Atomic magnetometer detection device without spin exchange relaxation based on multi-vent chamber

Abstract

A spin-exchange relaxation-free atomic magnetometer detection device based on multiple vent chambers can increase the optical rotation angle signal and improve detection sensitivity to overcome the shortcomings of the existing technology. It is characterized by including a double optical wedge and double reflector combination distributed on the detection light incident side and detection light exit side of the gas chamber. The double optical wedge and double reflector combination enables a single detection light to form a "Y"-shaped multi-pass optical path in the multiple vent chambers, thereby achieving the measurement of extremely weak magnetic fields by increasing the magnitude of the magneto-optical rotation angle.

Description

Technical Field

[0001] The invention relates to the technical field of quantum precision measuring instruments, in particular to a spin-exchange relaxation-free atomic magnetometer detection device based on a multi-ventilation chamber. Background Art

[0002] With the development of quantum technology, various scientific instruments based on quantum effects are continuously and significantly breaking through the measurement limits of traditional instruments. Atomic magnetometers, as quantum instruments that utilize atomic spin effects to achieve precise magnetic field measurements, offer unparalleled performance advantages over other types of magnetometers and are a key development direction for the next generation of ultra-high-sensitivity magnetometers.

[0003] The spin-exchange relaxation free (SERF) atomic magnetometer is a new type of alkali metal atom magnetometer operating in the SERF state. Its sensitivity is not affected by spin exchange relaxation. It is currently the most sensitive sensor and has the advantages of non-cryogenic operation, easy miniaturization, and high spatial resolution.

[0004] The basic principle of the SERF atomic magnetometer is that the interaction between linearly polarized light and alkali metal atoms in a specific excited state causes a change in polarization direction, generating a magneto-optical rotation signal. By measuring this optical rotation angle, information about the interaction between the atoms and light can be deduced. When the detection light travels a longer optical path in the gas cell, the optical rotation angle signal is increased, enabling higher-sensitivity measurements.

[0005] At present, multi-vent chambers have been applied to low-atom-density atomic magnetometers such as optically pumped atomic magnetometers and nonlinear magneto-optical rotational magnetometers. Existing research on high-atom-density atomic magnetometers such as SERF atomic magnetometers uses optical cavity structures, and the multi-vent chamber structure proposed in the present invention has not yet appeared. Summary of the Invention

[0006] The problem solved by the present invention is to provide a spin-exchange relaxation-free atomic magnetometer detection device based on a multi-ventilation chamber, which can increase the optical rotation angle signal and improve the detection sensitivity to overcome the shortcomings of the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] A spin-exchange relaxation-free atomic magnetometer detection device based on a multi-ventilated chamber is characterized by including a double optical wedge and double reflector combination distributed on the detection light incident side and the detection light exit side of the chamber. The double optical wedge and double reflector combination enables a single detection light to form an "U"-shaped multi-pass optical path in the multi-ventilated chamber, thereby achieving the measurement of extremely weak magnetic fields by increasing the size of the magneto-rotation angle.

[0009] The double optical wedge and double reflecting mirror combination includes a first optical wedge and a second reflecting mirror located on the incident side of the gas chamber detection light, and a second optical wedge and a first reflecting mirror located on the exit side of the gas chamber detection light. The first optical wedge causes the incident x-axis detection light to be emitted as upward obliquely penetrating gas chamber detection light and enter the first reflecting mirror. The first reflecting mirror reflects the upward obliquely penetrating gas chamber detection light as parallel reverse penetrating gas chamber detection light and enters the second reflecting mirror. The second reflecting mirror reflects the parallel reverse penetrating gas chamber detection light as downward obliquely penetrating gas chamber detection light and enters the second optical wedge. The second optical wedge adjusts the incident downward obliquely penetrating gas chamber detection light to the exiting x-axis detection light.

[0010] The expression of the optical rotation angle θ obtained by the emitted x-axis detection light is as follows:

[0011]

[0012] l tot =2lcosα+l

[0013] Where n is the atomic number density, r e is the classical electron radius, c is the speed of light, S x is the transverse polarizability of the alkali metal atom, f D1 is the oscillation intensity of the alkali metal D1 line, l is the length of the gas chamber, l tot is the optical path length of the interaction between the detection light and the polarized alkali metal atoms, v is the detection light frequency, v0 is the alkali metal D1 line transition resonance frequency, Γ D1 is the pressure broadening of the alkali metal D1 line, and α is the angle between the detection light passing through the gas cell obliquely upward and the x-axis.

[0014] The outgoing x-axis detection light is connected to the differential detector through a 1 / 2 wave plate and a lateral displacement polarization splitter prism in sequence, and the output end of the differential detector is connected to the magnetometer signal output end. The incident x-axis detection light comes from the detection laser, and the detection laser is connected to the first optical wedge through a first optical fiber collimator and a linear polarizer in sequence.

[0015] The ideal output voltage signal V at the magnetometer signal output end is expressed as follows:

[0016] V≈2GI pr η 3 θe OD

[0017] OD=nσl tot

[0018] Where G is the conversion coefficient of the photodetector, I pr$I_0$ is the initial incident detection light intensity, $\eta$ is the transmittance of the detection light passing through the cell glass each time, $e$ is the natural constant, $OD$ is the optical depth, and $\sigma$ is the absorption cross-sectional area of alkali metal atoms.

[0019] The z-axis pumping light emitted from the cell is connected to a photodetector, and the z-axis pumping light incident on the cell is sequentially connected to a pumping laser through a combined prism and a second fiber collimator.

[0020] Between the second fiber collimator and the pumping laser, and between the first fiber collimator and the detection laser, they are connected by their respective polarization-maintaining fibers.

[0021] An oven, a three-axis coil, and a magnetic shielding barrel are sequentially arranged outward around the cell, and the three-axis coil is connected to a function generator.

[0022] The technical effects of the present invention are as follows: The detection device of the spin-exchange relaxation-free atomic magnetometer based on a multi-pass cell of the present invention includes two parts: a pumping optical path and a detection optical path. The detection optical path uses a "fork" structure to realize a multi-pass optical path to increase the detection signal intensity. The method designed by the present invention is to use an optical wedge and a mirror to realize the optical path structure of the multi-pass cell, thereby realizing a three-fold optical path, increasing the magnitude of the magneto-optical rotation angle, and realizing the measurement of an extremely weak magnetic field. Compared with the commonly used detection methods and devices, this detection method and device can make the detection light reflect twice, that is, the distance of interaction between the detection light and alkali metal atoms is three times that of the original structure, and a large rotation angle signal can be generated, thereby improving the detection sensitivity of the spin-exchange relaxation-free atomic magnetometer.

[0023] The advantages of the present invention compared with the prior art are as follows:

[0024] (1) The detection light of the conventional SERF atomic magnetometer only passes through the cell once, so the distance of the detection light passing through the polarized atoms is short; while in the multi-pass cell, the detection light passes through the cell multiple times, increasing the optical path of the detection light and the interaction time with the polarized atoms, increasing the rotation angle, thereby increasing the intensity of the detection signal and improving the sensitivity of detecting the magnetic field.

[0025] (2) Most of the existing multi-pass cell atomic magnetometers are used in atomic magnetometers with low atomic number density. Most of such atomic magnetometers use an optical cavity (such as a Herriott cavity) to realize dozens or even more than a hundred reflections of the detection light in the cell. However, due to the high cell temperature (150 °C), dozens of reflections will attenuate the detection light intensity to 0, so this scheme cannot be applied to the SERF atomic magnetometer with high atomic number density. Compared with the traditional optical cavity, the detection device of the present invention has a simple and feasible structure, and the detection light intensity will not be lost too much under the condition of high atomic number density.

[0026] (3) In the multi-gas chamber, a "plus" - shaped detection optical path structure is formed by using an optical wedge and a mirror. This detection optical path structure makes the paths of the detection light in the gas chamber basically coincide, eliminating the influence of measurement gradients caused by uneven polarization of alkali metal atoms in the gas chamber. Moreover, the optical wedge and the mirror can conveniently adjust the direction of the optical path.

[0027] (4) The pump light and the detection light are introduced through a polarization-maintaining fiber and a non-magnetic fiber collimator head, without introducing an additional modulation magnetic field for modulation, which is convenient for miniaturization and integration of the gas chamber. Brief Description of the Drawings

[0028] Figure 1 FIG. is a schematic structural diagram of the detection device of the spin-exchange relaxation-free atomic magnetometer based on a multi-gas chamber according to the present invention.

[0029] Figure 2 is Figure 1 a schematic diagram of the detection optical path structure in

[0030] The reference numerals are listed as follows: 1 - pump laser; 2 - detection laser; 3 - function generator; 4 - first fiber collimator; 5 - linear polarizer; 6 - first optical wedge; 7 - second mirror; 8 - gas chamber; 9 - first mirror; 10 - second optical wedge; 11 - half-wave plate; 12 - lateral displacement polarization beam splitter prism; 13 - differential detector; 14 - second fiber collimator; 15 - combined prism; 16 - photodetector; 17 - oven; 18 - magnetometer signal or magnetometer signal output terminal; 19 - three-axis coil; 20 - magnetic shielding barrel; 21 - polarization-maintaining fiber; xyz - three axes of the Cartesian coordinate system (x-axis, y-axis, z-axis); l - gas chamber length; α - the angle between the incident detection light after passing through the first optical wedge and the x-axis. Detailed Embodiment

[0031] The present invention will be described below in conjunction with the drawings ( Figure 1-Figure 2 ) and embodiments.

[0032] Figure 1 FIG. is a schematic structural diagram of the detection device of the spin-exchange relaxation-free atomic magnetometer based on a multi-gas chamber according to the present invention. Figure 2 is Figure 1 a schematic diagram of the detection optical path structure in. Refer to Figures 1 to 2As shown, a spin-exchange relaxation-free atomic magnetometer detection device based on a multi-ventilated chamber includes a double optical wedge and double reflector combination distributed on the detection light incident side and the detection light exit side of the chamber. The double optical wedge and double reflector combination enables a single detection light to form a "U"-shaped multi-pass optical path in the multi-ventilated chamber to achieve the measurement of extremely weak magnetic fields by increasing the size of the magneto-rotation angle. The double optical wedge and double reflecting mirror combination includes a first optical wedge 6 and a second reflecting mirror 7 located on the incident side of the gas chamber detection light, and a second optical wedge 10 and a first reflecting mirror 9 located on the exit side of the gas chamber detection light. The first optical wedge 6 causes the incident x-axis detection light to be emitted as upward oblique gas chamber detection light and enter the first reflecting mirror 9. The first reflecting mirror 9 reflects the upward oblique gas chamber detection light as parallel reverse gas chamber detection light and enters the second reflecting mirror 7. The second reflecting mirror 7 reflects the parallel reverse gas chamber detection light as downward oblique gas chamber detection light and enters the second optical wedge 10. The second optical wedge 10 adjusts the incident downward oblique gas chamber detection light to the exiting x-axis detection light.

[0033] The expression of the optical rotation angle θ obtained by the emitted x-axis detection light is as follows:

[0034]

[0035] l tot =2lcosα+l

[0036] Where n is the atomic number density, r e is the classical electron radius, c is the speed of light, S x is the transverse polarizability of the alkali metal atom, f D1 is the oscillation intensity of the alkali metal D1 line, l is the length of the gas chamber, l tot is the optical path length of the interaction between the detection light and the polarized alkali metal atoms, v is the detection light frequency, v0 is the alkali metal D1 line transition resonance frequency, Γ D1 is the pressure broadening of the alkali metal D1 line, and α is the angle between the detection light passing through the gas cell obliquely upward and the x-axis.

[0037] The outgoing x-axis detection light is connected to the differential detector 13 through the 1 / 2 wave plate 11 and the lateral displacement polarization splitter prism 12 in sequence, and the output end of the differential detector 13 is connected to the magnetometer signal output end 18. The incident x-axis detection light comes from the detection laser 2, and the detection laser 2 is connected to the first optical wedge 6 through the first optical fiber collimator 4 and the linear polarizer 5 in sequence.

[0038] The ideal output voltage signal V of the magnetometer signal output terminal 18 is expressed as follows:

[0039] V≈2GI pr η 3 θe OD

[0040] OD = nσl tot

[0041] Where G is the conversion coefficient of the photodetector, I pr is the initial incident detection light intensity, η is the transmittance of the detection light passing through the cell glass each time, e is the natural constant, OD is the optical depth, and σ is the absorption cross-section of alkali metal atoms.

[0042] The z-axis pumping light emitted from the cell 8 is connected to the photodetector 16. The z-axis pumping light incident on the cell 8 sequentially passes through the combined prism 15 and the second fiber collimator 14 and is connected to the pumping laser 1. Between the second fiber collimator 14 and the pumping laser 1, and between the first fiber collimator 4 and the detection laser 2, they are connected by their respective polarization-maintaining fibers 21. An oven 17, a three-axis coil 19, and a magnetic shielding barrel 20 are sequentially arranged outward around the cell 8, and the three-axis coil 19 is connected to the function generator 3.

[0043] Using a multi-pass cell to design a detection device for a spin-exchange relaxation-free atomic magnetometer based on a multi-pass cell, its main components mainly include: a pumping laser (1), a detection laser (2), a function generator (3), a first fiber collimator (4), a linear polarizer (5), a first optical wedge (6), a second mirror (7), a cell (8), a first mirror (9), a second optical wedge (10), a half-wave plate (11), a lateral displacement polarization beam splitter prism (12), a differential detector (13), a second fiber collimator (14), a combined prism (15), a photodetector (16), an oven (17), a magnetometer signal (18), a three-axis coil (19), a magnetic shielding barrel (20), and a polarization-maintaining fiber (21). The two optical wedges and the two mirrors are located at fixed positions and are adjusted to the set angles through theoretical calculations.

[0044] The first optical wedge (6) and the second optical wedge (10) have the same wedge angle and the same placement method, so that when the detection light (2) is incident, it deflects a certain angle and is restored to the x-axis direction when it exits.

[0045] Through theoretical calculations, the angles between the second mirror (7) and the first mirror (9) and the z-axis direction can be determined. It is calculated that the two mirrors are symmetrically placed, thus realizing a "cross" - shaped symmetric optical path structure, making the detection light reflect twice and pass through the cell (8) three times, increasing the optical rotation angle, and thus improving the sensitivity of the SERF atomic magnetometer.

[0046] When the device is in the working state, the change of the detection optical signal in the detection optical path part is as follows:

[0047] (1) The detection laser emits detection light through the polarization-maintaining optical fiber and the first collimator (4), and the detection light is converted into linearly polarized light through the linear polarizer;

[0048] (2) The detection light converted into linearly polarized light passes through the first optical wedge (6) to change its propagation direction so that it passes through the oven and the gas chamber at a certain angle and is incident on the first reflector (9). The detection light incident on the first reflector (9) enters the gas chamber in parallel after reflection, and then passes through the second reflector (7) for the third time and is emitted from the gas chamber. The direction of the emitted detection light is changed to the x-axis direction by the second optical wedge (10), and the optical rotation angle θ is obtained as follows:

[0049]

[0050] l tot =2lcosα+l

[0051] Where n is the atomic number density, r e is the classical electron radius, c is the speed of light, S x is the transverse polarizability of the alkali metal atom, f D1 is the oscillation intensity of the alkali metal D1 line, l is the length of the gas chamber, l tot is the optical path length of the interaction between the detection light and the polarized alkali metal atoms, ν is the detection light frequency, v0 is the alkali metal D1 line transition resonance frequency, Γ D1 is the alkali metal D1 line pressure broadening, and α is the angle between the incident detection light and the x-axis after passing through the optical wedge.

[0052] (3) The detection light is split into two parts with mutually perpendicular polarization directions after passing through a half-wave plate and a lateral displacement polarization splitter prism. The light is then received by a differential detector (13) and subsequently processed to obtain the corresponding magnetometer signal (18). The formula is shown below. From this signal, the optical rotation angle θ and the atomic gas state information (the ideal output voltage signal V of the magnetometer) can be obtained.

[0053] V≈2GI pr η 3 θe OD

[0054] OD=nσl tot

[0055] Where G is the conversion coefficient of the photodetector, I pr is the initial incident detection light intensity, η is the transmittance of each detection light passing through the gas cell glass, e is the natural index, OD is the optical depth, and σ is the alkali metal atomic absorption cross section.

[0056] The invention discloses a spin-exchange relaxation-free atomic magnetometer detection device based on a multi-ventilation chamber, characterized by comprising: a pumping laser (1), a detection laser (2), a function generator (3), a first optical fiber collimator (4), a linear polarizer (5), a first optical wedge (6), a second reflector (7), an air chamber (8), a first reflector (9), a second optical wedge (10), a half-wave plate (11), a lateral displacement polarization splitter prism (12), a differential detector (13), a second optical fiber collimator (14), a combined prism (15), a photodetector (16), an oven (17), a magnetometer signal (18), a three-axis coil (19), a magnetic shielding barrel (20) and a polarization-maintaining optical fiber (21). The detection laser (2) emits detection light through the polarization-maintaining optical fiber (21) and the first optical fiber collimator (4). The detection light passes through the linear polarizer (5) to become linearly polarized light. The detection light then passes through the first optical wedge (6) to change its propagation direction so that it passes through the oven (17) and the air chamber (8) at a certain angle and is incident on the first reflector (9). The detection light incident on the first reflector (9) enters the air chamber (8) in parallel after reflection. Thereafter, the detection light passes through the air chamber (8) for the third time and is emitted. The direction of the emitted detection light is changed to the x-axis direction by the second optical wedge (10). Finally, the detection light passes through a 1 / 2 wave plate (11) and a lateral displacement polarization splitter prism (12) to be split into two parts with mutually perpendicular polarization directions and is then emitted. The detection light is then received by a differential detector (13) to detect the rotation signal of the polarization plane of the detection light, i.e., the optical rotation angle θ.

[0057] The invention also includes a pump laser (1), a polarization-maintaining optical fiber (21), a second optical fiber collimator (14), a combined prism (15), and a photodetector (16); the polarization-maintaining optical fiber (21) and the second optical fiber collimator (14) ensure that the light beam is incident horizontally; the combined prism (15) is composed of a right-angle prism, a linear polarizer, and a quarter-wave plate, and converts the pump light into circularly polarized light to illuminate the alkali metal gas chamber (8), thereby polarizing the atoms. The photodetector (16) is used to monitor whether the pump light emitted by the pump laser (1) has completely polarized the alkali metal in the gas chamber (8).

[0058] The invention also includes a function generator (3), a three-axis coil (19) and a magnetic shielding barrel (20); the purpose of the function generator (3) and the three-axis coil (19) is to use the in-situ magnetic compensation technology to control the magnetic field generated by the three-axis coil (19) through the function generator (3) to compensate the magnetic field felt by the atoms in the alkali metal gas chamber (8), so that the magnetic field felt by the atoms is 0, that is, the residual magnetic field in the three-axis direction of the SERF atomic magnetometer is compensated to zero; the magnetic shielding barrel (20) is to ensure that the spin-exchange relaxation free (SERF) magnetometer works in a weak magnetic environment.

[0059] The atoms in the alkali metal gas cell operate in a SERF state.

[0060] The first optical wedge (6) and the second optical wedge (10) are used to adjust the incident angle of the detection beam, so that when the detection light (2) is incident, it deflects by a certain angle and returns to the x-axis direction when it exits; the optical wedge is used to conveniently adjust the incident direction of the detection light.

[0061] Through theoretical calculation, the included angles between the second mirror (7) and the first mirror (9) and the z-axis direction can be determined. It is calculated that the two mirrors are symmetrically placed, thus realizing a "fork"-shaped symmetric optical path structure.

[0062] The entire multi-air chamber structure realizes a "fork"-shaped symmetric optical path. That is, after the first optical wedge (6), the second optical wedge (10), the second mirror (7) and the first mirror (9) are adjusted to the appropriate angles, they are fixed firmly, enabling the detection light to pass through the air chamber (8) three times, increasing the detected optical rotation angle, and thus improving the detection sensitivity of the SERF atomic magnetometer.

[0063] Using the "fork"-shaped symmetric optical path structure, the detection lights in the air chamber (8) overlap, enabling the detection light to interact with the same polarized alkali metal atoms multiple times, avoiding the influence of the magnetic field gradient on the detection sensitivity of the SERF atomic magnetometer; at the same time, the detection light passes through the air chamber (8) three times, increasing the detected optical rotation angle and improving the detection sensitivity of the SERF atomic magnetometer.

[0064] The present invention proposes a detection device for a spin-exchange relaxation-free atomic magnetometer based on a multi-air chamber. By fixing the position of the optical wedge and determining the included angles between the two mirrors and the z-axis direction through theoretical calculation, two reflections of the detection light can be achieved, and the detection light passes through the air chamber three times, thereby increasing the optical rotation angle and improving the sensitivity of the SERF atomic magnetometer.

[0065] Refer to Figures 1 to 2 , the present invention provides a detection method and device for a spin-exchange relaxation-free atomic magnetometer based on a multi-air chamber. As Figure 1 shown, the detection method and device for the spin-exchange relaxation-free atomic magnetometer based on a multi-air chamber include: a pumping laser 1, a detection laser 2, a function generator 3, a first fiber collimator 4, a linear polarizer ⑤, a first optical wedge 6, a second mirror 7, an air chamber 8, a first mirror 9, a second optical wedge 10, a half-wave plate 11, a lateral displacement polarization beam splitter prism 12, a differential detector 13, a second fiber collimator 14, a combined prism 15, a photodetector 16, an oven 17, a magnetometer signal 18, a three-axis coil 19, a magnetic shielding barrel 20, and a polarization-maintaining fiber 21.

[0066] The detection method for the spin-exchange relaxation-free atomic magnetometer based on a multi-air chamber in the present invention is specifically implemented as follows:

[0067] (1) First, complete the design and theoretical calculation of the optical path. Calculate the angle between the two reflectors and the z-axis. Based on the optical path structure, the two reflectors are symmetrically placed. In this example, a wedge is used to deflect the horizontally incident detection light by 8°. The calculated angle between the two reflectors and the z-axis is 4°, completing the construction of the optical path system.

[0068] (2) The alkali metal gas chamber 8 is installed in the shield barrel 20 and heated until the alkali metal atomic density reaches 10 13 ~10 14 pieces / cm 3 The laser frequency output by the pump laser 1 is adjusted to near the alkali metal atomic D1 line. The laser is then coupled into the SERF atomic magnetometer probe using a polarization-maintaining fiber 21 and a second fiber collimator 14. The light then passes through a combined prism 15 to convert it into circularly polarized light that illuminates the alkali metal gas chamber 8, achieving atomic polarization.

[0069] (3) The laser output by the detection laser 2 is transmitted through the polarization-maintaining fiber 21 to the first fiber collimator 4 and coupled into the SERF atomic magnetometer probe. After that, it passes through the linear polarizer 5 to become linearly polarized light and passes through the first optical wedge 6 to make the detection light enter the gas chamber 8 with an 8° deflection. Then, it passes through the first reflector 9 to make the detection light enter the gas chamber 8 horizontally again. Then, it is reflected by the second reflector 7 and enters the gas chamber for the third time. Finally, it passes through the second optical wedge 10 to change the direction of the detection light to horizontal. After passing through the gas chamber three times, its linear polarization angle changes slightly (rotation angle θ), thereby realizing the detection of atomic precession signals.

[0070]

[0071] l tot =2lcosα+l

[0072] Where, l tot That is, the optical path length of the detection light passing through the gas cell three times to interact with the polarized alkali metal atoms.

[0073] (4) After step (3), the detection light passes through the 1 / 2 wave plate 11 and enters the lateral displacement polarization splitter prism 12. The lateral displacement polarization splitter prism 12 splits the detection light into two beams and enters the differential detector 13. The differential detector 13 outputs the magnetometer signal 18.

[0074] V=GI m sin(2θ)

[0075] Assuming that the detection light is strong enough, the detection light intensity after passing through the gas chamber m times will become I m =I pr η m .

[0076] Where, Im is the intensity of the detected light after the light passes through the gas cell m times, I pr is the initial incident detection light intensity, and η is the transmittance of the detection light passing through the gas cell glass each time. In this example, the detection light passes through the gas cell three times, so m=3.

[0077] Since the optical rotation angle is in the order of mrad (milliradians), and taking light absorption into account, the above formula can be approximated as:

[0078] V≈2GI pr η 3 θe OD

[0079] In summary, the detection method and device based on a multi-vent chamber spin-exchange relaxation-free atomic magnetometer of the present invention boast a simple structure, convenient adjustment, and ease of fabrication and assembly. Within the multi-vent chamber, an optical wedge and reflector form a "Y"-shaped detection optical path. This structure enables the detection light to be reflected twice, generating a larger optical rotation angle, thereby improving the sensitivity of the SERF atomic magnetometer. Furthermore, this structure ensures that the detection light paths within the chamber are substantially aligned, eliminating the influence of measurement gradients caused by the uneven polarization of alkali metal atoms within the chamber.

[0080] Any content not described in detail in this specification is prior art known to those skilled in the art. It should be noted that the above description is intended to help those skilled in the art understand the present invention, but does not limit the scope of protection of the present invention. Any equivalent substitution, modification, improvement, and / or simplification of the above description that does not depart from the essence of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A spin-exchange relaxation-free atomic magnetometer detection device based on a multi-vent chamber, characterized in that: The invention comprises a double optical wedge and double reflector combination distributed on the detection light incident side and the detection light exit side of the gas chamber. The double optical wedge and double reflector combination enables a single detection light to form a "Y"-shaped multi-pass optical path with multiple gas chambers, thereby achieving the measurement of extremely weak magnetic fields by increasing the magneto-optical rotation angle. The double optical wedge and double reflecting mirror combination includes a first optical wedge and a second reflecting mirror located on the incident side of the gas cell detection light, and a second optical wedge and the first reflecting mirror located on the exit side of the gas cell detection light. The first optical wedge causes the incident x-axis detection light to exit as upward obliquely penetrating gas cell detection light and enter the first reflecting mirror. The first reflecting mirror reflects the upward obliquely penetrating gas cell detection light as parallel reverse penetrating gas cell detection light and enters the second reflecting mirror. The second reflecting mirror reflects the parallel reverse penetrating gas cell detection light as downward obliquely penetrating gas cell detection light and enters the second optical wedge. The second optical wedge adjusts the incident downward obliquely penetrating gas cell detection light to the exiting x-axis detection light. The first optical wedge deflects the horizontally incident detection light by 8°, and the angle between the first reflector and the second reflector and the z-axis direction is 4°.

2. The spin-exchange relaxation-free atomic magnetometer detection device based on a multi-vent chamber according to claim 1, characterized in that: The expression of the optical rotation angle θ obtained by the emitted x-axis detection light is as follows: l tot =2l cosα+l Where n is the atomic number density, r e is the classical electron radius, c is the speed of light, S x is the transverse polarizability of the alkali metal atom, f D1 is the oscillation intensity of the alkali metal D1 line, l is the length of the gas chamber, l tot is the optical path length of the interaction between the detection light and the polarized alkali metal atoms, v is the detection light frequency, v0 is the alkali metal D1 line transition resonance frequency, Γ D1 is the pressure broadening of the alkali metal D1 line, and α is the angle between the detection light passing through the gas cell obliquely upward and the x-axis.

3. The spin-exchange relaxation-free atomic magnetometer detection device based on a multi-vent chamber according to claim 1, characterized in that: The outgoing x-axis detection light is connected to the differential detector through a 1 / 2 wave plate and a lateral displacement polarization splitter prism in sequence, and the output end of the differential detector is connected to the magnetometer signal output end. The incident x-axis detection light comes from the detection laser, and the detection laser is connected to the first optical wedge through a first optical fiber collimator and a linear polarizer in sequence.

4. The spin-exchange relaxation-free atomic magnetometer detection device based on a multi-vent chamber according to claim 3, characterized in that: The ideal output voltage signal V at the magnetometer signal output end is expressed as follows: V≈2GI pr or 3 will OD OD=nσl tot Where G is the conversion coefficient of the photodetector, I pr is the initial incident detection light intensity, η is the transmittance of each detection light passing through the gas cell glass, e is a natural constant, OD is the optical depth, and σ is the alkali metal atomic absorption cross-sectional area.

5. The spin-exchange relaxation-free atomic magnetometer detection device based on a multi-vent chamber according to claim 3, characterized in that: The z-axial pumping light emitted from the gas cell is connected to a photodetector, and the z-axial pumping light incident on the gas cell is connected to a pumping laser through a combined prism and a second optical fiber collimator in sequence.

6. The spin-exchange relaxation-free atomic magnetometer detection device based on a multi-vent chamber according to claim 5, characterized in that: The second fiber collimator and the pumping laser, as well as the first fiber collimator and the detection laser, are connected via respective polarization-maintaining fibers.

7. The spin-exchange relaxation-free atomic magnetometer detection device based on a multi-vent chamber according to claim 1, characterized in that: An oven, a three-axis coil and a magnetic shielding barrel are sequentially arranged outwardly from the outer periphery of the air chamber, and the three-axis coil is connected to a function generator.

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