Device and method for measuring rubidium isotope proportion based on nuclear spin slowing factor

Abstract

According to the rubidium isotope proportion measuring device and method based on the nuclear spin slowing factor, two beams of orthogonal laser are driven through an automatic upper computer, magnetic resonance frequencies of a high-temperature alkali metal air chamber in different bias magnetic fields are searched under different optical powers, the gyromagnetic ratio is calculated through linear fitting, and therefore the nuclear spin slowing factor of an atom ensemble is obtained, and the rubidium isotope proportion measuring method based on the nuclear spin slowing factor is obtained. And solving an overdetermined equation set by using the relationship between the slowdown factor and the isotope proportion and the rubidium atom isotope proportion, thereby realizing accurate measurement of the rubidium atom gas chamber gas isotope proportion. Compared with a conventional method, the device and the method have the advantages of accuracy, rapidness, simplicity and lower cost, and the closed air chamber structure does not need to be damaged.

Description

Technical Field

[0001] This invention relates to a rubidium isotope ratio measurement device and method based on nuclear spin slowing factor, belonging to the field of optical detection technology. Background Technology

[0002] Rubidium atomic gas cells are widely used in various atomic magnetometers, gyroscopes, and atomic clocks, serving as a core sensing device in the interaction process between light and atoms. Depending on the application, the rubidium atomic gas cell contains two rubidium isotopes. 87 Rb and 85 Rb requires separation, purification, or proportional mixing. In traditional atomic gas chambers, although the solid rubidium atom source is proportionally mixed when filled with alkali metals, the proportions of gaseous isotopes may change when the atom is evaporated into rubidium atom vapor by heating. Therefore, the preparation of pure rubidium atom vapor requires further purification. 87 Rb and pure 85 When creating Rb gas chambers, due to limitations in the purification process, a small amount of another rubidium isotope may be present in the chamber. For already encapsulated unknown gas chambers, commonly used pure... 87 Rb, naturally abundant rubidium ( nat Rb), and pure 85 Rb cells cannot be distinguished from their appearance. Therefore, it is necessary to accurately measure the proportion of gaseous alkali metal isotopes that interact with light in the rubidium atom cells.

[0003] Traditional methods for measuring the proportion of gaseous alkali metal isotopes include mass spectrometry, fluorescence spectroscopy, and saturated absorption spectroscopy. Mass spectrometry is a destructive method; fluorescence spectroscopy is limited by instrument cost; and the absorption lines of saturated absorption spectroscopy are affected by frequency shifts and asymmetries caused by other components in the gas chamber, resulting in lower measurement accuracy. Due to process limitations, the most commonly used method is pure... 87 The Rb cell may contain a small amount of 85 For Rb atoms, and especially for the large number of encapsulated gas cells required for industrialization, achieving rapid and accurate isotope ratio detection while maintaining the uniformity of gas cell parameters is crucial for batch quality control. Therefore, a non-destructive, low-cost method for measuring the content of Rb atoms in high-temperature rubidium atomic gas cells needs to be proposed. 87 Rb and 85 Apparatus and method for measuring Rb ratio. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by proposing a device and method for measuring the proportion of rubidium isotopes based on nuclear spin slowing factors. An automated host computer drives two orthogonal laser beams to locate the magnetic resonance frequencies of a high-temperature alkali metal gas chamber under different bias magnetic fields at varying optical powers. The gyromagnetic ratio is calculated through linear fitting, thereby deriving the nuclear spin slowing factor of the atomic ensemble. The relationship between the slowing factor and the isotope proportion is used to solve an overdetermined set of equations related to the rubidium atomic isotope proportion, achieving accurate measurement of the gaseous isotope ratio in the rubidium atomic gas chamber. Compared to conventional methods, this device and method offer advantages such as accuracy, speed, simplicity, and lower cost, and do not require disruption of the sealed gas chamber structure.

[0005] The technical solution of the present invention is as follows:

[0006] A method for measuring the proportion of rubidium isotopes based on nuclear spin slowing factors, characterized by comprising the following steps:

[0007] Step 1: Initialize the laser in the rubidium atomic gas chamber isotope ratio measurement device and perform triaxial magnetic compensation using z-axis, x-axis, and y-axis opposing coils;

[0008] Step 2: By applying an amplitude-modulated bias magnetic field and a frequency-modulated calibration magnetic field, a magnetic resonance signal containing a slowing factor is generated;

[0009] Step 3: Acquire and fit the slowing factor output signal. By changing the laser power, control the steady-state polarization. Repeat the measurement in step 2 at the laser power corresponding to the maximum response of the slowing factor output signal and at the highest laser power to obtain at least three sets of nuclear spin slowing factor measurement results under different steady-state polarization.

[0010] Step 4: Use the rubidium atomic isotope ratio calculation equation set and the overdetermined equation set to calculate the rubidium atomic isotope ratio, and obtain an unbiased estimate of the rubidium atomic gas chamber isotope ratio for accurate measurement without destroying the sealed gas chamber structure.

[0011] The equations for calculating the rubidium atomic isotope ratio in step 4 are as follows:

[0012]

[0013] Where q n (P) is the nuclear spin slowing factor, a function of P, where P is the steady-state polarizability, and P is related to the laser power. 87 It is an isotope 87 The atomic number density ratio of Rb, and m 85 It is an isotope 85 The atomic number density percentage of Rb;

[0014] The overdetermined system of equations is as follows:

[0015]

[0016] Where P = 0, P = 0.5, and P = 1 are nuclear spin slowing factors q. n Three steady-state polarizability conditions, γ e It is the electron gyromagnetic ratio, and γ is the atomic gyromagnetic ratio.

[0017] Step 4 involves averaging the calculated rubidium atomic isotope ratios to obtain an unbiased estimate of the accurate measurement of the rubidium atomic gas chamber isotope ratios, expressed as follows:

[0018] m 87 =[m 87 (P=0)+m 87 (P=0.5)+m 87 [(P=1)] / 3,

[0019] m 85 =[m 85 (P=0)+m 85 (P=0.5)+m 85 (P=1)] / 3.

[0020] The rubidium atom gas cell isotope ratio measurement device in step 1 includes a laser system, a gas cell measurement system, and a signal extraction system connected in sequence. The laser system, gas cell measurement system, and signal extraction system are respectively connected to an automated host computer. The gas cell measurement system includes a rubidium atom gas cell located inside an electrically heated oven, which is located inside a magnetic compensation coil. The magnetic compensation coil includes a z-axis opposing coil, an x-axis opposing coil, and a y-axis opposing coil connected to the automated host computer via a signal generator. The laser system includes a first laser and a second laser. The laser frequency of the first laser is located at the rubidium atom D1 line, and the laser light from the first laser is used to pass through the rubidium atom gas cell along the z-axis. The laser frequency of the second laser is located at a detuned 50 GHz at the rubidium atom D1 line, and the laser light from the second laser is used to pass through the rubidium atom gas cell along the x-axis.

[0021] Step 2 involves applying a 0-50 nT linearly modulated bias magnetic field to the z-axis via a z-axis counter coil, inducing an observable slowing factor signal. Under each bias magnetic field, a 0-300 Hz linearly modulated calibration magnetic field is simultaneously applied to the y-axis via a y-axis counter coil, generating a magnetic resonance signal containing the slowing factor. An automated host computer is used to acquire the magnetic resonance linewidth curves of the slowing factor output signal under different bias magnetic fields. Based on the magnetic resonance linewidth fitting program, the magnetic resonance frequencies under different bias magnetic fields are calculated. Through linear fitting, a set of nuclear spin slowing factor numerical measurements under the current steady-state polarization are obtained.

[0022] A rubidium isotope ratio measurement device based on nuclear spin slowing factor, characterized in that it is used to perform the above-mentioned rubidium isotope ratio measurement method based on nuclear spin slowing factor.

[0023] The system includes a first laser, a first acousto-optic modulator, a first non-polarizing beam splitter, a first half-wave plate, a quarter-wave plate, a reflector, a rubidium atom gas chamber, a third photodetector, and an automated host computer, all connected in sequence. The reflecting side of the first non-polarizing beam splitter is connected to the automated host computer via the first photodetector. The rubidium atom gas chamber is located inside an electrically heated oven, which is located inside a magnetic compensation coil. The magnetic compensation coil is located inside a multi-layer magnetic shielding barrel. The magnetic compensation coil includes a z-axis opposed coil, an x-axis opposed coil, and a y-axis opposed coil, each connected to the automated host computer via a signal generator. The first laser and the first acousto-optic modulator are also connected to the automated host computer.

[0024] The system includes a second laser, a second acousto-optic modulator, a second unpolarized beam splitter, a rubidium atom gas cell, a second half-wave plate, and the input side of a polarized beam splitter connected in sequence. The reflective side of the polarized beam splitter is connected to the positive input of a differential amplifier via a fifth photodetector, and the transmissive side of the polarized beam splitter is connected to the negative input of the differential amplifier via a fourth photodetector. The output of the differential amplifier provides a slowing factor output signal to an automated host computer. The second laser and the second acousto-optic modulator are respectively connected to the automated host computer, and the reflective side of the second unpolarized beam splitter is connected to the automated host computer via a second photodetector.

[0025] The technical advantages of this invention are as follows: This invention provides a rubidium isotope ratio measurement device and method based on the nuclear spin slowing factor. Using a pre-programmed automatic control acquisition program for the nuclear spin slowing factor, an automated host computer drives two orthogonal laser beams. At different optical powers, a coil applies a linearly amplitude-modulated bias magnetic field to the z-axis and a linearly frequency-modulated calibration magnetic field to the y-axis, automatically finding the magnetic resonance frequency of the high-temperature alkali metal gas chamber. The linear relationship between the magnetic resonance frequency and the bias magnetic field allows for the calculation of the gyromagnetic ratio, thereby deriving the nuclear spin slowing factor of the atomic ensemble. Utilizing the relationship between the slowing factor and the isotope ratio, and the rubidium atomic isotope ratio, an overdetermined set of equations is solved, achieving accurate measurement of the gaseous isotope ratio in the rubidium atomic gas chamber. Compared with conventional methods, this device and method offer advantages in accuracy, speed, simplicity, and lower cost, and do not require destruction of the sealed gas chamber structure.

[0026] The advantages of this invention over existing technologies are as follows: It employs a laser to directly detect the proportion of gaseous isotopes inside a high-temperature rubidium atomic gas chamber, a non-destructive measurement method; the measurement is performed directly at the working temperature of the gas chamber, meeting practical requirements; by measuring physical constants and linearly fitting the data, it requires less data and ensures accuracy through multiple sets of measurements; the measurement process is automated and can be achieved using a low-power laser and simple optical components, resulting in lower costs compared to other measurement methods. For a large number of encapsulated gas chambers, it offers advantages in accuracy, speed, simplicity, and low cost, without damaging the sealed gas chamber structure. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a rubidium isotope ratio measurement device based on a nuclear spin slowing factor, which implements the present invention.

[0028] Figure 2 This is a schematic diagram of the process for implementing the rubidium isotope ratio measurement method based on the nuclear spin slowing factor of the present invention. Figure 2 The process includes: Step 1, initializing the laser and performing triaxial magnetic compensation in the rubidium atomic gas chamber isotope ratio measurement device; Step 2, applying an amplitude-modulated bias magnetic field and a frequency-modulated calibration magnetic field; Step 3, acquiring and fitting the slowing factor output signal, controlling the steady-state polarizability by changing the laser power, and repeating the measurement in Step 2 at the laser power corresponding to the maximum response of the slowing factor output signal and at the highest laser power to obtain at least three sets of nuclear spin slowing factor measurement results under different steady-state polarizabilities; Step 4, using the rubidium atomic isotope ratio solution equation set and the overdetermined equation set to calculate the rubidium atomic isotope ratio, obtaining an unbiased estimate for accurate measurement of the rubidium atomic gas chamber isotope ratio without destroying the sealed gas chamber structure.

[0029] The reference numerals in the attached figures are explained as follows: 1-Laser system; 2-Gas chamber measurement system; 3-Signal extraction system; 401-Automatic host computer; 101-First laser; 102-First acousto-optic modulator (AOM); 103-First non-polarizing beam splitter (NPBS); 104-First photodetector; 105-First half-wave plate; 106-Half-wave plate; 107-Second laser; 108-Second acousto-optic modulator (AOM); 109-Second non-polarizing beam splitter (NPBS); 110-Second photodetector; 20 1-Multi-layer magnetic shielding barrel; 202-Z-axis opposed coil; 203-X-axis opposed coil; 204-Y-axis opposed coil; 205-Signal generator; 206-Electric heating oven; 207-Russian atom gas chamber; 208-Reflector; 209-Third photodetector; 301-Second half-wave plate; 302-Polarizing beam splitter; 303-Fourth photodetector; 304-Fifth photodetector; 305-Differential amplifier; 306-Slowing factor output signal; xyz-Cartesian coordinate system three axes (i.e., x-axis, y-axis, and z-axis). Detailed Implementation

[0030] The following is in conjunction with the attached diagram ( Figures 1-2 The invention will be described in the following sections and examples.

[0031] Figure 1 This is a schematic diagram of a rubidium isotope ratio measurement device based on a nuclear spin slowing factor, which implements the present invention. Figure 2 This is a schematic flowchart illustrating the method for measuring the rubidium isotope ratio based on the nuclear spin slowing factor, as described in this invention. (Reference) Figures 1 to 2 As shown, a method for measuring the rubidium isotope ratio based on the nuclear spin slowing factor includes the following steps: Step 1, laser initialization is performed in the rubidium atom gas chamber isotope ratio measurement device, and triaxial magnetic compensation is performed using z-axis, x-axis, and y-axis opposed coils; Step 2, magnetic resonance signal containing the slowing factor is generated by applying an amplitude-modulated bias magnetic field and a frequency-modulated calibration magnetic field; Step 3, the slowing factor output signal is acquired and fitted, and the steady-state polarization is controlled by changing the laser power. The measurement in Step 2 is repeated at the laser power corresponding to the maximum response of the slowing factor output signal and at the highest laser power to obtain at least three sets of nuclear spin slowing factor measurement results under different steady-state polarizations; Step 4, the rubidium atom isotope ratio is calculated using the rubidium atom isotope ratio solution equation set and the overdetermined equation set to obtain an unbiased estimate for accurate measurement of the rubidium atom gas chamber isotope ratio without destroying the sealed gas chamber structure.

[0032] The equations for calculating the rubidium atomic isotope ratio in step 4 are as follows:

[0033]

[0034] Where q n (P) is the nuclear spin slowing factor, a function of P, where P is the steady-state polarizability, and P is related to the laser power. 87 It is an isotope 87 The atomic number density ratio of Rb, and m 85 It is an isotope 85 The atomic number density percentage of Rb;

[0035] The overdetermined system of equations is as follows:

[0036]

[0037] Where P = 0, P = 0.5, and P = 1 are nuclear spin slowing factors q. n Three steady-state polarizability conditions, γ e It is the electron gyromagnetic ratio, and γ is the atomic gyromagnetic ratio.

[0038] Step 4 involves averaging the calculated rubidium atomic isotope ratios to obtain an unbiased estimate of the accurate measurement of the rubidium atomic gas chamber isotope ratios, expressed as follows:

[0039] m 87 =[m 87 (P=0)+m 87 (P=0.5)+m 87 [(P=1)] / 3,

[0040] m 85 =[m 85 (P=0)+m 85 (P=0.5)+m 85 (P=1)] / 3.

[0041] The rubidium atom gas chamber isotope ratio measurement device in step 1 includes a laser system 1, a gas chamber measurement system 2, and a signal extraction system 3 connected in sequence. The laser system 1, gas chamber measurement system 2, and signal extraction system 3 are respectively connected to an automated host computer 401. The gas chamber measurement system 2 includes a rubidium atom gas chamber 207, which is located inside an electrically heated oven 206. The electrically heated oven 206 is located inside a magnetic compensation coil. The magnetic compensation coil includes components connected to the automated host computer 401 via a signal generator 205. The automated host computer 401 has a z-axis opposed coil 202, an x-axis opposed coil 203, and a y-axis opposed coil 204. The laser system 1 includes a first laser 101 and a second laser 107. The laser frequency of the first laser 101 is located at the rubidium atom D1 line, and the laser of the first laser 101 is used to pass through the rubidium atom gas chamber 207 along the z-axis. The laser frequency of the second laser 102 is located at the rubidium atom D1 line detuned at 50 GHz, and the laser of the second laser 107 is used to pass through the rubidium atom gas chamber 207 along the x-axis. Step 2 involves applying a 0-50 nT linearly modulated bias magnetic field to the z-axis via the z-axis counter coil 202, inducing an observable slowing factor signal. Under each bias magnetic field, a 0-300 Hz linearly modulated calibration magnetic field is simultaneously applied to the y-axis via the y-axis counter coil 204, generating a magnetic resonance signal containing the slowing factor. An automated host computer 401 is used to acquire the magnetic resonance linewidth curves of the slowing factor output signal under different bias magnetic fields. Based on the magnetic resonance linewidth fitting program, the magnetic resonance frequencies under different bias magnetic fields are calculated. Through linear fitting, a set of nuclear spin slowing factor numerical measurements under the current steady-state polarization are obtained.

[0042] A rubidium isotope ratio measurement device based on a nuclear spin slowing factor is used to perform the above-mentioned rubidium isotope ratio measurement method based on a nuclear spin slowing factor. The system includes a first laser 101, a first acousto-optic modulator 102, a first non-polarizing beam splitter 103, a first half-wave plate 105, a quarter-wave plate 106, a reflector 208, a rubidium atom gas chamber 207, a third photodetector 209, and an automated host computer 401 connected in sequence. The reflecting side of the first non-polarizing beam splitter 103 is connected to the automated host computer 401 via the first photodetector 104. The rubidium atom gas chamber 207 is located inside an electrically heated oven 206, which is located inside a magnetic compensation coil. The magnetic compensation coil is located inside a multi-layer magnetic shielding barrel 201. The magnetic compensation coil includes a z-axis opposed coil 202, an x-axis opposed coil 203, and a y-axis opposed coil 204, which are respectively connected to the automated host computer 401 via a signal generator 205. The first laser 101 and the first acousto-optic modulator 102 are respectively connected to the automated host computer 401.

[0043] The system includes the input side of a second laser 107, a second acousto-optic modulator 108, a second unpolarized beam splitter 109, a rubidium atom gas cell 207, a second half-wave plate 301, and a polarized beam splitter 302 connected in sequence. The reflection side of the polarized beam splitter 302 is connected to the positive input (+) of a differential amplifier 305 via a fifth photodetector 304. The transmission side of the polarized beam splitter 302 is connected to the negative input (-) of the differential amplifier 305 via a fourth photodetector 303. The output of the differential amplifier 305 provides a slowing factor output signal to an automated host computer 401. The second laser 107 and the second acousto-optic modulator 108 are respectively connected to the automated host computer 401. The reflection side of the second unpolarized beam splitter 109 is connected to the automated host computer 401 via a second photodetector 110.

[0044] A device and method for measuring the proportion of rubidium isotopes based on nuclear spin slowing factors are disclosed. Using a pre-programmed automatic acquisition program for the nuclear spin slowing factor, two orthogonal laser beams are driven by an automated host computer. At different optical powers, a linearly amplitude-modulated bias magnetic field is applied to the z-axis using coils, and a linearly frequency-modulated calibration magnetic field is applied to the y-axis, automatically finding the magnetic resonance frequency of the high-temperature alkali metal gas chamber. The linear relationship between the magnetic resonance frequency and the bias magnetic field allows for the calculation of the gyromagnetic ratio, thus yielding the nuclear spin slowing factor of the atomic ensemble. Utilizing the relationship between the slowing factor and the isotope proportion, and the rubidium atomic isotope proportion, an overdetermined set of equations is solved, achieving accurate measurement of the gaseous isotope ratio in the rubidium atomic gas chamber. Compared to conventional methods, this device and method offer advantages such as accuracy, speed, simplicity, and lower cost, and do not require disruption of the sealed gas chamber structure.

[0045] refer to Figure 1As shown, a rubidium isotope ratio measurement device based on nuclear spin slowing factor is disclosed. The device includes a laser system (1), a gas chamber measurement system (2), a signal extraction system (3), and an automated host computer (401). In the laser system (1), a first laser (101), a half-wave plate (105), and a quarter-wave plate (106) are used to generate circularly polarized light in spatial light form, and a second laser (107) generates linearly polarized light in spatial light form. The optical power is stabilized for a long time through AOM and closed-loop control. In the gas chamber measurement system (2), a multi-layer magnetic shielding barrel (201) is used for triaxial geomagnetic elimination, and a z-axis opposing coil (202) and an x-axis opposing coil (203) are used for triaxial geomagnetic elimination. The signal extraction system (3) includes a y-axis countercoil (204) and a signal generator (205) for triaxial remanent magnetization compensation, and applies a bias magnetic field to excite an observable slowing factor signal. A calibration magnetic field is applied to generate a magnetic resonance signal containing slowing factor information. An electric heating oven (206) is used to heat the rubidium atom gas chamber (207). A reflector (208) and a third photodetector (209) are used to reflect circularly polarized light and receive optical signals. The signal extraction system (3) includes a half-wave plate (301), a polarizing beam splitter (302), a fourth photodetector (303), a fifth photodetector (304), and a differential amplifier (305) to generate a slowing factor output signal (306).

[0046] Using the programmed automatic control acquisition program for the nuclear spin slowing factor, instructions are sent to the first laser (101) and the second laser (107) through the communication interface of the automated host computer (401) to achieve optical power adjustment and frequency adjustment, thereby realizing the control of the nuclear spin slowing factor; instructions are sent to the signal generator (205) through the automated host computer (401) to generate bias magnetic field and calibration magnetic field in the z-axis opposing coil (202), x-axis opposing coil (203) and y-axis opposing coil (204); the voltage data of the slowing factor output signal (306) is acquired through the automated host computer (401) to realize the acquisition of nuclear spin slowing factor data and the calculation of the isotope ratio of rubidium atom gas chamber.

[0047] The laser power is collected in real time using a first non-polarizing beam splitter (NPBS) (103) and a second non-polarizing beam splitter (109) with a beam splitting intensity ratio of 90:10, and a first photodetector (104) and a second photodetector (110). The voltage changes of the first acousto-optic modulator (AOM) (102) and the second acousto-optic modulator (108) are driven by an automated host computer (401), and the closed-loop control program of the automated host computer (401) is used to achieve long-term stability of the two laser beams and ensure the long-term accuracy of the collected data.

[0048] A method for measuring the proportion of rubidium isotopes based on nuclear spin slowing factors is proposed. An automated host computer (401) with an automatic nuclear spin slowing factor control and acquisition program drives a signal generator (205). A 0-50 nT linearly modulated bias magnetic field is applied to the z-axis via a z-axis countercoil (202), inducing an observable slowing factor signal. Under each bias magnetic field, a 0-300 Hz linearly modulated calibration magnetic field is simultaneously applied to the y-axis via a y-axis countercoil (204), generating a magnetic resonance signal containing the slowing factor. The automated host computer (401) then acquires the signal. The magnetic resonance linewidth curves of the slow factor output signal (306) under different bias magnetic fields are obtained by using a written magnetic resonance linewidth fitting program to extract the magnetic resonance frequencies under different bias magnetic fields and inversely solve the nuclear spin slowing factor. At the same time, the automated host computer (401) drives the first laser (101) to automatically change the laser power. When the gas chamber is under a specific steady-state polarization, three sets of measurements are performed. Based on the three sets of results, the unbiased estimate of the rubidium atomic isotope ratio of the gas chamber is obtained by solving the following rubidium atomic isotope ratio equations and overdetermined equations, without destroying the sealed gas chamber structure.

[0049] Including the system of equations for calculating the rubidium atomic isotope ratio:

[0050]

[0051] Where q n (P) is the nuclear spin slowing factor, a function of the steady-state polarizability P, m 87 and m 85 yes 87 Rb and 85 The atomic number density ratios of the two Rb isotopes have a relationship m 87 +m 85 =1, P is the steady-state polarizability, which is related to the laser power; the first expression in this equation reflects the relationship between the nuclear spin slowing factor, the isotope ratio, and the steady-state polarizability P. Multiple measurements are performed on the first laser (101) driven by an automated host computer (401) at extremely low power, the power corresponding to the maximum response of the slowing factor output signal (306), and the highest power. The following overdetermined equations are then solved multiple times:

[0052]

[0053] The three steady-state polarizability conditions, P=0, P=0.5, and P=1, are generated by the extremely low laser power of the first laser (101), the laser power corresponding to the maximum response of the slowing factor output signal (306), and the highest laser power, respectively. eThe electron gyromagnetic ratio is 2π·28Hz / nT, γ is the atomic gyromagnetic ratio, and γ is the slope of the linear relationship between the bias magnetic field and the resonant frequency, which is related to the steady-state polarizability P. Based on the calculated results, averaging is performed to obtain an unbiased estimate of the accurate measurement of the isotopic proportions in the rubidium atomic gas chamber. 87 The isotopic percentage of Rb is m 87 =[m 87 (P=0)+m 87 (P=0.5)+m 87 [(P=1)] / 3, 85 The isotopic percentage of Rb is m 85 =[m 85 (P=0)+m 85 (P=0.5)+m 85 (P=1)] / 3.

[0054] The method for measuring the isotope ratio of rubidium atoms in a gas chamber using the aforementioned rubidium isotope ratio measurement device based on nuclear spin slowing factor includes the following steps:

[0055] Step 1: Initialize the lasers by using an automated host computer (401) to drive the first laser (101) and the second laser (107) to extremely low laser power (P=0), adjust the laser frequency of the first laser (101) to near the D1 line of rubidium atoms, and adjust the laser frequency of the second laser (107) to detuned 50GHz near the D1 line of rubidium atoms; perform triaxial magnetic compensation by installing the rubidium atom gas chamber (207) to be tested inside an electric heating oven (206) and heating it to 160°C, and using the automated host computer (401) to drive the signal generator (205) to compensate for the triaxial residual magnetic field through the z-axis counter coil (202), x-axis counter coil (203), and y-axis counter coil (204).

[0056] Step 2: A 0-50 nT linear amplitude bias magnetic field is applied to the z-axis through the z-axis counter coil (202) to induce an observable slowing factor signal. Under each bias magnetic field, a 0-300 Hz linear frequency calibration magnetic field is applied to the y-axis through the y-axis counter coil (204) to generate a magnetic resonance signal containing the slowing factor. The automated host computer (401) is used to collect the magnetic resonance linewidth curves of the slowing factor output signal (306) under different bias magnetic fields. According to the written magnetic resonance linewidth fitting program, the magnetic resonance frequency under different bias magnetic fields is calculated. Through linear fitting, a set of nuclear spin slowing factor numerical measurements under the current steady-state polarization are obtained.

[0057] Step 3: The first laser (101) is driven by an automated host computer (401) to automatically change the laser power and control the steady-state polarization. The measurement in step 2 is repeated at the laser power (P=0.5) corresponding to the maximum response of the slowing factor output signal (306) and the highest laser power (P=1) to obtain three sets of nuclear spin slowing factor measurement results under different steady-state polarization.

[0058] Step 4: Using the results of multiple measurements of the nuclear spin slowing factor, perform multiple calculations based on the rubidium atomic isotope ratio calculation equations and overdetermined equations to obtain an unbiased estimate of the accurate measurement of the rubidium atomic gas chamber isotope ratio.

[0059] The specific principle of the rubidium isotope ratio measurement device and method based on nuclear spin slowing factor of the present invention is as follows:

[0060] like Figure 1 As shown, the automatic control and acquisition program of the nuclear spin slowing factor of the automated host computer (401) drives the signal generator (205) to apply a 0-50nT linear amplitude bias magnetic field to the z-axis through the z-axis counter coil (202), thereby inducing an observable slowing factor signal. Under each bias magnetic field, a 0-300Hz linear frequency modulation calibration magnetic field is simultaneously applied to the y-axis through the y-axis counter coil (204), generating a magnetic resonance signal containing the slowing factor. The automated host computer (401) acquires the magnetic resonance linewidth curves of the slowing factor output signal (306) under different bias magnetic fields. The magnetic resonance linewidth fitting program is used to extract the magnetic resonance frequencies under different bias magnetic fields. The magnetic resonance linewidth curves are fitted using the following formula:

[0061]

[0062] Where V(f) is the amplitude of the response voltage signal under different frequency calibration magnetic fields, k is the fitting parameter, Δν is the magnetic resonance linewidth, is the full width at half maximum (FWHM) of the frequency response curve, f is the frequency of the calibration magnetic field, and ν L It is the resonant frequency corresponding to the resonant peak.

[0063] The linear relationship between the bias magnetic field and the resonance frequency can be used to solve for the nuclear spin slowing factor, which can be fitted using the following formula:

[0064]

[0065] Where ν L It is the resonant frequency corresponding to the resonance peak, γ e It is the electron gyromagnetic ratio 2π·28Hz / nT, q n It is the nuclear spin slowing factor, B z This is the amplitude of the bias magnetic field. Based on the slope γ of the fitted straight line... e / (2πqn The results of calculating the nuclear spin slowing factor were used to solve for the rubidium atomic isotope ratio using the following system of equations:

[0066]

[0067] Where q n It is the nuclear spin slowing factor, m 87 and m 85 yes 87 Rb and 85 The atomic number density ratio of the two Rb isotopes is equal to 1, and P is the steady-state polarizability. To accurately measure the isotope ratio of rubidium atoms in the gas chamber, an automated host computer (401) drives the first laser (101) to automatically change the laser power and perform multiple measurements. At the lowest power, the corresponding steady-state polarizability P = 0. The isotope ratio of rubidium atoms is calculated using the following formula:

[0068]

[0069] When the slowing factor output signal (306) reaches its maximum response, the corresponding steady-state polarizability P = 0.5. The rubidium atomic isotope ratio is calculated using the following formula:

[0070]

[0071] At the highest power, the corresponding steady-state polarizability P = 1, and the rubidium atomic isotope ratio is calculated using the following formula:

[0072]

[0073] Based on the results of the overdetermined equations, an unbiased estimate of the accurate measurement of the isotope ratio in the rubidium atomic gas chamber is obtained through averaging. 87 The isotopic percentage of Rb is m 87 =[m 87 (P=0)+m 87 (P=0.5)+m 87 [(P=1)] / 3, 85 The isotopic percentage of Rb is m 85 =[m 85 (P=0)+m 85 (P=0.5)+m 85 (P=1)] / 3.

[0074] Contents not described in detail in this specification are prior art known to those skilled in the art. It is hereby indicated that the above description is intended to help those skilled in the art understand this invention, but does not limit the scope of protection of this invention. Any equivalent substitutions, modifications, improvements, and / or simplifications of the above descriptions that do not depart from the essential content of this invention fall within the scope of protection of this invention.

Claims

1. A method for measuring the proportion of rubidium isotopes based on nuclear spin slowing factors, characterized in that, Includes the following steps: Step 1: Initialize the laser in the rubidium atomic gas chamber isotope ratio measurement device and perform triaxial magnetic compensation using z-axis, x-axis, and y-axis opposing coils; Step 2: By applying an amplitude-modulated bias magnetic field and a frequency-modulated calibration magnetic field, a magnetic resonance signal containing a slowing factor is generated; Step 3: Acquire and fit the slowing factor output signal. By changing the laser power, control the steady-state polarization. Repeat the measurement in step 2 at the laser power corresponding to the maximum response of the slowing factor output signal and at the highest laser power to obtain at least three sets of nuclear spin slowing factor measurement results under different steady-state polarization. Step 4: Use the rubidium atomic isotope ratio calculation equation set and the overdetermined equation set to calculate the rubidium atomic isotope ratio, and obtain an unbiased estimate of the rubidium atomic gas chamber isotope ratio for accurate measurement without destroying the sealed gas chamber structure.

2. The method for measuring the rubidium isotope ratio based on the nuclear spin slowing factor according to claim 1, characterized in that, The equations for calculating the rubidium atomic isotope ratio in step 4 are as follows: Where q n (P) is the nuclear spin slowing factor, a function of P, where P is the steady-state polarizability, and P is related to the laser power. 87 It is an isotope 87 The atomic number density ratio of Rb, and m 85 It is an isotope 85 The percentage of atomic number density of Rb.

3. The method for measuring the rubidium isotope ratio based on the nuclear spin slowing factor according to claim 2, characterized in that, The overdetermined system of equations is as follows: Where P = 0, P = 0.5, and P = 1 are nuclear spin slowing factors q. n Three steady-state polarizability conditions, γ e It is the electron gyromagnetic ratio, and γ is the atomic gyromagnetic ratio.

4. The method for measuring the rubidium isotope ratio based on the nuclear spin slowing factor according to claim 3, characterized in that, Step 4 involves averaging the calculated rubidium atomic isotope ratios to obtain an unbiased estimate of the accurate measurement of the rubidium atomic gas chamber isotope ratios, expressed as follows: m 87 =[m 87 (P=0)+m 87 (P=0.5)+m 87 (P=1)] / 3, m 85 =[m 85 (P=0)+m 85 (P=0.5)+m 85 (P=1)] / 3。 5. The method for measuring the rubidium isotope ratio based on the nuclear spin slowing factor according to claim 1, characterized in that, The rubidium atom gas cell isotope ratio measurement device in step 1 includes a laser system, a gas cell measurement system, and a signal extraction system connected in sequence. The laser system, gas cell measurement system, and signal extraction system are respectively connected to an automated host computer. The gas cell measurement system includes a rubidium atom gas cell located inside an electrically heated oven, which is located inside a magnetic compensation coil. The magnetic compensation coil includes a z-axis opposing coil, an x-axis opposing coil, and a y-axis opposing coil connected to the automated host computer via a signal generator. The laser system includes a first laser and a second laser. The laser frequency of the first laser is located at the rubidium atom D1 line, and the laser light from the first laser is used to pass through the rubidium atom gas cell along the z-axis. The laser frequency of the second laser is located at a detuned 50 GHz at the rubidium atom D1 line, and the laser light from the second laser is used to pass through the rubidium atom gas cell along the x-axis.

6. The method for measuring the rubidium isotope ratio based on the nuclear spin slowing factor according to claim 1, characterized in that, Step 2 involves applying a 0-50 nT linearly modulated bias magnetic field to the z-axis via a z-axis counter coil, inducing an observable slowing factor signal. Under each bias magnetic field, a 0-300 Hz linearly modulated calibration magnetic field is simultaneously applied to the y-axis via a y-axis counter coil, generating a magnetic resonance signal containing the slowing factor. An automated host computer is used to acquire the magnetic resonance linewidth curves of the slowing factor output signal under different bias magnetic fields. Based on the magnetic resonance linewidth fitting program, the magnetic resonance frequencies under different bias magnetic fields are calculated. Through linear fitting, a set of nuclear spin slowing factor numerical measurements under the current steady-state polarization are obtained.

7. A rubidium isotope ratio measurement device based on nuclear spin slowing factor, characterized in that, This method is used to perform the rubidium isotope ratio measurement method based on nuclear spin slowing factor as described in any one of claims 1-6.

8. The rubidium isotope ratio measuring device based on nuclear spin slowing factor according to claim 7, characterized in that, The system includes a first laser, a first acousto-optic modulator, a first non-polarizing beam splitter, a first half-wave plate, a quarter-wave plate, a reflector, a rubidium atom gas chamber, a third photodetector, and an automated host computer, all connected in sequence. The reflecting side of the first non-polarizing beam splitter is connected to the automated host computer via the first photodetector. The rubidium atom gas chamber is located inside an electrically heated oven, which is located inside a magnetic compensation coil. The magnetic compensation coil is located inside a multi-layer magnetic shielding barrel. The magnetic compensation coil includes a z-axis opposed coil, an x-axis opposed coil, and a y-axis opposed coil, each connected to the automated host computer via a signal generator. The first laser and the first acousto-optic modulator are also connected to the automated host computer.

9. The rubidium isotope ratio measuring device based on nuclear spin slowing factor according to claim 7, characterized in that, The system includes a second laser, a second acousto-optic modulator, a second unpolarized beam splitter, a rubidium atom gas cell, a second half-wave plate, and the input side of a polarized beam splitter connected in sequence. The reflective side of the polarized beam splitter is connected to the positive input of a differential amplifier via a fifth photodetector, and the transmissive side of the polarized beam splitter is connected to the negative input of the differential amplifier via a fourth photodetector. The output of the differential amplifier provides a slowing factor output signal to an automated host computer. The second laser and the second acousto-optic modulator are respectively connected to the automated host computer, and the reflective side of the second unpolarized beam splitter is connected to the automated host computer via a second photodetector.

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