Low-frequency electric field measuring device and method

Abstract

The invention discloses a low-frequency electric field measuring device. Relates to the field of power frequency electric field measurement and solves the problem of electric field shielding during electric field measurement. The detection laser is generated through the quantum cascade laser and used for coupling the dipole molecules, the electric field intensity can be determined through the transition spectrum of the dipole molecules, and the dipole molecules do not generate free electrons for shielding an external electric field under the induction action of the external electric field, so that the shielding effect is avoided; by detecting energy level splitting caused by the Stark effect of the electric field, the electric field intensity is accurately and reversely deduced, and the limitation of a traditional method and a Rydberg atom technology in low-frequency electric field measurement is effectively solved.

Description

Technical Field

[0001] This application relates to the field of power frequency electric field measurement, and particularly to a low-frequency electric field measurement device. Background Art

[0002] Electric field sensors play an important role in fields such as electric power and national defense. With the rapid development of electric power technology, high-voltage direct current transmission systems have become an important part of the modern power grid structure. Quantum measurements based on Rydberg atoms rely on the Stark effect of electric fields on Rydberg atoms, use quantum coherent spectroscopy to measure energy level splitting, and infer electric field strength information. They have excellent characteristics such as high measurement accuracy, traceability to fundamental physical constants, and anti-electric field interference.

[0003] However, when a Rydberg atom electric field sensor measures low-frequency electric fields below kHz, a common technical problem is the electric field shielding effect. The specific mechanism is that after Rydberg atoms adsorb to the inner glass surface, free electrons will be generated under the action of factors such as laser excitation, thermal motion collision, or external electric field induction, thus forming a spatially closed conductive layer. Similar to the shielding effect of metals on external electric fields, free electrons are redistributed on the surface of the conductive layer, thereby shielding the external low-frequency or direct current electric field and causing the measurement method to fail.

[0004] Therefore, it can be seen that how to solve the electric field shielding problem during electric field measurement is a technical problem that needs to be urgently solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a low-frequency electric field measurement device to solve the electric field shielding problem during electric field measurement.

[0006] To solve the above technical problems, this application provides a low-frequency electric field measurement device, including: a quantum cascade laser, an optical path system, a dipole molecule gas cell, a data acquisition unit, a data processing module, and a control module; wherein, the dipole molecule gas cell is filled with dipole molecules;

[0007] The quantum cascade laser is connected to the optical path system through an optical fiber, the optical path system is connected to the dipole molecule gas cell, the data acquisition unit is connected to the dipole molecule gas cell, and the data processing module is connected to the data acquisition unit;

[0008] The control module controls the quantum cascade laser to generate probing laser, and the probing laser is incident on the dipole molecular gas cell through the optical path system to excite the molecules in the dipole molecular gas cell; the control module controls the data acquisition unit to collect the laser signal emitted from the dipole molecular gas cell, and processes the laser signal to obtain the transition spectrum between the lowest vibrational-rotational state and the lowest rotational state of the first vibrationally excited state; the control module controls the data processing module to determine the measured electric field strength of the space to be measured according to the transition spectrum.

[0009] As an optional solution, in the above-mentioned low-frequency electric field measurement device, the optical path system includes a first beam splitter, a second beam splitter, and a first reflector; the data acquisition unit includes: a reference photodetector and a measurement photodetector.

[0010] The quantum cascade laser is connected to the first beam splitter, and the probing laser generated by the quantum cascade laser is split into a reference laser and a measurement laser by the first beam splitter. Among them, the reference laser is incident on the second beam splitter, and the measurement laser is incident on the first reflector; the second beam splitter splits the reference laser into a first reference light and a second reference light, and enters the dipole molecular gas cell.

[0011] The first reference light enters the reference photodetector after passing through the dipole molecular gas cell; the second reference light enters the measurement photodetector through the first color mirror after passing through the dipole molecular gas cell; the measurement laser enters the measurement photodetector through the first color mirror after being reflected by the first reflector.

[0012] The output ends of the reference photodetector and the measurement photodetector are connected to the data processing module.

[0013] As an optional solution, in the above-mentioned low-frequency electric field measurement device, the dipole molecular gas cell is filled with HCl molecules.

[0014] As an optional solution, in the above-mentioned low-frequency electric field measurement device, the data processing module includes: a subtractor, a demodulator, and a data processing unit.

[0015] The output ends of the reference photodetector and the measurement photodetector are connected to the input end of the subtractor, the output end of the subtractor is connected to the demodulator, and the output end of the demodulator is connected to the data processing unit.

[0016] As an optional solution, in the above-mentioned low-frequency electric field measurement device, it further includes: an isolator, a first wave plate, and a first modulation signal source.

[0017] The output end of the first modulation signal source is connected to the quantum cascade laser and the demodulator.

[0018] The probing laser generated by the quantum cascade laser is incident on the first beam splitter through the isolator and the first wave plate in sequence.

[0019] As an alternative, the above low-frequency electric field measurement device further includes: a second wave plate, an electro-optic modulator, and a second modulation signal source;

[0020] The output end of the second modulation signal source is connected to the electro-optic modulator;

[0021] The reference laser passes through the electro-optic modulator and the second wave plate in sequence and is incident on the second beam splitter.

[0022] As an alternative, in the above low-frequency electric field measurement device, the frequency of the first modulation signal source is in the kHz order of magnitude, and the frequency of the second modulation signal source is in the MHz order of magnitude.

[0023] As an alternative, in the above low-frequency electric field measurement device, the wavelength of the probe laser generated by the quantum cascade laser is 6.749 micrometers.

[0024] To solve the above technical problems, the present application also provides a low-frequency electric field measurement method for a low-frequency electric field measurement device, where the low-frequency electric field measurement device includes: a quantum cascade laser, an optical path system, a dipole molecule gas cell, a data acquisition unit, a data processing module, and a control module; wherein, the dipole molecule gas cell is filled with dipole molecules; the quantum cascade laser is connected to the optical path system through an optical fiber, the optical path system is connected to the dipole molecule gas cell, the data acquisition unit is connected to the dipole molecule gas cell, and the data processing module is connected to the data acquisition unit; the method includes:

[0025] Controlling the quantum cascade laser to generate a probe laser, and the probe laser is incident on the dipole molecule gas cell through the optical path system to excite the molecules in the dipole molecule gas cell;

[0026] Controlling the data acquisition unit to collect the laser signal emitted from the dipole molecule gas cell, and processing the laser signal to obtain the transition spectrum between the lowest vibrational-rotational state and the lowest rotational state of the first vibrationally excited state;

[0027] Controlling the data processing module to determine the measured electric field strength of the space to be measured according to the transition spectrum.

[0028] As an alternative, the above low-frequency electric field measurement method further includes:

[0029] After applying a low-frequency electric field with a known electric field strength, entering the step of controlling the quantum cascade laser to generate a probe laser, and the probe laser is incident on the dipole molecule gas cell through the optical path system to excite the molecules in the dipole molecule gas cell;

[0030] Determining the attenuation factor according to the measured electric field strength and the known electric field strength.

[0031] The low-frequency electric field measurement device provided by this application includes: a quantum cascade laser, an optical path system, a dipole molecule gas cell, a data acquisition unit, a data processing module, and a control module; wherein, the dipole molecule gas cell is filled with dipole molecules; the quantum cascade laser is connected to the optical path system through an optical fiber, the optical path system is connected to the dipole molecule gas cell, the data acquisition unit is connected to the dipole molecule gas cell, and the data processing module is connected to the data acquisition unit; the control module controls the quantum cascade laser to generate a probing laser, the probing laser is incident on the dipole molecule gas cell through the optical path system to excite the molecules in the dipole molecule gas cell; the control module controls the data acquisition unit to collect the laser signal emitted from the dipole molecule gas cell, and processes the laser signal to obtain the transition spectrum between the lowest vibrational-rotational state and the lowest rotational state of the first vibrationally excited state; the control module controls the data processing module to determine the measured electric field strength of the space to be measured according to the transition spectrum. This application generates a probing laser through a quantum cascade laser for coupling dipole molecules, and the electric field strength can be determined through the transition spectrum of the dipole molecules. Since dipole molecules do not generate free electrons that shield the external electric field under the induction of an external electric field, there is no shielding effect. By detecting the energy level splitting caused by the electric field Stark effect, the electric field strength can be accurately deduced, effectively solving the limitations of traditional methods and Rydberg atom technology in low-frequency electric field measurement.

[0032] In addition, this application also provides a low-frequency electric field measurement method, corresponding to the above low-frequency electric field measurement device, with the same effect. Description of the Drawings

[0033] To more clearly illustrate the embodiments of this application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 It is a schematic diagram of a low-frequency electric field measurement device provided by an embodiment of this application;

[0035] Figure 2 It is a flowchart of a low-frequency electric field measurement method provided by an embodiment of this application.

[0036] Reference Signs:

[0037] 1 - Quantum cascade laser; 22 - Isolator; 31 - First waveplate; 32 - Second waveplate; 41 - First beam splitter; 42 - Second beam splitter; 51 - First mirror; 52 - Second mirror; 53 - Third mirror; 16 - First color mirror; 17 - Dipole molecular gas cell; 81 - Reference photodetector; 82 - Measurement photodetector; 91 - First modulation signal source; 92 - Second modulation signal source; 10 - Subtractor; 11 - Demodulator; 12 - Data processing unit; 13 - Electro - optic modulator. Detailed implementation manners

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0039] The core of the present application is to provide a low - frequency electric - field measurement device.

[0040] To enable those skilled in the art to better understand the solution of the present application, the present application will be further described in detail below with reference to the drawings and specific implementation manners.

[0041] When a Rydberg - atom electric - field sensor measures low - frequency electric fields below kHz, a common technical problem is the electric - field shielding effect. The specific mechanism is that after Rydberg atoms are adsorbed on the inner - layer glass surface, free electrons will be generated under the action of factors such as laser excitation, thermal - motion collision, or external - electric - field induction, thus forming a spatially closed conductive layer. Similar to the shielding effect of metals on external electric fields, free electrons are redistributed on the surface of the conductive layer, thereby shielding the external low - frequency or DC electric fields, resulting in the failure of the measurement method.

[0042] To overcome the electric - field shielding problem, traditional methods mainly explore from two directions: internalizing the atom - gas - cell electrodes and reducing the electrical conductivity of the inner - glass surface. Although internalizing the electrodes in the atom gas cell can study the atomic spectral response characteristics under low - frequency electric fields, it cannot measure the low - frequency electric fields outside the atom gas cell. In the direction of reducing the electrical conductivity of the inner - glass surface, by using sapphire materials or doped materials to make the atom gas cell, or using a four - energy - level three - laser coupling scheme to reduce the number of free electrons, the low - frequency electric - field shielding rate of the atom gas cell can be reduced to a certain extent. However, the attenuation of the external electric field in the atom gas cell increases rapidly as the electric - field frequency decreases. Therefore, in the ultra - low - frequency working region, especially near the power - frequency electric - field frequency concerned in the industrial field, there is almost no anti - shielding effect, and the anti - shielding effect fails completely in the DC - electric - field region.

[0043] To solve the above problems, an embodiment of the present application provides a low-frequency electric field measurement device, including: a quantum cascade laser 1, an optical path system, a dipole molecule gas cell 17, a data acquisition unit, a data processing module, and a control module; wherein, the dipole molecule gas cell 17 is filled with dipole molecules;

[0044] The quantum cascade laser 1 is connected to the optical path system through an optical fiber, the optical path system is connected to the dipole molecule gas cell 17, the data acquisition unit is connected to the dipole molecule gas cell 17, and the data processing module is connected to the data acquisition unit;

[0045] The control module controls the quantum cascade laser 1 to generate a probe laser, the probe laser is incident on the dipole molecule gas cell 17 through the optical path system, and excites the molecules in the dipole molecule gas cell 17; the control module controls the data acquisition unit to collect the laser signal emitted by the dipole molecule gas cell 17, and processes the laser signal to obtain the transition spectrum between the lowest vibrational-rotational state and the lowest rotational state of the first vibrationally excited state; the control module controls the data processing module to determine the measured electric field strength of the space to be measured according to the transition spectrum.

[0046] In this embodiment, the quantum cascade laser 1 is used as a laser light source to generate a probe laser with a specific wavelength for exciting the dipole molecules in the dipole molecule gas cell 17. The specific data of the laser wavelength is not limited in this embodiment. In a specific embodiment, the wavelength of the quantum cascade laser 1 is set to 6.749 micrometers, and this wavelength can efficiently couple the specific energy level transitions of hydrogen chloride (HCl) molecules. Under specific conditions, other types of lasers can be selected as the light source as long as they can generate a laser wavelength suitable for exciting dipole molecules. Figure 1 The control module is not shown in the figure. The control module is used to control the overall test process.

[0047] The optical path system is used to guide the laser generated by the quantum cascade laser 1 to be incident on the dipole molecule gas cell 17, and may include various optical elements for optimizing the optical path. It may include optical elements such as an isolator 22, a wave plate, a beam splitter, a mirror, and a color mirror, which are used to ensure that the laser is incident on the dipole molecule gas cell 17 in the best way, and may include an optical path design for eliminating background noise and optimizing signal processing. The specific composition of the optical path system is not limited as long as it can achieve efficient guidance of the laser and elimination of background noise.

[0048] Dipole molecule gas cell 17: It is internally filled with dipole molecules (such as HCl). Under laser excitation, the energy levels of the dipole molecules will change, and this change is related to the external electric field strength, which is the key to measuring the electric field strength. By replacing the gas cell filling molecules, such as carbon monoxide (CO), different frequency band electric field measurement requirements can be adapted.

[0049] The data acquisition unit is responsible for collecting and processing the laser signal emitted from the dipole molecular gas cell 17. It may include steps such as signal amplification, filtering, modulation and demodulation, etc.

[0050] The data processing module receives the processing result of the data acquisition unit, and determines the electric field strength of the space to be measured by analyzing the frequency or intensity change of the laser signal.

[0051] The low-frequency electric field measurement device provided by the embodiment of the present application includes: a quantum cascade laser 1, an optical path system, a dipole molecular gas cell 17, a data acquisition unit, a data processing module, and a control module; wherein, the dipole molecular gas cell 17 is filled with dipole molecules; the quantum cascade laser 1 is connected to the optical path system through an optical fiber, the optical path system is connected to the dipole molecular gas cell 17, the data acquisition unit is connected to the dipole molecular gas cell 17, and the data processing module is connected to the data acquisition unit; the control module controls the quantum cascade laser 1 to generate a probe laser, the probe laser is incident on the dipole molecular gas cell 17 through the optical path system to excite the molecules in the dipole molecular gas cell 17; the control module controls the data acquisition unit to collect the laser signal emitted from the dipole molecular gas cell 17, and processes the laser signal to obtain the transition spectrum between the lowest vibrational-rotational state and the lowest rotational state of the first vibrationally excited state; the control module controls the data processing module to determine the measured electric field strength of the space to be measured according to the transition spectrum. In the present application, the quantum cascade laser 1 generates a probe laser for coupling dipole molecules, and the electric field strength can be determined through the transition spectrum of the dipole molecules. Since the dipole molecules do not generate free electrons that shield the external electric field under the induction of the external electric field, there is no shielding effect. By detecting the energy level splitting caused by the electric field Stark effect, the electric field strength can be accurately deduced, effectively solving the limitations of traditional methods and Rydberg atom technology in low-frequency electric field measurement.

[0052] According to the above embodiment, in an alternative embodiment, in the above low-frequency electric field measurement device, the optical path system includes a first beam splitter 41, a second beam splitter 42, and a first mirror 51; the data acquisition unit includes: a reference photodetector 81 and a measurement photodetector 82;

[0053] The quantum cascade laser 1 is connected to the first beam splitter 41, and the probe laser generated by the quantum cascade laser 1 is split into a reference laser and a measurement laser by the first beam splitter 41. Among them, the reference laser is incident on the second beam splitter 42, and the measurement laser is incident on the first mirror 51; the second beam splitter 42 splits the reference laser into a first reference light and a second reference light, and enters the dipole molecular gas cell 17;

[0054] The first reference light enters the reference photodetector 81 after passing through the dipole molecular gas cell 17; the second reference light enters the measurement photodetector 82 through the first dichroic mirror 16 after passing through the dipole molecular gas cell 17; the measurement laser is emitted by the first mirror 51 and enters the measurement photodetector 82 through the first dichroic mirror 16;

[0055] The output ends of the reference photodetector 81 and the measurement photodetector 82 are connected to the data processing module.

[0056] The first beam splitter 41 divides the incident laser into a reference laser and a measurement laser, and the splitting ratio is adjustable. Specifically, the two beams of light are the same.

[0057] The second beam splitter 42 further divides the reference laser into a first reference light and a second reference light.

[0058] The first mirror 51 reflects the measurement laser to the first dichroic mirror 16 to ensure that there is no additional phase distortion in the optical path. In the specific optical path, optical path elements can be added according to actual needs, such as Figure 1 As shown, the first mirror 51 reflects to the second mirror 52 and then enters the first dichroic mirror 16. The first reference light enters the dipole molecular gas cell 17 through the third mirror 53.

[0059] The first dichroic mirror 16 is used to filter out stray light and only allows specific wavelengths of the reference light and the measurement laser to enter the detector.

[0060] In the above components, the specific models used in this embodiment are not specifically limited and can be set according to actual needs.

[0061] The reference photodetector 81 is used to receive the first reference light (the reference signal not affected by the electric field). The measurement photodetector 82 receives the superimposed signal of the second reference light (modulated by the electric field) and the measurement laser (directly affected by the electric field).

[0062] The reference photodetector 81 collects the first reference light not affected by the electric field. The measurement photodetector 82 simultaneously receives the second reference light modulated by the electric field and the measurement laser directly affected by the electric field, and extracts the electric field information by comparing the differences between the two signals.

[0063] According to the above embodiment, in an alternative embodiment, in the above low-frequency electric field measurement device, the data processing module includes: a subtractor 10, a demodulator 11, and a data processing unit 12;

[0064] The output ends of the reference photodetector 81 and the measurement photodetector 82 are connected to the input end of the subtractor 10, the output end of the subtractor 10 is connected to the demodulator 11, and the output end of the demodulator 11 is connected to the data processing unit 12.

[0065] The subtractor 10 receives the raw electrical signals from the reference photodetector 81 and the measurement photodetector 82, and performs a differential operation to eliminate the common-mode noise. Specifically, a differential amplifier circuit can be constructed using a high-precision operational amplifier.

[0066] The demodulator 11 extracts the modulation components (such as frequency or phase changes) related to the electric field strength from the differential signal. For DC electric field measurement, the demodulator 11 can be replaced by a low-pass filter (such as a cut-off frequency of 1 Hz) to directly extract the DC component of the signal.

[0067] The data processing unit 12 converts the demodulated signal into an electric field strength value, and completes calibration, filtering, and data output.

[0068] In this embodiment, through the cascaded architecture of the subtractor 10 and the demodulator 11 processing unit, a high-fidelity conversion from the original optoelectronic signal to the electric field strength is achieved, providing a complete signal chain solution for unshielded and high-precision low-frequency electric field measurement.

[0069] According to the above embodiment, in an alternative embodiment, the above low-frequency electric field measurement device further includes: an isolator 22, a first wave plate 31, and a first modulation signal source 91;

[0070] The output end of the first modulation signal source 91 is connected to the quantum cascade laser 1 and the demodulator 11;

[0071] The probing laser generated by the quantum cascade laser 1 is incident on the first beam splitter 41 through the isolator 22 and the first wave plate 31 in sequence.

[0072] The isolator 22 prevents the reflected light from returning to the quantum cascade laser 1, avoiding laser frequency instability.

[0073] The first wave plate 31 converts the linearly polarized light of the quantum cascade laser 1 into circularly polarized light, enhancing the symmetry of the light-electric field interaction in the dipole molecular cell 17.

[0074] The first modulation signal source 91 outputs a square wave / sine wave with an adjustable frequency of 1 - 100 kHz, synchronously triggering the quantum cascade laser 1 and the demodulator 11. The current of the quantum cascade laser 1 is modulated to periodically fine-tune the laser wavelength.

[0075] In this embodiment, through modulation enhancement and polarization optimization techniques, the sensitivity and robustness of low-frequency electric field measurement are significantly improved.

[0076] According to the above embodiment, in an alternative embodiment, the above low-frequency electric field measurement device further includes: a second wave plate 32, an electro-optic modulator 13, and a second modulation signal source 92;

[0077] The output end of the second modulation signal source 92 is connected to the electro-optic modulator 13;

[0078] The reference laser passes through the electro-optic modulator 13 and the second wave plate 32 in sequence and is incident on the second beam splitter 42.

[0079] The electro-optic modulator 13 (EOM) performs phase modulation on the reference laser. The demodulator 11 can extract the electric field signal in the modulation sideband based on the reference frequency of the second modulation signal source 92.

[0080] The second wave plate 32 adjusts the polarization direction of the reference laser and cooperates with the second beam splitter 42 (polarizing beam splitter) to achieve polarization modulation and suppress stray light interference.

[0081] The second modulation signal source 92 outputs a sinusoidal wave with an adjustable frequency of 1 MHz - 1 GHz, drives the EOM to generate periodic phase modulation, and synchronously triggers with the demodulator 11 to achieve demodulation. The signal spectrum is shifted to the high-frequency region through 1 MHz sinusoidal modulation to avoid low-frequency noise.

[0082] In this embodiment, through electro-optic modulation and polarization coding technologies, active optimization of the reference laser link is achieved.

[0083] According to the above embodiment, in an alternative embodiment, in the above low-frequency electric field measurement device, the frequency of the first modulation signal source 91 is in the kHz range and the frequency of the second modulation signal source 92 is in the MHz range.

[0084] Set the frequency of the first modulation signal source 91 in the kHz range, set the frequency of the second modulation signal source 92 in the MHz range, and set the demodulation mode to intensity demodulation. The hybrid modulation supports wideband electric field measurement from DC to 10 kHz.

[0085] To solve the above problems, an embodiment of the present application also provides a low-frequency electric field measurement method for a low-frequency electric field measurement device, including: a quantum cascade laser 1, an optical path system, a dipole molecular gas cell 17, a data acquisition unit, a data processing module, and a control module; wherein, the dipole molecular gas cell 17 is filled with dipole molecules; the quantum cascade laser 1 is connected to the optical path system through an optical fiber, the optical path system is connected to the dipole molecular gas cell 17, the data acquisition unit is connected to the dipole molecular gas cell 17, and the data processing module is connected to the data acquisition unit; the probe laser generated by the quantum cascade laser 1 is incident on the dipole molecular gas cell 17 through the optical path system to excite the molecules in the dipole molecular gas cell 17; the data acquisition unit collects and processes the laser signal emitted from the dipole molecular gas cell 17 and sends the signal processing result to the data processing module; the data processing module analyzes and determines the electric field strength in the space to be measured;

[0086] The method includes:

[0087] S11: Control the quantum cascade laser to generate a probe laser, and the probe laser is incident on the dipole molecular gas cell through the optical path system to excite the molecules in the dipole molecular gas cell;

[0088] S12: Control the data acquisition unit to collect the laser signal emitted from the dipole molecular cell, and process the laser signal to obtain the transition spectrum between the lowest vibrational-rotational state and the lowest rotational state of the first vibrationally excited state.

[0089] S13: Control the data processing module to determine the measured electric field strength of the space to be measured according to the transition spectrum.

[0090] The low-frequency electric field measurement method of this embodiment is particularly suitable for environments that require high-precision and high-sensitivity measurement of low-frequency electric fields (such as in the range of 0.1 Hz to 10 kHz). This method combines a quantum cascade laser 1 (QCL), an optical path system, a dipole molecular cell 17, a data acquisition unit, and a data processing module to achieve precise capture and analysis of weak electric field signals.

[0091] In step S11, control the quantum cascade laser 1 to generate a probe laser, which is incident on the dipole molecular cell 17 through the optical path system. The quantum cascade laser 1 can generate laser light of a specific wavelength, and this wavelength needs to match the molecular absorption line in the dipole molecular cell 17. In this embodiment, the wavelength of the QCL should be selected near the transition wavelength between the lowest vibrational-rotational state and the lowest rotational state of the first vibrationally excited state of the dipole molecule.

[0092] The optical path system is used to guide and focus the laser generated by the QCL into the dipole molecular cell 17. The design of the optical path system needs to ensure that the laser can efficiently enter the cell and minimize the losses in the optical path.

[0093] The dipole molecular cell 17 is filled with dipole molecules. These molecules will undergo the Stark effect under the irradiation of laser light of a specific wavelength, resulting in the splitting of molecular energy levels, so that the electric field strength can be measured by spectral analysis. However, the molecules will not generate free electrons that shield the external electric field under the induction of the external electric field, bringing a shielding effect.

[0094] In this step, through precise control of the output wavelength of the QCL and the guidance of the optical path system, effective excitation of the molecules in the dipole molecular cell 17 by the laser is achieved. Since it is necessary to ensure that the laser can efficiently excite the dipole molecules, this operation is performed under the condition that the internal pressure, temperature, and other conditions of the cell are stable to avoid the influence of external factors on the measurement results.

[0095] In step S12, obtain the transition spectrum between the lowest vibrational-rotational state and the lowest rotational state of the first vibrationally excited state. The transition spectrum refers to the spectral signal generated when the dipole molecule jumps from the lowest vibrational-rotational state to the lowest rotational state of the first vibrationally excited state under laser excitation. This spectral signal contains information about the electric field strength.

[0096] In this step, the data acquisition unit collects the laser signal emitted from the dipole molecular cell 17 and processes it (such as filtering, amplification, etc.) to obtain a clear transition spectrum.

[0097] Since the resolution and signal-to-noise ratio of the transition spectrum directly affect the measurement accuracy of the electric field strength, high-performance data acquisition units and processing algorithms are selected to ensure the accuracy of the spectral signal.

[0098] In step S13, the measured electric field strength of the space to be measured is determined according to the transition spectrum. In this step, the data processing module analyzes the collected transition spectrum and uses the principle of the Stark effect to calculate the electric field strength through the frequency shift or intensity change of the spectral line. Specifically, according to the known molecular polarizability and the relationship between the electric field strength and the frequency shift or intensity change of the spectral line, the electric field strength can be solved by methods such as fitting or numerical calculation.

[0099] Since the measurement accuracy of the electric field strength is affected by various factors (such as cell pressure, temperature fluctuations, laser wavelength stability, etc.), it is necessary to perform sufficient calibration and testing before the experiment to ensure the accuracy of the measurement results.

[0100] The low-frequency electric field measurement method of this embodiment realizes the effective excitation of the molecules in the dipole molecular cell 17 by precisely controlling the output wavelength of the QCL and the guidance of the optical path system; a clear transition spectrum is obtained through a high-performance data acquisition unit and processing algorithm; finally, the electric field strength is calculated using the principle of the Stark effect. This method has the advantages of high precision, high sensitivity, non-contact measurement, etc., and is particularly suitable for environments where weak low-frequency electric fields need to be measured. It can be used to measure low-frequency electric fields of different frequencies and intensities, and has broad application prospects.

[0101] According to the above embodiment, in an alternative embodiment, it further includes:

[0102] The step of applying a low-frequency electric field with a known electric field strength and then controlling the quantum cascade laser to generate a probe laser, and the probe laser is incident on the dipole molecular cell through the optical path system to excite the molecules in the dipole molecular cell;

[0103] Determine the attenuation factor according to the measured electric field strength and the known electric field strength.

[0104] This embodiment adds the step of applying a low-frequency electric field with a known electric field strength and determines the attenuation factor by comparing the measured electric field strength with the known electric field strength.

[0105] Specifically, based on the original process, this embodiment adds a key step: applying a low-frequency electric field with a known electric field strength into the path that controls the output of the probing laser of the quantum cascade laser 1, and this path includes being incident on the dipole molecular gas cell 17 through the optical path system. The purpose of this step is to calibrate and verify the accuracy of the entire measurement system.

[0106] After applying the known electric field, the system measures the electric field strength according to the transition spectrum generated by the dipole molecular gas cell 17 excited by the quantum cascade laser 1. Subsequently, this measured electric field strength is compared with the applied known electric field strength. Through this comparison, the attenuation factor of the entire measurement system (including the quantum cascade laser 1, the optical path system, the dipole molecular gas cell 17, the data acquisition unit, and the data processing module) can be determined.

[0107] The attenuation factor is an important parameter, which reflects the attenuation degree of the signal during the transmission process of the measurement system. By determining the attenuation factor, the measurement result can be corrected, thereby improving the measurement accuracy.

[0108] This optional embodiment makes the entire low-frequency electric field measurement system more perfect and can provide more accurate and reliable measurement results.

[0109] The above has introduced the low-frequency electric field measurement device provided by the present application in detail. The various embodiments in the specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present application, several improvements and modifications can still be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0110] It should also be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of another identical element in the process, method, article or device including the said element.

Claims

1. A low-frequency electric field measuring device, characterized in that: include: A quantum cascade laser, an optical path system, a dipole molecule gas chamber, a data acquisition unit, a data processing module, and a control module; wherein the dipole molecule gas chamber is filled with dipole molecules; The quantum cascade laser is connected to the optical path system through an optical fiber, the optical path system is connected to the dipole molecule gas chamber, the data acquisition unit is connected to the dipole molecule gas chamber, and the data processing module is connected to the data acquisition unit; The control module controls the quantum cascade laser to generate a detection laser, and the detection laser is incident on the dipole molecular gas chamber through the optical path system to excite the molecules in the dipole molecular gas chamber; the control module controls the data acquisition unit to collect the laser signal emitted by the dipole molecular gas chamber, and processes the laser signal to obtain a transition spectrum between the lowest vibrational state and the lowest rotational state of the first vibrational excited state; the control module controls the data processing module to determine the measurement electric field intensity of the space to be measured according to the transition spectrum.

2. The low-frequency electric field measuring device according to claim 1, characterized in that: The optical path system includes a first beam splitter, a second beam splitter, and a first reflector; the data acquisition unit includes a reference photodetector and a measurement photodetector; The quantum cascade laser is connected to the first beam splitter, and the detection laser generated by the quantum cascade laser is divided into a reference laser and a measurement laser by the first beam splitter, wherein the reference laser is incident on the second beam splitter and the measurement laser is incident on the first reflector; the second beam splitter divides the reference laser into a first reference light and a second reference light, which enter the dipole molecular gas chamber; The first reference light passes through the dipole molecular gas chamber and then enters the reference photodetector; the second reference light passes through the dipole molecular gas chamber and then enters the measurement photodetector through the first chromatic mirror; the measurement laser is emitted by the first reflector and then enters the measurement photodetector through the first chromatic mirror; The output ends of the reference photodetector and the measuring photodetector are connected to a data processing module.

3. The low-frequency electric field measuring device according to claim 1, characterized in that: The dipole molecular gas chamber is filled with HCl molecules.

4. The low-frequency electric field measuring device according to claim 2, characterized in that: The data processing module includes: a subtractor, a demodulator, and a data processing unit; The output ends of the reference photodetector and the measurement photodetector are connected to the input end of the subtractor, the output end of the subtractor is connected to the demodulator, and the output end of the demodulator is connected to the data processing unit.

5. The low-frequency electric field measuring device according to claim 4, characterized in that: Also includes: Isolator, first wave plate, first modulation signal source; The output end of the first modulation signal source is connected to the quantum cascade laser and the demodulator; The detection laser generated by the quantum cascade laser passes through the isolator and the first wave plate in sequence and is incident on the first beam splitter.

6. The low-frequency electric field measuring device according to claim 5, characterized in that: Also includes: A second wave plate, an electro-optic modulator, and a second modulation signal source; The output end of the second modulation signal source is connected to the electro-optical modulator; The reference laser passes through the electro-optic modulator and the second wave plate in sequence and is incident on the second beam splitter.

7. The low-frequency electric field measuring device according to claim 6, characterized in that: The frequency of the first modulation signal source is in the kHz order, and the frequency of the second modulation signal source is in the MHz order.

8. The low-frequency electric field measuring device according to claim 6, characterized in that: The wavelength of the detection laser generated by the quantum cascade laser is 6.749 microns.

9. A low-frequency electric field measurement method, characterized in that: For a low-frequency electric field measuring device, the low-frequency electric field measuring device comprises: a quantum cascade laser, an optical path system, a dipole molecule gas chamber, a data acquisition unit, a data processing module, and a control module; wherein the dipole molecule gas chamber is filled with dipole molecules; the quantum cascade laser is connected to the optical path system through an optical fiber, the optical path system is connected to the dipole molecule gas chamber, the data acquisition unit is connected to the dipole molecule gas chamber, and the data processing module is connected to the data acquisition unit; the method comprises: Controlling the quantum cascade laser to generate a detection laser, wherein the detection laser is incident on the dipole molecule gas chamber through an optical path system to excite molecules in the dipole molecule gas chamber; Controlling the data acquisition unit to acquire the laser signal emitted by the dipole molecular gas chamber, and processing the laser signal to obtain a transition spectrum between the lowest vibrational rotation state and the lowest rotational state of the first vibrational excited state; The data processing module is controlled to determine the measured electric field intensity of the space to be measured according to the transition spectrum.

10. The low-frequency electric field measurement method according to claim 9, characterized in that: Also includes: After applying a low-frequency electric field with a known electric field strength, the step of controlling the quantum cascade laser to generate a detection laser, wherein the detection laser is incident on the dipole molecular gas chamber through an optical path system to excite molecules in the dipole molecular gas chamber; The attenuation factor is determined based on the measured electric field strength and the known electric field strength.

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