SERF atom gyro signal detection device and method based on optical heterodyne method

Abstract

The invention discloses an SERF atomic gyro signal detection device and method based on an optical heterodyne method, and belongs to the technical field of atomic polarization stability control, after magnetic fields with x-axis frequency and y-axis frequency are applied to atoms in a sensitive unit air chamber, x-axis electron polarizability information under respective modulation frequencies comprises longitudinal polarizability information and longitudinal magnetic field information, and x-axis electron polarizability information and y-axis electron polarizability information under respective modulation frequencies comprise longitudinal polarizability information and longitudinal magnetic field information; the value of the longitudinal polarizability is obtained by resolving information contained in the two, and effective longitudinal polarizability closed-loop control is achieved through a liquid crystal phase delayer power stabilizing rate system. Based on the biaxial magnetic field modulation technology, interference of longitudinal magnetic field fluctuation on polarizability closed-loop control is effectively avoided, and effective polarizability in-situ closed-loop control is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of spin-exchange relaxation free (SERF) atomic gyroscope, and particularly relates to polarization stability control technology, and particularly relates to a SERF atomic gyroscope signal detection device and method based on optical heterodyne method. BACKGROUND

[0002] SERF atomic magnetometers, atomic gravimeters, etc. have been widely applied in the fields of basic physical research, medical disease research, biological magnetic field research, etc. and are the development direction of the next generation of precision measuring instruments. SERF atomic gyroscopes are considered as the development direction of the new generation of high-precision gyroscopes due to their ultra-high theoretical precision. However, there is still a large gap between the precision achieved at present and the theoretical limit, so it is of great significance to study the atomic polarization closed-loop control technology.

[0003] The traditional in-situ atomic spin polarization closed-loop control method indirectly obtains the longitudinal polarizability information of electrons by applying single-axis magnetic field modulation, but this method is simultaneously interfered by the longitudinal polarizability of electrons and the longitudinal magnetic field, and the sensitivity of this method to the longitudinal magnetic field is much higher than that to the electron polarization, so the in-situ electron polarization closed-loop method realized by this method is easily interfered by the longitudinal magnetic field, and therefore it is necessary to find an in-situ closed-loop control method for the longitudinal polarization of electrons which can effectively avoid the interference of the longitudinal magnetic field. SUMMARY

[0004] To solve the above technical problems, the present application provides a SERF atomic gyroscope signal detection device and method based on optical heterodyne method. Unlike the previous single-axis in-situ closed-loop control method, this method obtains two groups of signals containing polarizability and longitudinal magnetic field information by applying double-axis magnetic field modulation, and obtains the polarizability information by solving and effectively excludes the interference of the longitudinal magnetic field.

[0005] To achieve the above purpose, the present application adopts the following technical solutions:

[0006] A SERF atomic gyroscope signal detection device based on optical heterodyne method, comprising a pumping laser, a polarizer unit, a liquid crystal phase retarder, a quarter-wave plate, a polarization stability controller, a polarized atomic cell, a signal generator, an excitation coil, a detection laser, a third polarizer, a polarization beam splitter prism, a first photodetector, a second photodetector, and a lock-in amplifier; wherein,

[0007] The pumping laser emits light which is converted into linearly polarized light with changing optical power by the polarizer unit and the liquid crystal phase retarder, and then becomes circularly polarized light after passing through the quarter-wave plate and enters the polarized atomic cell to realize the continuous polarization of the atoms;

[0008] The signal generator applies modulation signals with frequencies of and to the excitation coils of the x-axis and y-axis respectively, which are located in the polarized atomic cell;

[0009] The detection laser emits linearly polarized light after passing through the third polarizer, and the linearly polarized light enters the polarized atomic cell to obtain a linearly polarized light signal containing polarization information. Then the linearly polarized light signal passes through a polarization beam splitter prism to form two linearly polarized lights with the same optical power. The two linearly polarized lights are detected by the first photodetector and the second photodetector respectively, and then enter the lock-in amplifier through difference. After processing the obtained signal, the lock-in amplifier sends the calculated polarization information to the liquid crystal phase retarder for stable control of the polarization rate based on the change of the degree of polarization.

[0010] Further, the frequencies of the two modulation signals output by the signal generator are in the range of 150Hz to 200Hz. and

[0011] Further, the polarizer unit includes a first polarizer and a second polarizer placed in sequence along the optical axis. The pump laser emits linearly polarized light after passing through the first polarizer. The linearly polarized light is deflected after passing through the liquid crystal phase retarder, and then enters the second polarizer and emits linearly polarized light with changed optical power.

[0012] Further, the linearly polarized light signal containing polarization information is adjusted by a half-wave plate, and then reaches the polarization beam splitter prism to form two linearly polarized lights with the same optical power.

[0013] Further, the lock-in amplifier processes the obtained signal to obtain two groups of signals with frequencies of and

[0014] Further, the sending of the calculated polarization information to the liquid crystal phase retarder for stable control of the polarization rate based on the change of the degree of polarization includes: the liquid crystal phase retarder changes the degree of polarization of the linearly polarized light based on the calculated polarization information, and the linearly polarized light with the changed degree of polarization changes the optical power of the pump light through the second polarizer, thereby realizing stable control of the polarization rate.

[0015] On the other hand, the application provides a SERF atomic gyroscope signal detection method based on optical heterodyne method, which is applied to the SERF atomic gyroscope signal detection device based on optical heterodyne method, and characterized by comprising the following steps:

[0016] Step 1, obtaining a linearly polarized light signal containing polarization information by differentiating the detection signals of the first photodetector and the second photodetector and​​ a modulated signal of frequency

[0017] Step 2, input the differential detection signal into a phase-locked amplifier, demodulate the amplitude signal containing the polarizability information through a rate controller, and send it to a liquid crystal phase delay device to realize the calculation of the polarizability information and the closed-loop control of the polarizability.

[0018] Further, the step 2 comprises:

[0019] The signal generator applies a modulated signal with a frequency of and to the excitation coils of the x-axis and y-axis respectively, so as to apply a modulated magnetic field to the polarized atomic cell, which is represented as:

[0020]

[0021]

[0022] wherein, and are the modulated magnetic fields applied to the x-axis and y-axis, and are the modulation amplitudes of the applied modulated magnetic fields, and respectively represent the modulation frequencies of the applied modulated magnetic fields, and t represents the time of wave propagation;

[0023] In the case of applying the modulated magnetic field, the electron transverse polarization component of the polarized atomic cell responds to the modulated magnetic field and enters the phase-locked amplifier through the differential detection signal to obtain and frequency information signals:

[0024]

[0025]

[0026] wherein, and respectively represent the frequency information signals obtained by the phase-locked amplifier, and represent the gyromagnetic ratio of the electron, represents the longitudinal polarizability of the electron, represents the slowing factor of the system, is the equivalent magnetic field of the electron, is the z-axis magnetic field interference from the outside world, is the total relaxation rate of the electron;

[0027] ​​​The longitudinal polarizability information of the electron is obtained by calculation of the stability rate controller, and the control of the longitudinal polarizability of the electron is realized.

[0028] In a third aspect, the present application provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned SERF atomic gyro signal detection method based on optical heterodyne method.

[0029] In a fourth aspect, the present application provides a computer readable storage medium, which stores executable instructions, and the instructions, when executed by a processor, enable the processor to implement the aforementioned SERF atomic gyro signal detection method based on optical heterodyne method.

[0030] The present application has the following beneficial effects:

[0031] The present application indirectly realizes the measurement of the electron polarizability by measuring the transverse polarizability information of the electron contained in the sensitive cell chamber after the x, y biaxial magnetic field modulation, and obtaining the polarizability information by calculation, thereby greatly suppressing the problem of in-situ closed-loop control of the longitudinal electron polarizability disturbed by the longitudinal magnetic field, and further realizing the closed-loop control, which is suitable for atomic magnetometer and atomic gravimeter. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 A SERF atomic gyro signal detection device based on optical heterodyne method.

[0033] Reference signs:

[0034] 1, pump laser, 2, first polarizer, 3, liquid crystal phase retarder, 4, second polarizer, 5, quarter-wave plate, 6, stability rate controller, 7, polarized atomic cell, 8, signal generator, 9, excitation coil, 10, detection laser, 11, third polarizer, 12, half-wave plate, 13, polarization beam splitter prism, 14, first photodetector, 15, second photodetector, 16, lock-in amplifier. DETAILED DESCRIPTION

[0035] The present application will be further described below in combination with the drawings and examples.

[0036] As Figure 1As shown, the SERF atomic gyro signal detection device based on the optical heterodyne method of the application comprises a pumping laser 1, a first polarizer 2, a liquid crystal phase retarder 3, a second polarizer 4, a quarter-wave plate 5, a stable rate controller 6, a polarized atomic cell 7, a signal generator 8, an excitation coil 9, a detection laser 10, a third polarizer 11, a half-wave plate 12, a polarization beam splitter prism 13, a first photodetector 14, a second photodetector 15, and a lock-in amplifier 16.

[0037] The light emitted by the pumping laser 1 arranged along the system optical axis passes through the first polarizer 2 to become linearly polarized light, then passes through the liquid crystal phase retarder 3 to make the linearly polarized light deflect, and then enters the second polarizer 4, and the outgoing linearly polarized light becomes circularly polarized light after passing through the quarter-wave plate 5, and finally enters the polarized atomic cell 7 to realize the continuous polarization of the atoms. The signal generator 8 applies modulation signals with frequencies of and to the x-axis and y-axis excitation coils 9 respectively, thereby applying a modulation magnetic field to the polarized atomic cell 7.

[0038] On the other hand, the application provides a SERF atomic gyro signal detection method based on the optical heterodyne method, which is applied to the above-mentioned device and can eliminate the polarization rate closed-loop control error introduced by the z-axis magnetic field fluctuation, and specifically comprises the following steps.

[0039] Step 1: Obtain the signal containing the polarization rate information through the differential detection of the first photodetector 14 and the second photodetector 15.

[0040] Step 2: Input the signal containing the polarization rate information into the lock-in amplifier 16 to demodulate the amplitude signal containing the polarization rate information, and finally realize the calculation of the polarization rate information and the closed-loop control of the polarization rate through the stable rate controller 6.

[0041] ​The x-axis and y-axis of the excitation coil 9 are applied with modulation signals by the signal generator 8, and the frequency is and respectively, and then the modulated magnetic field is applied to the polarized atomic cell 7, which is represented as:

[0042]

[0043] ,

[0044] wherein, and represent the modulated magnetic field applied to the x-axis and y-axis, and are the modulation amplitude of the applied modulated magnetic field, and represent the modulation frequency of the applied modulated magnetic field respectively, and t represents the time of wave propagation;

[0045] The electronic transverse polarization component of the polarized atomic cell 7 will respond to the modulated magnetic field, and after differential detection, it enters the lock-in amplifier 16 to obtain signals containing and frequency information, and the signals of different frequencies are:

[0046]

[0047] ,

[0048] wherein, and represent the signals containing and frequency information obtained by the lock-in amplifier 16, represents the gyromagnetic ratio of the electron, represents the longitudinal polarizability of the electron, represents the slowing-down factor of the system, is the equivalent magnetic field of the electron, is the z-axis magnetic field interference from the outside, is the total relaxation rate of the electron.

[0049] The signals containing and frequency information obtained by the lock-in amplifier 16 both contain the longitudinal polarizability information of the electron and the z-axis magnetic field information from the outside, so that the longitudinal polarizability information of the electron can be obtained through the calculation of the stability controller 6, and further the control of the longitudinal polarizability of the electron is realized.

[0050] In a third aspect, the present application provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; wherein the one or more programs, when executed by the one or more processors, enable the one or more processors to implement the above-mentioned SERF atom gyro signal detection method based on optical heterodyne method.

[0051] In a fourth aspect, the present application provides a computer-readable storage medium having stored thereon executable instructions that, when executed by a processor, enable the processor to implement the above-mentioned SERF atom gyro signal detection method based on optical heterodyne method.

[0052] The above-described specific embodiments further illustrate the purposes, technical solutions and beneficial effects of the present application, and it should be understood that the above-described specific embodiments are merely specific embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A SERF atomic gyroscope signal detection device based on optical heterodyne method, characterized in that, The system includes a pump laser (1), a polarizer unit, a liquid crystal phase delay unit (3), a quarter-wave plate (5), a power control unit (6), a polarized atomic gas cell (7), a signal generator (8), an excitation coil (9), a detection laser (10), a third polarizer (11), a polarizing beam splitter (13), a first photodetector (14), a second photodetector (15), and a lock-in amplifier (16); among which, The pump laser (1) outputs light through a polarizer unit and a liquid crystal phase delay unit (3) to be converted into linearly polarized light with altered optical power. After passing through a quarter-wave plate (5) to become circularly polarized light, it enters the polarized atomic gas cell (7) to achieve continuous polarization of atoms. The signal generator (8) applies a frequency of [frequency value] to the excitation coils (9) on the x-axis and y-axis respectively. and The modulation signal, the excitation coils (9) of the x-axis and y-axis are located in the polarized atomic gas chamber (7); The emitted light from the detection laser (10) is converted into linearly polarized light by the third polarizer (11) and then enters the polarized atomic gas cell (7) to obtain a linearly polarized light signal containing polarizability information. After passing through the polarization beam splitter (13), two beams of linearly polarized light with the same power are formed. They are detected by the first photodetector (14) and the second photodetector (15) respectively and then enter the lock-in amplifier (16) through differential. The lock-in amplifier (16) processes the obtained signal and sends it to the steady-state controller (6) for calculation. The calculated polarizability information is sent to the liquid crystal phase delay unit (3) for stable control of polarizability based on the change of polarization degree.

2. The SERF atomic gyroscope signal detection device based on optical heterodyne method according to claim 1, characterized in that, The two modulation signal frequencies output by the signal generator (8) and The frequency range is from 150Hz to 200Hz.

3. The SERF atomic gyroscope signal detection device based on optical heterodyne method according to claim 1, characterized in that, The polarizer unit includes a first polarizer (2) and a second polarizer (4) placed sequentially along the optical axis. The light emitted from the pump laser (1) is linearly polarized after passing through the first polarizer (2). After passing through the liquid crystal phase delay unit (3) to deflect the linearly polarized light, it is incident on the second polarizer (4) and emitted as linearly polarized light with changed optical power.

4. The SERF atomic gyroscope signal detection device based on optical heterodyne method according to claim 1, characterized in that, The linearly polarized light signal containing polarization information is adjusted by a half-wave plate (12) and then reaches a polarizing beam splitter (13) to form two beams of linearly polarized light with the same power.

5. The SERF atomic gyroscope signal detection device based on optical heterodyne method according to claim 1, characterized in that, The lock-in amplifier (16) processes the obtained signal to obtain two sets of frequencies respectively. and The signal.

6. The SERF atomic gyroscope signal detection device based on optical heterodyne method according to claim 3, characterized in that, The step of sending the calculated polarizability information to the liquid crystal phase retarder (3) for stable control of polarizability based on the change of polarization degree includes: the liquid crystal phase retarder (3) changes the polarization degree of the linearly polarized light based on the calculated polarizability information, and the linearly polarized light with the changed polarization degree changes the pump power through the second polarizer (4), thereby achieving stable control of polarizability.

7. A method for detecting SERF atomic gyroscope signals based on optical heterodyne, applied to the SERF atomic gyroscope signal detection device based on optical heterodyne as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Obtain information containing polarizability using the differential detection signals of the first photodetector (14) and the second photodetector (15). and Frequency modulation signal; Step 2: Input the differential detection signal into the lock-in amplifier (16), demodulate it through the steady-state controller (6) to obtain the amplitude signal containing polarizability information, and send it to the liquid crystal phase delay unit (3) to realize the calculation of polarizability information and closed-loop control of polarizability.

8. The SERF atomic gyroscope signal detection method based on optical heterodyne as described in claim 8, characterized in that, Step 2 includes: The signal generator (8) applies frequencies to the excitation coils (9) of the x-axis and y-axis respectively. and The modulation signal is used to apply a modulation magnetic field to the polarized atomic gas cell (7), as follows: ， in, and It is the modulated magnetic field applied along the x-axis and y-axis. and It is the modulation amplitude of the applied modulation magnetic field. and denoted by and , respectively, represent the modulation frequency of the applied modulation magnetic field, and t represents the wave propagation time; Under the application of a modulation magnetic field, the transverse polarization component of the polarized atomic gas cell (7) The signal responds to the modulated magnetic field and is then fed into the lock-in amplifier (16) via differential detection. and Frequency information signal: ， in, and These represent the results obtained by the lock-in amplifier (16), including... and Frequency information signal, The gyromagnetic ratio of an electron. Indicates the longitudinal polarizability of electrons. This represents the slowing factor of the system. It is the equivalent magnetic field of electrons. It is external z-axis magnetic field interference. It is the total relaxation rate of electrons; The longitudinal polarization information of electrons is obtained by the steady-state controller (6), thereby realizing the control of the longitudinal polarization of electrons.

9. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When one or more programs are executed by the one or more processors, the one or more processors implement the SERF atomic gyroscope signal detection method based on optical heterodyne method as described in any one of claims 7-8.

10. A computer-readable storage medium, characterized in that, It stores executable instructions that, when executed by a processor, enable the processor to implement the SERF atomic gyroscope signal detection method based on optical heterodyne as described in any one of claims 7-8.

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