Multi-optical-path SERF magnetometer probe based on multi-cavity air chamber

Abstract

The invention relates to a dual-optical-path SERF magnetometer probe based on a dual-cavity air chamber. The dual-optical-path SERF magnetometer probe comprises the dual-cavity air chamber, a first circular polarizer, a first detector, a second circular polarizer, a second detector, a heating device, a temperature sensor, a three-axis magnetic field coil, an air chamber clamping support, an air chamber clamping cover and a main body structure. The first laser beam passes through the first circular polarizer and the double-cavity gas chamber and then reaches the first detector; the second laser beam passes through the second circular polarizer and the double-cavity gas chamber and then reaches the second detector, and the direction of the first laser beam is perpendicular to that of the second laser beam. According to the invention, two light beams which are perpendicular to each other are adopted to excite different air chambers of the double-cavity air chamber, so that magnetic field vector measurement with equivalent three-axis sensitivity level can be realized, and meanwhile, the effect of magnetic field gradient measurement is realized. The double-cavity air chamber can be expanded into an N-cavity air chamber, the number of the cavities and the number of the corresponding optical paths are synchronously increased, more three-axis magnetic field information can be obtained, and the increased optical paths have the potential of expanding other functions.

Description

Technical Field

[0001] The invention belongs to the field of magnetic measurement, and in particular relates to a multi-optical path SERF magnetometer probe based on a multi-cavity air chamber. Background Art

[0002] Magnetic field measurement is an indispensable part of modern scientific research and technological development. It plays a vital role in many fields such as basic scientific research, navigation and positioning, resource exploration and biomedicine. With the development of magnetic field measurement technology, the requirements for magnetic field measurement accuracy are getting higher and higher. Among them, magnetometers based on the SERF principle are an important development direction in the field of magnetic field measurement.

[0003] At present, there are two main schemes for single-beam SERF magnetometers: transverse magnetic field modulation and discrete magnetic field modulation. Among them, transverse magnetic field modulation can realize the measurement of the magnetic field perpendicular to the direction of light propagation, but cannot measure the magnetic field along the direction of light propagation. For discrete magnetic field modulation, three-axis vector magnetic field measurement can usually be achieved, but there is a disadvantage of poor magnetic field sensitivity along the direction of pump light, and it is impossible to achieve the effect of equivalent three-axis sensitivity level. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a dual-optical path SERF magnetometer probe based on a dual-cavity air chamber, which adopts two mutually perpendicular light beams to excite different air chamber cavities of the dual-cavity air chamber, thereby realizing magnetic field vector measurement with equivalent three-axis sensitivity level and achieving the effect of magnetic field gradient measurement at the same time.

[0005] Another object of the present invention is to provide an N-optical path SERF magnetometer probe based on an N-cavity air chamber.

[0006] The above-mentioned purpose of the present invention is mainly achieved through the following technical solutions:

[0007] A dual-optical path SERF magnetometer probe based on a dual-cavity air chamber comprises a dual-cavity air chamber, a first circular polarizer, a first detector, a second circular polarizer, a second detector, a heating device, a three-axis magnetic field coil and a main structure; the dual-cavity air chamber is filled with an alkali metal in the air chamber cavity, and the dual-cavity air chamber comprises a first air chamber cavity and a second air chamber cavity;

[0008] The first laser beam passes through the first circular polarizer and then through the first air chamber in the double-cavity air chamber to reach the first detector to form a first optical path;

[0009] The second laser beam passes through the second circular polarizer and then through the second air chamber in the double-cavity air chamber to reach the second detector to form a second optical path;

[0010] The first laser beam and the second laser beam are perpendicular to each other, and the angle error range is ±0.5°;

[0011] The double-cavity air chamber, the first circular polarizer, the first detector, the second circular polarizer, the second detector, the heating device and the three-axis magnetic field coil are arranged in the main structure.

[0012] The heating device is fixed to the outer surface of the double-cavity air chamber and is used to heat the double-cavity air chamber to a set temperature. The heating device is provided with a through hole to ensure the passage of the laser beam.

[0013] The three-axis magnetic field coil is wound in a coil slot surrounding the six outer sides of the main structure. After the three-axis magnetic field coil is wound, the double-cavity air chamber is located at a uniform magnetic field position at the center of the magnetic field generated by the three-axis magnetic field coil.

[0014] The main structure has a circular polarizer mounting groove at the incident position of the two laser beams, and a detector mounting groove on the opposite side. The first circular polarizer and the second circular polarizer are respectively fixed to the circular polarizer mounting groove; the first detector and the second detector are respectively fixed to the detector mounting groove.

[0015] It also includes a temperature sensor, which is arranged on the heating device and is used to feed back the temperature of the double-cavity air chamber in real time.

[0016] It also includes an air chamber clamping support and an air chamber clamping cover. The double-chamber air chamber is placed in the air chamber clamping support. The air chamber clamping cover is covered on the air chamber clamping support and fixed. The air chamber clamping support is fixed to the air chamber mounting groove of the main structure. The center position of the double-chamber air chamber coincides with the center position of the main structure.

[0017] The materials of the air chamber clamping support and the air chamber clamping cover are non-magnetic high-temperature resistant materials; the air chamber clamping support, the air chamber clamping cover and the main structure are fixed by non-magnetic titanium screws.

[0018] All components of the magnetometer probe are non-magnetic components, and the magnetic intensity is less than 1nT.

[0019] Use insulation material to fill the space of the main structure except the light path and seal it with a cover plate;

[0020] The first circular polarizer and the second circular polarizer are fixed by glue dispensing, and the first detector and the second detector are fixed by non-magnetic titanium screws.

[0021] An N-optical path SERF magnetometer probe based on an N-cavity air chamber comprises an N-cavity air chamber, N circular polarizers, N detectors, a heating device, a three-axis magnetic field coil and a main structure; the N-cavity air chamber is filled with an alkali metal, and the N-cavity air chamber comprises N air chamber cavities;

[0022] The first laser beam passes through the first circular polarizer and then through the first air chamber in the N-cavity air chamber to reach the first detector to form a first optical path;

[0023] The second laser beam passes through the second circular polarizer and then through the second air chamber in the N-cavity air chamber before reaching the second detector to form a second optical path...

[0024] By analogy, the Nth laser beam passes through the Nth circular polarizer and then through the Nth air chamber in the Nth air chamber to reach the Nth detector to form the Nth optical path;

[0025] The directions of two adjacent laser beams among the N laser beams are perpendicular, and the angle error range is ±0.5°.

[0026] The N-cavity gas chamber is a whole, or is composed of N independent atomic gas chambers.

[0027] Each chamber of the N-cavity gas chamber is filled with one or more of alkali metal atoms potassium, rubidium, and cesium, and the wavelength of the N-th laser beam matches the alkali metal atom D1 line in the N-th gas chamber.

[0028] The value range of N is 3-6.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] (1) The present invention uses two or more mutually perpendicular light beams to excite different air chamber cavities of the air chamber, which can achieve magnetic field vector measurement with equivalent three-axis sensitivity levels and achieve the effect of magnetic field gradient measurement at the same time.

[0031] (2) The gas chamber of the present invention can be expanded to an N-cavity gas chamber, and the number of cavities and the corresponding number of optical paths are increased synchronously, which is conducive to obtaining more three-axis magnetic field information. The increased optical paths also have the potential to expand other functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the principle of the magnetometer probe of the present invention;

[0033] Figure 2 This is a schematic diagram of the optical path of the double-cavity air chamber of the magnetometer probe of the present invention;

[0034] Figure 3 It is a cross-sectional view of the magnetometer probe of the present invention along the xz plane;

[0035] Figure 4 It is a cross-sectional view of the magnetometer probe of the present invention along the yz plane;

[0036] Figure 5 This is a schematic diagram of the clamping part of the double-cavity air chamber of the magnetometer probe of the present invention;

[0037] Figure 6 A schematic diagram of the three-dimensional appearance of the magnetometer probe of the present invention;

[0038] Figure 7 It is a schematic diagram of the three-dimensional appearance of the magnetometer probe of the present invention;

[0039] Figure 8 It is a schematic diagram of the optical path of the multi-cavity air chamber of the magnetometer probe of the present invention. DETAILED DESCRIPTION

[0040] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0041] like Figure 1 As shown, the present invention proposes a dual-optical path SERF magnetometer probe based on a dual-cavity air chamber, comprising: a dual-cavity air chamber 1, a first circular polarizer 2, a first detector 3, a second circular polarizer 4, a second detector 5, a heating device 6, a temperature sensor 7, a three-axis magnetic field coil 8, an air chamber clamping support 9, an air chamber clamping cover 10 and a main structure 11.

[0042] First optical path: the first laser beam passes through the first circular polarizer 2 and then through one of the air chambers in the double-cavity air chamber 1 before reaching the first detector 3;

[0043] Second optical path: the second laser beam passes through the second circular polarizer 4 and then through the other air chamber in the double-cavity air chamber 1 before reaching the second detector 5 .

[0044] The first laser beam and the second laser beam are perpendicular to each other, and the allowable range of angular error is ±0.5°.

[0045] The two air chambers of the double-chamber air chamber 1 are filled with alkali metals corresponding to the laser wavelength. The laser beam polarizes the spin of the alkali metal and carries the magnetic field information to the detector. The first detector 3 and the second detector 5 convert the received optical signal into an electrical signal, which is transmitted to the host computer by a cable and then processed and analyzed to obtain the magnetic field measurement result.

[0046] Absolutely no magnetism does not exist in reality. In practice, according to the use requirements, it can be considered as no magnetism when the magnetic intensity is less than a certain level. All devices involved in this probe are required to be no magnetism devices, and the magnetic intensity is required to be less than 1nT.

[0047] The heating device 6 is a flexible heating sheet, which is pasted as much as possible on the flat positions of all surfaces outside the double-cavity air chamber 1. The heating sheet is used to heat the double-cavity air chamber 1 to the set temperature. The heating sheet has a through hole to ensure the passage of the laser beam. The temperature sensor 7 is pasted on the heating sheet and pasted on the surface of the double-cavity air chamber 1 with the heating sheet, which is used to feedback the temperature of the double-cavity air chamber 1 in real time. The air chamber clamping tray 9 and the air chamber clamping cover 10 are made of non-magnetic and high-temperature resistant materials such as polyimide. The double-cavity air chamber 1 with the heating sheet pasted on the surface is placed in the air chamber clamping tray 9, and the air chamber clamping cover 10 is covered on the air chamber clamping tray The air chamber mounting support 9 is fixed as a whole with non-magnetic titanium screws, and then the air chamber clamping support 9 is fixed to the air chamber mounting groove of the main structure 11 with non-magnetic titanium screws. At this time, the center position of the dual-chamber air chamber 1 should coincide with the center position of the probe main structure 11, and the contact area between the air chamber clamping support 9 and the air chamber clamping cover 10 and the main structure 11 is properly controlled to reduce the heat conduction area and make the temperature of the dual-chamber air chamber 1 more uniform and easy to control. In order to better ensure the temperature uniformity of the air chamber, cotton and other materials with good thermal insulation effect can be used to fill the space of the main structure except the optical path and seal it with a cover plate.

[0048] The first circular polarizer 2 and the second circular polarizer 4 are respectively fixed to the circular polarizer mounting grooves at the two laser beam incident positions of the main structure 11 by means of glue dispensing; the first detector 3 and the second detector 5 are respectively fixed to the detector mounting grooves on the opposite sides of the two laser beam incident positions of the main structure 11 by means of non-magnetic titanium screws; in terms of structural design and processing of the main structure 11, the matching clearance and processing error should be minimized as much as possible under the premise of achieving device matching. After assembly and debugging, the two laser beams are ensured to be vertical. In actual situations, absolute verticality is difficult to achieve. Usually, it is considered to be vertical within the allowable error range. For example, in this case, it is considered to be vertical if the angle error is within ±0.5°, and the beams reach the corresponding detectors through the circular polarizers and the air chamber cavity of the corresponding optical path respectively.

[0049] The three-axis magnetic field coil 8 is wound in the coil grooves surrounding the six external sides of the main structure 11, and is used to compensate for the ambient magnetic field and apply a modulated magnetic field. After the three-axis magnetic field coil 8 is wound, the double-cavity air chamber 1 should be located at a uniform magnetic field position at the center of the magnetic field generated by the three-axis magnetic field coil 8.

[0050] The first light path and the second light path are perpendicular to each other, and pass through the two chambers of the dual-chamber air chamber 1 in two directions respectively without the two beams of light contacting each other. The characteristics of the two beams of light respectively measuring the corresponding transverse magnetic field are used to achieve the effect of equal sensitivity levels of the three-axis magnetic field. The characteristics of the two beams of light respectively measuring the three-axis magnetic field can realize magnetic field gradient measurement;

[0051] The double-cavity air chamber 1 can be expanded into a multi-cavity air chamber, and the number of chambers and the number of corresponding optical paths increase synchronously, with a typical number of chambers being 3-6, and can be further expanded as required; each chamber of the double-cavity air chamber 1 and the multi-cavity air chamber can be filled with one or more of alkali metal atoms potassium, rubidium, and cesium as required; the wavelengths of the first laser beam, the second laser beam, and the laser beam after the optical path is increased match the D1 line of the alkali metal atoms in the corresponding air chamber; the double-cavity air chamber 1 and the multi-cavity air chamber can be a whole, or can be composed of two or more independent atomic air chambers;

[0052] like Figure 2 The figure shows a schematic diagram of the optical path of the double-cavity air chamber. The first laser beam 2 and the second laser beam 5 pass vertically through the two air chambers of the double-cavity air chamber 1. The two air chambers of the double-cavity air chamber 1 are filled with alkali metals corresponding to the laser wavelength. The laser beam polarizes the alkali metal spins and carries the magnetic field information to the detector.

[0053] Specific implementation principle: The Bloch equation is used to describe the dynamic process of atomic spins in the alkali metal gas chamber. Taking into account physical phenomena such as laser pump polarization, magnetic precession and atomic spin relaxation, the Bloch equation is used to describe the dynamic evolution of atomic spin polarization:

[0054]

[0055] Among them, P is the atomic spin polarization vector, B is the magnetic field vector, γ e is the atomic gyromagnetic ratio, R p is the optical pumping rate, s is the photon polarizability vector, and T2 is the atomic relaxation time. For the transverse magnetic field modulation scheme, when the transverse magnetic field modulation is applied, solving the above equation can obtain:

[0056]

[0057] Among them, J0 and J1 are Bessel functions, B m and ω m are the amplitude and frequency of the modulated magnetic field, and B0 is the magnetic field to be measured. Figure 2 In the two-optical path structure, the first optical path can only measure the y-axis and z-axis magnetic fields, and the second optical path can only measure the x-axis and z-axis magnetic fields. The measurement data of the two optical paths are combined to achieve the magnetic field vector measurement with equivalent sensitivity levels in three axes, and the z-axis magnetic field gradient measurement can also be achieved. Therefore, the present invention can achieve the magnetic field vector measurement with equivalent sensitivity levels in three axes, and achieve the effect of magnetic field gradient measurement at the same time;

[0058] like Figure 3The figure shows a cross-sectional view of the probe structure along the xz plane, wherein there is a first optical path along the x direction, and the first laser beam is sequentially along the incident direction to the first circular polarizer 2, one of the air chambers in the double-cavity air chamber 1, and the first detector 3, a heating plate is attached to the outside of the double-cavity air chamber 1, the double-cavity air chamber 1 is clamped in the air chamber clamping support 9 and the air chamber clamping cover 10 and is located at the center of the main structure 11, and a three-axis magnetic field coil 8 is wound in the groove on the outer surface of the main structure 11;

[0059] like Figure 4 The figure shows a cross-sectional view along the yz plane in the probe structure, wherein there is a second optical path along the y direction, and the second laser beam is sequentially along the incident direction to the second circular polarizer 4, another air chamber cavity in the double-cavity air chamber 1, and the second detector, a heating plate and a temperature sensor 7 are attached to the outside of the double-cavity air chamber 1, the double-cavity air chamber 1 is clamped in the air chamber clamping support 9 and the air chamber clamping cover 10 and is located at the center of the main structure 11, and a three-axis magnetic field coil 8 is wound in the groove on the outer surface of the main structure 11;

[0060] like Figure 5 The figure shows the schematic diagram of the probe double-chamber air chamber clamping part. The outer surface of the double-chamber air chamber 1 needs to be glued with a heating plate and a temperature sensor 7 using a high-temperature resistant thermal conductive adhesive, and then fixed to the air chamber mounting groove in the main structure 11 by the air chamber clamping support 9 and the air chamber clamping cover 10. The two circular polarizers and the two detectors also need to be fixed in the corresponding positions according to the optical path requirements.

[0061] like Figure 6 , Figure 7 Shown is a schematic diagram of the three-dimensional shape of the probe in two directions;

[0062] like Figure 8 The figure shows the optical path schematic diagram of the N optical path SERF magnetometer probe based on the N cavity air chamber. Figure 8 This is the light path arrangement plan when the number of chambers and light paths is 5.

[0063] The N optical path SERF magnetometer probe comprises an N cavity air chamber, N circular polarizers, N detectors, a heating device 6, a three-axis magnetic field coil 8 and a main structure 11; the N cavity air chamber is filled with an alkali metal, and the N cavity air chamber comprises N air chamber cavities, where N is 3-6;

[0064] The first laser beam passes through the first circular polarizer (2) and then through the first air chamber cavity in the N-cavity air chamber to reach the first detector (3) to form a first optical path;

[0065] The second laser beam passes through the second circular polarizer (4) and then through the second air chamber cavity in the N-cavity air chamber before reaching the second detector (5) to form a second optical path...

[0066] By analogy, the Nth laser beam passes through the Nth circular polarizer and then through the Nth air chamber in the Nth air chamber to reach the Nth detector to form the Nth optical path;

[0067] The N laser beams are arranged such that the directions of two adjacent laser beams are perpendicular to each other, and the angle error range is ±0.5°.

[0068] The N-cavity gas chamber is a whole, or is composed of N independent atomic gas chambers.

[0069] Each chamber of the N-cavity gas chamber is filled with one or more of alkali metal atoms potassium, rubidium, and cesium, and the wavelength of the N-th laser beam matches the alkali metal atom D1 line in the N-th gas chamber.

[0070] The above description is only the best specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

[0071] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. A dual-optical path SERF magnetometer probe based on a dual-cavity air chamber, characterized in that: The invention comprises a double-cavity air chamber (1), a first circular polarizer (2), a first detector (3), a second circular polarizer (4), a second detector (5), a heating device (6), a three-axis magnetic field coil (8) and a main structure (11); the double-cavity air chamber (1) is filled with an alkali metal in the air chamber cavity, and the double-cavity air chamber (1) comprises a first air chamber cavity and a second air chamber cavity; The first laser beam passes through the first circular polarizer (2) and then through the first air chamber cavity in the double-cavity air chamber (1) before reaching the first detector (3) to form a first optical path; The second laser beam passes through the second circular polarizer (4) and then through the second air chamber cavity in the double-cavity air chamber (1) before reaching the second detector (5) to form a second optical path; The first laser beam and the second laser beam are perpendicular to each other, and the angle error range is ±0.5°; The dual-chamber air chamber (1), the first circular polarizer (2), the first detector (3), the second circular polarizer (4), the second detector (5), the heating device (6) and the three-axis magnetic field coil (8) are arranged in a main structure (11).

2. According to claim 1, a dual-optical path SERF magnetometer probe based on a dual-cavity air chamber is characterized in that: The heating device (6) is fixed to the outer surface of the double-cavity air chamber (1) and is used to heat the double-cavity air chamber (1) to a set temperature. The heating device (6) is provided with a through hole to ensure the passage of the laser beam. The three-axis magnetic field coil (8) is wound in coil slots surrounding the six outer sides of the main structure (11). After the three-axis magnetic field coil (8) is wound, the double-cavity air chamber (1) is located at a uniform magnetic field position at the center of the magnetic field generated by the three-axis magnetic field coil (8).

3. According to claim 1, a dual-optical path SERF magnetometer probe based on a dual-cavity air chamber is characterized in that: The main structure (11) is provided with a circular polarizer mounting groove at the incident position of the two laser beams, and a detector mounting groove is provided on the opposite side; the first circular polarizer (2) and the second circular polarizer (4) are respectively fixed in the circular polarizer mounting grooves; and the first detector (3) and the second detector (5) are respectively fixed in the detector mounting grooves.

4. According to claim 2, a dual-optical path SERF magnetometer probe based on a dual-cavity air chamber is characterized in that: It also includes a temperature sensor (7), which is arranged on the heating device (6) and is used to provide real-time feedback on the temperature of the dual-chamber air chamber (1).

5. The dual-optical path SERF magnetometer probe based on a dual-cavity air chamber according to claim 1, characterized in that: It also includes an air chamber clamping support (9) and an air chamber clamping cover (10), the double-chamber air chamber (1) is placed in the air chamber clamping support (9), the air chamber clamping cover (10) is covered on the air chamber clamping support (9) and fixed, and the air chamber clamping support (9) is fixed to the air chamber installation groove of the main structure (11), and the center position of the double-chamber air chamber (1) coincides with the center position of the main structure (11).

6. A dual-optical path SERF magnetometer probe based on a dual-cavity air chamber according to claim 5, characterized in that: The air chamber clamping support (9) and the air chamber clamping cover (10) are made of non-magnetic high-temperature resistant materials; the air chamber clamping support (9), the air chamber clamping cover (10) and the main structure (11) are fixed by non-magnetic titanium screws.

7. The dual-optical path SERF magnetometer probe based on a dual-cavity air chamber according to claim 1, characterized in that: All components of the magnetometer probe are non-magnetic components, and the magnetic intensity is less than 1nT.

8. The dual-optical path SERF magnetometer probe based on a dual-cavity air chamber according to claim 1, characterized in that: Filling the space of the main structure (11) except the light path with a heat-insulating material and sealing it with a cover plate; The first circular polarizer (2) and the second circular polarizer (4) are fixed by glue dispensing, and the first detector (3) and the second detector (5) are fixed by non-magnetic titanium screws.

9. An N-optical path SERF magnetometer probe based on an N-cavity air chamber, characterized in that: It comprises N-cavity air chambers, N circular polarizers, N detectors, a heating device (6), a three-axis magnetic field coil (8) and a main structure (11); the air chamber of the N-cavity air chamber is filled with alkali metal, and the N-cavity air chamber comprises N air chamber cavities; The first laser beam passes through the first circular polarizer (2) and then through the first air chamber cavity in the N-cavity air chamber to reach the first detector (3) to form a first optical path; The second laser beam passes through the second circular polarizer (4) and then through the second air chamber cavity in the N-cavity air chamber before reaching the second detector (5) to form a second optical path... By analogy, the Nth laser beam passes through the Nth circular polarizer and then through the Nth air chamber in the Nth air chamber to reach the Nth detector to form the Nth optical path; The directions of two adjacent laser beams among the N laser beams are perpendicular, and the angle error range is ±0.5°.

10. The N-optical path SERF magnetometer probe based on the N-cavity air chamber according to claim 9, characterized in that: The N-cavity gas chamber is a whole, or is composed of N independent atomic gas chambers.

11. The N-optical path SERF magnetometer probe based on an N-cavity air chamber according to claim 9, characterized in that: Each chamber of the N-cavity gas chamber is filled with one or more of alkali metal atoms potassium, rubidium, and cesium, and the wavelength of the N-th laser beam matches the alkali metal atom D1 line in the N-th gas chamber.

12. The N-optical path SERF magnetometer probe based on an N-cavity air chamber according to claim 9, characterized in that: N is 3-6.

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