阅读说明：本技术 一种基于外差干涉的气室温度控制系统 (Air chamber temperature control system based on heterodyne interference ) 是由 王卓 刘祀浔 袁琪 王瑞钢 庞昊颖 秦博东 于 2021-08-09 设计创作，主要内容包括：一种基于外差干涉的气室温度控制系统,通过使一束单色光在包含气室的光学系统中形成经过所述气室的第一合束光和不经过气室的第二合束光,以便利用第一合束光与第二合束光之间的光程差或相位差实现对气室温度的测量,从而以基于纯光场进行测温的方式减少单点测温带来的温度梯度,提高气室温度测量精度。(A first beam combination light passing through the air chamber and a second beam combination light not passing through the air chamber are formed in an optical system comprising the air chamber through a beam of monochromatic light, so that the temperature of the air chamber is measured by using the optical path difference or phase difference between the first beam combination light and the second beam combination light, the temperature gradient caused by single-point temperature measurement is reduced in a pure optical field-based temperature measurement mode, and the temperature measurement precision of the air chamber is improved.)

1. A heterodyne interference-based gas chamber temperature control system is characterized by comprising an optical system, wherein the optical system enables a beam of monochromatic light to form a first beam combination light passing through a gas chamber and a second beam combination light not passing through the gas chamber, and the measurement of the gas chamber temperature is realized by utilizing the optical path difference or phase difference between the first beam combination light and the second beam combination light.

2. The heterodyne interference-based gas cell temperature control system as recited in claim 1, wherein the first combined beam is connected to a signal processor through a first photodetector, the second combined beam is connected to the signal processor through a second photodetector, the signal processor is configured to calculate an optical path difference or a phase difference between the first combined beam and the second combined beam, and the signal processor is respectively connected to the temperature control system and the upper computer.

3. The heterodyne interference-based gas cell temperature control system of claim 1, wherein the optical system includes a laser for generating the monochromatic light, the laser is connected to a first polarization beam splitter prism, the first polarization beam splitter prism enables the monochromatic light to be input into a first beam and a second beam, the first beam and the second beam have the same size and orthogonal polarization directions, the first beam is connected to a third polarization beam splitter prism through a second reflecting mirror, the third polarization beam splitter prism enables the first beam to be divided into a third beam and a fourth beam, the third beam is connected to a second laser beam combiner, the fourth beam is connected to the first laser beam combiner through a third reflecting mirror, the second beam is connected to the second polarization beam splitter prism after being generated into a second beam modulated light through a modulator, and the second polarization beam splitter prism divides the second beam modulated light into a fifth beam and a sixth beam, the fifth beam of light reaches a first laser beam combining mirror through an air chamber and a first reflecting mirror, the first laser beam combining mirror combines the fifth beam of light and the fourth beam of light into the first combined beam of light, the sixth beam of light is connected with a second laser beam combining mirror, and the second laser beam combining mirror combines the sixth beam of light and the third beam of light into the second combined beam of light.

4. The heterodyne interference-based gas cell temperature control system of claim 3, wherein the modulator is a noise attenuator or an electro-optic modulator or an acousto-optic modulator.

5. The heterodyne interference-based gas cell temperature control system of claim 3, wherein the temperature control system performs PID (Proportion Integration Differentiation) closed-loop control (PID) on the gas cell temperature.

6. The heterodyne interference-based gas chamber temperature control system as recited in claim 1, wherein the real-time temperature of the gas chamber is obtained by the phase difference signal obtained by the signal processor after preliminary calibration data.

7. The heterodyne interference-based gas cell temperature control system of claim 6, wherein the real-time temperature of the gas cell is obtained as follows:

defining the optical signal detected by the first photoelectric detector as a measurement signal and the optical signal detected by the second photoelectric detector as a reference signal;

after the laser is modulated by the modulator, the laser and unmodulated laser are combined by a second laser beam combining mirror, and an electric vector signal E of a reference signal received by a second photoelectric detector_refComprises the following steps:

E_ref＝A₁cos(k_mz-ω_mt)

k_m＝π(v₁-v₂)/c＝ω_m/c

wherein A is₁Combined electric vector signal E measured for the second photodetector_refThe mean value of the high-frequency component in the unit detection time, i.e. a DC component A₁；ν₁V and v₂The beam frequencies before and after passing through the modulator respectively; k is a radical of_mThe wave number of the combined light vector; omega_mThe angular frequency of the combined light vector; c is the speed of light in vacuum;

the light intensity of the reference signal detected by the second photodetector is I_ref(t) is a quantity that varies with time t:

wherein phi_refThe initial phase is a constant value, and the magnitude of the initial phase is determined by the optical path difference of the two beams of light before beam combination;

for the same reason, laserAfter being modulated by the modulator and passing through the air chamber, the laser beam is combined with unmodulated laser through the first laser beam combining mirror and detected by the first photoelectric detector to obtain the light intensity I of the obtained measuring signal_meas(t) is a quantity that varies with time t:

wherein A is₂For the average value of the high-frequency component in the combined electric vector signal measured by the second photodetector in unit detection time, i.e. a DC component A₂(ii) a Phi 'is an initial phase, the size of the initial phase is determined by the optical path difference of the two beams of light before beam combination, and the value of phi' is not a constant value due to the existence of the air chamber and changes along with the change of the refractive index n of the air chamber;

at this time, the reference signal and the measurement signal are the same frequency signal, and the phase difference phi is₁Comprises the following steps:

φ₁＝φ_ref-φ′＝φ₀+2k_m(n-1)l

wherein phi₀Is a constant value determined by the size of the optical path except the gas chamber, i is the length of the optical path passing through the gas chamber, and ideally the diameter of the gas chamber.

8. The heterodyne interference-based gas cell temperature control system of claim 7, wherein the atomic density, i.e., the gas cell temperature, is obtained using the following equation in which the refractive index n of the gas cell is directly temperature dependent:

n＝1-K(ω)·n_atom

wherein n is_atomIs atomic density, which is in direct proportional correlation with temperature; k (ω) is the proportionality coefficient between atomic density and refractive index; ω is the laser frequency before passing through the modulator.

Technical Field

The invention relates to the technical field of air chamber temperature control systems, can be applied to air chamber temperature measurement, can meet pure optical temperature measurement, and is particularly suitable for all-optical temperature measurement of an alkali metal air chamber.

Background

The gas cell is a key component of many scientific devices, and is a core sensitive component particularly for quantum measurement instruments. Wherein, the temperature inevitably influences the performance of the air chamber, so the realization of high-precision measurement and stable control of the air chamber temperature is of great significance.

At present, the temperature measurement modes of the research object mainly comprise two types, the first type is contact type temperature measurement of a temperature sensor, the temperature sensor is in close contact with a temperature measurement target, and the temperature measurement result is sent to a temperature measurement host computer in a wired or wireless communication mode, but the temperature measurement method is single-point temperature measurement and is difficult to solve the problem of temperature gradient, the cost is rapidly increased when a plurality of temperature measurement points are available, and the interference of the environmental temperature is easily introduced; the second type is mainly an infrared temperature measurement method, which mainly relies on the infrared temperature measurement principle and has the advantages of high non-contact temperature measurement safety, low precision and difficult application to high-precision instruments.

In conclusion, with the development and popularization of the light beam modulation technology and the light beam synthesis technology, a wide prospect is designed for a gas chamber temperature system, and research practice and research in the aspect are relatively lacked. The design of this patent from the totality, air chamber temperature control system based on heterodyne interference will provide guidance and reference for similar air chamber temperature measurement design.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the defects of the prior art are overcome, the heterodyne interference-based air chamber temperature control system is provided, a beam of monochromatic light forms a first beam combining light passing through the air chamber and a second beam combining light not passing through the air chamber in an optical system comprising the air chamber, so that the measurement of the temperature of the air chamber is realized by using the optical path difference or phase difference between the first beam combining light and the second beam combining light, the temperature gradient caused by single-point temperature measurement is reduced in a pure optical field-based temperature measurement mode, and the air chamber temperature measurement precision is improved.

The technical solution of the invention is as follows:

a heterodyne interference-based gas chamber temperature control system is characterized by comprising an optical system, wherein the optical system enables a beam of monochromatic light to form a first beam combination light passing through a gas chamber and a second beam combination light not passing through the gas chamber, and the measurement of the gas chamber temperature is realized by utilizing the optical path difference or phase difference between the first beam combination light and the second beam combination light.

The first beam combining light is connected with the signal processor through the first photoelectric detector, the second beam combining light is connected with the signal processor through the second photoelectric detector, the signal processor is used for calculating an optical path difference or a phase difference between the first beam combining light and the second beam combining light, and the signal processor is respectively connected with the temperature control system and the upper computer.

The optical system comprises a laser device for generating the monochromatic light, the laser device is connected with a first polarization beam splitter prism, the first polarization beam splitter prism enables the input monochromatic light to form a first beam of light and a second beam of light which are identical in size and orthogonal in polarization direction, the first beam of light is connected with a third polarization beam splitter prism through a second reflecting mirror, the third polarization beam splitter prism enables the first beam of light to be divided into a third beam of light and a fourth beam of light, the third beam of light is connected with a second laser beam combiner, the fourth beam of light is connected with the first laser beam combiner through a third reflecting mirror, the second beam of light is connected with the second polarization beam splitter prism after being generated into a second beam of modulated light through a modulator, the second polarization beam splitter prism divides the second beam of modulated light into a fifth beam of light and a sixth beam of light, and the fifth beam of light reaches the first laser beam combiner through an air chamber and the first reflecting mirror, the first laser beam combining mirror combines the fifth beam of light and the fourth beam of light into the first combined beam of light, the sixth beam of light is connected with the second laser beam combining mirror, and the second laser beam combining mirror combines the sixth beam of light and the third beam of light into the second combined beam of light.

The modulator is a noise attenuator or an electro-optic modulator or an acousto-optic modulator.

The temperature control system performs a PID closed-loop control (PID) on the temperature of the gas chamber.

The phase difference signal obtained by the signal processor is subjected to early calibration data, and then the real-time temperature of the air chamber can be obtained.

The method for obtaining the real-time temperature of the air chamber comprises the following steps:

defining the optical signal detected by the first photoelectric detector as a measurement signal and the optical signal detected by the second photoelectric detector as a reference signal;

after the laser is modulated by the modulator, the laser and unmodulated laser are combined by a second laser beam combining mirror, and an electric vector signal E of a reference signal received by a second photoelectric detector_refComprises the following steps:

E_ref＝A₁ cos(k_mz-ω_mt）

k_m＝π(v₁-v₂)/c＝ω_m/c

wherein A is₁Combined electric vector signal E measured for the second photodetector_refThe mean value of the high-frequency component in the unit detection time, i.e. a DC component A₁；v₁And v₂The beam frequencies before and after passing through the modulator respectively; k is a radical of_mThe wave number of the combined light vector; omega_mThe angular frequency of the combined light vector; c is the speed of light in vacuum;

the light intensity of the reference signal detected by the second photodetector is I_ref(t) is a quantity that varies with time t:

wherein phi_refThe initial phase is a constant value, and the magnitude of the initial phase is determined by the optical path difference of the two beams of light before beam combination;

similarly, after the laser is modulated by the modulator and passes through the air chamber, the laser and the unmodulated laser are combined by the first laser beam combining mirror and detected by the first photoelectric detector to obtain the light intensity I of the measurement signal_meas(t) is a quantity that varies with time t:

wherein A is₂For the average value of the high-frequency component in the combined electric vector signal measured by the second photodetector in unit detection time, i.e. a DC component A₂(ii) a Phi 'is an initial phase, the size of the initial phase is determined by the optical path difference of the two beams of light before beam combination, and the value of phi' is not a constant value due to the existence of the air chamber and changes along with the change of the refractive index n of the air chamber;

at this time, the reference signal and the measurement signal are the same frequency signal, and the phase difference phi is₁Comprises the following steps:

φ₁＝φ_ref-φ′＝φ₀+2k_m(n-1)l

wherein phi₀Is a constant value determined by the size of the optical path except the gas chamber, i is the length of the optical path passing through the gas chamber, and ideally the diameter of the gas chamber.

The atomic density, i.e. the temperature of the gas cell, is obtained using the following formula, where the refractive index n of the gas cell is directly determined by the temperature:

n＝1-K(ω)·n_atom

wherein n is_atomIs atomic density, which is in direct proportional correlation with temperature; k (ω) is the proportionality coefficient between atomic density and refractive index; ω is the laser frequency before passing through the modulator.

The invention has the following technical effects: the heterodyne interference-based gas chamber temperature control system provided by the invention is characterized in that a gas chamber is taken as a research object, aiming at the temperature measurement problem of the gas chamber, a scheme for measuring the atomic density of the gas chamber by utilizing the optical path difference is established by utilizing a method of influencing the atomic density by the temperature and combining different refractive indexes brought by utilizing different atomic densities, and the design effect of measuring the temperature of the gas chamber by utilizing the optical path difference is realized. The invention carries out temperature measurement based on the pure optical field, has the characteristic of convenient engineering realization (such as high efficiency and convenient engineering realization) when meeting the design requirement, reduces the temperature gradient caused by single-point temperature measurement, improves the measurement precision, is suitable for products with the functions of measuring and controlling the temperature of the air chamber and has very wide application prospect.

The invention has the following characteristics: compared with the existing temperature measuring method of the contact temperature sensor, the method has the advantages that the temperature change condition in the air chamber is directly acquired by utilizing the optical information, and indirect measurement is not carried out through a temperature monitoring point outside the air chamber. The interference of environmental noise of a monitoring point is avoided, and common mode noise such as vibration and light intensity change is effectively inhibited through the introduction of a reference signal. The invention is a non-magnetic temperature measurement method, avoids the interference of electromagnetic noise to signals in the transmission process of temperature measurement signals, and has great practical value for the ultra-high sensitive inertia and magnetic field measurement device based on the atomic spin effect; compared with the existing non-contact temperature measurement method, the method has higher precision. The measured information is the information of the whole temperature field in the air chamber, and is not the temperature information of the surface of the air chamber measured by the technologies such as an infrared temperature measurement method and the like.

Drawings

FIG. 1 is a schematic structural diagram of a heterodyne interference-based gas chamber temperature control system for implementing the present invention.

The reference numbers are listed below: 1-a laser (for generating a beam of monochromatic light); 2-a first polarization splitting prism (used for forming a first beam and a second beam which have the same size and are orthogonal in polarization direction); 3-a second mirror (for transmitting the first beam of light to the third polarization splitting prism); a 4-modulator (for laser wavelength modulation, modulating the second beam of light into a second beam of modulated light); 5-a third mirror (for transmitting the fourth beam of light to the first laser beam combiner); 6-third polarization splitting prism (for splitting the first beam into third and fourth beams); 7-a second polarization splitting prism (for splitting the second beam of modulated light into a fifth beam of light and a sixth beam of light); 8-a second laser beam combiner (for combining the third beam of light and the sixth beam of light into a second combined beam of light); 9-gas cell (fifth beam of light passes through the gas cell to the first mirror); 10-first mirror (for transmitting the fifth beam of light to the first laser beam combiner); 11-a first laser beam combiner (for combining the fifth beam of light and the fourth beam of light into a first combined beam of light); 12-a first photodetector (for transmitting the first combined beam optical signal to a signal processor); 13-a second photodetector (for transmitting the second combined beam optical signal to the signal processor); 14-a signal processor (for calculating an optical path difference or a phase difference between the first combined beam of light and the second combined beam of light to achieve measurement of the temperature of the gas cell); 15-a temperature control system (used for controlling the temperature of the air chamber in real time according to the measurement result of the temperature of the air chamber); and 16-an upper computer (used for an instructor to observe the real-time measurement result of the temperature of the air chamber).

Detailed Description

The invention is described below with reference to the accompanying drawings (fig. 1) and examples.

FIG. 1 is a schematic structural diagram of a heterodyne interference-based gas chamber temperature control system for implementing the present invention. Referring to fig. 1, a heterodyne interference-based gas cell temperature control system includes an optical system, where the optical system makes a monochromatic light beam form a first combined light beam passing through a gas cell 9 and a second combined light beam not passing through the gas cell, and an optical path difference or a phase difference between the first combined light beam and the second combined light beam is used to realize measurement of a gas cell temperature. The first combined beam light is connected with a signal processor 14 through a first photoelectric detector 12, the second combined beam light is connected with the signal processor 14 through a second photoelectric detector 13, the signal processor 14 is used for calculating an optical path difference or a phase difference between the first combined beam light and the second combined beam light, and the signal processor 14 is respectively connected with a temperature control system 15 and an upper computer 16.

The optical system comprises a laser 1 for generating the monochromatic light, the laser 1 is connected with a first polarization beam splitter prism 2, the first polarization beam splitter prism 2 enables the input monochromatic light to form a first beam of light and a second beam of light which are identical in size and orthogonal in polarization direction, the first beam of light is connected with a third polarization beam splitter prism 6 through a second reflecting mirror 3, the third polarization beam splitter prism 6 enables the first beam of light to be divided into a third beam of light and a fourth beam of light, the third beam of light is connected with a second laser beam combiner 8, the fourth beam of light is connected with a first laser beam combiner 11 through a third reflecting mirror 5, the second beam of light is connected with a second polarization beam splitter prism 7 after being generated into a second beam of modulated light through a modulator 4, the second polarization beam splitter prism 7 divides the second beam of modulated light into a fifth beam of light and a sixth beam of light, and the fifth beam of light reaches the first laser beam combiner 11 through an air chamber 9 and a first reflecting mirror 10, the first laser beam combining mirror 11 combines the fifth beam of light and the fourth beam of light into the first combined beam of light, the sixth beam of light is connected with the second laser beam combining mirror 8, and the second laser beam combining mirror 8 combines the sixth beam of light and the third beam of light into the second combined beam of light. The modulator 4 is a noise attenuator or an electro-optic modulator or an acousto-optic modulator. The temperature control system 15 performs a PID closed-loop control (PID) on the temperature of the gas chamber.

The phase difference signal obtained by the signal processor is subjected to early calibration data, and then the real-time temperature of the air chamber can be obtained.

The method for obtaining the real-time temperature of the air chamber comprises the following steps:

defining the optical signal detected by the first photoelectric detector as a measurement signal and the optical signal detected by the second photoelectric detector as a reference signal;

after the laser is modulated by the modulator, the laser and unmodulated laser are combined by a second laser beam combining mirror, and an electric vector signal E of a reference signal received by a second photoelectric detector_refComprises the following steps:

E_ref＝A₁ cos(k_mz-ω_mt)

k_m＝π(v₁-v₂)/c＝ω_m/c

wherein A is₁Combined electric vector signal E measured for the second photodetector_refThe mean value of the high-frequency component in the unit detection time, i.e. a DC component A₁；v₁And v₂The beam frequencies before and after passing through the modulator respectively; k is a radical of_mThe wave number of the combined light vector; omega_mThe angular frequency of the combined light vector; c is the speed of light in vacuum;

the light intensity of the reference signal detected by the second photodetector is I_ref(t) is a quantity that varies with time t:

wherein phi_refThe initial phase is a constant value, and the magnitude of the initial phase is determined by the optical path difference of the two beams of light before beam combination;

similarly, after the laser is modulated by the modulator and passes through the air chamber, the laser and the unmodulated laser are combined by the first laser beam combining mirror and detected by the first photoelectric detector to obtain the light intensity I of the measurement signal_meas(t) is a quantity that varies with time t:

wherein A is₂For the average value of the high-frequency component in the combined electric vector signal measured by the second photodetector in unit detection time, i.e. a DC component A₂(ii) a Phi 'is an initial phase, the size of the initial phase is determined by the optical path difference of the two beams of light before beam combination, and the value of phi' is not a constant value due to the existence of the air chamber and changes along with the change of the refractive index n of the air chamber;

at this time, the reference signal and the measurement signal are the same frequency signal, and the phase difference phi is₁Comprises the following steps:

φ₁＝φ_ref-φ′＝φ₀+2k_m(n-1)l

wherein phi₀Is a constant value determined by the size of the optical path except the gas chamber, i is the length of the optical path passing through the gas chamber, and ideally the diameter of the gas chamber.

The refractive index n of the gas cell is directly determined by the temperature:

n＝l-K(ω)·n_atom

wherein n is_atomIs atomic density, which is in direct proportional correlation with temperature; k (ω) is the proportionality coefficient between atomic density and refractive index; ω is the laser frequency before passing through the modulator.

A heterodyne interference-based air chamber temperature control system comprises a modulator 4, a laser beam combiner 8, a signal processor 14 and a temperature control system 15; a laser 1 is used for generating a beam of monochromatic light, the monochromatic light is just divided into two paths of lights with the same size and orthogonal polarization directions after passing through a first polarization beam splitter 2, the first beam of light is divided into two beams of lights with the same size and orthogonal polarization directions after sequentially passing through a modulator 4 and a second polarization beam splitter 7, and the first beam of light reaches a first laser beam combiner 11 after sequentially passing through a gas chamber 9 and a first reflector 10; the second beam of light split by the second polarization beam splitter prism 7 is sent to a second laser beam combiner 8; the second beam of light split by the first polarization beam splitter prism is sequentially split into two beams of light with the same size and orthogonal polarization directions after passing through the second reflecting mirror 3 and the third polarization beam splitter prism 6, and the first beam of light is sent to the first laser beam combiner 11 after passing through the third reflecting mirror 5; the second beam of light split by the third polarization beam splitter prism 6 is sent to a second laser beam combiner 8; the first laser beam combiner 11 combines two beams and then passes through the first photoelectric detector 12, an optical signal is converted into a current signal and is transmitted to the signal processor 14, the second laser beam combiner 8 combines the two beams and then transmits the combined beam to the second photoelectric detector 13, and the optical signal is converted into a current signal and is transmitted to the signal processor 14; the signal processor 14 compares the two input signals, and feeds the result back to the temperature control system 15 for air chamber temperature control and the upper computer 16 for the instructor to observe.

The modulator 4 in the optical path is a noise attenuator, an electro-optic modulator or an acousto-optic modulator for modulating the laser wavelength. And the laser beam combining mirror is used for splitting or combining the laser with the specific wavelength.

A heterodyne interference-based gas chamber temperature control method comprises the following steps:

(1) a sine wave voltage signal or a square wave voltage signal with a certain frequency is applied to the modulator 4, so that the outgoing laser wavelength generates fixed modulation;

(2) in order to stabilize the temperature of the gas chamber, PID closed-loop control is required to be performed on the temperature, a signal processor 14 is used for subtracting a phase signal of light emitted by the first laser beam combining mirror 11 detected by the first photoelectric detector (12) from a phase signal of light emitted by the second laser beam combining mirror 8 detected by the second photoelectric detector 13, the phase difference is converted into a voltage signal through the signal processor 14 to serve as a feedback quantity, the voltage signal is sent to a PID controller of a temperature control system 15, and the temperature of the gas chamber is controlled in real time.

A heterodyne interference-based gas chamber temperature control system and method are disclosed, wherein the real-time temperature of a gas chamber is obtained through a phase difference signal obtained by a signal processor 14 and early calibration data.

(1) A laser (1) is used for generating a beam of monochromatic light, the monochromatic light is just divided into two paths of light with the same size and orthogonal polarization directions after passing through a first polarization beam splitter prism (2), the first beam of light is divided into two beams of light with the same size and orthogonal polarization directions after sequentially passing through a modulator (4) and a second polarization beam splitter prism (7), and the first beam of light reaches a first laser beam combiner (11) after sequentially passing through a gas chamber (9) and a first reflector (10); the second beam split by the second polarization beam splitter prism (7) is sent to a second laser beam combiner (8); the second beam of light split by the first polarization beam splitter prism is sequentially split into two beams of light with the same size and orthogonal polarization directions after passing through a second reflecting mirror (3) and a third polarization beam splitter prism (6), and the first beam of light is sent to a first laser beam combiner (11) after passing through a third reflecting mirror (5); the second beam split by the third polarization beam splitter prism (6) is sent to a second laser beam combiner (8); the first laser beam combiner (11) combines two beams and then passes through the first photoelectric detector (12), an optical signal is converted into a current signal and is transmitted to the signal processor (14), the second laser beam combiner (8) combines the two beams and then transmits the combined beam to the second photoelectric detector (13), and the optical signal is converted into a current signal and is transmitted to the signal processor (14); the signal processor (14) compares the two paths of input signals, and simultaneously feeds the result back to the temperature control system (15) for air chamber temperature control and the upper computer for a mentor to observe. The modulator (4) is a noise attenuator, an electro-optic modulator or an acousto-optic modulator (the performance can not meet the requirement) and is used for modulating the laser wavelength.

(2) A sine wave voltage signal or a square wave voltage signal with a certain frequency acts on the modulator (4) to enable the wavelength of the optical path to generate fixed modulation;

(3) in order to stabilize the temperature of the air chamber, PID closed-loop control is needed to be carried out on the temperature, a signal processor (14) is used for carrying out difference on a phase signal of light emitted by a first laser beam combining mirror (11) and detected by a first photoelectric detector (12) and a phase signal of light emitted by a second laser beam combining mirror (8) and detected by a second photoelectric detector (13), the phase difference is converted into a voltage signal serving as a feedback quantity through the signal processor (14) and is sent to a PID controller of a temperature control system (15), and the temperature of the air chamber is controlled in real time.

(4) Phase difference signals obtained through the signal processor (14) can be subjected to table lookup to obtain real-time temperature of the air chamber after early calibration data, namely:

the optical signal detected by the first photodetector (12) is defined as a measurement signal, and the optical signal detected by the second photodetector (13) is defined as a reference signal.

After being modulated by the modulator (4), the laser and unmodulated laser are combined by the second laser beam combining mirror (8), and an electric vector signal E of a reference signal received by the second photoelectric detector (13)_refComprises the following steps:

E_ref＝A₁ cos(k_m z-ω_m t)

k_m＝π(v₁-v₂)/c＝ω_m/c

wherein A is₁For combining electric vector signals E_refThe frequency of the high-frequency component is far larger than the bandwidth (60KHz-40GHz) of the second photoelectric detector (13), so that the finally measured part is the average value in unit detection time, namely a direct current quantity A₁；v₁And v₂The frequency of the light beam before and after passing through the modulator (4) respectively; k is a radical of_mThe wave number of the combined light vector; omega_mThe angular frequency of the combined light vector; c is the speed of light in vacuum.

The light intensity of the reference signal detected by the second photodetector (13) is I_ref(t) is a quantity that varies with time t:

wherein phi_refThe initial phase is a constant value, and the magnitude of the initial phase is determined by the optical path difference of the two beams before beam combination.

In the same way, the laser is modulated by the modulator (4) and passes throughAfter passing through the air chamber (9), the laser beam and unmodulated laser are combined through a first laser beam combining mirror (11) and detected by a first photoelectric detector (12), and the light intensity I of the obtained measurement signal_meas(t) is a quantity that varies with time t:

wherein A is₂Is the high frequency component in the combined electric vector signal, but because the frequency is far larger than the bandwidth (60KHz-40GHz) of the first photoelectric detector (12), the part finally measured is the average value in unit detection time, namely a direct current quantity A₂(ii) a Phi 'is an initial phase, the magnitude of which is determined by the optical path difference of the two beams before beam combination, and the value of phi' is not constant due to the existence of the air chamber (9), but changes along with the change of the refractive index n of the air chamber (9).

At this time, the reference signal and the measurement signal are the same frequency signal, and the phase difference phi is₁Comprises the following steps:

φ₁＝φ_ref-φ′＝φ₀+2k_m(n-1)l

wherein phi₀Is a constant value determined by the size of the optical path except the gas chamber (9), i is the length of the optical path passing through the gas chamber (9), ideally the diameter of the gas chamber (9).

In general, the refractive index n of the gas cell (9) is directly determined by the temperature and can be expressed in the form:

n＝1-K(ω)·n_atom

wherein n is_atomIs atomic density, which is in direct proportional correlation with temperature; k (ω) is the proportionality coefficient between atomic density and refractive index; omega is the laser frequency before passing through the modulator (4).

Compared with the prior art, the invention has the advantages that: the invention utilizes laser to measure the temperature of the air chamber, realizes the measurement of the temperature of the air chamber by measuring the atom density in the air chamber at different temperatures, and avoids the defect of low precision caused by single-point temperature measurement in the traditional temperature measurement mode. Meanwhile, the pure light field is adopted for temperature measurement, so that direct contact is avoided, interference caused by fluctuation of ambient temperature is reduced, and the temperature measurement precision is further improved.

In a word, compared with the existing temperature measurement method of the contact temperature sensor, the method has the advantages that the temperature change condition in the air chamber is directly acquired by using the optical information, and indirect measurement is not carried out through a temperature monitoring point outside the air chamber. The interference of environmental noise of a monitoring point is avoided, and common mode noise such as vibration and light intensity change is effectively inhibited through the introduction of a reference signal. The method is a non-magnetic temperature measurement method, avoids the interference of electromagnetic noise to signals in the transmission process of temperature measurement signals, and has great practical value for the ultrahigh-sensitivity inertia and magnetic field measurement device based on the atomic spin effect; compared with the existing non-contact temperature measurement method, the method has higher precision. The measured information is the information of the whole temperature field in the air chamber, and is not the temperature information of the surface of the air chamber measured by the technologies such as an infrared temperature measurement method and the like.

Those skilled in the art will appreciate that the invention may be practiced without these specific details. It is pointed out here that the above description is helpful for the person skilled in the art to understand the invention, but does not limit the scope of protection of the invention. Any such equivalents, modifications and/or omissions as may be made without departing from the spirit and scope of the invention may be resorted to.