Alkali metal gas chamber non-magnetic heating method based on double-sided laser temperature control

Abstract

The invention discloses an alkali metal gas chamber non-magnetic heating method based on double-sided laser temperature control, which can eliminate magnetic interference introduced by traditional electric heating from a physical source and more effectively realize uniform, stable and continuous heat source temperature field distribution through double-sided laser closed-loop control. Comprising the steps that diamond sheets used for photo-thermal conversion are attached to the top face and the bottom face of a heat conduction layer defining an alkali metal air chamber, a first laser heating surface and a second laser heating surface are formed on the heat conduction layer respectively, the thickness of each diamond sheet ranges from 4 mm to 6 mm, the heat conductivity of each diamond sheet is 2000 W / m.K, a first temperature sensor is arranged on the first laser heating surface, and a second temperature sensor is arranged on the second laser heating surface. And a second temperature sensor is arranged on the second laser heating surface. The laser heating material has the main differences that the laser heating material has ultra-low material magnetic noise and ultra-high thermal conductivity; uniform heating of a large-size air chamber is realized through double-sided temperature control; a heating laser light path is separated from a pumping and detecting light path, and laser temperature control can be independently adjusted.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser heating of alkali metal gas chambers in quantum sensing, and in particular, is a non-magnetic heating method for alkali metal gas chambers based on double-sided laser temperature control. This method can eliminate the magnetic interference introduced by traditional electric heating from the physical source, and more effectively achieve uniform, stable and continuous heat source temperature field distribution through double-sided laser closed-loop control. Background Art

[0002] Alkali metal gas cells are the core sensitive units of highly sensitive atomic measurement instruments such as atomic gyroscopes, atomic magnetometers, atomic clocks, and atomic inertial measurement systems, and are widely used in the field of quantum precision measurement. By manipulating the atoms in the alkali metal gas cell to achieve the SERF state (Spin-Exchange Relaxation Free), ultra-high-precision angular velocity and magnetic field signal measurements can be achieved, providing a powerful means for inertial and magnetic field measurements. Temperature and magnetic field are key factors affecting highly sensitive magnetic field and inertial measurements. Temperature directly determines the saturated vapor pressure density of alkali metal atoms, which in turn affects the atomic number density within the alkali metal gas cell. The magnetic field affects the Larmor precession frequency of the atoms.

[0003] Traditional heating methods include hot air flow, electric heating, and optical heating. Hot air flow heating introduces vibration noise from the gas flow and is rarely used in practical applications. Electric heating inevitably introduces electromagnetic noise generated by the current. Coil winding and high-frequency modulation are commonly used to reduce the magnetic interference introduced by the heating current. Chinese patent CN 218213395 U discloses a temperature-controllable non-magnetic heating box for an atomic magnetometer, which effectively achieves heating of the atomic gas chamber. However, the wiring of the electric heating wire is dense and complex, and the twisted pair of the electric heating wire makes the implementation of the overall solution more cumbersome and difficult. Chinese patent CN118418910A discloses a transparent non-magnetic electric heating device based on MEMS technology. The device uses laser etching technology to etch wires on the surface of an indium tin oxide conductive film prepared by magnetron sputtering technology. This method has high technical requirements for the preparation process and still cannot avoid the problem of magnetic interference introduced by electric heating. Changes in the control signal often introduce sudden signal mutations in the coil loop, causing magnetic interference that is difficult to eliminate.

[0004] Laser heating technology essentially eliminates the source of magnetic interference and is an ideal way to heat alkali metal chambers. However, due to the high operating temperature of alkali metal chambers, usually 180-200°C, it is necessary to select light-absorbing materials with high photothermal conversion efficiency, high stability, and high durability. At the same time, in order to avoid introducing additional magnetic field sources, the light-absorbing material is required to be absolutely non-magnetic. The light-absorbing material in the existing technology is usually graphene, which is a two-dimensional structural material. The internal carbon atoms form a planar hexagonal structure. There are a large number of p-orbital electrons in the material that do not participate in hybridization to form delocalized π bonds; diamond is composed of sp 3 In the three-dimensional structure formed by hybridization, each carbon atom forms a tetrahedron with strong covalent bonds with four other carbon atoms. This greatly reduces the free electron concentration of the diamond material and the magnetic fluctuations introduced by the free electrons. At the same time, high-purity single-crystal diamond has an extremely low dislocation density and the local magnetic moment is greatly reduced. Therefore, diamond has a material magnetic noise far lower than that of graphene. In addition, the existing technology uses a dichroic mirror to split the pumping light and the heating laser. When adjusting the heating laser, it will inevitably introduce spin polarization efficiency fluctuations. Therefore, the heating laser light path needs to be separated from the pumping light and detection light paths, and a separate control scheme needs to be designed. In addition to not introducing additional magnetic interference and polarization fluctuations, the ideal heating method should also achieve uniform temperature distribution and stable and continuous temperature control. In particular, for large-sized gas chambers (≥15mm), the temperature feedback of a single measuring point cannot reflect the temperature distribution of the entire heating structure, and the reliability needs to be further improved.

[0005] In summary, laser heating is expected to achieve uniform and absolutely non-magnetic heating and simplify the design of the heating system. It is necessary to carry out detailed design of the non-magnetic heating device and method of the alkali metal gas chamber based on double-sided laser temperature control. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention provides an alkali metal chamber non-magnetic heating method based on double-sided laser temperature control, which can eliminate the magnetic interference introduced by traditional electric heating from the physical source, and more effectively achieve uniform, stable and continuous heat source temperature field distribution through double-sided laser closed-loop control.

[0007] The technical solutions of the present invention are as follows:

[0008] A non-magnetic heating method for an alkali metal gas chamber based on double-sided laser temperature control, characterized by comprising the following steps:

[0009] Step 1: Attaching diamond sheets for photothermal conversion to the top and bottom surfaces of the heat-conducting layer that encloses the alkali metal gas chamber, respectively forming a first laser heating surface and a second laser heating surface on the heat-conducting layer. The diamond sheet has a thickness of 4 mm to 6 mm and a thermal conductivity of 2000 W / m·K. A first temperature sensor is provided on the first laser heating surface, and a second temperature sensor is provided on the second laser heating surface.

[0010] Step 2: Covering the outer surface of the thermal conductive layer with a thermal insulation layer, providing a first heating laser light hole reaching the first laser heating surface on the top surface of the thermal insulation layer, providing a second heating laser light hole reaching the second laser heating surface on the bottom surface of the thermal insulation layer, providing detection light light holes on the front and back of the thermal insulation layer, and providing a pumping light light hole on the right or left side of the thermal insulation layer;

[0011] Step 3: Using a temperature-controlled circuit board and a first laser controller to control a first heating laser to deliver a first heating laser to the first laser-heated surface, and using a temperature-controlled circuit board and a second laser controller to control a second heating laser to deliver a second heating laser to the second laser-heated surface;

[0012] Step 4: The temperature control circuit board generates a first power control signal in real time based on the first set of temperature signals transmitted from the first temperature sensor and feeds it back to the first laser controller; the temperature control circuit board generates a second power control signal in real time based on the second set of temperature signals transmitted from the second temperature sensor and feeds it back to the second laser controller;

[0013] Step 5: The temperature control circuit board transmits both the first set of temperature signals and the second set of temperature signals to a host computer to display the temperature in real time.

[0014] The diamond sheet in step 1 is a diamond heat sink sheet prepared by chemical vapor deposition.

[0015] The diamond heat sink is adhered to the surface of the heat conducting layer by means of heat conducting adhesive.

[0016] The surface roughness of the diamond heat sink is reduced to ten micrometers or even below 1 nm based on a grinding and polishing process.

[0017] The heat conducting layer is made of boron nitride ceramic material, and its thermal conductivity is 25-33 W / m·K.

[0018] The thermal insulation layer in step 2 is made of aerogel material, whose thermal conductivity is 0.02 W / m·K.

[0019] The alkali metal gas chamber in step 1 is a sealed container made of glass, which contains one or two alkali metal atoms to provide electron spin sources, an inert gas to provide nuclear spin sources, and a quenching gas. The alkali metal atoms are K, Rb or Cs, the inert gas is He, Xe or Ne, and the quenching gas is N2.

[0020] In step 3, the first heating laser and the second heating laser are delivered through respective transmission optical fibers.

[0021] In step 3, the frequency of the first heating laser and the frequency of the second heating laser both deviate from the resonance frequency of the alkali metal atomic energy level inside the alkali metal gas chamber.

[0022] The technical effects of the present invention are as follows: The present invention provides a non-magnetic heating method for an alkali metal gas chamber based on double-sided laser temperature control, wherein diamond sheets for photothermal conversion are attached to opposite sides of a heating structure centered on the alkali metal gas chamber as two laser heating surfaces; high-power heating lasers are continuously incident vertically by heating lasers; during the heating process, high-precision temperature sensors are used to measure the temperatures of the two laser heating surfaces in real time, and the temperature signals are fed back to the temperature control circuit board for real-time closed-loop control of the power of each heating laser, thereby optimizing the temperature distribution uniformity of the alkali metal gas chamber. The present invention adopts a double-sided laser temperature control scheme to achieve non-magnetic heating of the alkali metal gas chamber, eliminating the magnetic interference introduced by traditional electric heating from the physical source, and achieving uniform, stable, and continuous heat source temperature field distribution through double-sided laser closed-loop control. The main differences of the present invention are: the laser heating material has ultra-low material magnetic noise and ultra-high thermal conductivity; double-sided temperature control achieves uniform heating of large-sized gas chambers; the heating laser optical path is separated from the pumping and detection optical paths, and the laser temperature control can be independently adjusted.

[0023] The present invention has the following features: 1) The laser heating surface utilizes a diamond sheet with high photothermal conversion efficiency, improving the heating efficiency of the alkali metal gas chamber. Furthermore, the laser heating replaces traditional electric heating with completely non-magnetic laser heating, eliminating the magnetic noise introduced by electric heating and the vibration noise introduced by airflow heating. The high-frequency modulation technology and power amplifier used in electric heating are omitted, reducing potential sources of interference and instability in the system and improving the sensitivity of the atomic instrument. 2) Double-sided laser temperature control with dual PID closed-loop control improves the heating efficiency and temperature distribution uniformity of the alkali metal atom gas chamber compared to single-sided laser temperature control. It can achieve uniform heating of the alkali metal gas chamber at a relatively fast speed and reduce the temperature gradient within the gas chamber. 3) The heating structure utilizes the integrated structure to the greatest extent possible, with only one side being detachable to facilitate installation of the alkali metal gas chamber, resulting in more uniform heat transfer and improved heating uniformity within the alkali metal gas chamber, thereby improving the temperature distribution uniformity within the alkali metal gas chamber. 4) The heating laser optical path is completely independent of the detection and pumping optical paths. The intensity of the detection light and the pumping light is completely unaffected by the heating laser, thereby avoiding the influence of the alkali metal gas chamber heating adjustment on the system signal detection and polarization pumping, and improving the stability and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of the system structure involved in implementing the non-magnetic heating method of an alkali metal gas chamber based on double-sided laser temperature control of the present invention.

[0025] Figure 2 yes Figure 1 Schematic diagram of the heat conduction layer structure involved.

[0026] Figure 3 yes Figure 1 Schematic diagram of the insulation layer structure involved.

[0027] Figure 4 This is a measured graph of the gas chamber temperature rise curve using single-sided laser temperature control technology in the existing technology.

[0028] Figure 5 This is a measured graph of the gas chamber temperature rise curve using the double-sided laser temperature control technology in the present invention.

[0029] The reference numerals in the figures are as follows: 1-alkali metal gas chamber; 2-first heating laser; 3-second heating laser; 4-heat conducting layer; 5-heat insulating layer; 6-first laser heating surface; 7-second laser heating surface; 8-first heating laser light hole; 9-second heating laser light hole; 10-detection light hole; 11-pumping light hole; 12-first temperature sensor; 13-second temperature sensor; 14-temperature control circuit board; 15-first laser controller; 16-second laser controller; 17-host computer. DETAILED DESCRIPTION

[0030] Below is the attached figure ( Figure 1-Figure 5 ) and Examples illustrate the present invention.

[0031] Figure 1 A schematic diagram of the system structure involved in implementing the non-magnetic heating method of an alkali metal gas chamber based on double-sided laser temperature control of the present invention. Figure 2 yes Figure 1 Schematic diagram of the heat conduction layer structure involved. Figure 3 yes Figure 1 Schematic diagram of the insulation layer structure involved.

[0032] Figure 4 This is a measured graph of the gas chamber temperature rise curve using single-sided laser temperature control technology in the existing technology. Figure 5 This is the measured graph of the gas chamber temperature rise curve using the double-sided laser temperature control technology in this invention. Figures 1 to 3 As shown, a non-magnetic heating method for an alkali metal gas chamber based on double-sided laser temperature control comprises the following steps: Step 1, attaching diamond sheets for light-heat conversion to the top and bottom surfaces of the heat-conducting layer that encloses the alkali metal gas chamber 1, respectively forming a first laser heating surface 6 and a second laser heating surface 7 on the heat-conducting layer 4, wherein the thickness of the diamond sheet is 4 mm to 6 mm and the thermal conductivity is 2000 W / m·K, and a first temperature sensor 12 is provided on the first laser heating surface 6, and a second temperature sensor 13 is provided on the second laser heating surface 7; Step 2, coating the outer surface of the heat-conducting layer 4 with a heat-insulating layer 5, providing a first heating laser light hole 8 reaching the first laser heating surface 6 on the top surface of the heat-insulating layer, providing a second heating laser light hole 9 reaching the second laser heating surface 7 on the bottom surface of the heat-insulating layer, providing detection light light holes 10 on the front and back of the heat-insulating layer 5, and A pumping light hole 11 is set on the right or left side; step 3, using the temperature control circuit board 14 to control the first heating laser 2 to transmit the first heating laser to the first laser heating surface 6 through the first laser controller 15, and using the temperature control circuit board 14 to control the second heating laser 3 to transmit the second heating laser to the second laser heating surface 7 through the second laser controller 16; step 4, the temperature control circuit board 14 generates a first power control signal in real time according to the first group of temperature signals transmitted by the first temperature sensor 12 and feeds it back to the first laser controller 15, and the temperature control circuit board 14 generates a second power control signal in real time according to the second group of temperature signals transmitted by the second temperature sensor 13 and feeds it back to the second laser controller 16; step 5, the temperature control circuit board 14 transmits both the first group of temperature signals and the second group of temperature signals to the host computer 17 to complete the real-time temperature display.

[0033] The diamond sheet in step 1 is a diamond heat sink produced using chemical vapor deposition. The diamond heat sink is attached to the surface of the thermally conductive layer using thermally conductive adhesive. A grinding and polishing process reduces the surface roughness of the diamond heat sink to 10 microns or even less than 1 nm. The thermally conductive layer is made of boron nitride ceramic material, with a thermal conductivity of 25 to 33 W / m·K. The thermal insulation layer in step 2 is made of aerogel material, with a thermal conductivity of 0.02 W / m·K.

[0034] The alkali metal gas chamber in step 1 is a sealed glass container containing one or two alkali metal atoms to provide an electron spin source, an inert gas to provide a nuclear spin source, and a quenching gas. The alkali metal atoms are K, Rb, or Cs, the inert gas is He, Xe, or Ne, and the quenching gas is N2. In step 3, the first and second heating lasers are delivered via separate transmission fibers. The frequencies of the first and second heating lasers in step 3 are both deviated from the resonant frequency of the alkali metal atomic energy levels within the alkali metal gas chamber.

[0035] The present invention addresses the need for non-magnetic heating of alkali metal gas chambers, overcoming the low-frequency vibration noise introduced by hot air flow heating methods and the magnetic noise of the energized coil and control signal interference introduced by traditional electric heating methods. The high-power heating laser is vertically incident on the composite coating of the two laser-heated surfaces to achieve photothermal conversion, thereby performing non-magnetic heating of the alkali metal gas chamber. At the same time, considering the problems of poor thermal uniformity and low heat transfer efficiency of single-sided laser heating, a double-sided temperature control design of the two laser heating optical paths is used to perform double-sided non-magnetic heating of the alkali metal gas chamber. The present invention innovatively adopts a double-sided laser temperature control method to reduce the possible introduction of magnetic field interference at the source, while improving the temperature uniformity of the non-magnetic heating of the alkali metal, achieving non-magnetic, stable, and uniform heating of the alkali metal gas chamber, which is expected to further enhance the measurement sensitivity of ultra-high sensitivity quantum instruments.

[0036] Diamond sheets for photothermal conversion are attached to opposite sides of the heating structure centered on the alkali metal chamber. Diamond heat sinks, produced using chemical vapor deposition, have an ultra-high thermal conductivity (2000W / m·K), significantly improving the photothermal conversion efficiency of non-magnetic heating. Furthermore, a grinding and polishing process reduces the roughness of the diamond coating surface to ten microns or even below 1nm, significantly reducing reflection losses from the heating laser on its surface and promoting internal heat diffusion, further improving heat transfer efficiency. The 5mm thick diamond sheets are attached to opposite sides of the heating structure using thermally conductive adhesive to achieve photothermal conversion.

[0037] refer to Figure 4, temperature sensor 1 tests the temperature of the laser heating surface, and temperature sensor 2 tests the temperature of the opposite side of the laser heating surface. The existing single-sided temperature control technology is used to laser heat a spherical air chamber with a diameter of 16mm (that is, the heat conductive layer only activates one side of the laser heating surface, and the laser heating surface on the opposite side is not activated). The laser heating surface reaches the preset temperature (200°C) in nearly 80 minutes, while the opposite side takes nearly 300 minutes to reach a stable temperature (about 190.85~190.92°C), and it is always unable to reach the preset temperature. The overall temperature difference is greater than 9°C; the small picture inside shows the temperature fluctuation after reaching the preset temperature. The temperature fluctuation of the laser heating surface is small, while the temperature fluctuation of the opposite side is large. The temperature fluctuation within 30 minutes is greater than 60mK, and the stability is poor. Reference Figure 5 Temperature sensor 1 tests the temperature of the first laser heating surface, and temperature sensor 2 tests the temperature of the second laser heating surface. Using the double-sided laser temperature control technology of the present invention, the first and second laser heating surfaces both reach the preset temperature (200°C) within 20 minutes, without obvious temperature difference, and maintain good long-term temperature stability. The temperature fluctuation within 30 minutes is less than ±5mK. The double-sided laser temperature control technology proposed in the present invention can achieve rapid and uniform heating of large-size gas chambers.

[0038] The main differences of the present invention are: the laser heating material has ultra-low material magnetic noise and ultra-high thermal conductivity; double-sided temperature control realizes uniform heating of large-sized gas chambers; the heating laser optical path is separated from the pumping and detection optical paths, and the laser temperature control can be independently adjusted.

[0039] A non-magnetic heating method for an alkali metal gas chamber based on double-sided laser temperature control is characterized in that the system is divided into four parts, namely an alkali metal gas chamber, a heating laser, a heating structure and a temperature control component.

[0040] The alkali metal gas chamber is used to provide a spin atom source that is sensitive to magnetic fields, angular velocities, etc., and needs to maintain a temperature of 180-200°C through non-magnetic heating to achieve the required gaseous atom number density; the heating laser is used to generate continuous and stable high-power heating laser to provide the energy required for non-magnetic heating of the alkali metal gas chamber, and to conduct the high-power heating laser vertically to the two laser heating surfaces of the heating structure; the heating structure efficiently and uniformly conducts the heat of the two laser heating surfaces to the alkali metal gas chamber, thereby achieving uniform heating of the alkali metal gas chamber; the temperature control component is used to control the heating temperature in a real-time double closed-loop manner, and controls the laser power of the heating laser in real time according to the temperatures of the two laser heating surfaces, thereby stably heating the alkali metal gas chamber to a preset value.

[0041] The alkali metal gas chamber is a sealed container made of glass, which contains one or two alkali metal atoms such as K, Rb, Cs to provide electron spin sources, and also contains an inert gas such as He, Xe, Ne to provide nuclear spin sources and quenching gas N2; the alkali metal gas chamber is tightly adhered to the gas chamber handle made of high thermal conductivity material through silica gel, and the alkali metal gas chamber is fixed inside the heating structure through the threads on the surface of the gas chamber handle, and the center position of the alkali metal gas chamber coincides with the center position of the heating structure.

[0042] The heating laser includes a heating laser source, a transmission optical fiber and a laser collimator. The heating laser source emits the high-power heating laser, whose frequency deviates from the resonant frequency of the alkali metal atomic energy level inside the alkali metal gas chamber; the transmission optical fiber is used to transmit the high-power heating laser to the two laser heating surfaces of the heating structure; the laser collimator adjusts and controls the direction of the high-power heating laser to generate a collimated beam distribution that is vertically incident on the two laser heating surfaces.

[0043] The heating structure comprises a heat-conducting layer, a heat-insulating layer, and a support structure. The heat-conducting layer has a hollow interior for mounting the gas chamber and is made of a hard, highly thermally conductive material. One side is a detachable portion for easy installation, connected by bolts with good thermal conductivity. The remaining sides are of an integrated design to ensure efficient heat transfer. The alkali metal gas chamber is mounted to the center of the heat-conducting layer. One set of opposing sides of the heat-conducting layer is affixed with diamond sheets for photothermal conversion, serving as two laser heating surfaces. The other two sets of opposing sides of the heat-conducting layer are free of diamond sheets and have central openings for detection light and pumping light, respectively. The heat-conducting layer can be of any shape, such as a cube, cylinder, or sphere, as long as it achieves the laser heating surface configuration described above. The material should provide high-efficiency thermal conductivity and be absolutely non-magnetic. The heat-conducting layer is wrapped with a heat-insulating layer with a volume at least three times its own. The material and shape of the heat-insulating layer are not limited, as long as it effectively insulates the heating structure from the external environment and is absolutely non-magnetic. The material of the support structure is not limited, as long as it meets the support strength requirements of the heat-conducting and heat-insulating layers and is absolutely non-magnetic.

[0044] The temperature control component includes a high-precision temperature sensor, a temperature control circuit board, a laser controller and a host computer. The high-precision temperature sensor is used to measure the temperature of the two laser heating surfaces. It is required to be non-magnetic, small in size, with high temperature measurement accuracy and small temperature measurement delay. Its material and type are not limited. The temperature control circuit board converts the two sets of measured temperature signals into voltage signals, generates power control signals for the two heating lasers according to the measured temperature, and transmits the real-time control signal to the two laser controllers to realize negative feedback control of the double-sided temperature. At the same time, the two sets of temperature signals are transmitted to the host computer to complete real-time temperature display.

[0045] The high-power heating laser power of the two laser heating surfaces is not necessarily the same, depending on the deviation between the measured temperature of the two laser heating surfaces and the preset temperature, to avoid overheating or overcooling on one side of the heating structure and achieve more uniform non-magnetic heating.

[0046] The high-power heating laser is separated from the optical paths of the detection light and the pumping light, and its power change is independent of the regulation of the detection light and the pumping light. The non-magnetic heating of the alkali metal gas chamber does not affect the detection and pumping stability of the system.

[0047] The main steps are:

[0048] Step 1: The two heating laser sources (the first heating laser 2 and the second heating laser 3) emit high-power heating lasers, which pass through their respective transmission optical fibers and laser collimators and are vertically incident on the two laser heating surfaces (i.e., the first laser heating surface 6 and the second laser heating surface 7);

[0049] Step 2: The heating structure is centered on the alkali metal gas chamber 1, and the composite coating for photothermal conversion is deposited on the two laser heating surfaces to absorb high-power heating laser and achieve high-efficiency photothermal conversion;

[0050] Step 3: The heat-conducting layer 4 of the heating structure efficiently transmits the heat source generated by the high-power heating laser on the two laser heating surfaces to the entire heat-conducting layer 4, and reduces external heat dissipation through the heat-insulating layer 5, forming a uniform and stable heat source environment, and quickly heating the internal alkali metal gas chamber 1;

[0051] Step 4: During the heating process, the temperatures of the two laser heating surfaces are obtained in real time through the temperature control component (high-precision temperature sensor, i.e., the first temperature sensor 12 and the second temperature sensor 13, the temperature control circuit board 14, the two heating laser controllers, i.e., the first laser controller 15, the second laser controller 16 and the host computer 17), and the two sets of temperatures are fed back to the temperature control circuit board 14. The light intensity of the two high-power heating lasers is controlled in real time according to the preset temperature, and control signals of the two heating lasers are generated. PID control (PID, i.e., proportional integral differential) is performed on the high-power heating laser of each laser heating surface respectively, thereby realizing double-sided laser temperature-controlled alkali metal gas chamber non-magnetic heating with the real-time temperature of both sides as the feedback quantity, and the host computer displays the current two sets of temperatures in real time.

[0052] A double-sided laser temperature control device for non-magnetic heating of an alkali metal gas chamber, comprising the following:

[0053] The alkali metal gas chamber 1 is a sealed glass container containing one or two alkali metal atoms, such as K, Rb, or Cs, to provide an electron spin source, an inert gas, such as He, Xe, or Ne, to provide a nuclear spin source, and a quenching gas, N2. The alkali metal gas chamber is tightly adhered to the gas chamber handle, which is made of a high-thermal-conductivity material, using silica gel. The alkali metal gas chamber is fixed to the interior of the heating structure via threads on the surface of the gas chamber handle, with the center of the alkali metal gas chamber aligning with the center of the heating structure. The shape and size of the alkali metal gas chamber are not limited; in this case, a spherical alkali metal gas chamber is selected.

[0054] The first heating laser 1 and the second heating laser 2 are respectively used to generate and transmit the high-power heating laser of their respective laser heating surfaces, and both include a heating laser source, a transmission optical fiber and a laser collimator. The frequency of the high-power heating laser deviates from the resonant frequency of the alkali metal atomic energy level inside the alkali metal gas chamber.

[0055] The heating structure includes a heat-conducting layer 4, a heat-insulating layer 5 and a supporting structure. The interior of the heat-conducting layer 4 is a hollow structure and is composed of a hard high-thermal conductivity material. One side is a detachable part for easy installation, which is connected by bolts with good thermal conductivity. The other sides are of an integrated design to ensure high-efficiency heat transfer. The alkali metal gas chamber is installed to its inner center; diamond sheets for photothermal conversion are deposited on one group of opposite sides of the heat-conducting layer 4 as the two laser heating surfaces (i.e., the first laser heating surface 6 and the second laser heating surface 7), and openings are provided in the heat-insulating layer 5 (i.e., the first heating laser light hole 8 and the second heating laser light hole 9) to facilitate the vertical incidence of the high-power heating laser; there are no diamond sheets on the other two groups of opposite sides of the heat-conducting layer, and openings are provided in the center (i.e., the detection light light hole 10 and the pumping light light hole 11) for the detection light and the pumping light respectively. The heat-conducting layer 4 can be in any shape such as a cube, cylinder or sphere, as long as the laser heating surface configuration is achieved, and the material should meet the requirements of high-efficiency heat conduction and absolute non-magnetic. In this embodiment, the heat-conducting layer 4 is a cubic structure, and a boron nitride ceramic with a high thermal conductivity (25-33 W / m·K) is used. The material and shape of the heat-insulating layer 5 are not limited, as long as the effective heat insulation between the heating structure and the external environment is achieved and it is absolutely non-magnetic. In this case, a cylindrical structure wrapped around the outside of the heating structure is selected, and an aerogel material with a low heat transfer rate (0.02 W / m·K) is selected. The material of the supporting structure is not limited, as long as it meets the strength requirements and is absolutely non-magnetic. In this case, a material with low thermal conductivity (0.29 W / m·K), high Young's modulus (3.7-4.1 GPa), and low thermal expansion coefficient (45-55×10 -6 m / K) of polyetheretherketone.

[0056] The temperature control component includes the high-precision temperature sensors (i.e., the first temperature sensor 12 and the second temperature sensor 13) on the two laser heating surfaces, the temperature control circuit board 14, the two heating laser controllers (i.e., the first laser controller 15 and the second laser controller 16) and the host computer 17. The high-precision temperature sensors (i.e., the first temperature sensor 12 and the second temperature sensor 13) are used to measure the temperature of the laser heating surfaces (i.e., the first laser heating surface 6 and the second laser heating surface 7). The temperature control circuit board 14 is required to convert the two sets of measured temperature signals into voltage signals and transmit the real-time control signals to the two heating laser controllers (i.e., the first laser controller 15 and the second laser controller 16). At the same time, the two sets of temperature signals are transmitted to the host computer 17 to complete the real-time temperature display.

[0057] The contents not described in detail in the specification of the present invention belong to the prior art known to those skilled in the art.

[0058] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any form. Any person skilled in the art who, without departing from the scope of the technical solution of the present invention, utilizes the technical content disclosed above to make more possible changes and modifications to the technical solution of the present invention, or modifications are all equivalent embodiments of the present invention. Therefore, any equivalent and equivalent changes made in accordance with the ideas of the present invention without departing from the content of the technical solution of the present invention should be included in the scope of protection of the present invention.

[0059] It should be understood that the foregoing describes only some embodiments, and changes, modifications, additions and / or variations may be made without departing from the scope and spirit of the disclosed embodiments, which are illustrative and not restrictive. In addition, the embodiments described relate to what are currently considered to be the most practical and preferred embodiments, and it should be understood that the embodiments should not be limited to the disclosed embodiments, but rather are intended to cover different modifications and equivalent arrangements that are included within the spirit and scope of the embodiments. In addition, the various embodiments described above may be used in conjunction with other embodiments, such as aspects of one embodiment may be combined with aspects of another embodiment to achieve yet another embodiment. In addition, each independent feature or component of any given component may constitute another embodiment.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A non-magnetic heating method for an alkali metal gas chamber based on double-sided laser temperature control, characterized in that: The following steps are involved: Step 1: Attaching diamond sheets for photothermal conversion to the top and bottom surfaces of the heat-conducting layer that encloses the alkali metal gas chamber, respectively forming a first laser heating surface and a second laser heating surface on the heat-conducting layer. The diamond sheet has a thickness of 4 mm to 6 mm and a thermal conductivity of 2000 W / m·K. A first temperature sensor is provided on the first laser heating surface, and a second temperature sensor is provided on the second laser heating surface. Step 2: Covering the outer surface of the thermal conductive layer with a thermal insulation layer, providing a first heating laser light hole reaching the first laser heating surface on the top surface of the thermal insulation layer, providing a second heating laser light hole reaching the second laser heating surface on the bottom surface of the thermal insulation layer, providing detection light light holes on the front and back of the thermal insulation layer, and providing a pumping light light hole on the right or left side of the thermal insulation layer; Step 3: Using a temperature-controlled circuit board and a first laser controller to control a first heating laser to deliver a first heating laser to the first laser-heated surface, and using a temperature-controlled circuit board and a second laser controller to control a second heating laser to deliver a second heating laser to the second laser-heated surface; Step 4: The temperature control circuit board generates a first power control signal in real time based on the first set of temperature signals transmitted from the first temperature sensor and feeds it back to the first laser controller; the temperature control circuit board generates a second power control signal in real time based on the second set of temperature signals transmitted from the second temperature sensor and feeds it back to the second laser controller; Step 5: The temperature control circuit board transmits both the first set of temperature signals and the second set of temperature signals to a host computer to display the temperature in real time.

2. The non-magnetic heating method of an alkali metal gas chamber based on double-sided laser temperature control according to claim 1, characterized in that: The diamond sheet in step 1 is a diamond heat sink sheet prepared by chemical vapor deposition.

3. The non-magnetic heating method of an alkali metal gas chamber based on double-sided laser temperature control according to claim 2, characterized in that: The diamond heat sink is adhered to the surface of the heat conducting layer by means of heat conducting adhesive.

4. The non-magnetic heating method of an alkali metal gas chamber based on double-sided laser temperature control according to claim 2, characterized in that: The surface roughness of the diamond heat sink is reduced to ten micrometers or even below 1 nm based on a grinding and polishing process.

5. The non-magnetic heating method of an alkali metal gas chamber based on double-sided laser temperature control according to claim 1, characterized in that: The heat conducting layer is made of boron nitride ceramic material, and its thermal conductivity is 25-33 W / m·K.

6. The non-magnetic heating method of an alkali metal gas chamber based on double-sided laser temperature control according to claim 1, characterized in that: The thermal insulation layer in step 2 is made of aerogel material, whose thermal conductivity is 0.02 W / m·K.

7. The non-magnetic heating method of an alkali metal gas chamber based on double-sided laser temperature control according to claim 1, characterized in that: The alkali metal gas chamber in step 1 is a sealed container made of glass, which contains one or two alkali metal atoms to provide electron spin sources, an inert gas to provide nuclear spin sources, and a quenching gas. The alkali metal atoms are K, Rb or Cs, the inert gas is He, Xe or Ne, and the quenching gas is N2.

8. The non-magnetic heating method of an alkali metal gas chamber based on double-sided laser temperature control according to claim 1, characterized in that: In step 3, the first heating laser and the second heating laser are delivered through respective transmission optical fibers.

9. The non-magnetic heating method of an alkali metal gas chamber based on double-sided laser temperature control according to claim 1, characterized in that: In step 3, the frequency of the first heating laser and the frequency of the second heating laser both deviate from the resonance frequency of the alkali metal atomic energy level inside the alkali metal gas chamber.

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