A vehicle-mounted dual optical comb system for outdoor testing

Abstract

This invention discloses a vehicle-mounted dual-optical-comb system for outdoor testing, comprising an oscillator module, a power amplifier module, a frequency conversion module, a gas measurement module, a signal detection, acquisition, and processing module, and a vehicle-mounted platform module. The oscillator module generates two optical frequency comb signals with slightly different repetition frequencies. The power amplifier module amplifies the two optical frequency comb signals. The frequency conversion module outputs a combined dual-optical-comb beam. The gas measurement module enables the dual-optical-comb beam to interact with the gas to be tested in an open environment. The signal detection, acquisition, and processing module receives the optical signal absorbed by the gas to be tested, converts it into an electrical signal, and acquires and processes the electrical signal to obtain the absorption spectrum information of the gas to be tested. The vehicle-mounted platform module is used to fix and install each module. The advantages of this invention are: stable operation, strong resistance to environmental interference, low power consumption, and suitability for long-term vehicle-mounted operation.

Description

Technical Field

[0001] This invention relates to the field of ultrafast optics, and in particular to a vehicle-mounted dual optical comb system for outdoor testing. Background Technology

[0002] The atmosphere, as a vital environmental medium for life on Earth, plays a crucial role in maintaining climate stability, regulating energy transmission, and supporting ecosystem balance. With the increasing demand for gas detection in environmental monitoring, energy utilization, and industrial safety, the development of rapid-response, high-sensitivity, and high-resolution gas detection technologies is of great significance. Currently, various methods exist for detecting atmospheric composition and content, such as gas chromatography, mass spectrometry, electrochemical methods, and optical detection techniques like tunable diode absorption spectroscopy, Fourier transform spectrometry, and differential optical absorption spectrometry. While these technologies each have advantages in measurement accuracy, response speed, the range of gases that can be measured, and the breadth of application scenarios, they cannot simultaneously meet all measurement requirements.

[0003] Dual-comb spectroscopy utilizes two optical combs with slightly different repetition frequencies to achieve rapid, broadband spectral measurements without mechanical scanning, combining the broadband advantages of traditional Fourier transform spectroscopy with the high-resolution characteristics of laser absorption spectroscopy. Especially in the mid-infrared band, DCS technology can achieve highly sensitive detection of various atmospheric gases, thus showing broad application prospects in atmospheric trace gas monitoring and open-path environment detection. However, almost all current experiments using dual-comb spectroscopy for atmospheric detection rely on a "telescope-backward mirror" device to achieve the "emission-reception" of the dual-comb laser beam, and the measured gas concentration results are the average results after integrating the optical path. In many real-world scenarios, influenced by multiple sources such as local leaks and emissions, the gas components and their concentrations in the atmosphere often exhibit significant spatiotemporal nonuniformity, making it difficult to effectively characterize spatial concentration gradients using a single fixed optical path measurement method. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the prior art by providing a vehicle-mounted dual optical comb system for outdoor inspection. This system includes an oscillator module, a power amplifier module, a frequency conversion module, a gas measurement module, a signal detection, acquisition and processing module, and a vehicle-mounted platform module. Utilizing optical frequency comb technology, this system achieves stable operation and measurement in a mobile vehicle environment, enabling atmospheric inspection of multiple road sections and the detection and location of natural gas leaks.

[0005] The objective of this invention is achieved through the following technical solutions: A vehicle-mounted dual optical comb system for outdoor testing, the vehicle-mounted dual optical comb system includes an oscillator module, a power amplifier module, a frequency conversion module, a gas measurement module, a signal detection, acquisition and processing module, and a vehicle-mounted platform module; The oscillator module is used to generate two optical frequency comb signals with slightly different repetition frequencies. The two output terminals of the oscillator module are respectively connected to the two input terminals of the power amplifier module. The power amplifier module is used to amplify the two optical frequency comb signals, and the two output terminals of the power amplifier module are connected to the two input terminals of the frequency conversion module. The frequency conversion module is used to achieve spectral expansion and coherence preservation of the two amplified optical frequency comb signals through a nonlinear optical process, and to achieve spatial beam combining of the two amplified optical frequency comb signals inside the frequency conversion module, and output the combined dual optical comb beam. The gas measurement module is used to enable the dual-comb beam to interact with the gas to be measured in an open environment; The signal detection, acquisition and processing module is used to receive the optical signal absorbed by the gas to be tested and convert it into an electrical signal, and to acquire and process the electrical signal to obtain the absorption spectrum information of the gas to be tested; The oscillator module, the power amplifier module, the frequency conversion module, the gas measurement module, and the signal detection, acquisition, and processing module are integrated into a single structure and fixedly mounted on the vehicle platform module to achieve gas detection in motion.

[0006] The two oscillators in the oscillator module generate optical frequency comb signals in one of the following ways: nonlinear amplifying ring mirror mode-locking, nonlinear polarization rotation mode-locking, nonlinear saturable absorber mode-locking, or nonlinear polarization evolution mode-locking.

[0007] Both oscillators in the oscillator module and both power amplifiers in the power amplifier module utilize diode lasers as pump sources.

[0008] The two oscillators of the oscillator module generate optical frequency comb signals with the same center wavelength. The gain medium of the oscillator is a rare earth ion doped gain medium, which is one of the following: ytterbium-doped, erbium-doped, thulium-doped, holmium-doped, or praseodymium-doped optical fiber or solid gain medium. The solid gain medium is YAG or YLF.

[0009] The repetition frequencies of the two oscillators in the oscillator module are relatively stable, and the repetition frequencies are either in a free-running state or a locked state. In the free-running state, the repetition frequency drift is compensated by subsequent signal processing.

[0010] The power amplifier module is equipped with a dispersion control unit, which is one of a transmission grating compressor, a reflection grating compressor, a dispersion-compensating fiber, or a chirped fiber grating.

[0011] The frequency conversion module includes a first mirror, a second mirror, a third mirror, a fourth mirror, a fifth mirror, a sixth mirror, a first dichroic mirror, a second dichroic mirror, a first thin-film beam splitter, a second thin-film beam splitter, a first nonlinear optical medium, a second nonlinear optical medium, and a continuous light laser. The first nonlinear optical medium and the second nonlinear optical medium are both nonlinear optical waveguides or nonlinear crystals. The amplified two optical frequency comb signals are the first amplified optical frequency comb signal and the second amplified optical frequency comb signal, respectively. The first amplified optical frequency comb signal is incident on the first dichroic mirror via the second mirror and the first mirror in sequence; The second amplified optical frequency comb signal is sequentially incident on the second dichroic mirror via the third and fourth reflecting mirrors; The laser beam output by the continuous light laser is split into a first laser beam and a second laser beam by the first thin-film beam splitter. The first laser beam is incident on the first dichroic mirror and is combined with the first amplified optical frequency comb signal to form a first combined beam. The first combined beam passes through the first nonlinear optical medium and is then incident on the second thin-film beam splitter. The second laser beam is incident on the second dichroic mirror through the fifth reflecting mirror, and is combined with the second amplified optical frequency comb signal to form a second combined beam. The second combined beam passes through the second nonlinear optical medium and the sixth reflecting mirror in sequence before being incident on the second thin-film beam splitter. The first beam combiner and the second beam combiner are combined at the second thin-film beam splitter to form the dual-comb beam.

[0012] The gas measurement module includes an open multi-pass gas cell with high-reflectivity mirrors on both sides, allowing the dual-comb beam to propagate back and forth multiple times in the open space to extend the effective absorption optical path.

[0013] The signal detection, acquisition and processing module includes a balanced detector, a data acquisition card and a computer; The balanced detector is used to convert the received optical signal into the electrical signal, and the balanced detector is one of an infrared photodiode detector and an optical balanced detector; The data acquisition card is used to acquire the electrical signal. The data acquisition card is synchronized with an external clock, which is one of an atomic clock, an optical clock, or a signal generator. The computer is used to process the electrical signal to obtain the absorption spectrum information of the gas to be measured.

[0014] The vehicle platform module can be a sports multi-purpose vehicle, a family sedan, a commercial vehicle, or a tricycle. The vehicle platform module is equipped with a vibration damping mounting structure to reduce the impact of vibration during vehicle movement on the stability of the vehicle-mounted dual optical comb system.

[0015] The advantages of this invention are: (1) Based on the heterodyne beat frequency detection of two optical frequency combs, the absorption spectra of various gases in the optical path were measured at high speed and high resolution by the small difference in the repetition frequency of the output pulse light of the two combs, thus avoiding the inherent shortcomings of traditional detection methods such as tunable diode lasers and Fourier transform spectrometers. (2) The pre-seed light source is a nonlinear amplifying ring mirror mode-locked laser, and the all-fiber design greatly improves the integration and stability; (3) Change the repetition frequency difference of the dual optical comb The measurement speed can be adjusted. Generally, a repetition frequency of 100 MHz can achieve a repetition frequency difference of several kHz, achieving a time resolution on the order of milliseconds, allowing the vehicle system to travel at high speeds. (4) By using a highly nonlinear optical medium, picosecond pulses can achieve a certain efficiency in frequency conversion, thus eliminating the need for a dispersion compensation module to compress the pulse duration. (5) The output spectrum range of the dual optical comb can be precisely adjusted by changing the waveguide polarization period, thereby covering the absorption spectrum characteristics of different gases, which is practical. (6) The passive coherence of the two optical frequency combs was achieved by using optical modulation technology. Stable coherence can be achieved without the need for electrical locking such as servo feedback, while greatly reducing the complexity and stability of the system. (7) An open multi-pass gas cell was adopted, and the 25-meter effective optical path greatly improved the absorption intensity. The open structure can realize real-time on-site atmospheric inspection. (8) Balanced detection technology is adopted to eliminate the common-mode noise of the two optical combs. Differential noise reduction is used to amplify the beat frequency signal, which can achieve a higher signal-to-noise ratio than that of a single-point detector. (9) The measurement data is absorption spectrum information, which can not only retrieve gas composition and concentration, but also measure gas temperature, such as the dual-line thermometry method; (10) The whole system has been integrated and has a shock absorption design, making it suitable for installation on small mobile platforms such as vehicle and airborne, and has high flexibility and portability. Attached Figure Description

[0016] Figure 1This is a modular block diagram of the vehicle-mounted dual optical comb system for outdoor testing according to the present invention; Figure 2 This is a schematic diagram of the vehicle-mounted dual optical comb system for outdoor testing according to the present invention; Figure 3 This is a schematic diagram of the absorption spectrum obtained by the vehicle-mounted dual optical comb system for outdoor testing according to the present invention. like Figures 1-3 As shown in the figure, the markings represent: Oscillator module 1, first oscillator 11, second oscillator 12; Power amplifier module 2, first power amplifier 21, second power amplifier 22; Frequency conversion module 3, first reflector 31, second reflector 32, third reflector 33, fourth reflector 34, fifth reflector 35, sixth reflector 36, first dichroic mirror 37, second dichroic mirror 38, first thin-film beam splitter 39, second thin-film beam splitter 310, first nonlinear optical medium 311, second nonlinear optical medium 312, continuous light laser 313; Gas measurement module 4; Open multi-pass gas cell 41; Signal detection, acquisition and processing module 5; Balance detector 51; Data acquisition card 52; Computer 53; Vehicle platform module 6. Detailed Implementation

[0017] The features and other related features of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate understanding by those skilled in the art: Example: Figures 1-2As shown, this embodiment relates to a vehicle-mounted dual optical comb system for outdoor detection. The system mainly includes an oscillator module 1, a power amplifier module 2, a frequency conversion module 3, a gas measurement module 4, a signal detection, acquisition, and processing module 5, and a vehicle-mounted platform module 6. The oscillator module 1 generates two optical frequency comb signals with slightly different repetition frequencies. The two outputs of the oscillator module 1 are connected to the two inputs of the power amplifier module 2. The power amplifier module 2 amplifies the two optical frequency comb signals. The two outputs of the power amplifier module 2 are connected to the two inputs of the frequency conversion module 3. Specifically, the oscillator module 1 includes two oscillators, namely a first oscillator 11 and a second oscillator 12. The power amplifier module 2 includes two power amplifiers, namely a first power amplifier 21 and a second power amplifier 22. A diode laser is installed inside the oscillator package, serving as the pump light source for the oscillator and the power amplifier, respectively. The two optical frequency comb signals generated by oscillator module 1, with slight differences in repetition frequency, have the same center wavelength. After being amplified to 500 mW by the first power amplifier 21 and the second power amplifier 22, the center wavelength is 1030 nm, and the pulse duration is 4 ps. The repetition frequency of the oscillator is relatively stable, either in a free-running state or a locked state. In the free-running state, the repetition frequency drift is compensated for by subsequent signal processing. The oscillator generates the optical frequency comb signal using one of the following methods: nonlinear amplifying ring mirror mode-locking, nonlinear polarization rotation mode-locking, nonlinear saturable absorber mode-locking, or nonlinear polarization evolution mode-locking. The gain medium of the oscillator is a rare earth ion-doped gain medium, which is one of the following: ytterbium-doped (Yb³⁺), erbium-doped (Er³⁺), thulium-doped (Tm³⁺), holmium-doped (Ho³⁺), or praseodymium-doped (Pr³⁺) optical fiber or solid-state gain medium. That is, the rare earth ion-doped gain medium is one of the following: ytterbium-doped optical fiber, erbium-doped optical fiber, thulium-doped optical fiber, holmium-doped optical fiber, praseodymium-doped optical fiber, ytterbium-doped solid-state gain medium, erbium-doped solid-state gain medium, thulium-doped solid-state gain medium, holmium-doped solid-state gain medium, or praseodymium-doped solid-state gain medium. The solid-state gain medium is YAG (Yttrium Aluminum Garnet) or YLF (Yttrium Lithium Fluoride). The optical frequency comb in oscillator module 1 is locked using at least one of the following feedback excitation methods: piezoelectric ceramic, current, temperature, electro-optic modulation crystal, saturable absorber, carbon nanotube, or graphene modulator. Power amplifier module 2 is equipped with a dispersion control unit, which is one of a transmission grating compressor, a reflection grating compressor, dispersion-compensating fiber, or a chirped fiber grating.

[0018] The frequency conversion module 3 is used to achieve spectral expansion and coherence preservation of the two amplified optical frequency comb signals through a nonlinear optical process, and to achieve spatial beam combining of the two amplified optical frequency comb signals within the frequency conversion module 3, outputting a combined dual-comb beam. Specifically, the frequency conversion module 3 includes a first reflector 31, a second reflector 32, a third reflector 33, a fourth reflector 34, a fifth reflector 35, a sixth reflector 36, a first dichroic mirror 37, a second dichroic mirror 38, a first thin-film beam splitter 39, a second thin-film beam splitter 310, a first nonlinear optical medium 311, a second nonlinear optical medium 312, and a continuous light laser 313. The first nonlinear optical medium 311 and the second nonlinear optical medium 312 are both nonlinear optical waveguides or nonlinear crystals. In this embodiment, both the first nonlinear optical medium 311 and the second nonlinear optical medium 312 are nonlinear optical waveguides. The two amplified optical frequency comb signals are the first amplified optical frequency comb signal and the second amplified optical frequency comb signal, respectively. The first amplified optical frequency comb signal is sequentially incident on the first dichroic mirror 37 via the second reflector 32 and the first reflector 31. The second amplified optical frequency comb signal is sequentially incident on the second dichroic mirror 38 via the third reflector 33 and the fourth reflector 34. The laser beam output from the continuous-wave laser 313 is split into a first laser beam and a second laser beam by the first thin-film beam splitter 39. The first laser beam is incident on the first dichroic mirror 37 and combines with the first amplified optical frequency comb signal to form a first combined beam. The first combined beam passes through the first nonlinear optical medium 311 and then enters the second thin-film beam splitter 310. The second laser beam is incident on the second dichroic mirror 38 via the fifth reflector 35 and combines with the second amplified optical frequency comb signal to form a second combined beam. The second combined beam passes through the second nonlinear optical medium 312 and the sixth reflector 36 before entering the second thin-film beam splitter 310. The first and second combined beams are combined at the second thin-film beam splitter 310 to form a dual-comb beam. The wavelength of the dual-comb beam output by the frequency conversion module 3 covers at least one of the following bands: extreme ultraviolet, ultraviolet, visible light, near-infrared, mid-infrared, or far-infrared. In this embodiment, the wavelength of the dual-comb beam output by the frequency conversion module 3 is 3.35-3.47 nm. .

[0019] The gas measurement module 4 is used to enable the dual-comb beam to interact with the gas to be measured in an open environment. Specifically, the gas measurement module 4 includes an open multi-pass gas cell 41, with high-reflectivity mirrors on both sides of the open multi-pass gas cell 41, which allows the dual-comb beam to propagate back and forth multiple times in the open space to extend the effective absorption optical path. The total effective optical path of the open multi-pass gas cell 41 is 25 m.

[0020] The signal detection, acquisition, and processing module 5 receives the optical signal absorbed by the gas to be tested and converts it into an electrical signal. It then acquires and processes the electrical signal to obtain the absorption spectrum information of the gas to be tested. Specifically, the signal detection, acquisition, and processing module 5 includes a balanced detector 51, a data acquisition card 52, and a computer 53. The balanced detector 51 converts the received optical signal into an electrical signal. The balanced detector 51 is one of an infrared photodiode detector or an optical balanced detector. The balanced detector 51 is connected to the data acquisition card 52 after passing through a low-pass electrical filter with a cutoff frequency lower than half the repetition frequency. The data acquisition card 52 (such as an FPGA digital acquisition card) is used to acquire the electrical signal. The data acquisition card 52 uses an external clock for synchronization. The external clock can be one of an atomic clock, an optical clock, or a signal generator. When running on a vehicle-mounted mobile platform, the data acquisition card 52 can also operate without clock synchronization. The error caused by not using clock synchronization is much smaller than the error caused by the repetition frequency jitter of the oscillator module 1 and the center wavelength jitter of the continuous light laser 313 in the frequency conversion module 3. The computer 53 processes the acquired signal to obtain gas composition and concentration information.

[0021] The oscillator module 1, power amplifier module 2, frequency conversion module 3, gas measurement module 4, and signal detection, acquisition, and processing module 5 are integrated into a single structure and fixedly mounted on the vehicle platform module 6 to achieve gas detection in motion. The vehicle platform module 6 can be used in SUVs, sedans, commercial vehicles, or tricycles. It features a vibration-damping mounting structure to reduce the impact of vehicle vibrations on the stability of the dual-comb system. Specifically, the gas measurement module 4 and frequency conversion module 3 can be placed on the roof rack, while the oscillator module 1, power amplifier module 2, and signal detection, acquisition, and processing module 5 can be placed inside the vehicle. For vehicles unsuitable for roof mounting, the entire system can be placed inside the vehicle, using a high-power exhaust fan to promptly draw outside gas to the vicinity of the gas pool inside for detection. Furthermore, the vehicle platform module 6 can also supply power to each module.

[0022] When formally measuring atmospheric composition and concentration outdoors, the vehicle speed can be controlled according to the required spatial resolution and the system's measurement speed, or the measurement speed can be adjusted within an appropriate range based on the vehicle speed to obtain the target spatial resolution. For example, at a repetition frequency of 400 Hz, a concentration spatial resolution of 1.39 cm can be obtained at a vehicle speed of 20 km / h. Real-time absorption spectra can be obtained through a real-time acquisition card, thus enabling real-time acquisition of the target gas concentration information.

[0023] like Figure 3 The diagram shown is a schematic of the absorption spectrum measured by the vehicle-mounted dual optical comb system. This diagram can be used to determine the gas composition and concentration information.

[0024] The beneficial technical effects of this embodiment are as follows: (1) Based on the heterodyne beat frequency detection of two optical frequency combs, the absorption spectra of various gases in the optical path were measured at high speed and high resolution by the small difference in the repetition frequency of the output pulse light of the two combs, thus avoiding the inherent shortcomings of traditional detection methods such as tunable diode lasers and Fourier transform spectrometers. (2) The pre-seed light source is a nonlinear amplifying ring mirror mode-locked laser, and the all-fiber design greatly improves the integration and stability; (3) Change the repetition frequency difference of the dual optical comb The measurement speed can be adjusted. Generally, a repetition frequency of 100 MHz can achieve a repetition frequency difference of several kHz, achieving a time resolution on the order of milliseconds, allowing the vehicle system to travel at high speeds. (4) By using a highly nonlinear optical medium, picosecond pulses can achieve a certain efficiency in frequency conversion, thus eliminating the need for a dispersion compensation module to compress the pulse duration. (5) The output spectrum range of the dual optical comb can be precisely adjusted by changing the waveguide polarization period, thereby covering the absorption spectrum characteristics of different gases, which is practical. (6) The passive coherence of the two optical frequency combs was achieved by using optical modulation technology. Stable coherence can be achieved without the need for electrical locking such as servo feedback, while greatly reducing the complexity and stability of the system. (7) An open multi-pass gas cell was adopted, and the 25-meter effective optical path greatly improved the absorption intensity. The open structure can realize real-time on-site atmospheric inspection. (8) Balanced detection technology is adopted to eliminate the common-mode noise of the two optical combs. Differential noise reduction is used to amplify the beat frequency signal, which can achieve a higher signal-to-noise ratio than that of a single-point detector. (9) The measurement data is absorption spectrum information, which can not only retrieve gas composition and concentration, but also measure gas temperature, such as the dual-line thermometry method; (10) The whole system has been integrated and has a shock absorption design, making it suitable for installation on small mobile platforms such as vehicle and airborne, and has high flexibility and portability.

Claims

1. A vehicle-mounted dual optical comb system for outdoor testing, characterized in that... The vehicle-mounted dual optical comb system includes an oscillator module, a power amplifier module, a frequency conversion module, a gas measurement module, a signal detection, acquisition and processing module, and a vehicle-mounted platform module. The oscillator module is used to generate two optical frequency comb signals with a slight difference in repetition frequency. The two output terminals of the oscillator module are respectively connected to the two input terminals of the power amplifier module. The power amplifier module is used to amplify the two optical frequency comb signals, and the two output terminals of the power amplifier module are connected to the two input terminals of the frequency conversion module. The frequency conversion module is used to achieve spectral expansion and coherence preservation of the two amplified optical frequency comb signals through a nonlinear optical process, and to achieve spatial beam combining of the two amplified optical frequency comb signals inside the frequency conversion module, and output the combined dual optical comb beam. The gas measurement module is used to enable the dual-comb beam to interact with the gas to be measured in an open environment; The signal detection, acquisition and processing module is used to receive the optical signal absorbed by the gas to be tested and convert it into an electrical signal, and to acquire and process the electrical signal to obtain the absorption spectrum information of the gas to be tested; The oscillator module, the power amplifier module, the frequency conversion module, the gas measurement module, and the signal detection, acquisition, and processing module are integrated into a single structure and fixedly mounted on the vehicle platform module to achieve gas detection in motion.

2. The vehicle-mounted dual optical comb system for outdoor testing as described in claim 1, characterized in that... The two oscillators in the oscillator module generate optical frequency comb signals in one of the following ways: nonlinear amplifying ring mirror mode-locking, nonlinear polarization rotation mode-locking, nonlinear saturable absorber mode-locking, or nonlinear polarization evolution mode-locking.

3. The vehicle-mounted dual optical comb system for outdoor testing as described in claim 1, characterized in that... Both oscillators in the oscillator module and both power amplifiers in the power amplifier module utilize diode lasers as pump sources.

4. The vehicle-mounted dual optical comb system for outdoor testing as described in claim 1, characterized in that... The two oscillators of the oscillator module generate optical frequency comb signals with the same center wavelength. The gain medium of the oscillator is a rare earth ion doped gain medium, which is one of the following: ytterbium-doped, erbium-doped, thulium-doped, holmium-doped, or praseodymium-doped optical fiber or solid gain medium. The solid gain medium is YAG or YLF.

5. A vehicle-mounted dual optical comb system for outdoor testing as described in claim 1, characterized in that... The repetition frequencies of the two oscillators in the oscillator module are relatively stable, and the repetition frequencies are either in a free-running state or a locked state. In the free-running state, the repetition frequency drift is compensated by subsequent signal processing.

6. A vehicle-mounted dual optical comb system for outdoor testing as described in claim 1, characterized in that... The power amplifier module is equipped with a dispersion control unit, which is one of a transmission grating compressor, a reflection grating compressor, a dispersion-compensating fiber, or a chirped fiber grating.

7. A vehicle-mounted dual optical comb system for outdoor testing as described in claim 1, characterized in that... The frequency conversion module includes a first mirror, a second mirror, a third mirror, a fourth mirror, a fifth mirror, a sixth mirror, a first dichroic mirror, a second dichroic mirror, a first thin-film beam splitter, a second thin-film beam splitter, a first nonlinear optical medium, a second nonlinear optical medium, and a continuous light laser. The first nonlinear optical medium and the second nonlinear optical medium are both nonlinear optical waveguides or nonlinear crystals. The amplified two optical frequency comb signals are the first amplified optical frequency comb signal and the second amplified optical frequency comb signal, respectively. The first amplified optical frequency comb signal is incident on the first dichroic mirror via the second mirror and the first mirror in sequence; The second amplified optical frequency comb signal is sequentially incident on the second dichroic mirror via the third and fourth reflecting mirrors; The laser beam output by the continuous light laser is split into a first laser beam and a second laser beam by the first thin-film beam splitter. The first laser beam is incident on the first dichroic mirror and is combined with the first amplified optical frequency comb signal to form a first combined beam. The first combined beam passes through the first nonlinear optical medium and is then incident on the second thin-film beam splitter. The second laser beam is incident on the second dichroic mirror through the fifth reflecting mirror, and is combined with the second amplified optical frequency comb signal to form a second combined beam. The second combined beam passes through the second nonlinear optical medium and the sixth reflecting mirror in sequence before being incident on the second thin-film beam splitter. The first beam combiner and the second beam combiner are combined at the second thin-film beam splitter to form the dual-comb beam.

8. A vehicle-mounted dual optical comb system for outdoor testing as described in claim 1, characterized in that... The gas measurement module includes an open multi-pass gas cell with high-reflectivity mirrors on both sides, allowing the dual-comb beam to propagate back and forth multiple times in the open space to extend the effective absorption optical path.

9. A vehicle-mounted dual optical comb system for outdoor testing as described in claim 1, characterized in that... The signal detection, acquisition and processing module includes a balanced detector, a data acquisition card and a computer; The balanced detector is used to convert the received optical signal into the electrical signal, and the balanced detector is one of an infrared photodiode detector and an optical balanced detector; The data acquisition card is used to acquire the electrical signal. The data acquisition card is synchronized with an external clock, which is one of an atomic clock, an optical clock, or a signal generator. The computer is used to process the electrical signal to obtain the absorption spectrum information of the gas to be measured.

10. A vehicle-mounted dual optical comb system for outdoor testing as described in claim 1, characterized in that... The vehicle platform module is a sports multi-purpose vehicle, a family sedan, a commercial vehicle, or a tricycle. The vehicle platform module is equipped with a vibration damping mounting structure to reduce the impact of vibration during vehicle movement on the stability of the vehicle-mounted dual optical comb system.

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