Wide-range gas measurement method and device based on single-photon optical scanning

Abstract

The invention provides a large-range gas measuring device and method based on single-photon optical scanning. The large-range gas measuring device comprises a three-dimensional scanning holder, wherein a single-photon laser emitting unit and a single-photon detecting and counting unit are borne on the three-dimensional scanning holder; the three-dimensional scanning holder is used for adjusting the orientation of the single-photon laser emission unit and the single-photon detection counting unit pointing to the gas to be detected; the single-photon laser emission unit comprises a tunable wavelength laser module, a laser power amplifier module and an optical beam expanding collimation module; the single-photon detection and counting unit comprises a reflected light receiving telescope module, a narrow-band filter module, a single-photon detector and a single-photon counter; the central control processing unit comprises a control subunit, a data acquisition subunit and a data processing subunit and is used for controlling and receiving gas single photon detection data in a preset direction. The device has the advantages of low detection limit, strong anti-interference capability, high spatial resolution and the like, and is suitable for leakage detection of extremely low-concentration gas and large-range environment monitoring.

Description

Technical Field

[0001] This invention belongs to the field of optical gas composition measurement technology, and particularly relates to a method and apparatus for large-scale gas measurement based on single-photon optical scanning. Background Technology

[0002] In the fields of environmental monitoring, industrial safety, and scientific research, highly sensitive and spatially resolved concentration measurements of specific gas components are of great significance. Traditional gas detection methods, such as electrochemical sensors or conventional laser absorption spectroscopy (TDLAS), have limitations in detection sensitivity, measurement distance, or spatial resolution. Especially for trace gases at extremely low concentrations or in long-distance measurement scenarios, the signal is weak, and traditional intensity detection methods have insufficient signal-to-noise ratio, making it difficult to achieve effective spatial distribution visualization.

[0003] Chinese Patent Publication CN112180392A discloses an atmospheric composition detection lidar based on dispersion gating. This lidar stretches a femtosecond laser into a wide-pulse laser in the time domain through dispersion. The femtosecond spectrum is mapped onto the broadened laser pulse due to group velocity dispersion. After time-domain gating by an intensity modulator, a preset wavelength of laser light is selected. The laser wavelength is scanned by adjusting the delay of the electrical drive signal of the intensity modulator. By scanning the laser wavelength, the absorption spectrum of a specific atmospheric component is obtained, thereby measuring the concentration of atmospheric gas components. This atmospheric composition detection lidar can accurately gating any wavelength of the emitted laser, with high wavelength selection accuracy. Furthermore, by adjusting the center wavelength of the filter, it can achieve scanning and detection of multiple gases.

[0004] Chinese Patent Publication CN115343256A discloses a device and method for measuring gas concentration using a spherical resonant cavity. The device includes a signal generator, a laser controller, and a laser. A collimating lens is placed at the laser's output port. After collimation, the laser beam is coupled into the spherical resonant cavity. An inlet and an outlet are respectively installed at the upper and lower ends of the cavity. The laser beam reflects and absorbs gas within the cavity. The transmitted light is focused by a focusing lens onto a single-photon avalanche diode detector, which is then connected to an oscilloscope. The oscilloscope transmits the signal to a computer for signal processing, and the concentration is then inverted to obtain the concentration of the gas to be measured. This invention utilizes a single-photon detection device to improve detection sensitivity. The spherical resonant cavity design and the use of a signal generator to generate a modulation signal synchronously implement cavity enhancement and strong ring-down techniques, thereby improving gas detection sensitivity.

[0005] Single-photon detection technology, as an extreme detection method, can detect individual photon events with sensitivity far exceeding that of traditional detectors. However, current technologies lack an efficient solution that can effectively integrate single-photon-level sensitivity with systematic spatial scanning to ultimately generate intuitive three-dimensional distribution images. Applying single-photon detection technology to gas concentration distribution measurement still requires solving the problem of how to combine single-point sensitivity with spatial scanning to achieve rapid and accurate three-dimensional distribution measurement and inversion calculation. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the first aspect of the present invention proposes a large-scale gas measurement device based on single-photon optical scanning, the gas measurement device comprising: a three-dimensional scanning gimbal, a single-photon laser emitting unit, a single-photon detection and counting unit, and a central control and processing unit; The three-dimensional scanning gimbal supports the single-photon laser emitting unit and the single-photon detection and counting unit; the three-dimensional scanning gimbal is used to adjust the orientation of the single-photon laser emitting unit and the single-photon detection and counting unit toward the gas to be measured; The single-photon laser emitting unit includes a tunable wavelength laser module, a laser power amplifier module, and an optical beam expander and collimator module arranged in sequence. The single-photon detection and counting unit includes: a reflected light receiving telescope module, a narrowband filter module, a single-photon detector, and a single-photon counter arranged in sequence. The central control and processing unit includes: a control subunit, a data acquisition subunit, and a data processing subunit. The control subunit controls the three-dimensional scanning gimbal to rotate in three-dimensional directions; The control subunit controls the single-photon laser emitting unit and the single-photon detection and counting unit to work together to receive gas single-photon detection data from a predetermined location.

[0007] As described in the first aspect of the invention, in the gas measuring device, the control subunit controls the tunable wavelength laser module to emit a laser beam with a specified center wavelength, the laser beam being modulated by a predetermined modulation frequency output by the control subunit. The laser beam is fed into the laser power amplifier module and amplified to a predetermined laser power before being input into the optical beam expander and collimator module, which generates a beam of a specified diameter. The control subunit controls the rotation of the three-dimensional scanning gimbal to ensure that the beam of a specified diameter illuminates the target and is reflected by the reflective target; the gas to be tested is located between the optical beam expander and collimator module and the reflective target.

[0008] As described in the first aspect of the gas measuring device of the present invention, the light beam reflected by the reflective target is filtered out by the narrow-band filter module after passing through the reflective light receiving telescope module to remove stray light signals. The light beam received by the reflective light receiving telescope module is focused onto a single-photon detector located on the focal plane of the reflective light receiving telescope module. The single-photon detector converts the detected reflected light into an electrical signal and inputs it into a single-photon counter for counting.

[0009] In the gas measuring device as described in the first aspect of the present invention, the single-photon detector is an avalanche photodiode or a superconducting nanowire single-photon detector.

[0010] In the gas measuring device according to the first aspect of the present invention, the predetermined modulation frequency range is 1KHz to 100KHz, and the modulation waveform is a triangular wave or a sawtooth wave.

[0011] A second aspect of the present invention provides a large-scale gas measurement method based on single-photon optical scanning, the method being used to operate a large-scale gas measurement device based on single-photon optical scanning as described in any of the preceding claims to measure gas composition and concentration; the method includes the following steps: Step 1: The control subunit controls the single-photon laser emitting unit to emit a laser beam of a specified center wavelength to irradiate the gas located between the single-photon laser emitting unit and the reflective target; Step 2: The data acquisition subunit and the data processing subunit calculate the gas concentration value at the current spatial measurement point based on the photon count-wavelength relationship data; Step 3: For each spatial measurement point, the control subunit controls the single-photon detector to receive the light beam reflected by the reflective target and measures the photon count-wavelength relationship data for each spatial measurement point. Step 4: The data processing subunit fuses the gas concentration values ​​of all spatial measurement points with the three-dimensional spatial coordinates corresponding to all spatial measurement points to generate a three-dimensional point cloud distribution image of gas concentration.

[0012] As described in the second aspect of the gas measurement method of the present invention, step 1 includes the following sub-steps: Step 1.1, the laser beam is modulated by a predetermined modulation frequency output by the control subunit; Step 1.2: The control subunit controls the rotation of the three-dimensional scanning gimbal so that the laser beam points sequentially to a series of spatial measurement points in the target area along a preset path; a reflective target is set in the target area.

[0013] As described in the second aspect of the gas measurement method of the present invention, step 2 includes the following sub-steps: Step 2.1: At each of the spatial measurement points, the beam signal reflected by the reflective target through the gas to be measured is received by a single-photon detector. Step 2.2. Using time-correlated single-photon counting technology, the relative relationship between photon arrival time and laser modulation signal is recorded. The control subunit controls the single-photon counter to count only photon events within the laser wavelength scanning cycle. Step 2.3: Suppress background noise using time gating; record the photon count-wavelength relationship data for the spatial measurement points.

[0014] As described in the second aspect of the gas measurement method of the present invention, step 3 includes the following sub-steps: Step 3.1: Based on the recorded photon count-wavelength relationship data for all the spatial measurement points, statistically calculate the change in photon count rate caused by the absorption of the measurement gas. Step 3.2: Calculate the gas concentration value according to the change in photon count rate.

[0015] As described in the second aspect of the gas measurement method of the present invention, the laser beam emitted by the single-photon laser emitting unit irradiates the gas to be measured and is reflected by a reflective target. The reflected light signal is focused onto a single-photon detector located on the focal plane of the reflective light receiving telescope module after passing through the reflective light receiving telescope module. A narrowband filter module for filtering out stray light signals is provided between the reflective light receiving telescope module and the single-photon detector. The center wavelength of the narrowband filter module corresponds to the absorption wavelength of the gas to be measured.

[0016] The present invention has the following beneficial effects: By employing single-photon detection technology, signal detection at the photon level is achieved, improving the ultimate detection sensitivity: reducing the detection limit of gas components, making it suitable for measuring gas components at extremely low concentrations or over ultra-long distances.

[0017] This invention utilizes a precision 3D gimbal for point-by-point scanning, enabling the acquisition of high spatial resolution measurement data. The point cloud distribution map clearly displays the subtle spatial structure of gas concentration. The combination of single-photon counting technology and time-gating technology effectively suppresses background light noise interference, improving the detection signal-to-noise ratio.

[0018] The three-dimensional point cloud images of this invention intuitively display the spatial distribution of gas. This intuitive and visualized detection result facilitates the location of leak sources of specific gases and gas diffusion analysis. Attached Figure Description

[0019] Figure 1 This is a flowchart of a large-scale gas measurement method based on single-photon optical scanning proposed in this invention; Figure 2 This is a structural diagram of a large-scale gas measurement device based on single-photon optical scanning proposed in this invention.

[0020] The components are as follows: 101—Laser drive and tuning module; 102—Laser power amplification module; 103—3D scanning gimbal; 104—Optical beam expander and collimator module; 105—Reflected light receiving telescope module; 106—Narrowband filter module; 107—Single photon detector module; 108—Single photon counter; 109—Control unit; 110—Data acquisition unit; 111—Data processing unit; 112—Reflected target. Detailed Implementation

[0021] This invention addresses the technical deficiencies of existing technologies by providing a method and apparatus for large-scale gas measurement based on single-photon optical scanning. The apparatus controls a wavelength-tunable laser, modulates the laser beam to transmit radiation through the gas to be measured, and then reflects it off a target. The reflected laser light is received and its spectrum of a specific gas component is obtained through photon counting, thereby measuring the concentration of the predetermined gas component.

[0022] This invention relates to a large-scale gas measurement device and method based on single-photon optical scanning. It can precisely tune the emitted laser wavelength, achieving high accuracy and speed in wavelength selection. A narrow-band filter at the receiver removes stray light signals outside the laser's center wavelength. This invention can scan and detect various gases and calculate the concentration of the gas to be measured. This improves the sensitivity, robustness, anti-interference ability, and laser sensing efficiency of gas detection.

[0023] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] Example 1: Appendix Figure 2 This is a structural diagram of a large-scale gas measurement device based on single-photon optical scanning proposed in this invention.

[0025] The first aspect of the present invention provides a large-scale gas measurement device based on single-photon optical scanning, the gas measurement device comprising: a three-dimensional scanning gimbal, a single-photon laser emitting unit, a single-photon detection and counting unit, and a central control and processing unit; The three-dimensional scanning gimbal supports the single-photon laser emitting unit and the single-photon detection and counting unit; the three-dimensional scanning gimbal is used to adjust the orientation of the single-photon laser emitting unit and the single-photon detection and counting unit toward the gas to be measured; The single-photon laser emitting unit includes a tunable wavelength laser module, a laser power amplifier module, and an optical beam expander and collimator module arranged in sequence. The single-photon detection and counting unit includes: a reflected light receiving telescope module, a narrowband filter module, a single-photon detector, and a single-photon counter arranged in sequence. The central control and processing unit includes: a control subunit, a data acquisition subunit, and a data processing subunit. The control subunit controls the three-dimensional scanning gimbal to rotate in three-dimensional directions; The control subunit controls the single-photon laser emitting unit and the single-photon detection and counting unit to work together to receive gas single-photon detection data from a predetermined location.

[0026] The aforementioned 3D pan-tilt unit carries and fixes the single-photon laser emitting unit and the single-photon detection and counting unit; the central processing unit can be a computer or a dedicated computing device. The computer can be directly installed on the 3D scanning pan-tilt unit, or it can be connected to a computer room outside the 3D scanning pan-tilt unit via a network cable to perform calculations.

[0027] In the single-photon laser emitting unit with a fixed three-dimensional gimbal, the output optical axis of the optical beam expander and collimator module has a predetermined angle with the center of the optical axis of the reflected light receiving telescope module in the single-photon detection and counting unit; this ensures that the laser beam output by the optical beam expander and collimator module can be received by the reflected light receiving telescope module after being reflected by the reflective target, so as to accurately obtain the measurement data of the gas to be measured.

[0028] The single-photon detection and counting module uses a time-correlated single-photon counter to achieve photon-level weak signal measurement and detects gas absorption spectra at extremely low concentrations through single-photon detection.

[0029] Alternatively, the optical axes of the optical beam expanding and collimating module and the reflected light receiving telescope module can be designed to rotate together under the control of the control submodule, ensuring that the laser beam output by the optical beam expanding and collimating module can be received by the reflected light receiving telescope module after being reflected by the reflected target, regardless of the distance of the reflecting target.

[0030] The optical beam expander and collimator module can be a Kepler telescope structure composed of multiple concave lenses and multiple convex lenses, or a reflecting telescope structure composed of concave mirrors.

[0031] The reflected light receiving telescope module can also use a Keplerian telescope structure or a reflecting telescope structure. The center wavelengths of the optical beam expander and collimator module and the reflected light receiving telescope module correspond to the center wavelength of the tunable wavelength laser module.

[0032] As described in the first aspect of the invention, in the gas measuring device, the control subunit controls the tunable wavelength laser module to emit a laser beam with a specified center wavelength, the laser beam being modulated by a predetermined modulation frequency output by the control subunit. The laser beam is fed into the laser power amplifier module and amplified to a predetermined laser power before being input into the optical beam expander and collimator module, which generates a beam of a specified diameter. The control subunit controls the rotation of the three-dimensional scanning gimbal to ensure that the beam of a specified diameter illuminates the emission target and is reflected by the reflection target; the optical system of the gas under test is located between the beam expanding and collimating module and the reflection target.

[0033] As described in the first aspect of the gas measuring device of the present invention, the light beam reflected by the reflective target is filtered out by the narrow-band filter module after passing through the reflective light receiving telescope module to remove stray light signals. The light beam received by the reflective light receiving telescope module is focused onto a single-photon detector located on the focal plane of the reflective light receiving telescope module. The single-photon detector converts the detected reflected light into an electrical signal and inputs it into a single-photon counter for counting.

[0034] In the gas measuring device as described in the first aspect of the present invention, the single-photon detector is an avalanche photodiode or a superconducting nanowire single-photon detector.

[0035] In the gas measuring device according to the first aspect of the present invention, the predetermined modulation frequency range is 1KHz to 100KHz, and the modulation waveform is a triangular wave or a sawtooth wave.

[0036] Taking the scanning monitoring of methane leakage in a natural gas pipeline valve chamber as an example: 1. System Configuration: A distributed feedback laser (DFB) with a center wavelength of 1653 nm and a modulation frequency of 10 kHz is used. The scanning pan-tilt unit has an angular resolution of 0.01°. An InGaAs single-photon detector (SPAD) is employed, with detector timing jitter less than 100 ps.

[0037] 2. Measurement Process: The device is placed 50 meters from the valve chamber. The scanning range is set to: horizontal ±30°, pitch 0° to 20°, with a step size of 0.1°. The integration time per point is 100 ms. The system automatically completes the scan, recording the photon counting curve and angle at each point.

[0038] 3. Data Processing: For each data point, calculate the decrease in photon count rate at the 1653.7 nm absorption peak, and invert the CH4 concentration (ppm·m) based on the calibration curve. Convert the angles to three-dimensional coordinates.

[0039] 4. Results: The generated 3D point cloud map clearly shows a distinct high-concentration point cloud cluster at the valve flange, with a concentration exceeding 50 ppm·m, successfully locating the leak point.

[0040] As attached Figure 1 The flowchart shown is a method for large-scale gas measurement based on single-photon optical scanning.

[0041] A second aspect of the present invention provides a large-scale gas measurement method based on single-photon optical scanning, the method being used to operate a large-scale gas measurement device based on single-photon optical scanning as described in any of the preceding claims to measure gas composition and concentration; the method includes the following steps: Step 1: The control subunit controls the single-photon laser emitting unit to emit a laser beam of a specified center wavelength to irradiate the gas located between the single-photon laser emitting unit and the reflective target; Step 2: The data acquisition subunit and the data processing subunit calculate the gas concentration value at the current spatial measurement point based on the photon count-wavelength relationship data; Step 3: For each spatial measurement point, the control subunit controls the single-photon detector to receive the light beam reflected by the reflective target and measures the photon count-wavelength relationship data for each spatial measurement point. Step 4: The data processing subunit fuses the gas concentration values ​​of all spatial measurement points with the three-dimensional spatial coordinates corresponding to all spatial measurement points to generate a three-dimensional point cloud distribution image of gas concentration.

[0042] Example 2 Based on the above-described apparatus, the large-scale gas measurement method based on single-photon optical scanning according to the present invention includes the following steps: System initialization and parameter settings • Start the system and initialize the laser, single-photon counter, and 3D scanning gimbal.

[0043] • Set laser modulation parameters: Modulation waveform is triangular wave or sawtooth wave, set modulation frequency and scanning range.

[0044] • Set scan parameters: Scan parameters include: the start / end azimuth angle of the scan area, the elevation angle of the scan area, the scan step size, and the integration time for each measurement point.

[0045] • Set the single-photon counter parameters: time gate width and time delay value.

[0046] Point-by-point scanning and data acquisition • Control the movement of the 3D scanning gimbal to precisely point the laser beam at the first preset measurement point.

[0047] • At the current point, the laser performs wavelength scanning according to the set parameters. At the same time, the single-photon detector receives the returned photon signal, and the single-photon counter synchronously accumulates photon counts to obtain a curve showing the change of photon count rate with wavelength (or time) within one scanning cycle.

[0048] • Store the photon counting curve data of the current point and the corresponding gimbal angle coordinates (α, β).

[0049] • The gimbal moves to the next point at a preset step size, repeating the above data acquisition process until the entire target area is scanned.

[0050] The inversion calculation process for single-point gas concentration is as follows: • Preprocess the photon counting curves acquired at each scanning point, including background noise subtraction.

[0051] • Extract the photon count rate change within the wavelength modulation range corresponding to gas absorption.

[0052] • Compare the measured photon count rate curve with a reference curve when there is no gas absorption, or calculate the decrease in photon count rate due to gas absorption using a fitting algorithm, thereby retrieving the gas concentration value along the laser path. The specific method is as follows: The absorption peaks are fitted with the Voigt line shape function to obtain the absorption peak model within the spectral range. A polynomial fitting algorithm is used to obtain the absorption spectrum baseline. The fitted absorption peaks are compared with the spectral baseline to obtain the absorbance corresponding to each peak. The absorbance α is obtained by comparing the absorption peak intensity with the spectral baseline; the calculation formula is as follows: (1) Among them, I out To output light intensity, I in The input light intensity.

[0053] Calculate the gas concentration using the following formula: (2) In the formula, α( v i ) Let be the absorbance at a certain frequency, vi be the optical frequency, P be the pressure, L be the absorption optical path length, and S(T) be the absorption spectrum line shape function, which can be obtained from the HITRAN database. X abs The concentration of the gas to be measured is given.

[0054] Step 4: Generation and Visualization of 3D Point Cloud Images • Based on the gimbal angle (α, β) and known measurement distance (L) of each measurement point, calculate its rectangular coordinates (X, Y, Z) in three-dimensional space through coordinate transformation.

[0055] • Associate the spatial coordinates (X, Y, Z) of all measurement points with the gas concentration values ​​obtained from their inversion to form a three-dimensional point cloud dataset.

[0056] • Use 3D visualization software to render point cloud data into a gas concentration distribution map, where color or the size of the dots represents the concentration level.

[0057] As described in the second aspect of the gas measurement method of the present invention, step 1 includes the following sub-steps: Step 1.1, the laser beam is modulated by a predetermined modulation frequency output by the control subunit; Step 1.2 The control subunit controls the rotation of the three-dimensional scanning gimbal so that the laser beam points sequentially to a series of spatial measurement points in the target area along a preset path; a reflective target is set in the target area.

[0058] The voltage and / or current signals output by the control subunit provide a predetermined modulation frequency to modulate the intensity or frequency of the laser beam over time.

[0059] As described in the second aspect of the gas measurement method of the present invention, step 2 includes the following sub-steps: Step 2.1: At each of the spatial measurement points, the beam signal reflected by the reflective target through the gas to be measured is received by a single-photon detector. Step 2.2. Using time-correlated single-photon counting technology, the relative relationship between photon arrival time and laser modulation signal is recorded. The control subunit controls the single-photon counter to count only photon events within the laser wavelength scanning cycle. Step 2.3: Suppress background noise using time gating; record the photon count-wavelength relationship data for the spatial measurement points.

[0060] The control subunit controls the single-photon counter to count photon events of the reflected light only within the laser wavelength scanning period; a time-gated method is used to suppress background noise in the reflected light.

[0061] As described in the second aspect of the gas measurement method of the present invention, step 3 includes the following sub-steps: Step 3.1: Based on the recorded photon count-wavelength relationship data for all the spatial measurement points, statistically calculate the change in photon count rate caused by the absorption of the measurement gas. Step 3.2: Calculate the gas concentration value according to the change in photon count rate.

[0062] It will be apparent to those skilled in the art that the embodiments of the present invention are not limited to the details of the exemplary embodiments described above, and that the embodiments of the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the embodiments of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the embodiments of the present invention is defined by the appended claims rather than the foregoing description. Therefore, all variations falling within the meaning and scope of equivalents of the claims are intended to be encompassed within the embodiments of the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it is clear that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units, modules, or devices recited in the system, apparatus, or terminal claims may also be implemented by the same unit, module, or device through software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any particular order.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention and are not intended to limit them. Although the embodiments of the present invention have been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the embodiments of the present invention should not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wide-range gas measurement device based on single-photon optical scanning, characterized in that, The gas measuring device includes: a three-dimensional scanning gimbal, a single-photon laser emitting unit, a single-photon detection and counting unit, and a central control and processing unit; The three-dimensional scanning gimbal supports the single-photon laser emitting unit and the single-photon detection and counting unit; the three-dimensional scanning gimbal is used to adjust the orientation of the single-photon laser emitting unit and the single-photon detection and counting unit toward the gas to be measured; The single-photon laser emitting unit includes, in sequence, a tunable wavelength laser module, a laser power amplifier module, and an optical beam expander and collimator module. The single-photon detection and counting unit includes: a reflected light receiving telescope module, a narrowband filter module, a single-photon detector, and a single-photon counter arranged in sequence. The central control and processing unit includes: a control subunit, a data acquisition subunit, and a data processing subunit. The control subunit controls the three-dimensional scanning gimbal to rotate in three-dimensional directions; The control subunit controls the single-photon laser emitting unit and the single-photon detection and counting unit to work together to receive gas single-photon detection data from a predetermined location.

2. The gas measuring device as described in claim 1, characterized in that, The control subunit controls the tunable wavelength laser module to emit a laser beam with a specified center wavelength, and the laser beam is modulated by a predetermined modulation frequency output by the control subunit. The laser beam is fed into the laser power amplifier module and amplified to a predetermined laser power before being input into the optical beam expander and collimator module, which generates a beam of a specified diameter. The control subunit controls the rotation of the three-dimensional scanning gimbal to ensure that the beam of a specified diameter illuminates the reflective target and is reflected by the reflective target; the gas to be tested is located between the optical beam expander and collimator module and the reflective target.

3. The gas measuring device as described in claim 2, characterized in that, The light beam reflected by the reflective target is filtered out by the narrowband filter module after passing through the reflective light receiving telescope module to remove stray light signals. The light beam received by the reflective light receiving telescope module is focused onto the single-photon detector located on the focal plane of the reflective light receiving telescope module. The single-photon detector converts the detected reflected light into an electrical signal and inputs it into the single-photon counter for counting.

4. The gas measuring device as described in claim 3, characterized in that, The single-photon detector is an avalanche photodiode or a superconducting nanowire single-photon detector.

5. The gas measuring device as described in claim 2, characterized in that, The predetermined modulation frequency range is 1KHz to 100KHz, and the modulation waveform is a triangular wave or a sawtooth wave.

6. A method for measuring a large range of gases based on single-photon optical scanning, the method being used to operate a large range of gas measuring device based on single-photon optical scanning as described in any one of claims 1-5, to measure gas composition and concentration; characterized in that, The method includes the following steps: Step 1: The control subunit controls the single-photon laser emitting unit to emit a laser beam of a specified center wavelength to irradiate the gas located between the single-photon laser emitting unit and the reflective target; Step 2: The data acquisition subunit and the data processing subunit calculate the gas concentration value at the current spatial measurement point based on the photon count-wavelength relationship data; Step 3: For each spatial measurement point, the control subunit controls the single-photon detector to receive the light beam reflected by the reflective target and measures the photon count-wavelength relationship data for each spatial measurement point. Step 4: The data processing subunit fuses the gas concentration values ​​of all spatial measurement points with the three-dimensional spatial coordinates corresponding to all spatial measurement points to generate a three-dimensional point cloud distribution image of gas concentration.

7. The gas measurement method as described in claim 6, characterized in that, Step 1 includes the following sub-steps: Step 1.1, the laser beam is modulated by a predetermined modulation frequency output by the control subunit; Step 1.2: The control subunit controls the rotation of the three-dimensional scanning gimbal so that the laser beam points sequentially to a series of spatial measurement points in the target area along a preset path; a reflective target is set in the target area.

8. The gas measurement method as described in claim 7, characterized in that, Step 2 includes the following sub-steps: Step 2.1: At each of the spatial measurement points, the beam signal reflected by the reflective target through the gas to be measured is received by a single-photon detector. Step 2.

2. Using time-correlated single-photon counting technology, the relative relationship between photon arrival time and laser modulation signal is recorded. The control subunit controls the single-photon counter to count only photon events within the laser wavelength scanning cycle. Step 2.3: Suppress background noise using time gating; record the photon count-wavelength relationship data for the spatial measurement points.

9. The gas measurement method as described in claim 8, characterized in that, Step 3 includes the following sub-steps: Step 3.1: Based on the recorded photon count-wavelength relationship data for all the spatial measurement points, statistically calculate the change in photon count rate caused by the absorption of the measurement gas. Step 3.2: Calculate the gas concentration value according to the change in photon count rate.

10. The gas measurement method as described in claim 6, characterized in that, The laser beam emitted by the single-photon laser emitting unit irradiates the gas to be measured and is reflected by the reflective target. The reflected light signal is then focused onto the single-photon detector located on the focal plane of the reflective light receiving telescope module. A narrowband filter module for filtering out stray light signals is provided between the reflective light receiving telescope module and the single-photon detector. The center wavelength of the narrowband filter module corresponds to the absorption wavelength of the gas to be measured.

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