CN106017783A - Method of measuring pressures of two gases in alkali metal gas chamber simultaneously - Google Patents

Abstract

The invention relates to a method of measuring the pressures of two gases in an alkali metal gas chamber simultaneously. First, an alkali metal gas chamber filled with two gases is heated and controlled at a stable temperature; then, the laser absorption spectra of an alkali metal atom wire D1 and an alkali metal atom wire D2 are measured separately, and the measured spectral lines are data-processed and fitted to get corresponding pressure broadening values; and finally, the pressures of the two gases are calculated according to the known spectral line pressure broadening values corresponding to unit pressure gases. The method is applicable to parameter detection of an alkali metal gas chamber which has large filling pressure and contains two gases, such as a gas chamber used in atomic magnetometers, atomic spin gyroscopes and other instruments.

Description

A kind of method of two kinds of gas pressure intensities in alkali metal air chamber of measurement simultaneously

Technical field

The present invention relates to a kind of measure the method for two kinds of gas pressure intensities in alkali metal air chamber simultaneously, can be used for atom magnetic strength The measurement of the alkali metal plenum interior gas parameter in the instruments such as meter, atomic spin gyroscope.

Background technology

Alkali metal air chamber is the core Sensitive Apparatus of the quantum measuring instrument such as atom magnetometer, atomic gyroscope.Alkali metal In air chamber in addition to alkali metal atom, generally also need to fill one or several gases of system.As a example by atom magnetometer, generally need Filling two kinds of gases of system, one is used for reducing bubble wall collision relaxation as buffer gas, and another kind is used for disappearing as cancellation gas Except radiation capture effect.The number filling gas processed in air chamber directly affects the relaxation of atom and choosing of other parameter of system, The most accurately the pressure of detection gas indoor gas has great significance.

Conventional detection method is to measure the laser absorption spectrum of alkali metal air chamber, owing to the gas of the system of filling can cause absorption The pressure broadening of spectral line, and the existing pertinent literature of the broadening of spectral lines that gas with various unit pressure causes is given, and therefore measures spectral line Broadening value just can calculate the pressure of gas.When generally adopting in this way, only measure one fine-structure levels correspondence of alkali metal Spectral line, measurement more accurate to gas pressure intensity can be realized when only having a kind of gas in air chamber, but when fill two kinds of gas of system Just cannot be distinguished by two kinds of gas respective pressure during body, the most generally ignore the gas that pressure is less, this can cause significantly surveying Amount error.

Summary of the invention

The problem that the present invention solves is: overcome the deficiency of existing conventional method, method based on laser absorption spectrum, it is provided that A kind of can measure the method for two kinds of gas pressure intensities in alkali metal air chamber simultaneously.It is fine that the method measures alkali metal atom two respectively The absorption line of energy level, and two spectral lines are carried out theoretical fitting obtain corresponding pressure broadening value, further according to known two kinds The broadening of spectral lines value that gas unit pressure causes calculates two kinds of respective pressure of gas.

The technical solution of the present invention is: a kind of method of two kinds of gas pressure intensities in alkali metal air chamber of measurement simultaneously, its Implementation method and step are as follows:

(1) alkali metal air chamber to be measured is heated and controls in stable temperature；

(2) wavelength tuning range narrow linewidth semiconductor laser near alkali metal atom D1 line is used, by narrow linewidth The laser of semiconductor laser output is irradiated in alkali metal air chamber frequency sweep, measures the transmitance of different frequency incident laser, from And calculate optical depth curve；Then optical depth curve is carried out Lorentzian matching, it is thus achieved that the spectral line pressure of D1 line Broadening value Γ_D1；

(3) laser instrument used in step (2) is replaced by wavelength tuning narrow linewidth near alkali metal atom D2 line Semiconductor laser, is irradiated in alkali metal air chamber frequency sweep by the laser that narrow linewidth semiconductor laser exports, and measures different frequency The transmitance of rate incident laser, thus calculate optical depth curve；Then optical depth curve is carried out Lorentzian plan Close, obtain spectral line pressure broadening value Γ of alkali metal atom D2 line_D2；

(4) alkali metal D1 line and D2 pressure broadening value Γ that the first gas unit pressure known causes are utilized_{g1_D1}With Γ_{g1_D2}, and the alkali metal D1 line that causes of known the second gas unit pressure and D2 pressure broadening value Γ_{g2_D1}And Γ_{g2_D2}, And the Γ obtained in step (2) and (3)_D1And Γ_D2, calculate two kinds of gas respective pressure P₁And P₂, the formula of employing is:

$\left\{\begin{array}{c}{P}_1{\mathrm{\Γ}}_{g1\_D1}+P_2{\mathrm{\Γ}}_{g2\_D1}={\mathrm{\Γ}}_{D1}\\ P_1{\mathrm{\Γ}}_{g1\_D2}+P_2{\mathrm{\Γ}}_{g2\_D2}={\mathrm{\Γ}}_{D2}\end{array}\right.$

Γ_{g1_D1}、Γ_{g1_D2}、Γ_{g2_D1}、Γ_{g2_D2}These 4 parameters refer to the pressure broadening value that unit pressure causes, and are Know size, Γ_D1And Γ_D2The value of the two parameter is the pressure broadening value that actual measurement obtains.

Fill in described alkali metal air chamber and be shaped with two kinds of gases, and the pressure broadening value that gas causes is much larger than nature exhibition Width and dopplerbroadening.

Optical depth curve computing formula in described step (2) is:

$OD\left(v\right)=-ln\frac{I_2}{I_1}$

Wherein v is the frequency of incident laser, I₂And I₁It is respectively alkali metal air chamber outgoing and the light intensity of incident laser.

Lorentzian in described step (2) is:

$L(v-v_0)=K\frac{{\mathrm{\Γ}}_L/2}{{(v-v_0)}^2+{({\mathrm{\Γ}}_L/2)}^2}$

Wherein K is proportionality coefficient, and v is laser frequency, v₀Centered by frequency, Γ_LFull width at half maximum for Lorentz curve.

The principle of the present invention is: the absorption line of alkali metal atom has certain width, deposits not having other gas There is nature broadening and dopplerbroadening in case.When there is gas in air chamber, spectral line there will be pressure broadening, pressure The size of power broadening is directly proportional to the pressure of gas, and when in air chamber, gas pressure intensity is bigger, pressure broadening will be much larger than nature exhibition Width and dopplerbroadening.The different fine-structure levels broadening value in different gas of alkali metal is different, existing a lot of relevant The pressure broadening value of each fine-structure levels spectral line that unit pressure gas is caused by document carried out detailed measurements.Therefore, by surveying The broadening of spectral lines value of two alkali metal fine-structure levels of amount, according to the known measurement in document, it is possible to calculate two kinds The pressure of gas.

Present invention advantage compared with prior art is: the present invention is by measuring two fine-structure levels D1 of alkali metal atom The pressure broadening value of line and D2 line, the spectral line pressure broadening value caused according to unit pressure known to institute's inflatable body, calculate two The pressure of kind of gas, it is to avoid that only measures that a fine-structure levels spectral line causes ignores less pressure gas problem, therefore improves The certainty of measurement of gas pressure intensity in air chamber.

Accompanying drawing explanation

Fig. 1 is the measuring method flow chart of the present invention；

Fig. 2 is the experimental provision schematic diagram that in the present invention, laser absorption spectrum is measured.

Detailed description of the invention

As it is shown in figure 1, the present invention to be embodied as step as follows:

(1) the alkali metal air chamber 8 that to be measured filling is shaped with two kinds of gases is installed in experimental system as shown in Figure 2, will It heats and controls in stable temperature.Laser instrument 1 is initially with tunable range narrow linewidth near alkali metal atom D1 Semiconductor laser, the laser of its output is divided into two-beam after fiber optic splitter 2, and a branch of transmission wavemeter 3 is to measure it Frequency, another bundle transmission is to optical fiber collimator 4.Laser in optical fiber is converted to spatial light output by optical fiber collimator 4, leads to afterwards Cross the polarizer 5 and be converted to line polarized light, be divided into two bundles, a branch of entrance by the depolarization Amici prism that splitting ratio is 1:1 afterwards Photodetector 7, another bundle is through entering photodetector 9 after alkali metal air chamber 8.Utilize photodetector 7 and 9 to measure to obtain Light intensity respectively I₂And I₁。

(2) by the output of laser instrument 1 frequency sweep near alkali metal atom D1 line, corresponding laser frequency v and light are recorded The output I of electric explorer₂And I₁, thus realize the measurement of absorption line.The light of alkali metal air chamber 8 is calculated according to experimental data Learning depth curve OD (v), formula is as follows:

$OD\left(v\right)=-ln\frac{I_2}{I_1}$

Utilizing Lorentzian that OD (v) carries out data matching, fitting formula is as follows:

$L(v-v_0)=K\frac{{\mathrm{\Γ}}_L/2}{{(v-v_0)}^2+{({\mathrm{\Γ}}_L/2)}^2}$

Wherein L (v-v₀) it is Lorentzian, K is proportionality coefficient, and v is laser frequency, v₀Centered by frequency, Γ_LFor long-range navigation Spectral line pressure broadening value Γ of the hereby full width at half maximum of curve, i.e. alkali metal atom D1 line_D1。

(3) laser instrument 1 used in step (2) is replaced by wavelength tuning narrow linewidth near alkali metal atom D2 line Semiconductor laser, by the output of laser instrument 1 frequency sweep near alkali metal atom D2 line, other experimentation and step (2) phase With, it is thus achieved that spectral line pressure broadening value Γ of alkali metal atom D2 line_D2；

(4) alkali metal D1 line and D2 pressure broadening value Γ that the first gas unit pressure known causes are utilized_{g1_D1}With Γ_{g1_D2}, and the alkali metal D1 line that causes of known the second gas unit pressure and D2 pressure broadening value Γ_{g2_D1}And Γ_{g2_D2}, And the Γ obtained in step (2) and (3)_D1And Γ_D2, calculate pressure size P of the gas of two kinds₁And P₂, computing formula is

$\left\{\begin{array}{c}{P}_1{\mathrm{\Γ}}_{g1\_D1}+P_2{\mathrm{\Γ}}_{g2\_D1}={\mathrm{\Γ}}_{D1}\\ P_1{\mathrm{\Γ}}_{g1\_D2}+P_2{\mathrm{\Γ}}_{g2\_D2}={\mathrm{\Γ}}_{D2}\end{array}\right.$

The content not being described in detail in description of the invention belongs to prior art known to professional and technical personnel in the field.

Claims (4)

1. measure the method for two kinds of gas pressure intensities in alkali metal air chamber for one kind, it is characterised in that comprise the following steps simultaneously:

(1) alkali metal air chamber to be measured is heated and controls in stable temperature；

(2) use wavelength tuning range narrow linewidth semiconductor laser near alkali metal atom D1 line, narrow linewidth is partly led The laser of body laser output is irradiated in alkali metal air chamber frequency sweep, measures the transmitance of different frequency incident laser, thus counts Calculate optical depth curve；Then optical depth curve is carried out Lorentzian matching, it is thus achieved that the spectral line pressure broadening of D1 line Value Γ_D1；

(3) laser instrument used in step (2) is replaced by wavelength tuning narrow linewidth near alkali metal atom D2 line partly to lead Body laser, is irradiated in alkali metal air chamber frequency sweep by the laser that narrow linewidth semiconductor laser exports, and measures different frequency and enters Penetrate the transmitance of laser, thus calculate optical depth curve；Then optical depth curve is carried out Lorentzian matching, Spectral line pressure broadening value Γ to alkali metal atom D2 line_D2；

(4) alkali metal D1 line and D2 pressure broadening value Γ that the first gas unit pressure known causes are utilized_{g1_D1}With Γ_{g1_D2}, and the alkali metal D1 line that causes of known the second gas unit pressure and D2 pressure broadening value Γ_{g2_D1}And Γ_{g2_D2}, And the Γ obtained in step (2) and (3)_D1And Γ_D2, calculate two kinds of gas respective pressure P₁And P₂, the formula of employing is:

$\left\{\begin{array}{c}{P}_1{\mathrm{\Γ}}_{g1\_D1}+P_2{\mathrm{\Γ}}_{g2\_D1}={\mathrm{\Γ}}_{D1}\\ P_1{\mathrm{\Γ}}_{g1\_D2}+P_2{\mathrm{\Γ}}_{g2\_D2}={\mathrm{\Γ}}_{D2}\end{array}\right.$

Γ_{g1_D1}、Γ_{g1_D2}、Γ_{g2_D1}、Γ_{g2_D2}These 4 parameters refer to the pressure broadening value that unit pressure causes, be known greatly Little, Γ_D1And Γ_D2The value of the two parameter is the pressure broadening value that actual measurement obtains.

The method of two kinds of gas pressure intensities in a kind of alkali metal air chamber of measurement simultaneously the most according to claim 1, its feature exists In: fill in described alkali metal air chamber and be shaped with two kinds of gases, and the pressure broadening value that causes of gas much larger than nature broadening with Dopplerbroadening.

The method of two kinds of gas pressure intensities in a kind of alkali metal air chamber of measurement simultaneously the most according to claim 1, its feature exists In: the optical depth curve computing formula in described step (2) is:

$OD\left(v\right)=-\ln \frac{I_2}{I_1}$

Wherein v is the frequency of incident laser, I₂And I₁It is respectively alkali metal air chamber outgoing and the light intensity of incident laser.

The method of two kinds of gas pressure intensities in a kind of alkali metal air chamber of measurement simultaneously the most according to claim 1, its feature exists In: the Lorentzian in described step (2) is:

$L(v-v_0)=K\frac{{\mathrm{\Γ}}_L/2}{{(v-v_0)}^2+{({\mathrm{\Γ}}_L/2)}^2}$

Wherein K is proportionality coefficient, and v is laser frequency, v₀Centered by frequency, Γ_LFull width at half maximum for Lorentz curve.