System and method for measuring alkali metal atomic density and air chamber pressure

Abstract

The invention provides a system and a method for measuring alkali metal atomic density and gas chamber pressure. The system comprises a laser generation and control module, a light beam power and polarization regulation and control module, a gas chamber and a heating module thereof, a frequency monitoring module, a data acquisition module and an upper computer, performing linear frequency sweeping through a laser; monitoring and controlling the temperature of the alkali metal gas chamber; performing dual-light-path absorption spectrum monitoring and frequency synchronous acquisition; spectrum drawing and parameter fitting are carried out, and a background noise removal scheme based on an absorption spectrum measurement process is adopted, so that the precision of a measurement system is remarkably improved; the interference of external factors such as air chamber glass, oven window pieces and optical components on a measurement result can be effectively eliminated; meanwhile, interference caused by power fluctuation of the laser is eliminated by removing background noise, so that the absorption spectrum is more accurate, and the spectral measurement precision is greatly improved; more accurate measurement of the atomic density and pressure of the air chamber can be realized, and the method is suitable for popularization.

Description

Technical Field

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

[0002] At present, high-precision quantum precision measurement has been achieved for common physical quantities such as inertial force, magnetic field, and time, showing excellent application potential in the fields of inertial navigation, biomagnetic field detection, time-frequency measurement, etc.; among them, alkali metal gas chambers are the core components of precision measurement equipment such as atomic magnetometers and quantum gyroscopes, and their 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. The alkali metal atoms have a single-electron outer layer structure and are easy to optically manipulate, while the buffer gas can reduce the collision between alkali metal atoms and between them 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 cell include: alkali metal atomic density and gas pressure; they are closely related to the signal intensity 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 prior art has the following technical defects in measuring the parameters of alkali metal gas chambers:

[0006] ① Manual measurement has low efficiency and poor accuracy: The traditional method of measuring air chamber parameters mainly relies on manual adjustment and recording, which cannot achieve high-precision and high-efficiency parameter measurement, and the human error is significant. The data measured by measurement personnel with different experience and ability are uneven.

[0007] ② Unable to eliminate the interference of optical components: The optical absorption and scattering effects of the glass wall outside the gas chamber and the oven window introduce background noise interference, which seriously interferes with the optical absorption measurement results and leads to insufficient measurement accuracy of gas chamber parameters.

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

[0009] Therefore, based on the above-mentioned deficiencies, those skilled in the art are in urgent need of exploring a new path that is not affected by background noise, has high precision, and is automated. Summary of the invention

[0010] In order to solve the above technical problems, the present invention provides a system and method for measuring the density of alkali metal atoms and gas chamber pressure. Through the creative optimization design of the optical path structure and the improvement of the measurement algorithm, high-precision and automated measurement of gas chamber parameters at various temperatures is achieved after removing background noise, thus meeting the requirements of quantum precision measuring instruments for high-sensitivity measurement.

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

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

[0013] Laser generation and control module, beam power and polarization control module, gas chamber and its heating module, frequency monitoring module, data acquisition module and host computer;

[0014] The laser generation and control module includes: a laser and a laser control system; the laser control system is used to control the working parameters of the laser to achieve linear frequency sweep of the laser;

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

[0016] The beam power and polarization control module includes: a beam splitter prism, a 1 / 2 wave plate, a reflector and a polarization beam splitter prism;

[0017] Used for splitting and modulating light beams, dividing the laser into an experimental group light path and a control group light path; the experimental group light path passes through an alkali metal gas chamber, and the control group light path passes through a buffer gas gas chamber; the experimental group is used to record light absorption characteristics, and the control group is used to eliminate interference from optical components;

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

[0019] Another linearly polarized light follows the original optical 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 beams of light with the same optical power, and the two beams of light with the same optical power are perpendicular to each other.

[0020] As an example, the two beams of light with the same optical power enter the first oven and the second oven respectively; the first oven and the second oven have the same specifications, models and oven windows to ensure the consistency of experimental conditions, thereby eliminating errors that may be caused by equipment differences.

[0021] The light passing through the alkali metal gas chamber is absorbed by the oven window at 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 of the first oven at the rear side from incident to emitted; this is the light path of the experimental group;

[0022] The light passing through the buffer gas chamber passes through the oven window at 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 of the second oven at the rear side from incident to emitted; this is the light path of the control group;

[0023] Wherein: the light passing through the alkali metal gas chamber is absorbed by the atomic vapor one more time than the light passing through the buffer gas gas chamber, and the peak value of the measured absorption spectrum is relatively lower;

[0024] By taking the absorption spectrum of the light beam passing through the buffer gas chamber and the absorption spectrum of the light beam passing through the alkali metal chamber, the influence of the front oven window of the first oven, the front wall of the alkali metal chamber, the rear wall of the alkali metal chamber, and the rear oven window of the first oven on the light beam absorption can be removed to obtain the absorption spectrum of the alkali metal vapor.

[0025] The gas chamber and the heating module thereof include: a first oven with oven windows symmetrically arranged on the left and right, a second oven with oven windows symmetrically arranged on the left and right, an alkali metal gas chamber arranged in the first oven, and a buffer gas gas chamber arranged in the second oven;

[0026] It is used to heat and control the internal temperature of the alkali metal gas chamber and adjust the density of alkali metal atoms; ensure the stable evaporation of alkali metal atoms in the alkali metal gas chamber and the regulation of the buffer gas pressure in the buffer gas chamber.

[0027] As an example, the first oven and the second oven both use a heating structure in which a temperature control system cooperates with a heating resistor wire and a thermistor.

[0028] 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 collected optical power data.

[0029] The data acquisition module includes: 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 optical signal (transmission signal) after passing through the alkali metal gas chamber, and convert the optical signal into an electrical signal and amplify 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 converts the optical signal into an electrical signal and amplifies it to ensure the availability of the signal;

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

[0033] As an example, 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 with the background noise differentially removed, and finally accurately calculate the atomic density and gas chamber pressure of the alkali metal gas chamber.

[0034] A method for measuring alkali metal atom density and gas chamber pressure, comprising:

[0035] Step 1: Linear frequency sweep of the laser;

[0036] By means of the laser generation and control module, the operating parameters of the laser are adjusted so that the laser wavelength is swept around the specific transition frequency of the alkali metal atoms;

[0037] As an example, the frequency sweeping near the specific transition frequency of the alkali metal atoms refers to: tuning the laser wavelength to the resonant wavelength of the alkali metal atoms through a linear frequency sweeping method to ensure that the laser matches the absorption frequency of the alkali metal atoms, thereby achieving optical pumping and measuring the light absorption characteristics of the alkali metal atoms in the alkali metal gas chamber near the specific transition frequency.

[0038] Step 2: Alkali metal gas chamber temperature monitoring and control;

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

[0040] The deviation between the target temperature and the actual temperature is measured by the thermistor, 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 synchronization 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 optical path and a frequency monitoring optical path;

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

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

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

[0046] 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, and is input into the other end of the data acquisition card, and converted into a digital signal and transmitted to the host computer;

[0047] Step 4: Spectrum drawing and parameter fitting;

[0048] The host computer receives the optical frequency signal and optical power signal collected by the data acquisition module, uses a linear interpolation algorithm to adjust the step size to match the number of sampling points, and the absorption spectrum of the alkali metal vapor obtained by processing is fitted by a Lorentz line type. The atomic density and the gas chamber pressure in the alkali metal gas chamber are calculated by the fitting parameters, and finally an accurate measurement result is output.

[0049] Beneficial effects of the present invention:

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

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

[0052] Figure 1 The present invention is an overall structural design diagram of a system for measuring alkali metal atom density and gas chamber pressure. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present application, and reference is made to the accompanying drawings in the embodiments of the present application. Figure 1 As shown,

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

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

[0056] Laser generation and control module 1, beam power and polarization control module 4, gas chamber and heating module 9, frequency monitoring module 16, data acquisition module 24 and host computer 19;

[0057] The laser generation and control module 1 includes: 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 achieve linear frequency sweep of the laser;

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

[0059] The beam power and polarization control module 4 includes: a beam splitter prism 5, a 1 / 2 wave plate 6, a reflector 7 and a polarization beam splitter prism 8;

[0060] Used for splitting and modulating light beams, dividing the laser into an experimental group light path and a control group light path; the experimental group light path passes through the alkali metal gas chamber 12, and the control group light path passes through the buffer gas gas chamber 22. The experimental group is used to record the optical absorption characteristics of the optical element and the alkali metal atoms, and the control group is used to record the optical absorption characteristics of the optical element. By comparing the two sets of data, the interference effect of the optical element can be eliminated;

[0061] As an example, the beam splitter 5: splits the laser into two linear polarized lights, one of which is perpendicular to the original optical path and incident on the optical fiber coupler 17 and then transmitted to the wavelength meter 18. The wavelength meter 18 transmits the wavelength to the host computer 19 according to a specific acquisition frequency;

[0062] Another beam of linearly polarized light follows the original optical 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 light with the same optical power, and the two beams of light with the same optical power 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 gas chamber 12 is absorbed by the oven window 10 on the front side of the first oven 11, the front wall of the alkali metal gas chamber 12, the alkali metal vapor, the rear wall of the alkali metal gas chamber 12, and the oven window 13 of the first oven 11 on the rear side from incident to emitted; this is the light path of the experimental group;

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

[0066] Wherein: the light passing through the alkali metal gas chamber 12 is absorbed by the atomic vapor one more time than the light passing through the buffer gas gas chamber 22, and the peak value of the measured absorption spectrum is relatively lower;

[0067] By taking the absorption spectrum of the light beam passing through the buffer gas chamber 22 and the absorption spectrum of the light beam passing through the alkali metal chamber 12 as a quotient, the influence of the front oven window of the first oven 11, the front wall of the alkali metal chamber 12, the rear wall of the alkali metal chamber 12, and the rear oven window of the first oven 11 on the light beam absorption can be eliminated to obtain the absorption spectrum of the alkali metal vapor.

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

[0069] It is used to heat and control the internal temperature of the alkali metal gas chamber 12 and adjust the density of alkali metal atoms; ensure the stable evaporation of alkali metal atoms in the alkali metal gas chamber 12 and the adjustment of the buffer gas pressure in the buffer gas chamber 22.

[0070] As an example, the first oven 11 and the second oven 21 both use a heating structure in which a temperature control system cooperates with a heating resistor wire and a thermistor.

[0071] The frequency monitoring module 16 includes: a fiber coupler 17, a wavelength meter 18 and supporting software; and is used to monitor the laser frequency in real time to ensure that the laser frequency is stable and matches 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 optical signal (transmission signal) after passing through the alkali metal gas chamber 12, and converts the optical signal into an electrical signal and amplifies it to ensure the availability of the signal;

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

[0075] The host computer 19 is used to process the collected signals, eliminate the influence of irrelevant variables, and calculate the atomic density and the gas chamber pressure.

[0076] As an example, the host computer 19 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 with the background noise differentially removed, and finally accurately calculate the atomic density and gas chamber pressure of the alkali metal gas chamber.

[0077] A method for measuring alkali metal atom density and gas chamber pressure, comprising:

[0078] Step 1: Linear frequency sweep of the laser;

[0079] By means of the laser generation and control module, the operating parameters of the laser are adjusted so that the laser wavelength is swept around the specific transition frequency of the alkali metal atoms;

[0080] As an example, the frequency sweeping near the specific transition frequency of the alkali metal atoms refers to: tuning the laser wavelength to the resonant wavelength of the alkali metal atoms through a linear frequency sweeping method to ensure that the laser matches the absorption frequency of the alkali metal atoms, thereby achieving optical pumping and measuring the light absorption characteristics of the alkali metal atoms in the alkali metal gas chamber near the specific transition frequency.

[0081] Step 2: Alkali metal gas chamber temperature monitoring and control;

[0082] After setting the desired heating temperature and PID parameters, the air chamber 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 deviation between the target temperature and the actual temperature is measured by the thermistor, 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 gas state and reach a stable working state.

[0084] Step 3: Dual-optical path absorption spectrum monitoring and frequency synchronization acquisition;

[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 optical path and a frequency monitoring optical path;

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

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

[0088] The optical signal of the experimental group optical path is converted into an amplified electrical signal after passing through 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 optical signal of the control group optical path is converted into an amplified electrical signal after passing through the second photodetector 24 and the second transimpedance amplifier 27, and 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 4: Spectrum drawing and parameter fitting;

[0091] The host computer receives the optical frequency signal and optical power signal collected by the data acquisition module, uses a linear interpolation algorithm to adjust the step size to match the number of sampling points, and the absorption spectrum of the alkali metal vapor obtained by processing is fitted by a Lorentz line type. The atomic density and the gas chamber pressure in the alkali metal gas chamber are calculated by the fitting parameters, and finally an accurate measurement result is output.

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

[0093] In order to better illustrate the design principle and calculation process of the present invention, a specific embodiment is now used to illustrate the calculation as follows:

[0094] Embodiment 1:

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

[0096] The present invention is operated in a laboratory environment, and the internal temperatures of the first oven 11 and the second oven 21 are simultaneously heated to 50-100° C., so that the alkali metal atoms in the alkali metal atom gas chamber 12 are vaporized. The output light power of the experimental group is I0, and the output light power of the control group is I0′. The optical depth of the absorption spectrum of the alkali metal atoms to light is: The curve of optical depth changing with frequency satisfies the Lorentz line shape:

[0097] The Lorentz line shape is used to fit the experimentally measured absorption spectrum of alkali metal vapor, and the fitting coefficients k and Γ can be obtained. xL , the density of alkali metals 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 gas chamber; the pressure of the gas chamber is Γ0 is the air chamber expansion under standard conditions and is a constant; T represents the current temperature value and T0 is the temperature under standard conditions.

[0098] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

[0099] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the present application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0100] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0101] In the embodiments provided in the present application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0102] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or may be distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0103] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0104] The above are only preferred embodiments of the present invention. It should be understood that the description of the above embodiments is only used to help understand the method and core ideas of the present invention, and is not used to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, etc. made within the ideas and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A system for measuring alkali metal atom density and gas chamber pressure, characterized in that: include: Laser generation and control module, beam power and polarization control module, gas chamber and its heating module, frequency monitoring module, data acquisition module and 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 working 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 1 / 2 wave plate, a reflector and a polarization beam splitter prism; it is used to split and modulate the beam, and divide the laser into an experimental group light path and a control group light path; the experimental group light path passes through an alkali metal gas chamber, and the control group light path passes through a buffer gas gas chamber; the experimental group is used to record the optical absorption characteristics of the optical element and the alkali metal atom, and the control group is used to record the optical absorption characteristics of the optical element, and the interference of the optical element is eliminated by comparing the two sets of data; The gas chamber and its heating module include: a first oven with oven windows symmetrically arranged on the left and right, a second oven with oven windows symmetrically arranged on the left and right, an alkali metal gas chamber arranged in the first oven, and a buffer gas gas chamber arranged in the second oven; used to heat and control the internal temperature of the alkali metal gas chamber, adjust the density of alkali metal atoms; ensure the stable evaporation of alkali metal atoms in the alkali metal gas chamber and the adjustment of the buffer gas pressure in the buffer gas gas chamber; The frequency monitoring module includes: a 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 collected 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 the gas chamber pressure.

2. A system for measuring alkali metal atom density and gas chamber pressure according to claim 1, characterized in that: The operating parameters include: frequency, power and temperature.

3. A system for measuring alkali metal atom density and gas chamber pressure according to claim 1, characterized in that: The beam splitter prism: splits the laser into two linear polarized lights, one of which is perpendicular to the original optical path and incident on the optical fiber coupler and then transmitted to the wavelength meter, which transmits the wavelength to the host computer according to a specific acquisition frequency; Another linearly polarized light follows the original optical 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 beams of light with the same optical power, and the two beams of light with the same optical power are perpendicular to each other.

4. A system for measuring alkali metal atom density and gas chamber pressure 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 by the oven window at 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 of the first oven at the rear side from incident to emitted; this is the light path of the experimental group; The light passing through the buffer gas chamber passes through the oven window at 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 of the second oven at the rear side from incident to emitted; this is the light path of the control group; Wherein: the light passing through the alkali metal gas chamber is absorbed by the atomic vapor one more time than the light passing through the buffer gas gas chamber, and the peak value of the measured absorption spectrum is relatively lower; By taking the absorption spectrum of the light beam passing through the buffer gas chamber and the absorption spectrum of the light beam passing through the alkali metal chamber, the influence of the front oven window of the first oven, the front wall of the alkali metal chamber, the rear wall of the alkali metal chamber, and the rear oven window of the first oven on the light beam absorption can be removed to obtain the absorption spectrum of the alkali metal vapor.

5. A system for measuring alkali metal atom density and gas chamber pressure according to claim 1, characterized in that: The first oven and the second oven both use a heating structure in which a heating resistance wire and a thermistor are electrically connected by a temperature control system.

6. A system for measuring alkali metal atom density and gas chamber pressure according to claim 1, characterized in that: The first transimpedance amplifier cooperates with the first photodetector to collect the optical signal after passing through the alkali metal gas chamber, and converts the optical signal into an electrical signal and amplifies it to ensure the availability of the signal; The second transimpedance amplifier cooperates with the second photodetector to collect the optical signal after passing through the buffer gas chamber, and converts the optical signal into an electrical signal and amplifies the electrical signal to ensure the availability of the signal.

7. A system for measuring alkali metal atom density and gas chamber pressure 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 with the background noise differentially removed, and finally accurately calculate the atomic density and gas chamber pressure of the alkali metal gas chamber.

8. A method for measuring alkali metal atom density and gas chamber pressure, characterized in that: include: Step 1: Linear frequency sweep of the laser; By means of 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 the alkali metal atoms; Step 2: Alkali metal gas chamber temperature monitoring and control; After setting the desired heating temperature and PID parameters, the air chamber and its heating module monitor the temperature in the first oven and the second oven through the built-in thermistor; The deviation between the target temperature and the actual temperature is measured by the thermistor, 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; Step 3: Dual-optical path absorption spectrum monitoring and frequency synchronization acquisition; The laser emitted by the laser is processed by the beam power and polarization control module and is divided into: an absorption spectrum measurement optical path and a frequency monitoring optical path; The absorption spectrum measurement optical path is divided into the experimental group optical path and the control group optical path by the polarization beam splitter prism; the experimental group optical path passes through the alkali metal gas chamber, and the control group optical path passes through the buffer gas gas chamber; 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 optical path of the experimental group is converted into an amplified electrical signal after passing through the first photodetector and the first transimpedance amplifier, and is input into one end of the data acquisition card, and converted into a digital signal and 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, and is input into the other end of the data acquisition card, and converted into a digital signal and transmitted to the host computer; Step 4: Spectrum drawing and parameter fitting; The host computer receives the optical frequency signal and optical power signal collected by the data acquisition module, uses a linear interpolation algorithm to adjust the step size to match the number of sampling points, and the absorption spectrum of the alkali metal vapor obtained by processing is fitted by a Lorentz line type. The atomic density and the gas chamber pressure in the alkali metal gas chamber are calculated by the fitting parameters, and finally an accurate measurement result is output.

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

10. The method for measuring alkali metal atom density and gas chamber pressure 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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