CN114601465A - Small-size double-beam double-channel atomic magnetometer system - Google Patents
Small-size double-beam double-channel atomic magnetometer system Download PDFInfo
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Abstract
The utility model provides a small-size double-beam binary channels's atomic magnetometer system, through set up first combination polarization beam splitter prism and second combination polarization beam splitter prism in the biax binary channels gauge outfit that has pumping light beam input interface and measuring beam input interface, first combination polarization beam splitter prism divides the pumping light beam splitting to first pumping light beam and second pumping light beam in order to act on first alkali metal air chamber and second alkali metal air chamber respectively, second combination polarization beam splitter prism divides the measuring beam splitting to first measuring beam and second measuring beam in order to shine first alkali metal air chamber and second alkali metal air chamber respectively, utilizes double-beam to realize that the pumping detects the separation, introduces beam splitting module, difference detection, can obtain high accuracy binary channels magnetic field information simultaneously, has sensitivity height, integrated level, the high characteristics of detection efficiency, is favorable to forming high accuracy, high density magnetometer array, the method is used for the fields of magnetoencephalography, magnetocardiography and the like.
Description
Technical Field
The invention belongs to the technical field of magnetometers, and particularly relates to a double-beam double-channel atomic magnetometer which is characterized in that a first combined polarization beam splitter prism and a second combined polarization beam splitter prism are arranged in a double-shaft double-channel gauge outfit with a pumping beam input interface and a detection beam input interface, the first combined polarization beam splitter prism splits a pumping beam into a first pumping beam and a second pumping beam to respectively act on a first alkali metal air chamber and a second alkali metal air chamber, the second combined polarization beam splitter prism splits a detection beam into a first detection beam and a second detection beam to respectively irradiate the first alkali metal air chamber and the second alkali metal air chamber, pumping detection separation is realized by double beams, a beam splitting module and differential detection are introduced, high-precision double-channel magnetic field information can be obtained simultaneously, and the double-beam double-channel atomic magnetometer has the characteristics of high sensitivity, high integration degree and high detection efficiency, the method is favorable for forming a high-precision and high-density magnetometer array and serves the fields of magnetoencephalography, magnetocardiography and the like.
Background
The application of magnetic field information is widely applied to modern science and technology and human life, accurate magnetic field measurement can help people to better understand the world, and especially the high-precision weak magnetic field measurement is widely applied to the fields of biological magnetic field detection, geomagnetic detection, deep space magnetic detection, magnetic anomaly detection and the like. The capability of measuring the extremely weak magnetic field depends on the technical level of a magnetic sensor, so the development of the ultra-high sensitivity magnetometer is closely related to the improvement of national comprehensive strength and the health of people. With the continuous development of quantum precision measurement technology, there appears a Spin-Exchange Relaxation Free (SERF) -based atomic magnetometer, which has extremely high theoretical sensitivity, however, the magnetic field measurement sensitivity of the current single-beam SERF atomic magnetometer is close to the limit, which is difficult to be greatly improved, and the measurement efficiency is low, while the dual-beam atomic magnetometer can improve the precision, but inevitably can greatly increase the volume, and reduce the density of the magnetometer array.
Disclosure of Invention
The invention provides a double-beam double-channel atomic magnetometer aiming at the defects in the prior art, which is characterized in that a first combined polarization beam splitter prism and a second combined polarization beam splitter prism are arranged in a double-shaft double-channel meter head with a pumping beam input interface and a detection beam input interface, the first combined polarization beam splitter prism splits a pumping beam into a first pumping beam and a second pumping beam to respectively act on a first alkali metal air chamber and a second alkali metal air chamber, the second combined polarization beam splitter prism splits a detection beam into a first detection beam and a second detection beam to respectively irradiate the first alkali metal air chamber and the second alkali metal air chamber, the pumping detection separation is realized by double beams, a beam splitting module and differential detection are introduced, high-precision double-channel magnetic field information can be simultaneously obtained, and the double-beam double-channel atomic magnetometer has the characteristics of high sensitivity, high integration level and high detection efficiency, the method is favorable for forming a high-precision and high-density magnetometer array and serves the fields of magnetoencephalography, magnetocardiography and the like.
The technical solution of the invention is as follows:
the utility model provides a two-beam binary channels atomic magnetometer, its characterized in that, includes two-axis binary channels gauge outfit, two-axis binary channels gauge outfit has pumping beam input interface and detection beam input interface, the inner chamber of two-axis binary channels gauge outfit is provided with first combination polarization beam splitter prism and second combination polarization beam splitter prism, first combination polarization beam splitter prism with pumping beam input interface position corresponds, second combination polarization beam splitter prism with detection beam input interface position corresponds, first combination polarization beam splitter prism splits the pumping beam into first pumping beam and second pumping beam, first pumping beam is arranged in the atom of pumping first alkali metal air chamber, second pumping beam is arranged in the atom of pumping second alkali metal air chamber, second combination polarization beam splitter prism splits the detection beam into first detection beam and second detection beam, the first detection beam is used for irradiating the first alkali metal gas chamber, and the second detection beam is used for irradiating the second alkali metal gas chamber.
The second combined polarization beam splitter prism comprises a fourth polarization beam splitter prism, the x-axis input side of the fourth polarization beam splitter prism is connected with the detection light beam input interface, the x-axis transmission side is provided with a fourth lambda/4 wave plate, the outer surface of the fourth lambda/4 wave plate is provided with a second reflection film, the z-axis negative reflection side is provided with a first combined triangular prism, the first combined triangular prism transmits the first detection light beam to the first polarization beam splitter prism through the first alkali metal air chamber along the y-axis negative direction, the z-axis positive reflection side of the fourth polarization beam splitter prism is provided with a second combined triangular prism, and the second combined triangular prism transmits the second detection light beam to the second polarization beam splitter prism through the second alkali metal air chamber along the y-axis negative direction.
The device comprises a first polarization splitting prism, a second polarization splitting prism, a third polarization splitting prism, a fourth polarization splitting prism, a fifth photoelectric detector, a sixth photoelectric detector, a third photoelectric detector and a fourth photoelectric detector, wherein the z-axis negative reflection side of the second polarization splitting prism is provided with the fifth photoelectric detector, the y-axis negative transmission side of the second polarization splitting prism is provided with the sixth photoelectric detector, the z-axis negative reflection side of the first polarization splitting prism is provided with the third photoelectric detector, the y-axis negative transmission side of the first polarization splitting prism is provided with the fourth photoelectric detector, and the measurement of the magnetic field strength in the x-axis or z-axis direction is realized by detecting the change of the light polarization direction caused by the change of the magnetic field strength.
The first combined polarization beam splitter prism comprises a third polarization beam splitter prism, the x-axis input side of the third polarization beam splitter prism is connected with the pumping beam input interface, the x-axis transmission side is provided with a third lambda/4 wave plate, the outer surface of the third lambda/4 wave plate is provided with a first reflection film, the z-axis negative reflection side is provided with a first lambda/4 wave plate, the polarization beam splitter prism splits linearly polarized light incident in the x-axis direction into first vertical polarized light reflected along the z-axis negative direction and horizontal polarized light transmitted along the x-axis direction, the first lambda/4 wave plate changes the first vertical polarized light into first circularly polarized light serving as the first pumping beam, and the horizontal polarized light is reflected back by the first reflection film after passing through the third lambda/4 wave plate to form second vertical polarized light reflected along the z-axis positive direction, the second λ/4 plate changes the second vertically polarized light into second circularly polarized light as the second pump beam.
And a first photoelectric detector is arranged on the negative z-axis side of the first alkali metal gas chamber, a second photoelectric detector is arranged on the positive z-axis side of the second alkali metal gas chamber, and the first photoelectric detector and the second photoelectric detector are used for detecting the absorption change of the pumping light signal to obtain the polarization degree of the alkali metal atom.
The first combined triangular prism and the second combined triangular prism both comprise triangular prisms, and polarizing plates are bonded on the negative y-axis side of each triangular prism.
The first non-magnetic electric heater and the first three-dimensional magnetic coil structure are installed in the outside of first alkali metal air chamber, second non-magnetic electric heater and the second three-dimensional magnetic coil structure are installed in the outside of second alkali metal air chamber.
The pump light beam input interface is connected with a first optical fiber collimator, the first optical fiber collimator is connected with the pump laser through a first polarization maintaining optical fiber, the detection light beam input interface is connected with a second optical fiber collimator, and the second optical fiber collimator is connected with the detection laser through a second polarization maintaining optical fiber.
Magnitude of magnetic field in x-axis direction, and electric polarizability P in y-axis direction of magnetometeryAnd (3) correlation:
wherein, P0Is the steady state polarizability of the electron spin in the z-axis direction,
Rpoptical pumping power, R, of alkali metal electrons for pumping a beam in the z-axis directionrelIs the relaxation rate of alkali metal electrons, betax、βy、βzEquivalent vector magnetic fields in x, y and z directions, betax＝γeBx/(Rp+Rrel)，βy＝γeBy/(Rp+Rrel)，βz＝γeBz/(Rp+Rrel)，γeIs the ratio of the gyromagnetic force of electrons, Bx、By、BzThe magnetic field intensity of the environment to be measured in the x direction, the y direction and the z direction respectively.
Magnitude of magnetic field in x-axis direction, and electric polarizability P in y-axis direction of magnetometeryAnd (3) correlation:
the formulaDescription of the preferred embodimentsyFor the magnetic field B to be measured in the x-axis directionxThe sensitivity is high, so that the magnetic field intensity to be measured in the x-axis direction of the two channels can be obtained through the detection light beam in the y-axis direction.
The invention has the following technical effects: the invention discloses a double-beam double-channel atomic magnetometer which comprises pumping laser, detection laser, a collimation module and a double-shaft double-channel meter head, wherein the double-shaft double-channel meter head comprises an alkali metal air chamber, a non-magnetic electric heating part, a three-dimensional magnetic coil, a beam splitting module and a differential detection module. The collimation module consists of two polarization maintaining fibers with fiber collimators at the tail parts, so that light emitted by pumping laser and detection laser is collimated and focused into a specific spot size to be transmitted into the double-shaft double-channel gauge outfit; the alkali metal gas chamber contains alkali metal atoms; the alkali metal atoms work in a high-temperature and low-magnetic-field environment without magnetic electric heating and three-dimensional magnetic coils, so that efficient pumping is ensured; the beam splitting module consists of a combined polarization beam splitter prism, a combined beam splitter prism and a combined triangular prism, and enables pumping light and detection light to be split; the differential detection module consists of a polarization beam splitter prism and a photoelectric detector; the pumping laser is used for polarizing alkali metal atoms, and the pumping light collimated by the collimating module generates two independent pumping lasers through the beam splitting module and is emitted into the alkali metal air chamber to polarize the alkali metal atoms; the detection laser is used for sensing the magnetic field intensity of the atomic magnetometer in the axial direction, the detection light collimated by the collimation module generates two independent and reverse detection lasers through the beam splitting module and simultaneously emits the two detection lasers into the alkali metal air chamber to detect the magnetic field intensity of the two channels, and the measurement result is demodulated by the phase-locked amplifier through a differential detection method. The invention obtains high precision by utilizing double-beam differential detection, adds the beam splitting module to simultaneously obtain the magnetic field information of two-channel double-shaft, has the characteristics of high sensitivity, high integration level and high detection efficiency, and has wide application prospect in the fields of magnetoencephalography, magnetocardiography and the like.
Compared with the prior art, the invention has the advantages that: the invention uses light with different wavelengths as pumping light and detection light, introduces a differential detection method, and has high magnetic field measurement sensitivity and stability; and the beam splitting system is introduced to drive the double air chambers, so that double-channel vector magnetic field signals can be obtained at the same time, the measurement efficiency and the integration level are improved, a magnetometer array is favorably formed, and the method has wide application prospects in the fields of magnetoencephalography, magnetocardiography and the like.
Drawings
FIG. 1 is a schematic diagram of a compact dual beam dual channel atomic magnetometer system embodying the present invention.
Fig. 2 is a schematic structural view of the dual-axis dual-channel gauge head of fig. 1.
Fig. 3 is a schematic structural diagram of the combined beam splitter prism in fig. 2. In fig. 3, the left side is a first combined beam splitter prism, and the right side is a second combined beam splitter prism.
The reference numbers are listed below: 1-pump laser; 2-detection of the laser; 3-a first polarization maintaining fiber; 4-a second polarization maintaining fiber; 5-a first fiber collimator; 6-a second fiber collimator; 7-double-shaft double-channel gauge outfit; 700-a first combined polarization beam splitter prism; 701-a first alkali metal gas cell; 702-a second alkali metal gas cell; 703-a first photodetector; 704-a second photodetector; 705-a second combined polarizing beam splitter prism; 706-a first combination triangular prism; 707-a second combination triangular prism; 708-a first polarizing beam splitter prism; 709-a second polarization splitting prism; 710-a third photodetector; 711-a fourth photodetector; 712-a fifth photodetector; 713-a sixth photodetector; 715-a first non-magnetic electric heater; 716-a first three-dimensional magnetic coil structure; 717-a second nonmagnetic electric heater; 718-a second three-dimensional magnetic coil structure; 7001-a third polarization beam splitter prism; 7002-a first λ/4 plate; 7003-a second λ/4 plate; 7004-a third λ/4 waveplate; 7005-first reflective film; 7051-fourth polarizing beam splitter prism; 7052-fourth λ/4 plate; 7053-second reflective film (or second mirror).
Detailed Description
The invention is explained below with reference to the figures (fig. 1-3) and examples.
FIG. 1 is a schematic diagram of a compact dual beam dual channel atomic magnetometer system embodying the present invention. Fig. 2 is a schematic structural view of the dual-axis dual-channel gauge head of fig. 1. Fig. 3 is a schematic structural diagram of the combined beam splitter prism in fig. 2. Referring to fig. 1 to 3, a dual-beam dual-channel atomic magnetometer includes a dual-axis dual-channel gauge outfit 7, the dual-axis dual-channel gauge outfit 7 has a pumping beam input interface and a detection beam input interface, an inner cavity of the dual-axis dual-channel gauge outfit is provided with a first combined polarization beam splitter prism 700 and a second combined polarization beam splitter prism 705, the first combined polarization beam splitter prism 700 corresponds to the pumping beam input interface position, the second combined polarization beam splitter prism 705 corresponds to the detection beam input interface position, the first combined polarization beam splitter prism 700 splits a pumping beam into a first pumping beam and a second pumping beam, the first pumping beam is used for pumping atoms in a first alkali metal gas chamber 701, the second pumping beam is used for pumping atoms in a second alkali metal gas chamber 702, the second combined polarization beam splitter prism 705 splits a detection beam into a first detection beam and a second detection beam, the first detection beam is used to illuminate the first alkali metal gas cell 701 and the second detection beam is used to illuminate the second alkali metal gas cell 702.
The second combined polarization beam splitter prism 705 comprises a fourth polarization beam splitter prism 7051, an x-axis input side of the fourth polarization beam splitter prism 7051 is connected to the detection beam input interface, an x-axis transmission side is provided with a fourth λ/4 wave plate 7052, an outer surface of the fourth λ/4 wave plate 7052 is provided with a second reflection film 7053, a z-axis negative reflection side is provided with a first combined triangular prism 706, the first combined triangular prism 706 transmits the first detection beam to the first polarization beam splitter prism 708 through the first alkali metal gas chamber 701 along the y-axis negative direction, a z-axis positive reflection side of the fourth polarization beam splitter prism 7051 is provided with a second combined triangular prism 707, and the second combined triangular prism 707 transmits the second detection beam to the second polarization beam splitter prism 709 through the second alkali metal gas chamber 702 along the y-axis negative direction. A fifth photodetector 712 is disposed on the z-axis negative reflection side of the second polarization splitting prism 709, a sixth photodetector 713 is disposed on the y-axis negative transmission side, a third photodetector 710 is disposed on the z-axis negative reflection side of the first polarization splitting prism 708, and a fourth photodetector 711 is disposed on the y-axis negative transmission side, so that the measurement of the magnetic field strength in the x-axis or z-axis direction is realized by detecting the change of the polarization direction of the detection light caused by the change of the magnetic field strength.
The first combined polarization beam splitter 700 comprises a third polarization beam splitter 7001, the x-axis input side of the third polarization beam splitter 7001 is connected with the pumping beam input interface, the x-axis transmission side is provided with a third lambda/4 wave plate 7004, the outer surface of the third lambda/4 wave plate 7004 is provided with a first reflection film 7005, the z-axis negative reflection side is provided with a first lambda/4 wave plate 7002, the polarization beam splitter 7001 splits linearly polarized light incident in the x-axis direction into first vertically polarized light reflected along the z-axis negative direction and horizontally polarized light transmitted along the x-axis negative direction, the first lambda/4 wave plate 7002 changes the first vertically polarized light into first circularly polarized light serving as the first pumping beam, the horizontally polarized light passes through the third lambda/4 wave plate 7004 and then is reflected back by the first reflection film 7005 to form second vertically polarized light reflected along the z-axis positive direction, the second λ/4 plate 7003 changes the second vertically polarized light into a second circularly polarized light which is the second pump beam.
A first photoelectric detector 703 is arranged on the negative z-axis side of the first alkali metal gas cell 701, a second photoelectric detector 704 is arranged on the positive z-axis side of the second alkali metal gas cell 702, and both the first photoelectric detector 703 and the second photoelectric detector 704 are used for detecting the absorption change of the pumping light signal to obtain the alkali metal atom polarization degree. The first combination triangular prism 706 and the second combination triangular prism 707 each include a triangular prism, and a polarizing plate is bonded to the y-axis negative side of the triangular prism. A first non-magnetic electric heater 715 and a first three-dimensional magnetic coil structure 716 are installed on the outer side of the first alkali metal air chamber 701, and a second non-magnetic electric heater 717 and a second three-dimensional magnetic coil structure 718 are installed on the outer side of the second alkali metal air chamber 702. The pump light beam input interface is connected with a first optical fiber collimator 5, the first optical fiber collimator 5 is connected with a pump laser 1 through a first polarization maintaining optical fiber 3, the detection light beam input interface is connected with a second optical fiber collimator 6, and the second optical fiber collimator 6 is connected with a detection laser 2 through a second polarization maintaining optical fiber 4.
Magnitude of magnetic field in x-axis direction, and electric polarizability P in y-axis direction of magnetometeryAnd (3) correlation:
wherein, P0Is the steady state polarizability of the electron spin in the z-axis direction,
Rpoptical pumping rate, R, of alkali metal electrons for pumping a beam in a z-axis directionrelIs the relaxation rate of alkali metal electrons, betax、βy、βzEquivalent vector magnetic fields in x, y and z directions, betax＝γeBx/(Rp+Rrel)，βy＝γeBy/(Rp+Rrel)，βz＝γeBz/(Rp+Rrel)，γeIs the ratio of the gyromagnetic force of electrons, Bx、By、BzThe magnetic field intensity of the environment to be measured in the x direction, the y direction and the z direction respectively.
Magnitude of magnetic field in x-axis direction, and electric polarizability P in y-axis direction of magnetometeryAnd (3) correlation:
description of the formula PyFor the magnetic field B to be measured in the x-axis directionxThe sensitivity is high, so that the magnetic field intensity to be measured in the x-axis direction of the two channels can be obtained through the detection light beam in the y-axis direction.
A small-sized double-beam and double-channel atomic magnetometer system is composed of pumping laser 1, detection laser 2, a first polarization maintaining fiber 3, a second polarization maintaining fiber 4, a first collimator 5, a second collimator 6 and a double-shaft and double-channel gauge outfit 7; the dual-axis dual-channel meter head 7 comprises a first combined polarization splitting prism 700, a first alkali metal gas chamber 701, a second alkali metal gas chamber 702, a first photodetector 703, a second photodetector 704, a second combined polarization splitting prism 705, a first combined triangular prism 706, a second combined triangular prism 707, a first polarization splitting prism 708, a second polarization splitting prism 709, a third photodetector 710, a fourth photodetector 711, a fifth photodetector 712, a sixth photodetector 713, a first non-magnetic electric heating 715, a first three-dimensional magnetic coil structure 716, a second non-magnetic electric heating 717 and a second three-dimensional magnetic coil structure 718; the first alkali metal air chamber 701 and the second alkali metal air chamber 702 are symmetrically arranged at two sides inside the double-shaft double-channel gauge outfit 7, the middle part is provided with a first combined polarization beam splitter prism 700, the external structures of the first alkali metal air chamber 701 and the second alkali metal air chamber 702 are respectively a first non-magnetic electric heating 715, a first three-dimensional magnetic coil structure 716, a second non-magnetic electric heating 717 and a second three-dimensional magnetic coil structure 718, the air chamber heating is realized through the non-magnetic electric heating, and the magnetic compensation is realized through the three-dimensional magnetic coils; pumping light enters a double-shaft double-channel gauge outfit 7 through a first polarization maintaining fiber 3 and a first collimator 5 by pumping laser 1, is split into a first pumping light beam and a second pumping light beam after passing through a first combined polarization beam splitter prism 700 in the double-shaft double-channel gauge outfit 7, and is respectively and correspondingly emitted into a first alkali metal air chamber 701 and a second alkali metal air chamber 702, and the light penetrating through the alkali metal air chambers is respectively received by a first photoelectric detector 703 and a second photoelectric detector 704; detection light enters a double-shaft double-channel meter head 7 through a detection laser 2 through a second polarization maintaining optical fiber 4 and a second collimator 6, the detection light is divided into a first detection light beam and a second detection light beam through a second combined polarization splitting prism 705 in the double-shaft double-channel meter head 7, the first detection light beam is split into a third photoelectric detector 710 and a fourth photoelectric detector 711 after passing through a first combined triangular prism 706, a first alkali metal air chamber 701 and a first polarization splitting prism 708 in sequence, and the second detection light beam is split into a fifth photoelectric detector 712 and a sixth photoelectric detector 713 after passing through a second combined triangular prism 707, a second alkali metal air chamber 702 and a second polarization splitting prism 709 in sequence; the optical signal entering the photodetector is converted into an electrical signal and is transmitted to the lock-in amplifier for demodulation, so as to obtain the vector magnetic field intensity sensed by the atoms in the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702, and finally, the magnetic field intensity data obtained by demodulation is processed and displayed in the signal processor.
The first pumping light beam and the second pumping light beam generated by beam splitting after passing through the first combined polarization beam splitter prism 700 are left-handed circularly polarized light with opposite propagation directions, the two pumping light beams are respectively emitted into the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 along the-z-axis direction and the z-axis direction, and the emitted light beams are finally received by the first photoelectric detector 703 and the second photoelectric detector 704; the first combined polarization beam splitter 700 comprises a polarization beam splitter 7001, a first lambda/4 wave plate 7002, a second lambda/4 wave plate 7003, a third lambda/4 wave plate 7004 and a first reflection film 7005, the first lambda/4 wave plate 7002, the polarization beam splitter 7001 and the second lambda/4 wave plate 7003 are arranged along the z axis in sequence, the lambda/4 wave plates are adhered to the surface of the polarization beam splitter 7001, and the third lambda/4 wave plate 7004 and the first reflection film 7005 are adhered to the surface of the polarization beam splitter 7001 along the x axis; the pumping light beam optical signal received by the photoelectric detector is used for obtaining the polarization efficiency of the alkali metal atoms in the first alkali metal gas cell 701 and the second alkali metal gas cell 702.
The first detection light beam and the second detection light beam generated by beam splitting after passing through the second combined polarization beam splitter prism 705 are linearly polarized light with opposite propagation directions, the propagation directions and polarization states of the two detection light beams are changed by the first combined triangular prism 706 and the second combined triangular prism 707, and the two detection light beams emitted by the combined triangular prism respectively pass through the first alkali metal air chamber 701 and the second alkali metal air chamber 702 along the-y axis direction, respectively pass through the first polarization beam splitter prism 708 and the second polarization beam splitter prism 709 respectively and enter the third photodetector 710, the fourth photodetector 711, the fifth photodetector 712 and the sixth photodetector 713; the second combined polarization splitting prism 705 is composed of a polarization splitting prism 7051, a fourth lambda/4 wave plate 7052 and a second reflection film 7053, and the fourth lambda/4 wave plate 7052 and the second reflection film 7053 are bonded to the outer surface of the polarization splitting prism 7051 along the x axis.
The first detection light beam and the second detection light beam are both linear polarized lasers, the change of the polarization direction of the detection light caused by the change of the magnetic field intensity of the detection light is detected, the first polarization beam splitter 708, the third photoelectric detector 710, the fourth photoelectric detector 711, the second polarization beam splitter 709, the fifth photoelectric detector 712 and the sixth photoelectric detector 713 respectively detect the light difference of the two channels, a part of noise is filtered out by a difference method, the optical signals received by the photoelectric detectors are converted into electric signals which are demodulated by a phase-locked amplifier, the magnetic field intensity in the x-axis direction and the magnetic field intensity in the z-axis direction are detected, and the detection sensitivity is improved.
The parameters of the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 are the same, and alkali metal atoms and buffer gas are contained in the first alkali metal gas chamber and the second alkali metal gas chamber.
The first photodetector 703, the second photodetector 704, the third photodetector 710, the fourth photodetector 711, the fifth photodetector 712, and the sixth photodetector 713 are of the same type.
The first combined triangular prism 706 and the second combined triangular prism 707 have the same structural parameters, and both the triangular prisms are bonded with a polaroid along the-y axis surface.
The first polarization beam splitter prism 708 and the second polarization beam splitter prism 709 have the same model.
The pumping laser 1 and the detection laser 2 can output enough power so as to realize the simultaneous driving of a plurality of probes in the later period.
The first pumping light beam and the second pumping light beam respectively propagate along the-y axis direction and the y axis direction, the first detection light beam and the second detection light beam both propagate along the-z axis direction, and the pumping light beam is perpendicular to the propagation direction of the detection light beams and meets the centers of the corresponding alkali metal air chambers. Alkali metal atoms and buffer gas are filled in the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702, the alkali metal atoms are working atoms, are general alkali metal elements such as K, Rb, Cs and the like, and are in a non-spin exchange relaxation state during working; the buffer gas is an inert gas and is used for reducing the spin collision among atoms.
The principle of vector magnetic field detection of a high-precision miniaturized double-channel atomic magnetometer system is as follows:
1. the first non-magnetic electric heating 715, the first three-dimensional magnetic coil structure 716, the second non-magnetic electric heating 717 and the second three-dimensional magnetic coil structure 718 are started, the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 are heated to set temperatures respectively, then the current amount of the three-dimensional magnetic coils is controlled, and the magnetic field generated by the three-dimensional magnetic coils is adjusted, so that residual magnetic fields in the directions of the x axis, the y axis and the z axis in the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 are compensated to be zero, the influence of the external residual magnetic field on the measurement result is avoided, and at the moment, the alkali metal atoms in the alkali metal gas chambers work in a non-spin exchange relaxation state.
2. When passing through the first alkali metal gas cell 701 and the second alkali metal gas cell 702, the dual-channel pumping light beams are respectively along the-z axis direction and the z axis direction and are used for polarizing high-temperature alkali metal atoms; the double-channel detection beams are along the-y axis and the y axis and are used for detecting the magnetic field in the x axis direction and the electronic polarizability P in the y axis direction of the magnetometeryAnd (3) correlation:
wherein, P0Is the steady state polarizability of the electron spin in the z-axis direction,
Rpoptical pumping rate, R, of alkali metal electrons for pumping a beam in a z-axis directionrelRelaxation rate of electrons of alkali metals, betax、βy、βzEquivalent vector magnetic fields in x, y and z directions, betax＝γeBx/(Rp+Rrel)，βy＝γeBy/(Rp+Rrel)，βz＝γeBz/(Rp+Rrel)，γeIs the ratio of the gyromagnetic force of electrons, Bx、By、BzThe magnetic field intensity of the environment to be measured in the x direction, the y direction and the z direction respectively.
The alkali metal atoms are in a non-spin-exchange relaxation state, and the ambient magnetic field Bx、By、BzTypically in the order of nanometers, i.e. | βx|＜＜1、|βy|＜＜1、|β z1, neglecting second-order small quantity, the transverse polarizability of the electron in the y-axis direction can be simplified as follows:
description of the formula PyFor the magnetic field B to be measured in the x-axis directionxThe sensitivity is high, so that the magnetic field intensity to be measured in the x-axis direction of the two channels can be obtained through the detection light beam in the y-axis direction.
The invention discloses a small double-beam and double-channel atomic magnetometer system which mainly comprises pumping laser 1, detection laser 2, a first polarization maintaining fiber 3, a second polarization maintaining fiber 4, a first collimator 5, a second collimator 6 and a double-shaft and double-channel gauge outfit 7 as shown in figure 1. The pumping laser provides a polarized alkali metal atom light source, the detection laser provides a detection magnetic field change light source, the pumping laser and the detection laser are respectively transmitted through corresponding polarization maintaining optical fibers and collimators, and the light with required size enters the double-shaft double-channel gauge outfit 7 after being collimated and expanded.
As shown in fig. 2, the biaxial dual-channel probe 7 includes a first combined polarization splitting prism 700, a first alkali metal gas cell 701, a second alkali metal gas cell 702, a first photodetector 703, a second photodetector 704, a second combined polarization splitting prism 705, a first combined triangular prism 706, a second combined triangular prism 707, a first polarization splitting prism 708, a second polarization splitting prism 709, a third photodetector 710, a fourth photodetector 711, a fifth photodetector 712, a sixth photodetector 713, a first electromagnetic-free heating 715, a first three-dimensional magnetic coil structure 716, a second electromagnetic-free heating 717, and a second three-dimensional magnetic coil structure 718.
As shown in fig. 2, pumping light entering the dual-axis dual-channel probe 7 passes through the first combined polarization beam splitter prism 700 and then is split into two circularly polarized pumping light beams, one of which enters the first alkali metal gas chamber 701 and the other of which enters the second alkali metal gas chamber 702, so as to pump atoms.
As shown in FIG. 3, the first combined polarization beam splitter 700 comprises a third polarization beam splitter 7001, a first lambda/4 wave plate 7002, a second lambda/4 wave plate 7003, a third lambda/4 wave plate 7004 and a first reflection film 7005, the first reflection film 7005 is plated on the outer surface of the x-axis of the third polarization beam splitter 7001, the first lambda/4 wave plate 7002 and the second lambda/4 wave plate 7003 are symmetrically bonded on the two outer surfaces of the x-axis, the long axis of the lambda/4 wave plate forms an angle of 45 degrees with the vertical polarization, the light emitted from the first combined polarization beam splitter 700 is circularly polarized light, enters the first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 in the-z-axis and z-axis directions, is received by the first photodetector 703 and the second photodetector 704 after being transmitted, and the optical signal entering the photodetectors is converted into an electrical signal, and the polarization degree of the alkali metal atoms is obtained by detecting the absorption change.
As shown in fig. 2 and 3, the detection light entering the dual-axis dual-channel probe 7 is divided into two linear polarization detection lights after passing through the second combined polarization beam splitter 705, the second combined polarization beam splitter 705 is composed of a fourth polarization beam splitter 7051, a fourth λ/4 wave plate 7052 and a second reflection film 7053, the fourth λ/4 wave plate 7052 and the second reflection film 7053 are bonded to the outer surface of the x axis of the fourth polarization beam splitter 7051, the long axis of the λ/4 wave plate and the vertical polarization form 45 °, and the two outgoing detection lights are both vertical polarization.
As shown in fig. 2, two beams of vertical polarization detection light respectively pass through a combination triangular prism to change the propagation direction and polarization state, a polarizer is adhered to the y-axis surface of the combination triangular prism to generate the required linear polarization detection light, the light emitted from the combination triangular prism enters an alkali metal gas chamber, the light transmitted through the alkali metal gas chamber from the two channels respectively passes through a first polarization beam splitter prism 708 and a second polarization beam splitter prism 709 to split into corresponding photodetectors, the z-axis magnetic field strength measurement is realized by detecting the change of the polarization direction of the detection light caused by the change of the magnetic field strength, the change of the polarization component of the light caused by the change of the polarization direction of the detection light is measured, the change of the polarization direction of the detection light can be obtained by measuring the change of the optical signals after the first polarization beam splitter prism 708 and the second polarization beam splitter prism 709, the optical signals are converted into electrical signals after passing through the photodetectors and transmitted to a lock-in amplifier for modulation and demodulation, and the demodulated magnetic field intensity data is processed and displayed in a signal processor through difference.
The first alkali metal gas chamber 701 and the second alkali metal gas chamber 702 are filled with alkali metal atoms and buffer gas, the alkali metal atoms are working atoms, generally K, Rb, Cs and other alkali metal elements, and work at high temperature, the temperature is different according to different alkali metal elements, generally greater than 100 ℃, and the alkali metal atoms are in a non-spin exchange relaxation state during work; the buffer gas is an inert gas and is used for reducing the spin collision among atoms.
The working temperature is realized by nonmagnetic electric heating, the first alkali metal air chamber 701 and the second alkali metal air chamber 702 are heated to a set temperature by starting the first nonmagnetic electric heating 715 and the second nonmagnetic electric heating 717, and magnetic fields generated by the first three-dimensional magnetic coil structure 716 and the second three-dimensional magnetic coil structure 718 are adjusted by controlling the current amount of the three-dimensional magnetic coils, so that residual magnetic fields in the directions of an x axis, a y axis and a z axis in the two-channel alkali metal air chambers are compensated to be zero, and the influence of the external residual magnetic fields on a measurement result is avoided.
When passing through the first alkali metal gas cell 701 and the second alkali metal gas cell 702, the dual-channel pumping light beams are respectively along the-z axis direction and the z axis direction and are used for polarizing high-temperature alkali metal atoms; the double-channel detection beams are all along the-y-axis direction and are used for detecting the magnitude of the magnetic field in the x-axis direction and the electron polarizability P in the y-axis direction of the magnetometeryAnd (4) correlating.
Those skilled in the art will appreciate that the invention may be practiced without these specific details. It is pointed out here that the above description is helpful for the person skilled in the art to understand the invention, but does not limit the scope of protection of the invention. Any such equivalents, modifications and/or omissions as may be made without departing from the spirit and scope of the invention may be resorted to.
Claims (10)
1. The utility model provides a two-beam binary channels atomic magnetometer, its characterized in that, includes two-axis binary channels gauge outfit, two-axis binary channels gauge outfit has pumping beam input interface and detection beam input interface, the inner chamber of two-axis binary channels gauge outfit is provided with first combination polarization beam splitter prism and second combination polarization beam splitter prism, first combination polarization beam splitter prism with pumping beam input interface position corresponds, second combination polarization beam splitter prism with detection beam input interface position corresponds, first combination polarization beam splitter prism splits the pumping beam into first pumping beam and second pumping beam, first pumping beam is arranged in the atom of pumping first alkali metal air chamber, second pumping beam is arranged in the atom of pumping second alkali metal air chamber, second combination polarization beam splitter prism splits the detection beam into first detection beam and second detection beam, the first detection beam is used for irradiating the first alkali metal gas chamber, and the second detection beam is used for irradiating the second alkali metal gas chamber.
2. The dual-beam, dual-channel atomic magnetometer of claim 1, wherein the second combined polarizing beam splitter prism comprises a fourth polarizing beam splitter prism, the x-axis input side of the fourth polarization beam splitter prism is connected with the detection beam input interface, the x-axis transmission side is provided with a fourth lambda/4 wave plate, the outer surface of the fourth lambda/4 wave plate is provided with a second reflecting film, the negative reflection side of the z axis is provided with a first combined triangular prism, the first combined triangular prism transmits the first detection beam to a first polarization beam splitter prism through the first alkali metal air chamber along the negative direction of the y axis, and a second combined triangular prism is arranged on the z-axis positive reflection side of the fourth polarization beam splitter prism, and transmits the second detection beam to the second polarization beam splitter prism through the second alkali metal air chamber along the y-axis negative direction.
3. The dual-beam dual-channel atomic magnetometer of claim 2, wherein the second polarization splitting prism is provided with a fifth photodetector on the z-axis negative reflection side, a sixth photodetector on the y-axis negative transmission side, the first polarization splitting prism is provided with a third photodetector on the z-axis negative reflection side, and a fourth photodetector on the y-axis negative transmission side, and the x-axis or z-axis magnetic field strength measurement is realized by detecting the change in the polarization direction of the detection light caused by the change in the magnetic field strength.
4. The dual-beam dual-channel atomic magnetometer of claim 1, wherein the first combined polarization splitting prism comprises a third polarization splitting prism, an x-axis input side of the third polarization splitting prism is connected to the pump beam input interface, an x-axis transmission side of the third polarization splitting prism is provided with a third λ/4 wave plate, an outer surface of the third λ/4 wave plate is provided with a first reflection film, a z-axis negative reflection side of the third polarization splitting prism is provided with a first λ/4 wave plate, the polarization splitting prism splits linearly polarized light incident in the x-axis direction into a first vertically polarized light reflected along the z-axis direction and a horizontally polarized light transmitted along the x-axis direction, the first λ/4 wave plate changes the first vertically polarized light into a first circularly polarized light serving as the first pump beam, and the horizontally polarized light passes through the third λ/4 wave plate and is reflected back by the first reflection film to form a second vertically polarized light reflected along the z-axis direction Light, the second λ/4 plate changing the second vertically polarized light into second circularly polarized light as the second pump light beam.
5. The dual-beam dual-channel atomic magnetometer of claim 1, wherein the first alkali metal gas cell is provided with a first photodetector on the negative z-axis side, and the second alkali metal gas cell is provided with a second photodetector on the positive z-axis side, and the first photodetector and the second photodetector are both used for detecting the absorption change of the pumping light signal to obtain the polarization degree of the alkali metal atom.
6. The dual-beam, dual-channel atomic magnetometer of claim 2, wherein the first combined triangular prism and the second combined triangular prism each comprise a triangular prism having a polarizer bonded to a y-axis negative side of the triangular prism.
7. The dual-beam dual-channel atomic magnetometer of claim 1, wherein a first non-magnetic electric heater and a first three-dimensional magnetic coil structure are installed on the outer side of the first alkali metal gas chamber, and a second non-magnetic electric heater and a second three-dimensional magnetic coil structure are installed on the outer side of the second alkali metal gas chamber.
8. The dual-beam dual-channel atomic magnetometer of claim 1, wherein the pump beam input interface is connected to a first fiber collimator, the first fiber collimator is connected to the pump laser through a first polarization maintaining fiber, the detection beam input interface is connected to a second fiber collimator, and the second fiber collimator is connected to the detection laser through a second polarization maintaining fiber.
9. The dual beam dual channel atomic magnetometer of claim 1 wherein the magnitude of the magnetic field in the x-axis direction is related to the electric susceptibility P of the magnetometer in the y-axis directionyAnd (3) correlation:
wherein, P0Is the steady state polarizability of the electron spin in the z-axis direction,
Rpoptical pumping power, R, of alkali metal electrons for pumping a beam in the z-axis directionrelIs the relaxation rate of alkali metal electrons, betax、βy、βzEquivalent vector magnetic fields in x, y and z directions, betax＝γeBx/(Rp+Rrel)，βγ＝γeBy/(Rp+Rrel)，βz＝γeBz/(Rp+Rrel)，γeIs the ratio of the gyromagnetic force of electrons, Bx、By、BzThe magnetic field intensity of the environment to be measured in the x direction, the y direction and the z direction respectively.
10. The dual beam dual channel atomic magnetometer of claim 1 wherein the magnitude of the magnetic field in the x-axis direction is related to the electric susceptibility P of the magnetometer in the y-axis directionyAnd (3) correlation:
description of the formula PyFor the magnetic field B to be measured in the x-axis directionxSensitivity, so that two-channel to-be-detected magnetism in the x-axis direction can be obtained through the detection light beam in the y-axis directionThe field strength.
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