overall negative feedback, ensures the reliable and stable of system.Signal through coupling after deliver to phase-sensitive detector (PSD) A3 part, COM4 be Strobe Controller provide with the reference signal of 1kHz rate variation, signal exports to controlled integrator finally by after R34, C7 filtering.
Amplitude discriminator circuit for differentiating that the amplitude design of two frequency-doubled signals adopts bar shaped driving chip LM3914, circuit as shown in Figure 4, in order to improve reference voltage, chip outer meeting resistance R9 and R50, reference voltage design such as formula (4), and is divided into 10 grades; Selected voltage comparator 3 (i.e. LED3) is as threshold voltage end; When two frequency-doubled signal amplitudes are higher than threshold voltage, LED1 ~ LED3 output low level; When two frequency-doubled signal amplitudes are lower than threshold voltage, LED3 ~ LEDl0 exports high level; Now just remove by the exporting change of LED3 port the gating controlling Strobe Controller signal, thus realize the object of following the tracks of external magnetic field fast.
The controlled integrator of integrator circuit is the part A in circuit, and the phase sensitive detection of control end COM3 and fundamental frequency signal exports acting in conjunction in controlled integrator.
The input end that the extraction of phase shift and phase-sensitive detection circuit still adopts active filter UAF42 to come, forms proportional integral circuit as shown in the figure; A3 part is proportional amplifier, its D amplification coefficient Av=-R42/R41; In A4 part, R4 and C9 realizes phase shift function, signal through C10 coupling after deliver to phase-sensitive detector (PSD) A1 part, COMl be here Strobe Controller provide with the reference signal of 2kHz rate variation, signal exports to amplitude Discr. finally by after R43, C11 filtering.
Voltage controlled oscillator adopts the form of 2 grades of circuit to form varactor voltage controlled oscillator: l level circuit is that oscillatory circuit is strangled in west, in order to produce oscillator signal; 2nd grade of circuit is connected into common emitter form, plays the effect of amplification.
Oscillatory circuit west is strangled in west, and to strangle circuit be sprinkle on the basis of circuit at carat, a small capacitances C4 in parallel at inductance L two ends, and meet C1, C2 much larger than C3, and C4; Adopt the method for multiple varactor parallel connection in order to realize the wide variation of capacitance, thus realize the increase of voltage controlled oscillator reference frequency output.
Common emitter form circuit is, the positive pole of varactor is received on-12V power supply, thus make it be operated in reverse bias condition, in this voltage controlled oscillator, L is vibration inductance, 3 varactors VD1, VD2 and VD3, connect with electric capacity C after in parallel, and and L, C, form the perceptual branch road of oscillator together, the oscillating capacitance c. between transistor collector and emitter, the oscillating capacitance C2 between base stage and emitter are respectively two capacitive branch.C5, C6 and C7 are coupling and shunt capacitance respectively.
Claims (1)
1. an optically pumped magnetometer, is characterized in that, comprising: voltage controlled oscillator, amplifying circuit, optical pumping magnet-sensitive element, low noise amplifier circuit, phase sensitive detection, phase-shift circuit and frequency selection circuit chief component;
Adopt the method for multiple varactor parallel connection, be designed to strangle oscillatory circuit form based on west, form the voltage controlled oscillator with enlarging function, provide suitable frequency to optical pumping sensitive element, and through the amplification of amplifier, pumping signal is stabilized in suitable amplitude;
Sensitive Apparatus produces very little output under the influence of a magnetic field, and this output signal can improve signal to noise ratio (S/N ratio) through the effect of low noise amplifier, reduces the impact of spurious signal;
Then form a detection control loop by the effect of phase sensitive detection, phase-shift circuit and frequency selection circuit, adopt the method simultaneously applying fundamental frequency and two frequency-doubled signals, utilize the feature of two frequency-doubled signal amplitude changes to complete acceleration integral action, thus realize the quick tracking of external magnetic field change.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106073751A (en) * | 2016-05-30 | 2016-11-09 | 中国科学院电工研究所 | A kind of portable brain magnetic detection device |
| CN111562527A (en) * | 2020-03-28 | 2020-08-21 | 电子科技大学 | A method to improve the sensitivity of magnetometer |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106073751A (en) * | 2016-05-30 | 2016-11-09 | 中国科学院电工研究所 | A kind of portable brain magnetic detection device |
| CN106073751B (en) * | 2016-05-30 | 2019-06-04 | 中国科学院电工研究所 | A portable brain magnetic detection device |
| CN111562527A (en) * | 2020-03-28 | 2020-08-21 | 电子科技大学 | A method to improve the sensitivity of magnetometer |
| CN111562527B (en) * | 2020-03-28 | 2021-10-26 | 电子科技大学 | Method for improving sensitivity of magnetometer |
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