A system and method for measuring alkali metal atomic density and cell pressure

Abstract

The application provides a system and method for measuring alkali metal atomic density and chamber pressure, comprising a laser generation and control module, a light beam power and polarization regulation module, a chamber and its heating module, a frequency monitoring module, a data acquisition module and an upper computer; the laser is linearly swept; the alkali metal chamber temperature is monitored and controlled; double light path absorption spectrum monitoring and frequency synchronous acquisition are performed; spectrum drawing and parameter fitting are performed; a background noise removal scheme based on the absorption spectrum measurement process is adopted, so that the precision of the measurement system is significantly improved; the interference of external factors such as chamber glass, oven window sheet and optical components on the measurement result can be effectively eliminated; at the same time, the removal of background noise also eliminates the interference caused by laser power fluctuation, so that the absorption spectrum is more accurate, the spectrum measurement precision is greatly improved; more accurate chamber atomic density and pressure measurement can be realized, and the application is suitable for promotion.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mixed vapor parameter measurement, and in particular to a system and method for measuring alkali metal atomic density and gas chamber pressure after removing background noise. BACKGROUND

[0002] At present, common physical quantities such as inertial force, magnetic field, and time have realized high-precision quantum precision measurement, and have shown excellent application potential in the fields of inertial navigation, biological magnetic field detection, time-frequency measurement, etc. Among them, the alkali metal gas chamber as the core component of the atomic magnetometer, quantum gyroscope and other precision measurement equipment, its performance directly determines the measurement sensitivity and accuracy of the instrument.

[0003] The alkali metal gas chamber is usually composed of a glass shell, filled with alkali metal and buffer gas, and the buffer gas is usually nitrogen. Alkali metal atoms have a single electron outer shell structure, which is easy to be optically controlled, and the buffer gas can reduce the collision between alkali metal atoms and between the alkali metal atoms and the gas chamber wall, significantly reducing the relaxation effect and improving the sensitivity and accuracy of the system.

[0004] The key parameters of the alkali metal gas chamber include the alkali metal atomic density and the gas pressure, which are closely related to the signal strength and relaxation rate of the measuring instrument, respectively. Accurate measurement of these parameters is an important prerequisite for ensuring high sensitivity and high stability of the instrument.

[0005] However, the existing technology has the following technical defects in the measurement of the parameters of the alkali metal gas chamber:

[0006] ① Low efficiency and poor accuracy of manual measurement: The traditional gas chamber parameter measurement method mainly relies on manual adjustment and recording, which cannot realize high-precision and high-efficiency parameter measurement, and the human error is significant, and the data measured by different experience and ability of the measuring personnel is uneven.

[0007] ② Unable to exclude the interference of optical elements: The optical absorption and scattering effect of the glass wall outside the gas chamber and the oven window sheet introduces background noise interference, which seriously interferes with the optical absorption measurement result, resulting in insufficient accuracy of the gas chamber parameter measurement.

[0008] ③ Nonlinear correspondence problem between frequency and optical power: During the laser frequency sweeping process, the frequency fluctuation is difficult to control linearly, and the existing measurement method cannot accurately calibrate the correspondence between the frequency and the optical power, further limiting the measurement accuracy.

[0009] Therefore, based on the above deficiencies, the technical personnel in the field urgently need to develop a new path that is not disturbed by background noise, high-precision and automated. SUMMARY

[0010] In order to solve the above technical problems, the application provides a system and method for measuring alkali metal atomic density and gas chamber pressure, through the creative optimization design of the light path structure and the improvement of the measurement algorithm, the high-precision and automatic measurement of the gas chamber parameters at each temperature after removing the background noise is realized, and the demand of quantum precision measurement instrument for high-sensitivity measurement is met.

[0011] A system and method for measuring alkali metal atomic density and gas chamber pressure, wherein:

[0012] A system for measuring alkali metal atomic density and gas chamber pressure, comprising:

[0013] A laser generation and control module, a beam power and polarization regulation module, a gas chamber and its heating module, a frequency monitoring module, a data acquisition module and an upper computer;

[0014] The laser generation and control module comprises a laser and a laser control system; the laser control system is used to control the working parameters of the laser, so as to realize the linear sweep of the laser;

[0015] As an example, the working parameters include frequency, power and temperature.

[0016] The beam power and polarization regulation module comprises a beam splitter prism, a 1 / 2 wave plate, a mirror and a polarization beam splitter prism;

[0017] The beam splitter prism is used to split and modulate the light beam, and the laser is split into an experimental group light path and a control group light path; the experimental group light path passes through the alkali metal gas chamber, and the control group light path passes through the buffer gas chamber; the experimental group is used to record the light absorption characteristics, and the control group is used to eliminate the interference of the optical element;

[0018] As an example, the beam splitter prism splits the laser into two linearly polarized light beams, one of which is perpendicular to the original light path and is transmitted to a wavelength meter after being incident on a fiber coupler, and the wavelength meter transmits the wavelength to the upper computer according to a specific acquisition frequency;

[0019] The other linearly polarized light beam follows the original light path, passes through the 1 / 2 wave plate to adjust the polarization angle of the linearly polarized light, and then passes through the polarization beam splitter prism to be split into two light beams with the same light power, which are perpendicular to each other.

[0020] As an example, the two light beams with the same light power enter the first oven and the second oven respectively; the specifications, models and oven window sheets of the first oven and the second oven are the same, so as to ensure the consistency of the experimental conditions and eliminate the errors caused by the differences between the equipment.

[0021] The light passing through the alkali metal cell is absorbed by the oven window piece in front of the first oven, the front wall of the alkali metal cell, the alkali metal vapor, the rear wall of the alkali metal cell and the oven window piece of the first oven behind, from the incident to the emission; this is the experimental group light path;

[0022] The light passing through the buffer gas cell is absorbed by the oven window piece in front of the second oven, the front wall of the buffer gas cell, the rear wall of the buffer gas cell and the oven window piece of the second oven behind, from the incident to the emission; this is the control group light path;

[0023] Wherein: the light passing through the alkali metal cell is absorbed by the alkali metal vapor more than once than the light passing through the buffer gas cell, and the peak of the measured absorption spectrum is relatively reduced;

[0024] The absorption spectrum of the light beam passing through the buffer gas cell is divided by the absorption spectrum of the light beam passing through the alkali metal cell, so that the influence of the first oven window piece in front of the oven, the front wall of the alkali metal cell, the rear wall of the alkali metal cell and the first oven window piece behind the oven on the light beam absorption is removed, and the absorption spectrum of the alkali metal vapor is obtained.

[0025] The gas cell and its heating module comprise: a first oven with oven window pieces arranged symmetrically left and right, a second oven with oven window pieces arranged symmetrically left and right, an alkali metal cell arranged in the first oven and a buffer gas cell arranged in the second oven;

[0026] For heating and controlling the temperature inside the alkali metal cell, adjusting the density of alkali metal atoms; ensuring the stable evaporation of alkali metal atoms in the alkali metal cell and the adjustment of the pressure of the buffer gas in the buffer gas cell.

[0027] As an example, the first oven and the second oven both adopt a heating structure of a temperature control system cooperating with a heating resistance wire and a thermistor.

[0028] The frequency monitoring module comprises: a fiber coupler, a wavelength meter and a matching software; for real-time monitoring of laser frequency, ensuring the stability of laser frequency, and matching the collected optical power data.

[0029] The data acquisition module comprises: a first transimpedance amplifier, a second transimpedance amplifier, a data acquisition card, a first photodetector and a second photodetector;

[0030] The first transimpedance amplifier cooperates with the first photodetector to collect the light signal (transmission signal) passing through the alkali metal cell, and converts the light signal into an electrical signal and amplifies it to ensure the availability of the signal;

[0031] The second transimpedance amplifier cooperates with the second photodetector to collect the optical signal (transmission signal) after passing through the buffer gas chamber, and convert and amplify the optical signal into an electrical signal to ensure the availability of the signal.

[0032] The host computer is configured to process the collected signals, eliminate irrelevant variables, and calculate the atomic density and the chamber pressure.

[0033] As an example, the host computer is configured to analyze and process the signals collected by the experimental group and the control group, eliminate the influence of background noise and irrelevant variables, obtain the absorption spectrum after removing the background noise difference, and finally accurately calculate the atomic density and the chamber pressure of the alkali metal chamber.

[0034] A method for measuring the atomic density and the chamber pressure of alkali metal, comprising:

[0035] Step 1: linear sweep of the laser

[0036] The laser generation and control module adjusts the working parameters of the laser to sweep the laser wavelength near the specific transition frequency of the alkali metal atom.

[0037] As an example, the sweep near the specific transition frequency of the alkali metal atom means that the laser wavelength is tuned to the resonance wavelength of the alkali metal atom by linear sweep method, to ensure that the laser matches the absorption frequency of the alkali metal atom, so as to realize optical pumping and measure the optical absorption characteristics of the alkali metal atom near the specific transition frequency in the alkali metal chamber.

[0038] Step 2: temperature monitoring and control of the alkali metal chamber

[0039] After setting the desired heating temperature and PID parameters, the chamber and its heating module monitor the temperature in the first oven and the second oven through the built-in thermistor.

[0040] The thermistor measures the deviation between the target temperature and the actual temperature, and the temperature control system adjusts the power output of the heating resistor wire through the PID algorithm to stabilize the temperature of the first oven and the second oven at the set value, ensuring that the alkali metal atoms are fully evaporated into a gaseous state and reach a stable working state.

[0041] Step 3: dual optical path absorption spectrum monitoring and frequency synchronous acquisition

[0042] The laser emitted by the laser is processed by the beam power and polarization control module, and is divided into an absorption spectrum measurement light path and a frequency monitoring light path.

[0043] The absorption spectrum measurement light path is divided into the experimental group light path and the control group light path by the polarization beam splitter prism; the experimental group light path passes through the alkali metal gas chamber, and the control group light path passes through the buffer gas chamber;

[0044] The light frequency of the frequency monitoring light path enters the frequency monitoring module and is finally sent to the host computer;

[0045] The light signal of the experimental group light path is converted into an amplified electrical signal after passing through the first photodetector and the first transimpedance amplifier, is input to one end of the data acquisition card, and is converted into a digital signal and transmitted to the host computer;

[0046] The light signal of the control group light path is converted into an amplified electrical signal after passing through the second photodetector and the second transimpedance amplifier, is input to the other end of the data acquisition card, and is converted into a digital signal and transmitted to the host computer;

[0047] Step four, spectrum drawing and parameter fitting;

[0048] The host computer receives the light frequency signal and the light power degree signal collected by the data acquisition module, adjusts the step size by using a linear interpolation algorithm to match the number of sampling points, processes the obtained absorption spectrum of the alkali metal vapor by Lorentz line fitting, calculates the atomic density and the chamber pressure in the alkali metal gas chamber through the fitting parameters, and finally outputs accurate measurement results.

[0049] Advantages of the present application:

[0050] The present application adopts a background noise removal scheme in the absorption spectrum measurement process, thereby significantly improving the accuracy of the measurement system; in the method, a buffer gas chamber not containing alkali metal atoms is added as a control group light path, which is compared with the alkali metal gas chamber in the experimental group light path; through this control setting, the interference of external factors such as the gas chamber glass, the oven window sheet and the optical components on the measurement results can be effectively excluded; at the same time, the removal of background noise also eliminates the interference caused by the laser power fluctuation, so that the absorption spectrum is more accurate, and the spectral measurement accuracy is greatly improved; the method can realize more accurate measurement of the atomic density and the pressure in the chamber, and ensures the reliability and accuracy of the experimental data.

[0051] The alkali metal gas chamber atomic density and pressure measurement method of the present application effectively excludes the interference of optical elements and laser power fluctuation by adding a buffer gas chamber control group, significantly improves the accuracy of spectral measurement, and can more accurately measure the atomic density and pressure in the chamber. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 It is a whole structure design drawing of a system for measuring alkali metal atomic density and chamber pressure. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application, and reference Figure 1

[0054] A system and method for measuring alkali metal atomic density and gas chamber pressure, wherein:

[0055] A system for measuring alkali metal atomic density and gas chamber pressure, comprising:

[0056] A laser generation and control module 1, a beam power and polarization regulation module 4, a gas chamber and a heating module 9 thereof, a frequency monitoring module 16, a data acquisition module 24, and a host computer 19.

[0057] The laser generation and control module 1 comprises a laser 2 and a laser control system 3; the laser control system 3 is used to control the working parameters of the laser 2 to realize linear frequency sweeping of the laser.

[0058] As an example, the working parameters include frequency, power, and temperature.

[0059] The beam power and polarization regulation module 4 comprises a beam splitter prism 5, a 1 / 2 wave plate 6, a mirror 7, and a polarization beam splitter prism 8.

[0060] The beam splitter prism 5 is used to split the laser into two linearly polarized beams, one of which is perpendicular to the original light path and is transmitted to a wavelength meter 18 after being incident on a fiber coupler 17, and the wavelength meter 18 transmits the wavelength to the host computer 19 according to a specific acquisition frequency.

[0061] As an example, the beam splitter prism 5 splits the laser into two linearly polarized beams, one of which is perpendicular to the original light path and is transmitted to a fiber coupler 17 after being incident on a wavelength meter 18, and the wavelength meter 18 transmits the wavelength to the host computer 19 according to a specific acquisition frequency.

[0062] The other linearly polarized beam follows the original light path, passes through the 1 / 2 wave plate 6 to adjust the polarization angle of the linearly polarized light, and then passes through the polarization beam splitter prism 8 to be split into two beams of the same optical power, which are perpendicular to each other.

[0063] ​As an example, the two beams of light with the same optical power enter the first oven 11 and the second oven 21 respectively;

[0064] The light passing through the alkali metal cell 12 is absorbed by the oven window 10 on the front side of the first oven 11, the front wall of the alkali metal cell 12, the alkali metal vapor, the rear wall of the alkali metal cell 12, and the oven window 13 on the rear side of the first oven 11 from the incident to the emission; this is the experimental group light path;

[0065] The light passing through the buffer gas cell 22 is absorbed by the oven window 20 on the front side of the second oven 21, the front wall of the buffer gas cell 22, the rear wall of the buffer gas cell 22, and the oven window 23 on the rear side of the second oven 21 from the incident to the emission; this is the control group light path;

[0066] Among them, the light passing through the alkali metal cell 12 is absorbed by the alkali metal vapor once more than the light passing through the buffer gas cell 22, and the peak of the measured absorption spectrum is relatively lower;

[0067] Taking the absorption spectrum of the light beam passing through the buffer gas cell 22 and the absorption spectrum of the light beam passing through the alkali metal cell 12, the influence of the front oven window of the first oven 11, the front wall of the alkali metal cell 12, the rear wall of the alkali metal cell 12, and the rear oven window of the first oven 11 on the light beam absorption can be removed to obtain the absorption spectrum of the alkali metal vapor.

[0068] The cell and its heating module 9 include: the first oven 11 with oven windows arranged symmetrically left and right, the second oven 21 with oven windows arranged symmetrically left and right, the alkali metal cell 12 arranged in the first oven 11, and the buffer gas cell 22 arranged in the second oven 21;

[0069] For heating and controlling the temperature inside the alkali metal cell 12 to adjust the density of alkali metal atoms, and ensuring the stable evaporation of alkali metal atoms in the alkali metal cell 12 and the adjustment of the pressure of the buffer gas in the buffer gas cell 22.

[0070] As an example, the first oven 11 and the second oven 21 both use a temperature control system to cooperate with the heating structure of the heating resistance wire and the thermistor.

[0071] The frequency monitoring module 16 includes: an optical fiber coupler 17, a wavelength meter 18, and a matching software; for real-time monitoring of the laser frequency, ensuring the stability of the laser frequency, and matching the collected optical power data.

[0072] The data acquisition module 25 includes: a first transimpedance amplifier 15, a second transimpedance amplifier 27, a data acquisition card 26, a first photodetector 14, and a second photodetector 24;

[0073] The first transimpedance amplifier 15 cooperates with the first photodetector 14 to collect the light signal (transmission signal) after passing through the alkali metal cell 12, and convert and amplify the light signal into an electrical signal to ensure the availability of the signal.

[0074] The second transimpedance amplifier 27 cooperates with the second photodetector 24 to collect the light signal (transmission signal) after passing through the buffer gas cell 22, and convert and amplify the light signal into an electrical signal to ensure the availability of the signal.

[0075] The host computer 19 is configured to process the collected signals, eliminate irrelevant variables, and calculate the atomic density and cell pressure.

[0076] As an example, the host computer 19 is configured to analyze and process the signals collected by the experimental group and the control group, eliminate the effects of background noise and irrelevant variables, obtain the absorption spectrum after removing the background noise difference, and finally accurately calculate the atomic density and cell pressure of the alkali metal cell.

[0077] A method for measuring the atomic density and cell pressure of alkali metal, comprising:

[0078] Step 1: Linear sweep of the laser

[0079] The laser generation and control module adjusts the working parameters of the laser to sweep the laser wavelength near the specific transition frequency of the alkali metal atom.

[0080] As an example, the sweep near the specific transition frequency of the alkali metal atom means that the laser wavelength is tuned to the resonance wavelength of the alkali metal atom by linear sweep method, ensuring that the laser matches the absorption frequency of the alkali metal atom, thereby realizing optical pumping and measuring the light absorption characteristics of the alkali metal atom near the specific transition frequency in the alkali metal cell.

[0081] Step 2: Temperature monitoring and control of the alkali metal cell

[0082] After setting the desired heating temperature and PID parameters, the cell and its heating module 9 monitor the temperature in the first oven 11 and the second oven 21 through the built-in thermistor.

[0083] The thermistor measures the deviation between the target temperature and the actual temperature, and the temperature control system adjusts the power output of the heating resistor wire through the PID algorithm to stabilize the temperature of the first oven 11 and the second oven 21 at the set value, ensuring that the alkali metal atoms are fully evaporated into a gaseous state and reach a stable working state.

[0084] Step 3: Dual-path absorption spectrum monitoring and frequency synchronous collection

[0085] The laser emitted by the laser 1 is processed by the beam power and polarization control module 4, and is divided into an absorption spectrum measurement light path and a frequency monitoring light path.

[0086] The absorption spectrum measurement light path is divided into the experimental group light path and the control group light path by the polarization beam splitter 8; the experimental group light path passes through the alkali metal gas chamber 12, and the control group light path passes through the buffer gas chamber 22.

[0087] The light frequency of the frequency monitoring light path enters the frequency monitoring module 16 and is finally sent to the host computer 19.

[0088] The light signal of the experimental group light path is converted into an amplified electrical signal after the first photodetector 14 and the first transimpedance amplifier 15, and is input to one end of the data acquisition card 26; the amplified electrical signal is converted into a digital signal and transmitted to the host computer 19.

[0089] The light signal of the control group light path is converted into an amplified electrical signal after the second photodetector 24 and the second transimpedance amplifier 27, and is input to the other end of the data acquisition card 26; the amplified electrical signal is converted into a digital signal and transmitted to the host computer 19.

[0090] Step four, spectrum drawing and parameter fitting;

[0091] The host computer receives the light frequency signal and the light power degree signal collected by the data acquisition module, adjusts the step size using the linear interpolation algorithm to match the number of sampling points, processes the obtained absorption spectrum of the alkali metal vapor by Lorentz line fitting, calculates the atomic density and chamber pressure in the alkali metal chamber through the fitting parameters, and finally outputs the accurate measurement result.

[0092] As an example, the alkali metal chamber 12 is filled with alkali metal atoms and buffer gas; the buffer gas chamber 22 is filled with buffer gas.

[0093] In order to better illustrate the design principle and calculation process of the present application, the following example calculation is given:

[0094] Example 1:

[0095] The diode operating temperature and current of the laser 2 are set by the laser controller 3 to ensure that the wavelength of the emitted light is near the Rb atom D1 transition line (794.979 nm), and the beam power is high, so as to avoid being absorbed by the oven window piece 10, the oven window piece 13 and the glass and atoms of the alkali metal chamber 12, so as to ensure that the complete absorption spectrum can be measured;

[0096] The application is operated in a laboratory environment, the first oven 11 and the second oven 21 are synchronously heated to 50-100℃, the alkali metal atoms in the alkali metal atom gas chamber 12 are vaporized, the light power of the experimental group is I0, the light power of the control group is I0', the optical depth of the alkali metal atoms to the absorption spectrum of light is: The curve of the optical depth changing with the frequency satisfies the Lorentz line type:

[0097] Using the Lorentz line type to fit the absorption spectrum of the alkali metal vapor measured in the experiment, the fitting coefficients k and Γ can be obtained xL , the alkali metal density is: r e is the electron radius, c is the speed of light, f=2 / 3, L is the path length of light through the medium or the gas chamber; the pressure of the gas chamber is Γ0 is the gas chamber broadening under standard conditions, which is a constant; T represents the current temperature value, and T0 is the temperature under standard conditions.

[0098] The embodiments of the application are described above in combination with the drawings, but the application is not limited to the specific embodiments described above, and the specific embodiments described above are only illustrative but not restrictive, and those skilled in the art can make many forms under the inspiration of the application without departing from the scope of the application and the protection scope of the claims.

[0099] Those skilled in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in the embodiments of the application can be realized by electronic hardware or a combination of computer software and electronic hardware. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the application.

[0100] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the system, device and unit described above can refer to the corresponding processes in the foregoing method embodiments, which will not be described here.

[0101] In the embodiments of the present application, it should be understood that the disclosed system and method can be implemented in other manners. For example, the embodiments of the system described above are merely schematic; for example, the division of the units is only a logical function division; there can be another division manner for the actual implementation; for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between the units can be indirect couplings or communication connections through some interfaces, devices or units, and can be electric, mechanical or in other forms.

[0102] The units described as separated components can or can not be physically separated, and the components displayed as units can or can not be physical units; that is, they can be located in one place, or also can be distributed on a plurality of network units; some or all of the units can be selected according to the actual needs to achieve the purposes of the embodiments of the present application.

[0103] In addition, each function unit in the embodiments of the present application can be integrated in a processing unit, or each unit can exist physically as a separate unit, or two or more units can be integrated in a unit.

[0104] The above only provides preferred embodiments of the present application, and it should be understood that the above description of the embodiments is only used to help understand the method of the present application and its core idea, and does not limit the protection scope of the present application; any modification, equivalent replacement, etc. within the idea and principles of the present application should be included in the protection scope of the present application.

Claims

1. A system for measuring the atomic density of alkali metals and the pressure of a gas chamber, characterized in that, include: The system includes a laser generation and control module, a beam power and polarization control module, a gas chamber and its heating module, a frequency monitoring module, a data acquisition module, and a host computer. The laser generation and control module includes: a laser and a laser control system; the laser control system is used to control the operating parameters of the laser to achieve linear frequency sweep of the laser. The beam power and polarization control module includes: a beam splitter prism, a half-wave plate, a mirror, and a polarizing beam splitter prism; used to split and modulate the beam, dividing the laser into an experimental group optical path and a control group optical path; the experimental group optical path passes through an alkali metal gas chamber, and the control group optical path passes through a buffer gas chamber. The experimental group is used to record the light absorption characteristics of optical elements and alkali metal atoms, and the control group is used to record the light absorption characteristics of optical elements. By comparing the two sets of data, interference from optical elements is eliminated. The gas chamber and its heating module include: a first oven with oven windows symmetrically arranged on the left and right sides, a second oven with oven windows symmetrically arranged on the left and right sides, an alkali metal gas chamber disposed in the first oven, and a buffer gas gas chamber disposed in the second oven; used to heat and control the internal temperature of the alkali metal gas chamber, adjust the alkali metal atom density; ensure the stable evaporation of alkali metal atoms in the alkali metal gas chamber and adjust the buffer gas pressure in the buffer gas gas chamber; The frequency monitoring module includes: an optical fiber coupler, a wavelength meter, and supporting software; it is used to monitor the laser frequency in real time to ensure that the laser frequency is stable and matches the acquired optical power data. The data acquisition module includes: a first transimpedance amplifier, a second transimpedance amplifier, a data acquisition card, a first photodetector, and a second photodetector; The host computer is used to: process the collected signals, eliminate the influence of irrelevant variables, and calculate the atomic density and gas chamber pressure.

2. The system for measuring the atomic density of alkali metals and the pressure of the gas chamber according to claim 1, characterized in that, The operating parameters include: frequency, power, and temperature.

3. The system for measuring the atomic density of alkali metals and the pressure of the gas chamber according to claim 1, characterized in that, The beam splitter splits the laser into two linearly polarized beams. One beam of linearly polarized light is perpendicular to the original optical path and is transmitted to the wavelength meter after being incident on the fiber coupler. Another linearly polarized beam follows the original optical path, passes through the half-wave plate to adjust the polarization angle of the linearly polarized beam, and then passes through the polarizing beam splitter to split into two beams of equal power, which are perpendicular to each other.

4. The system for measuring the atomic density of alkali metals and the pressure of the gas chamber according to claim 3, characterized in that, The two beams of light with the same optical power enter the first oven and the second oven, respectively. The light passing through the alkali metal gas chamber is absorbed from incident to exit by the oven window on the front side of the first oven, the front wall of the alkali metal gas chamber, the alkali metal vapor, the rear wall of the alkali metal gas chamber, and the oven window on the rear side of the first oven; this is the light path of the experimental group. The light passing through the buffer gas chamber travels from incident to exit, passing through the oven window on the front side of the second oven, the front wall of the buffer gas chamber, the rear wall of the buffer gas chamber, and the oven window on the rear side of the second oven; this is the control group light path. Wherein: the light passing through the alkali metal gas cell undergoes one more atomic vapor absorption than the light passing through the buffer gas cell, and the peak value of the measured absorption spectrum is relatively lower; By dividing the absorption spectrum of the light beam passing through the buffer gas chamber by the absorption spectrum of the light beam passing through the alkali metal chamber, the influence of the oven window in front of the first oven, the front wall of the alkali metal chamber, the rear wall of the alkali metal chamber, and the oven window in rear of the first oven on the light beam absorption can be eliminated, thus obtaining the absorption spectrum of the alkali metal vapor.

5. The system for measuring the atomic density of alkali metals and the pressure of the gas chamber according to claim 1, characterized in that, Both the first and second ovens employ a heating structure that uses a temperature control system to electrically connect the heating resistance wire and the thermistor.

6. The system for measuring the atomic density of alkali metals and the pressure of the gas chamber according to claim 1, characterized in that, The first transimpedance amplifier works in conjunction with the first photodetector to collect the optical signal after it passes through the alkali metal gas cell, and converts the optical signal into an electrical signal and amplifies it to ensure the availability of the signal; The second transimpedance amplifier works in conjunction with the second photodetector to collect the optical signal after it passes through the buffer gas chamber, convert the optical signal into an electrical signal and amplify it to ensure signal availability.

7. The system for measuring the atomic density of alkali metals and the pressure of the gas chamber according to claim 1, characterized in that, The host computer is used to analyze and process the signals collected by the optical paths of the experimental group and the control group, eliminate the influence of background noise and irrelevant variables, obtain the absorption spectrum after background noise differential removal, and finally accurately calculate the atomic density and gas chamber pressure of the alkali metal gas chamber.

8. A method for measuring the atomic density of alkali metals and the pressure of a gas chamber, characterized in that, include: Step 1: Linear frequency sweep of the laser; By adjusting the laser generation and control module, the operating parameters of the laser are adjusted so that the laser wavelength is near the specific transition frequency of alkali metal atoms. Step 2: Temperature monitoring and control of the alkali metal gas chamber; After setting the desired heating temperature and PID parameters, the air chamber and its heating module monitor the temperature inside the first and second ovens through the built-in thermistor; The deviation between the target temperature and the actual temperature is measured by a thermistor. The temperature control system adjusts the power output of the heating resistance wire through a PID algorithm to stabilize the temperature of the first oven and the second oven at the set value, ensuring that the alkali metal atoms are fully evaporated into a gaseous state and reach a stable working state. Step 3: Dual-path absorption spectrum monitoring and synchronous frequency acquisition; The laser emitted by the laser is processed by the beam power and polarization control module and divided into: an absorption spectrum measurement optical path and a frequency monitoring optical path; The absorption spectroscopy measurement optical path is divided into an experimental group optical path and a control group optical path by a polarizing beam splitter; the experimental group optical path passes through an alkali metal gas cell, and the control group optical path passes through a buffer gas cell. The optical frequency of the frequency monitoring optical path enters the frequency monitoring module and is finally sent to the host computer. The optical signal of the experimental group's optical path is converted into an amplified electrical signal after passing through the first photodetector and the first transimpedance amplifier. This amplified signal is then input to one end of the data acquisition card and converted into a digital signal, which is then transmitted to the host computer. The optical signal of the control group optical path is converted into an amplified electrical signal after passing through the second photodetector and the second transimpedance amplifier. This amplified electrical signal is then input to the other end of the data acquisition card and converted into a digital signal, which is then transmitted to the host computer. Step 4: Spectrum plotting and parameter fitting; The host computer receives the optical frequency signal and optical power signal collected by the data acquisition module, adjusts the step size using a linear interpolation algorithm to match the number of sampling points, and fits the absorption spectrum of the alkali metal vapor obtained by the processing through Lorentz line fitting. The atomic density and pressure of the alkali metal gas chamber are calculated by the fitting parameters, and finally the accurate measurement results are output.

9. The method for measuring the atomic density of alkali metals and the pressure of the gas chamber according to claim 8, characterized in that, The frequency sweeping near a specific transition frequency of alkali metal atoms refers to: using a linear frequency sweeping method, tuning the laser wavelength to the resonance wavelength of alkali metal atoms to ensure that the laser wavelength matches the absorption frequency of alkali metal atoms, thereby achieving optical pumping and measuring the optical absorption characteristics of alkali metal atoms in the alkali metal chamber near a specific transition frequency.

10. The method for measuring the atomic density of alkali metals and the pressure of the gas chamber according to claim 8, characterized in that, The alkali metal chamber is filled with alkali metal atoms and a buffer gas; the buffer gas chamber is filled with a buffer gas.

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