A device and method for gas pressure measurement based on femtosecond dual optical comb

Abstract

A device and method for measuring gas pressure based on a femtosecond dual-comb optical spectrum, belonging to the field of laser measurement. The gas pressure measuring device of this invention includes a light source module, a measurement module, a detection module, and a data processing module. The light source module includes a first optical frequency comb and a second optical frequency comb. A first 1×2 fiber beam splitter divides the laser energy into 70%–90% and 10%–30%, with the 70%–90% laser energy transmitted to a beam expander. This invention utilizes the advantages of a femtosecond dual-comb spectral system, such as broadband spectrum, extremely high spectral resolution, and fast laser spectroscopy. The broadband spectrum of the dual-comb spectrum simultaneously acquires multiple absorption lines of the same gas, improving the measurement accuracy of gas partial pressure; the broadband spectrum simultaneously acquires absorption lines of multiple gases, enabling simultaneous measurement of the pressure of multiple gas components. The total gas pressure is obtained by summing the partial pressures of the mixed gases. Higher spectral resolution and a faster dual-comb spectral sampling rate improve the speed of gas partial pressure measurement, meeting the requirements of online dynamic measurement.

Description

Technical Field

[0001] This invention relates to a device and method for measuring gas pressure based on a femtosecond dual optical comb, belonging to the field of laser measurement technology. Background Technology

[0002] Pressure measurement has wide applications in aerospace, biomedicine, nuclear energy, and other fields. Gas pressure measurement is a crucial component, and accurate gas pressure measurement technology is indispensable. Currently, the main method for gas pressure measurement relies on traditional pressure sensors. While these sensors offer high accuracy and low cost, they suffer from wear and tear due to repetitive and long-term operation, decreased accuracy, and calibration errors. Mass spectrometry, represented by quadrupole mass spectrometers, is also widely used for gas partial pressure measurement. However, this technology has certain drawbacks: 1. Variations in the ionization probabilities of different gases lead to inconsistent output gain, making calibration extremely complex and difficult; 2. The measured values ​​of gas partial pressure often depend on the partial pressures and total pressure of other gases, making independent calibration of gas mixtures and total pressure virtually impossible; 3. This technology cannot operate in low vacuum (10⁻⁶ km² / h). -2 When operating at pressures above a certain pressure (Pa), the measurement sensitivity becomes unstable. Optical, especially laser-based, non-invasive measurement offers an excellent technical solution to address these issues, and exploring the application of laser technology in pressure measurement and calibration is currently an important research direction.

[0003] Optical non-contact pressure measurement methods can be broadly categorized into laser interferometry and laser spectroscopy. Laser interferometry primarily utilizes the correlation between changes in gas density, refractive index, and optical path length caused by variations in gas pressure. It measures the change in optical path length using a laser interferometer to achieve gas pressure measurement. Laser interferometry is mainly used for measuring nonpolar gas molecules. Laser spectroscopy primarily utilizes gas absorption spectroscopy for pressure measurement. While interferometry and spectroscopy differ in their technical principles, they are complementary in application. In spectroscopy, tunable diode laser absorption spectroscopy (TDLAS) is widely used for gas concentration measurement, enabling the identification and concentration measurement of gas molecules in mixed gases. Furthermore, the absorption spectrum of a gas contains pressure information about its molecules, thus TDLAS can also measure gas pressure. Although TDLAS avoids most of the problems associated with mass spectrometry pressure measurement, the spectral bandwidth of diode lasers is limited, generally limiting TDLAS to measuring only a single gas component. Therefore, the multi-gas measurement capability and accuracy of TDLAS are affected. Furthermore, the slow speed of acquiring spectral information through scanning also affects the measurement speed, significantly reducing its ability to meet the needs of online dynamic measurements. Essentially, these shortcomings of TDLAS stem primarily from its extremely narrow spectral band and slow electronic tuning spectrum acquisition method. In summary, current gas pressure measurement technologies all suffer from some degree of technical deficiencies and limitations. Summary of the Invention

[0004] The purpose of this invention is to provide a device and method for measuring gas pressure based on a femtosecond dual-comb optical spectrum. This method utilizes the advantages of a femtosecond dual-comb optical spectrum system, such as broadband spectroscopy, extremely high spectral resolution, and fast laser spectroscopy, to simultaneously acquire multiple absorption lines of the same gas, thereby improving the measurement accuracy of gas partial pressure. The broadband spectrum simultaneously acquires absorption lines of multiple gases, enabling simultaneous measurement of the pressure of multiple gas components. The total gas pressure is obtained by summing the partial pressures of the mixed gases, achieving simultaneous online dynamic measurement of the pressure of multiple gas components.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention discloses a gas pressure measurement device based on a femtosecond dual optical comb, comprising a light source module, a measurement module, a detection module, and a data processing module. The light source module includes a first optical frequency comb and a second optical frequency comb, outputting two near-infrared broadband optical frequency combs for measurement. The light source module uses optical fibers to transmit the two laser beams to the measurement module. The measurement module adjusts and couples the laser beams to form a measurement path and a reference path in the measurement optical path. After receiving two laser beams from the light source module, the measurement module amplifies the laser energy of the first optical frequency comb by connecting it to a first power amplifier via optical fiber, and amplifies the laser energy of the second optical frequency comb by connecting it to a second power amplifier via optical fiber. The first power amplifier filters the laser energy by connecting it to a first wavelength division multiplexer via optical fiber, reducing the spectral linewidth to improve measurement resolution, sampling rate, and measurement speed. Similarly, the second power amplifier is connected to a second wavelength division multiplexer via optical fiber to reduce the spectral linewidth. The first wavelength division multiplexer is connected to a first 1×2 fiber beam splitter via optical fiber to split the laser into two beams, beam 1 and beam 2. Similarly, the second wavelength division multiplexer and the second 1×2 fiber beam splitter are connected via optical fiber to split the laser into two beams, beam 3 and beam 4. Finally, beams 1 and 4 beat to form the measurement path signal, and beams 2 and 3 beat to form the reference path signal. The first 1×2 fiber optic beam splitter's beam 1 is connected to a beam expander via optical fiber. The beam expander outputs a spatial laser beam as the measurement optical path, expanding the laser beam to increase the contact volume between the laser and the gas. The spatial laser beam is input to a collimating lens, coupling it into an optical fiber, and then input to a second 2×2 fiber optic coupler via optical fiber. The second 1×2 fiber optic beam splitter's beam 2 is input to the first 2×2 fiber optic coupler via optical fiber. The second 1×2 fiber optic beam splitter's beam 3 and beam 4 are input to the second 2×2 fiber optic coupler via optical fiber. The first and second 2×2 fiber optic couplers couple the two input laser beams and output them to the detection module via optical fiber. The detection module includes a first balanced detector and a second balanced detector, which convert the input beat frequency signal into an electrical signal output for easy signal acquisition. A first 2×2 fiber optic coupler is connected to the first balanced detector to output a reference path signal, and a second 2×2 fiber optic coupler is connected to the second balanced detector to output a measurement path signal. All are connected to the data processing module via a data transmission line. The data processing module includes a host computer for data processing from the data acquisition card, which performs calculations on the acquired signals to obtain gas pressure values.

[0007] In order to increase the laser energy of the measurement path, thereby improving the signal-to-noise ratio of the measurement signal and optimizing the utilization of laser energy, as a preferred method, the first 1×2 fiber beam splitter divides the laser energy into 70%–90% and 10%–30%, with 70%–90% of the laser energy being transmitted to the beam expander.

[0008] To maximize the laser energy of the measurement path and the signal-to-noise ratio of the measurement signal, as a further preferred option, the first 1×2 fiber beam splitter divides the laser energy into 90% and 10%, with 90% of the laser energy being transmitted to the beam expander.

[0009] This invention discloses a gas pressure measurement method based on a femtosecond dual optical comb, implemented using a gas pressure measurement device based on a femtosecond dual optical comb. The gas pressure measurement method based on a femtosecond dual optical comb includes the following steps:

[0010] Step 1: Construct the gas pressure measurement device according to the femtosecond dual-comb-based gas pressure measurement device. Near-infrared laser emitted from the first optical frequency comb is amplified by the first power amplifier to increase its measurement energy. The laser then passes through a first wavelength division multiplexer and a first 1×2 fiber beam splitter, splitting the laser energy into beam 1 and beam 2. Beam 2 is transmitted to a first 2×2 fiber coupler, while beam 1's laser energy is transmitted to a beam expander as the measurement path signal. The measurement path laser is absorbed by gas molecules in a high-pressure gas chamber, obtaining a gas absorption signal, which is then received by a collimating lens and transmitted to a second 2×2 fiber coupler. The first and second wavelength division multiplexers are identical, but they reduce the spectral linewidth to improve measurement resolution, sampling rate, and measurement speed. The second optical frequency comb emits near-infrared laser light with a repetition frequency similar to that of the first optical frequency comb. The laser energy is amplified by a second power amplifier, then passed through a second wavelength division multiplexer, and finally through a second 1×2 fiber beam splitter, splitting the laser energy into beams 3 and 4. Beam 3 is transmitted to a first 2×2 fiber coupler, and beam 4 is transmitted to a second 2×2 fiber coupler. The first 2×2 fiber coupler transmits the signal to a first balanced detector, which acquires the time-domain interferogram after frequency beating as the measurement path signal. The second 2×2 fiber coupler transmits the signal to a second balanced detector, which acquires the time-domain interferogram after frequency beating as the reference path signal. The measurement path signal and the reference path signal are then transmitted to a data processing host computer for data processing. After performing Fourier transform and filtering on the interferogram signal, the spectral results of the measurement path and the reference path are obtained in the frequency domain.

[0011] Step 2: Based on the measured spectral line results, calculate the gas partial pressure value to realize gas pressure measurement based on femtosecond dual optical comb.

[0012] Step 2.1: Perform spectral calibration on the light intensity I0(ν) of the spectral line of the measurement path and the light intensity I(ν) of the spectral line of the reference path.

[0013] Step 2.2: Preprocess the spectral absorption data to filter out low-frequency and high-frequency noise, then normalize the spectral data, extract the characteristic absorption peaks, and calculate the integral absorbance A of the target gas using equation (1). absWhere I(ν) is the light intensity of the measured path, mW; and I0(ν) is the light intensity of the reference path, mW.

[0014]

[0015] Step 2.3: Determine the absorption length L of the interaction between the light beam and the sample gas, and determine the absorption line intensity S, cm, of the target gas. -1 / (molec·cm -2 ).

[0016] Step 2.4: Calculate the molecular number density n of the target gas according to the formula, and then calculate the partial pressure P of the target gas according to formula (3). partial .

[0017]

[0018] P partial =nkL (3)

[0019] Where: k is Boltzmann constant; T is gas temperature, K.

[0020] Step 2.5: Obtain the near-infrared broadband bands of the first and second optical frequency combs to acquire the spectral lines of a broadband measurement path and reference path. Simultaneously, obtain multiple absorption peaks of the same gas, calculate a partial pressure value for each absorption peak, and obtain multiple pressure values ​​in parallel. Averaging these values ​​yields the final, more accurate measurement result P. p The calculation uses formula (4):

[0021]

[0022] Where N represents the number of pressure values ​​calculated using the absorption peaks of the same gas.

[0023] The broadband spectral output of the dual optical comb covers the band from 1.3 μm to 1.7 μm, covering the absorption spectra of various gases (methane, carbon dioxide, etc.). At the same time, the partial pressures of different gases in the mixed gas are measured in parallel, and the total pressure P of the mixed gas is obtained by summing the partial pressures. The calculation is performed using formula (5):

[0024]

[0025] Where: P pi Let be the partial pressure of the i-th gas in the gas mixture.

[0026] The various gases include methane and carbon dioxide.

[0027] Beneficial effects:

[0028] 1. The present invention discloses a device and method for gas pressure measurement based on femtosecond dual optical comb. The gas pressure measurement is based on near-infrared dual optical comb, which makes full use of the advantages of the broadband spectrum of dual optical comb, and obtains multiple absorption peaks of the same gas molecule at the same time. Multiple measurement results are obtained in parallel, and the random error of pressure measurement is reduced by averaging multiple measurement values, thereby improving the measurement accuracy of gas pressure.

[0029] 2. This invention discloses a device and method for gas pressure measurement based on a femtosecond dual-comb optical spectrum. It fully utilizes the advantages of the wideband spectral output of the dual-comb, with a spectral width ranging from 1.3 μm to 1.7 μm, covering the absorption lines of various gases (methane, carbon dioxide, etc.). Therefore, this invention can accurately measure the partial pressures of different gases in a gas mixture in parallel, and the total pressure of the mixture is obtained by summing the partial pressures. Higher spectral resolution and a faster dual-comb spectral sampling rate improve the speed of gas partial pressure measurement, meeting the requirements of online dynamic measurement.

[0030] 3. The present invention discloses a device and method for gas pressure measurement based on femtosecond dual optical combs, which makes full use of the advantages of the broadband spectral output of dual optical combs to acquire molecular broadband spectral information in real time in a system without mechanical scanning components, thereby improving measurement speed and efficiency.

[0031] 4. The present invention discloses a device and method for measuring gas pressure based on femtosecond dual optical combs. The first 1×2 fiber beam splitter divides the laser energy into 70% to 90% and 10% to 30%. The 70% to 90% laser energy is transmitted to the beam expander 9, which can increase the laser energy of the measurement path, thereby improving the signal-to-noise ratio of the measurement signal and improving the laser energy utilization rate. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a gas pressure measurement device based on a femtosecond dual optical comb. In the diagram, 1-first optical frequency comb, 2-second optical frequency comb, 3-first power amplifier, 4-second power amplifier, 5-first wavelength division multiplexer, 6-second wavelength division multiplexer, 7-first 1×2 fiber optic beam splitter, 8-second 1×2 fiber optic beam splitter, 9-beam expander, 10-high-pressure gas chamber, 11-collimating lens, 12-first 2×2 fiber optic coupler, 13-second 2×2 fiber optic coupler, 14-first balanced detector, 15-second balanced detector, and 16-data processing host computer. Detailed Implementation

[0033] To better illustrate the purpose and advantages of the present invention, the invention will be further described below in conjunction with the accompanying drawings and examples.

[0034] Example 1:

[0035] like Figure 1As shown, this embodiment discloses a gas pressure measurement device based on a femtosecond dual optical comb, including a light source module, a measurement module, a detection module, and a data processing module. The light source module includes a first optical frequency comb 1 and a second optical frequency comb 2. The light source module outputs two near-infrared broadband optical frequency combs for measurement. The light source module uses optical fibers to output the two laser beams to the measurement module. The measurement module adjusts and couples the laser beams to form a measurement path and a reference path in the measurement optical path. After the measurement module receives two laser beams from the light source module, the laser from the first optical frequency comb 1 is amplified by connecting to the first power amplifier 3 via optical fiber, and the laser from the second optical frequency comb 2 is amplified by connecting to the second power amplifier 4 via optical fiber. The first power amplifier 3 is filtered by connecting to the first wavelength division multiplexer 5 via optical fiber, reducing the spectral linewidth to improve measurement resolution, sampling rate, and measurement speed. Similarly, the second power amplifier 4 is connected to the second wavelength division multiplexer 6 via optical fiber to reduce the spectral linewidth. The first wavelength division multiplexer 5 is connected to the first 1×2 fiber beam splitter 7 via optical fiber to split the laser into two beams, beam 1 and beam 2. Similarly, the second wavelength division multiplexer 6 and the second 1×2 fiber beam splitter 8 are connected via optical fiber to split the laser into two beams, beam 3 and beam 4. Finally, beams 1 and 4 beat frequencies form the measurement path signal, and beams 2 and 3 beat frequencies form the reference path signal. Beam 1 receives 90% of the laser energy, beam 2 receives 10%, beam 3 receives 50%, and beam 4 receives 50%. Figure 1 As shown. Beam 1 from the first 1×2 fiber beam splitter 7 is connected to a beam expander 9 via optical fiber. The beam expander 9 outputs a spatial laser beam as the measurement optical path, expanding the laser beam to increase the contact volume between the laser and the gas. The spatial laser beam is input to a collimating lens 11, which couples it into an optical fiber, and then inputs it to a second 2×2 fiber coupler 13 via optical fiber. Beam 2 from the first 1×2 fiber beam splitter 7 is input to a first 2×2 fiber coupler 12 via optical fiber. Beam 3 from the second 1×2 fiber beam splitter 8 is input to the first 2×2 fiber coupler 12 via optical fiber, and beam 4 from the second 1×2 fiber beam splitter 8 is input to the second 2×2 fiber coupler 13 via optical fiber. The first 2×2 fiber coupler 12 and the second 2×2 fiber coupler 13 couple the two input laser beams and output them to the detection module via optical fiber. The detection module includes a first balanced detector 14 and a second balanced detector 15, which convert the input beat frequency signal into an electrical signal output for easy signal acquisition. A first 2×2 fiber optic coupler 12 is connected to the first balanced detector 14 to output a reference path signal, and a second 2×2 fiber optic coupler 13 is connected to the second balanced detector 15 to output a measurement path signal. All are connected to the data processing module via a data transmission line. The data processing module includes a data processing host computer 16 from the data acquisition card, which processes the acquired signals to obtain gas pressure values.

[0036] This embodiment discloses a gas pressure measurement method based on a femtosecond dual optical comb, implemented using a gas pressure measurement device based on a femtosecond dual optical comb. The gas pressure measurement method based on a femtosecond dual optical comb includes the following steps:

[0037] Step 1: Construct the gas pressure measurement device according to the femtosecond dual-comb-based gas pressure measurement device. Near-infrared laser emitted from the first optical frequency comb 1 is amplified by the first power amplifier 3 to increase its measurement energy. The laser then passes through the first wavelength division multiplexer 5 and the first 1×2 fiber beam splitter 7, splitting the laser energy into beam 1 and beam 2. Beam 2 is transmitted to the first 2×2 fiber coupler 12, while beam 1's laser energy is transmitted to the beam expander 9 as the measurement path signal. The measurement path laser passes through the high-pressure gas chamber 10 and is absorbed by gas molecules to obtain the gas absorption signal, which is then received by the collimating lens 11 and transmitted to the second 2×2 fiber coupler 13. The first wavelength division multiplexer 5 and the second wavelength division multiplexer 6 are identical, but the first wavelength division multiplexer 5 and the second wavelength division multiplexer 6 reduce the spectral linewidth to improve measurement resolution, sampling rate, and measurement speed. The second optical frequency comb 2 emits near-infrared laser light with a repetition frequency similar to that of the first optical frequency comb 1. The laser energy is amplified by the second power amplifier 4, then passed through the second wavelength division multiplexer 6, and finally through the second 1×2 fiber beam splitter 8, splitting the laser energy into beams 3 and 4. Beam 3 is transmitted to the first 2×2 fiber coupler 12, and beam 4 is transmitted to the second 2×2 fiber coupler 13. The first 2×2 fiber coupler 12 transmits the signal to the first balanced detector 14, which collects the time-domain interferogram after frequency beating as the measurement path signal. The second 2×2 fiber coupler 13 transmits the signal to the second balanced detector 15, which collects the time-domain interferogram after frequency beating as the reference path signal. The measurement path signal and the reference path signal are transmitted to the data processing host computer 16 for data processing. After performing Fourier transform, filtering, and other data processing on the interferogram signal, the spectral results of the measurement path and the reference path are obtained in the frequency domain.

[0038] Step 2: Calculate the gas partial pressure value based on the measured spectral lines of the two spectra.

[0039] Step 2.1: Perform spectral calibration on the light intensity I0(ν) of the spectral line of the measurement path and the light intensity I(ν) of the spectral line of the reference path.

[0040] Step 2.2: Preprocess the spectral absorption data to filter out low-frequency and high-frequency noise, then normalize the spectral data, extract the characteristic absorption peaks, and calculate the integral absorbance A of the target gas using equation (1). abs Where I(ν) is the light intensity of the measured path, mW; and I0(ν) is the light intensity of the reference path, mW.

[0041]

[0042] Step 2.3: Determine the absorption length L of the interaction between the light beam and the sample gas, and determine the absorption line intensity S, cm, of the target gas. -1 / (molec·cm -2 ).

[0043] Step 2.4: Calculate the molecular number density n of the target gas according to formula (2), and then calculate the partial pressure P of the target gas according to formula (3). partial .

[0044]

[0045] P partial =nkL (3)

[0046] Where: k is Boltzmann constant; T is gas temperature, K.

[0047] Step 2.5: Obtain the near-infrared broadband bands of the first optical frequency comb 1 and the second optical frequency comb 2 to obtain the spectral lines of a broadband measurement path and a reference path. Simultaneously, obtain multiple absorption peaks of the same gas, calculate a partial pressure value for each absorption peak, obtain multiple pressure values ​​in parallel, and average these values ​​to obtain the final, more accurate measurement result P. p The calculation uses formula (4):

[0048]

[0049] Where N represents the number of pressure values ​​calculated using the absorption peaks of the same gas.

[0050] The broadband spectral output of the dual optical comb covers the band from 1.3 μm to 1.7 μm, covering the absorption spectra of various gases (methane, carbon dioxide, etc.). At the same time, the partial pressures of different gases in the mixed gas are measured in parallel, and the total pressure P of the mixed gas is obtained by summing the partial pressures. The calculation is performed using formula (5):

[0051]

[0052] Where: P pi Let be the partial pressure of the i-th gas in the gas mixture.

[0053] The various gases include methane, carbon dioxide, etc.

[0054] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A gas pressure measuring device based on a femtosecond dual optical comb, characterized in that: The system includes a light source module, a measurement module, a detection module, and a data processing module. The light source module includes a first optical frequency comb (1) and a second optical frequency comb (2). The light source module outputs two near-infrared broadband optical frequency combs for measurement. The light source module uses optical fibers to output the two laser beams to the measurement module. The measurement module adjusts and couples the laser beams to form the measurement path and the reference path of the measurement optical path. After receiving the two laser beams from the light source module, the laser beam from the first optical frequency comb (1) is connected to the first power amplifier (3) via optical fiber to amplify the laser energy. The laser beam from the second optical frequency comb (2) is connected to the second power amplifier (4) via optical fiber to amplify the laser energy. The first power amplifier (3) uses optical fiber and a first wavelength division multiplexing (WDM) to amplify the laser energy. The laser is filtered by the first wavelength division multiplexer (5) to reduce the spectral width, thereby improving the measurement resolution, sampling rate, and measurement speed. The second power amplifier (4) is connected to the second wavelength division multiplexer (6) using optical fiber to reduce the spectral width. The first wavelength division multiplexer (5) is connected to the first 1×2 fiber beam splitter (7) using optical fiber to split the laser into two beams, beam 1 and beam 2. Similarly, the second wavelength division multiplexer (6) and the second 1×2 fiber beam splitter (8) are connected using optical fiber to split the laser into two beams, beam 3 and beam 4. Beams 1 and 4 beat to form the measurement path signal, and beams 2 and 3 beat to form the reference path signal. Beam 1 of the first 1×2 fiber beam splitter (7) is connected to the second wavelength division multiplexer (6) using optical fiber and the second wavelength division multiplexer (8) to split the laser into two beams, beam 3 and beam 4. Beams 1 and 4 beat to form the measurement path signal, and beams 2 and 3 beat to form the reference path signal. The beam expander (9) is connected to the collimator (11), and the output space laser of the beam expander (9) is used as the measurement optical path to expand the laser beam to increase the contact volume between the laser and the gas. The space laser is input to the collimator (11) and coupled into the optical fiber. The laser beam is then input into the second 2×2 fiber coupler (13) using the optical fiber. The beam 2 split from the first 1×2 fiber beam splitter (7) is input into the first 2×2 fiber coupler (12) using the optical fiber. The beam 3 from the second 1×2 fiber beam splitter (8) is input into the first 2×2 fiber coupler (12) using the optical fiber. The beam 4 from the second 1×2 fiber beam splitter (8) is input into the second 2×2 fiber coupler (13) using the optical fiber. The first 2×2 fiber coupler (12) is input into the second 2×2 fiber coupler (13). The first 2×2 fiber optic coupler (12) and the second 2×2 fiber optic coupler (13) couple the two input laser beams and output them to the detection module via optical fiber. The detection module includes a first balanced detector (14) and a second balanced detector (15), which convert the input beat frequency signal into an electrical signal for easy signal acquisition. The first 2×2 fiber optic coupler (12) and the first balanced detector (14) are connected to output the reference path signal, and the second 2×2 fiber optic coupler (13) and the second balanced detector (15) are connected to output the measurement path signal. The data processing module is connected to the data processing module via a data transmission line. The data processing module includes a data processing host computer (16) of the data acquisition card, which performs calculations on the acquired signals to obtain the gas pressure value.

2. The gas pressure measuring device based on a femtosecond dual optical comb as described in claim 1, characterized in that: The first 1×2 fiber beam splitter (7) divides the laser energy into 70%–90% and 10%–30%, and 70%–90% of the laser energy is transmitted to the beam expander (9).

3. The gas pressure measuring device based on a femtosecond dual optical comb as described in claim 2, characterized in that: The first 1×2 fiber beam splitter (7) divides the laser energy into 90% and 10%, with 90% of the laser energy being transmitted to the beam expander (9).

4. A gas pressure measurement method based on a femtosecond dual optical comb, implemented based on a gas pressure measurement device based on a femtosecond dual optical comb as described in claim 1, 2, or 3, characterized in that: Includes the following steps, Step 1: Construct a gas pressure measuring device according to the femtosecond dual optical comb-based gas pressure measuring device; the near-infrared laser emitted by the first optical frequency comb (1) is amplified by the first power amplifier (3), and the laser energy is split into beam 1 and beam 2 by the first wavelength division multiplexer (5) and the first 1×2 fiber beam splitter (7). Beam 2 is transmitted to the first 2×2 fiber coupler (12), and the laser energy of beam 1 is transmitted to the beam expander (9) as the measurement path signal. The measurement path laser is absorbed by gas molecules in the high-pressure gas chamber (10) to obtain the gas absorption signal, which is then received by the collimator (11) and transmitted to the second 2×2 fiber coupler (13); the first wavelength division multiplexer (5) and the second wavelength division multiplexer (6) are the same. The first wavelength division multiplexer (5) and the second wavelength division multiplexer (6) reduce the spectral linewidth to improve the measurement resolution, sampling rate and measurement speed; the second optical frequency comb (2) emits The near-infrared laser, whose repetition frequency is not much different from that of the first optical frequency comb (1), is amplified by the second power amplifier (4), then passed through the second wavelength division multiplexer (6), and then through the second 1×2 fiber beam splitter (8) to split the laser energy into beam 3 and beam 4. Beam 3 is transmitted to the first 2×2 fiber coupler (12), and beam 4 is transmitted to the second 2×2 fiber coupler (13). The first 2×2 fiber coupler (12) transmits the signal to the first balanced detector (14) and collects the time-domain interferogram after frequency beating as the measurement path signal. The second 2×2 fiber coupler (13) transmits the signal to the second balanced detector (15) and collects the time-domain interferogram after frequency beating as the reference path signal. The measurement path signal and the reference path signal are transmitted to the data processing host computer (16) for data processing. After performing Fourier transform, filtering and other data processing on the interferogram signal, the spectral results of the measurement path and the reference path are obtained in the frequency domain. Step 2: Based on the measured spectral line results, calculate the gas partial pressure value to realize gas pressure measurement based on femtosecond dual optical comb; Step 2.1: Perform spectral calibration on the light intensity I0(ν) of the spectral line of the measurement path and the light intensity I(ν) of the spectral line of the reference path; Step 2.2: Preprocess the spectral absorption data to filter out low-frequency and high-frequency noise, then normalize the spectral data, extract the characteristic absorption peaks, and calculate the integral absorbance A of the target gas using equation (1). abs Where I(ν) is the light intensity of the measured path, mW; and I0(ν) is the light intensity of the reference path, mW. Step 2.3: Determine the absorption length L of the interaction between the light beam and the sample gas, and determine the absorption line intensity S, cm, of the target gas. -1 / (molec·cm -2 ); Step 2.4: Calculate the molecular number density n of the target gas according to formula (2), and then calculate the partial pressure P of the target gas according to formula (3). partial ; P partial =nkL (3) Where: k is the Boltzmann constant; T is the gas temperature, K; Step 2.5: Obtain the near-infrared broadband bands of the first optical frequency comb (1) and the second optical frequency comb (2) to obtain the spectral lines of a broadband measurement path and a reference path. At the same time, obtain multiple absorption peaks of the same gas. Calculate a partial pressure value for each absorption peak. Obtain multiple pressure values ​​in parallel. Average these values ​​to obtain the final, more accurate measurement result P. p The calculation uses formula (4): Where N is the number of pressure values ​​calculated using the absorption peaks of the same gas; The broadband spectral output of the dual optical comb covers the band from 1.3 μm to 1.7 μm, covering the absorption lines of various gases. At the same time, the partial pressures of different gases in the mixed gas are measured in parallel, and the total pressure P of the mixed gas is obtained by summing the partial pressures. The calculation is performed using formula (5): Where: P pi Let be the partial pressure of the i-th gas in the gas mixture.

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