Alkali gas cell laser heating temperature control method based on SERF atom gyro

Abstract

The application relates to the field of quantum sensing, and provides a laser heating temperature control method based on a SERF atom gyro. The main purpose is to realize a SERF atom gyro alkali metal cell heating temperature control with high precision, high stability and low magnetic field noise. The main scheme comprises the following steps: placing the cell in a cavity of a heating structure, and then placing the heating structure in a permalloy shielding barrel and a ferrite; a heating laser emits laser through a light transmission hole of the heating structure to irradiate on graphene, photo-thermal conversion is carried out on the heating surface of the graphene, heat conduction is carried out to heat the cell; a platinum resistance PT1000 measures the outer wall temperature of the cell in real time, and transmits the temperature signal to a temperature control circuit board; the temperature control circuit board outputs a control signal to control the light output power of the heating laser; a fiber grating measures the temperature in the cell, and according to the measurement result, the temperature control program and the heating structure are optimized.

Description

Technical Field

[0001] This invention relates to the field of quantum sensing and provides a laser heating temperature control method based on a SERF atomic gyroscope. Background Technology

[0002] The SERF (Spin-exchange Relaxation-free) atomic spin gyroscope, developed based on the fixed-axis characteristics of atomic spin in inertial space, theoretically has an accuracy that is only related to quantum noise and is unaffected by other interferences, enabling completely undamped rotational measurements. Its high precision, miniaturization, and low cost meet the urgent needs of deep-sea submersibles, deep space exploration, large aircraft, and autonomous driving, and it is expected to become a next-generation inertial measurement instrument.

[0003] In experimental research on SERF atomic spin gyroscopes, manipulating atomic spins into the SERF state is a prerequisite for realizing ultra-high precision atomic spin gyroscopes. Manipulating the SERF state of atomic spins requires, on the one hand, increasing the density of sensitive atoms to improve the rate of atomic spin-exchange collisions, and on the other hand, reducing the ambient magnetic field to lower the Larmor precession frequency of the atoms.

[0004] SERF atomic spin gyroscopes typically use alkali metal atoms as sensing atoms. Since alkali metal atoms are generally solid at room temperature, the alkali metal gas chamber containing these atoms needs to be heated to increase the saturated vapor density and achieve a suitable saturated vapor pressure. This increases the electron spin density, improving the ability to drive and detect nuclear spin. To achieve this, a heating device is needed at the gyroscope's sensor head—the alkali metal gas chamber—to achieve the required atomic density. The temperature of the alkali metal gas chamber directly affects the atomic source relaxation and the intensity of the detection signal; therefore, optimizing the gas chamber temperature parameters is crucial to the performance of the atomic gyroscope. Furthermore, the stability of the scaling factor of the SERF atomic spin gyroscope is directly related to the stability of the alkali metal atom density, which is determined by the heating temperature of the gas chamber. Therefore, achieving high stability of the scaling factor requires high stability of the gas chamber heating temperature.

[0005] There are four main traditional heating methods.

[0006] The first method is hot airflow heating. The disadvantages of this method are that the airflow disturbance is large, it is difficult to integrate, and it is difficult to achieve high stability and high precision temperature control.

[0007] The second method is intermittent electric heating. The disadvantage of this method is that it cannot achieve continuous measurement, which limits the bandwidth, and the intermittent heating process limits the temperature control accuracy.

[0008] The third method is high-frequency electric heating, but the disadvantage of this method is that it introduces interfering magnetic fields.

[0009] The fourth method involves laser heating. This method utilizes a pump laser, employing a dichroic mirror in the path of the pump light leading to the alkali metal chamber. The heating light from the combined beam is then applied to the alkali metal chamber containing the graphite photothermal structure to achieve heating. A drawback of this method is that achieving high-precision temperature control can affect the stability of the pump light.

[0010] Because SERF atomic spin gyroscopes are extremely sensitive to external magnetic fields, the gyroscope head itself should avoid introducing interfering magnetic fields as much as possible to reduce the Larmor precession frequency of the atoms. Since the alkali metal gas chamber requires high-temperature heating, but the gas chamber heating device is usually the biggest source of interfering magnetic fields, achieving low magnetic field noise and high stability heating has become a key technology for atomic gyroscopes.

[0011] In summary, the development of a high-precision, high-stability, and low-magnetic-field-noise method for heating and controlling the alkali metal gas chamber of a SERF atomic gyroscope is of great significance for ensuring the performance of the SERF atomic spin gyroscope and achieving high precision in atomic gyroscopes. Summary of the Invention:

[0012] To address the shortcomings of existing technologies, this invention provides a laser heating and temperature control method for alkali metal gas chambers based on SERF atomic gyroscopes.

[0013] To achieve the above objectives, the present invention employs the following technical means:

[0014] This invention provides a method for preparing a heated graphene layer, comprising the following steps:

[0015] Grain boundary defects are created on the heated surface of graphene, but not on the thermally conductive surface. Then, the graphene is subjected to high-temperature oxidation treatment at temperatures above 2000℃ to obtain the final heated graphene layer.

[0016] The present invention also provides an alkali metal gas chamber laser heating device based on a SERF atomic gyroscope, comprising a gas chamber, a heating graphene layer covering the gas chamber, and a heating laser, wherein the laser of the heating laser irradiates the heating graphene layer.

[0017] In the above technical solution, a fiber optic grating is introduced from the air chamber handle of the air chamber to measure the internal temperature of the air chamber, and a platinum resistance thermometer PT1000 is installed on the outer wall of the air chamber to measure the temperature of the outer wall of the air chamber.

[0018] The above technical solution also includes a heating structure, which has a cavity with a light-transmitting hole 19 inside. The inner wall of the cavity has an aerogel that serves as a heat-insulating agent, and the air chamber is placed in the cavity of the heating structure 6.

[0019] In the above technical solution, the heating structure is placed in a permalloy shielded barrel + ferrite.

[0020] In the above technical solution, the heated graphene layer is disposed on the top, bottom and side surfaces of the gas chamber.

[0021] This invention also provides a method for temperature control of alkali metal gas cell laser heating based on SERF atomic gyroscope, characterized by comprising the following steps:

[0022] Step 1: Design a heating structure with good heat preservation effect and all-fiber optic cable. The heating structure has a cavity with light-transmitting holes inside. The inner wall of the cavity has aerogel for heat preservation. The air chamber is placed in the cavity of the heating structure. Then, the heating structure is placed in a permalloy shielding barrel + ferrite.

[0023] Step 2: The heated laser emits a laser beam, which shines onto the graphene through the light-transmitting hole of the heated structure. Photothermal conversion occurs on the heated surface of the graphene, and heat is conducted to the gas chamber through the top and bottom surfaces.

[0024] Step 3: The PC9 program is written and burned into the temperature control circuit board. The platinum resistance thermometer PT1000 measures the outer wall temperature of the gas chamber in real time and transmits the temperature signal to the temperature control circuit board. After receiving the current gas chamber temperature signal, the temperature control circuit board converts the signal and performs control, outputting a control signal to the heating laser controller to control the output power of the heating laser. The whole system constitutes a negative feedback system to keep the gas chamber temperature at 180℃.

[0025] Step 4: The temperature control circuit board collects the temperature signal in real time and transmits the temperature signal to the PC in real time. The PC transmits the signal to the host computer to display the temperature change curve of the air chamber in real time. In the comprehensive testing stage, the fiber optic grating measures the temperature gradient signal of the air chamber and transmits the signal to the fiber optic grating demodulator to demodulate the temperature gradient of the air chamber. Based on the measurement results, the temperature control program and heating structure are optimized.

[0026] Because the present invention employs the above-mentioned technical means, it has the following beneficial effects:

[0027] 1. Existing graphene, with each sheet exhibiting consistent properties, is prone to aging and failure due to repeated heating, leading to reduced photothermal conversion efficiency, slower heat conduction, and easy graphene detachment. This invention addresses these issues by employing specially formulated graphene: For photothermal conversion efficiency, a 975nm wavelength heating laser creates grain boundary defects on the heating surface of the graphene, further enhancing the efficiency of photon recombination into electrons, thus improving photothermal conversion efficiency; for heat conduction, to ensure the high electron mobility of the graphene itself and maintain a high heat conduction rate, grain boundary defects are not created on the heat-conducting surface; for aging resistance, the graphene undergoes high-temperature oxidation treatment at temperatures above 2000℃, extending its lifespan and improving its aging resistance. A laser with wavelengths detuned to the pump and detection lasers is used as the heating laser, which directly acts on the alkali metal gas chamber loaded with the specially formulated graphene, heating the alkali metal gas chamber. Unlike traditional laser heating methods that use dichroic mirrors, the laser heating method of this invention directly heats the gas chamber and utilizes specially made graphene to achieve light conversion and heat conduction. This not only ensures rapid, non-magnetic heating without light frequency shift or stray light introduction, thus extending the graphene's lifespan, but also guarantees uniform heating to a certain extent. This achieves the goal of minimizing the temperature gradient in the gas chamber, ensuring high-precision, high-stability, and low-magnetic-field noise heating and temperature control.

[0028] 2. This invention employs a fiber optic grating to measure the internal temperature of the gas chamber, achieving magnetic-free temperature measurement. SERF atomic gyroscopes require high temperature stability within the gas chamber. Traditional PT1000 temperature measurement methods rely solely on measuring the external temperature of the gas chamber to determine the internal temperature gradient, which cannot guarantee the accuracy of the internal temperature data and introduces magnetic field interference during the measurement process. This invention uses a fiber optic grating to measure the internal temperature of the gas chamber, ensuring not only reliable data but also achieving magnetic-free temperature measurement, thus providing a foundation for subsequent improvements in temperature control methods. Attached image description:

[0029] Figure 1 This is a schematic diagram of the system structure involved in implementing the alkali metal gas chamber laser heating temperature control method based on SERF atomic gyroscope of the present invention.

[0030] Figure 2 yes Figure 1 The diagram shows the graphene encapsulation structure involved. Figure 3 yes Figure 1 The specific structural diagram of the heating structure involved is shown in the figure.

[0031] The reference numerals in the attached diagram are listed below: 1-Gas chamber; 2-Graphene; 3-Laser; 4-PT1000; 5-Heating laser; 6-Heating structure; 7-Permalloy shielding barrel + ferrite; 8-Temperature control circuit board; 9-PC; 10-Host computer; 11-Fiber Bragg grating; 12-Fiber Bragg grating demodulator; 13-Heating surface; 14-Top surface; 15-Bottom surface; 16-Gas chamber handle; 17-Concave groove; 18-Aerogel; 19-Light transmission hole. Detailed implementation method:

[0032] The following is in conjunction with the attached diagram ( Figures 1-3 The invention will be illustrated by examples.

[0033] Figure 1 This is a schematic diagram of the system structure involved in implementing the alkali metal gas chamber laser heating temperature control method based on SERF atomic gyroscope of the present invention. Figure 2 yes Figure 1 The diagram shows the graphene encapsulation structure involved. Figure 3 yes Figure 1 The diagram illustrates how the heating laser passes through the heating structure. (Reference) Figures 1 to 3 As shown, a method for controlling the temperature of alkali metal gas chamber laser heating based on SERF atomic gyroscope includes the following steps: Step 1, designing a heating structure 6 with good heat preservation effect through all-fiber optic cable, the heating structure 6 having a cavity 17 with a light-transmitting hole 19 inside, the inner wall of the cavity 17 having an aerogel 18 for heat preservation, the gas chamber 1 being placed in the cavity 17 of the heating structure 6, and then placing the heating structure 6 in a permalloy shielding barrel + ferrite 7. Step 2: The heating laser 5 emits laser 3, which shines on the graphene 2 through the light-transmitting hole 19 of the heating structure 6. Photothermal conversion occurs on the heating surface 13 of the graphene 2, and heat is conducted to the gas chamber 1 through the top surface 14 and the bottom surface 15. Step 3: The PC9 writes the control program and burns it onto the temperature control circuit board 8. The platinum resistance thermometer PT10004 measures the outer wall temperature of the gas chamber 1 in real time and transmits the temperature signal to the temperature control circuit board 8. After receiving the current temperature signal of the gas chamber 1, the temperature control circuit board 8 converts the signal and controls it, outputting a control signal to the heating laser controller 5 to control the light output power of the heating laser 5. The whole process constitutes a negative feedback system to keep the temperature of the gas chamber 1 at 180°C. Step 4: The temperature control circuit board 8 collects the temperature signal in real time and transmits the temperature signal to the PC9 in real time. The PC9 transmits the signal to the host computer 10 to display the gas chamber temperature change curve in real time. During the comprehensive testing phase, the fiber optic grating 11 measures the temperature gradient signal of the air chamber and transmits the signal to the fiber optic grating demodulator 12 to demodulate the temperature gradient of the air chamber. Based on the measurement results, the temperature control program and heating structure are optimized.

[0034] The graphene 2 is encapsulated in the heating surface 13, top surface 14 and top surface 15 of the gas chamber 1.

Claims

1. A method for temperature control of alkali metal gas cell laser heating based on SERF atomic gyroscope, characterized in that, Includes the following steps: Step 1: Design a heating structure (6) with good heat preservation effect and all-fiber optic transmission. The heating structure (6) has a cavity (17) with light transmission holes (19) inside. The inner wall of the cavity (17) has aerogel (18) for heat preservation. The air chamber (1) is placed in the cavity (17) of the heating structure (6). Then, the heating structure (6) is placed in a permalloy shielding barrel + ferrite (7). The heated graphene layer (2) covers the outside of the air chamber (1). Step 2: The heating laser (5) emits laser (3), and the laser (3) shines on the heated graphene layer (2) through the light-transmitting hole (19) of the heating structure (6). Photothermal conversion occurs on the heating surface (13) of the heated graphene layer (2), and heat is conducted to the gas chamber (1) through the top surface (14) and the bottom surface (15) for heating. Step 3, PC (9) writes the control program and burns it into the temperature control circuit board (8). The platinum resistance thermometer PT1000 (4) measures the outer wall temperature of the gas chamber (1) in real time and transmits the temperature signal to the temperature control circuit board (8). After receiving the current temperature signal of the gas chamber (1), the temperature control circuit board (8) performs signal conversion and control, and outputs the control signal to the heating laser controller (5) to control the output power of the heating laser (5). The whole system constitutes a negative feedback system to keep the temperature of the gas chamber (1) at 180°C. Step 4: The temperature control circuit board (8) collects the temperature signal in real time and transmits the temperature signal to the PC (9) in real time. The PC (9) transmits the signal to the host computer (10) to display the temperature change curve of the air chamber in real time. In the comprehensive test stage, the fiber optic grating (11) measures the temperature gradient signal of the air chamber and transmits the signal to the fiber optic grating demodulator (12) to demodulate the temperature gradient of the air chamber. Based on the measurement results, the temperature control program and heating structure are optimized.

2. The method for temperature control of alkali metal gas chamber laser heating based on SERF atomic gyroscope according to claim 1, characterized in that, The method for preparing a heated graphene layer includes the following steps: Grain boundary defects are created on the heated surface of graphene, but not on the thermally conductive surface. Then, the graphene is subjected to high-temperature oxidation treatment at temperatures above 2000℃ to obtain the final heated graphene layer.

Images