An optical path variable gas measuring device

Abstract

The application relates to the field of gas measurement, in particular to a light path variable gas measurement device. The device comprises a base, a laser module, a first shell, a first mirror, a gas cell assembly, a focusing lens barrel, a sensor module, a circuit module and the like. The laser beam emitted by the laser module is emitted to the first mirror through the through hole, is reflected on the second mirror and the third mirror back and forth, the third mirror can be rotated to adjust the position of the light emitting hole to adjust the reflection light path, and finally the laser beam is emitted to the focusing lens through the light emitting hole and reaches the sensor module. The application can realize the adjustment of the reflection light path, flexibly cope with different concentration ranges, different types of gas and different measurement environments, and meet the high-precision measurement requirement.

Description

Technical Field

[0001] This application relates to the field of sludge drying equipment technology, and in particular to a variable optical path gas measuring device. Background Technology

[0002] In the field of gas measurement technology, with the continuous growth of demands from industrial production, environmental monitoring, and other sectors, the requirements for the accuracy and flexibility of gas measurement are increasing. Gas measurement technology plays a crucial role in many fields, including industrial safety monitoring, atmospheric environmental quality assessment, and indoor air quality testing. Accurate measurement of gas composition and concentration helps enterprises promptly identify potential safety hazards and ensure the smooth operation of production processes; in environmental monitoring, it helps to grasp the real-time status of air pollution and provides a scientific basis for formulating environmental protection policies. At the same time, with continuous technological advancements, the miniaturization and convenience of gas measurement equipment also present new challenges and opportunities.

[0003] Traditional gas measurement techniques mostly rely on the principle of spectral absorption, which involves passing light through the gas being measured and determining the gas concentration based on the degree of absorption of light at a specific wavelength. However, traditional spectral absorption measurement devices generally have a fixed optical path, making it difficult to flexibly adjust the reflected optical path. This results in limitations in meeting the demands for high-precision measurements when dealing with different concentration ranges, different types of gases, and different measurement environments, thus restricting their application scope and measurement performance. Utility Model Content

[0004] The purpose of this application is to overcome the above-mentioned technical problems and provide a variable optical path gas measuring device, which adopts the following solution:

[0005] A variable optical path gas measuring device includes: a base; a laser module located in the base, the base having a through hole corresponding to the laser module for a laser beam to pass through; a first housing covering the upper end of the base, used to form a first accommodating cavity with the base; a first reflector located in the first accommodating cavity and positioned relative to the laser module to reflect the laser beam; and a gas cell assembly located on the upper end of the base relative to the first housing, including a first fixing member, a second fixing member, a gas cell cover, a support shaft, a second reflector, and a third reflector. The first fixing member and the second fixing member are positioned opposite each other, the first fixing member is fixed to the outside of the first housing, one end of the gas cell cover is fixed to the first fixing member, and the other end is fixed to the second fixing member to form a second accommodating cavity for accommodating the gas to be measured, and the support shaft is located in the second accommodating cavity, with both ends fixed to the first fixing member and the second fixing member, respectively. The second and third reflectors are located within the second accommodating cavity and are respectively sleeved at both ends of the support shaft. The third reflector has a light-emitting hole and is rotatably mounted relative to the support shaft to adjust the position of the light-emitting hole relative to the second reflector, thereby adjusting the reflected optical path. The focusing lens barrel is fixed to the side of the second fixing member away from the first fixing member, and a focusing lens is provided inside the focusing lens barrel. A sensor module is located at the end of the focusing lens barrel away from the second fixing member. A circuit module is located in the base and electrically connected to the laser module and the sensor module. The laser beam emitted by the laser module exits through the through hole and is reflected by the first reflector. The reflected laser beam exits through the second and third reflectors for back-and-forth reflection, so that after the reflected laser beam exits through the light-emitting hole and exits through the focusing lens, it is then exited through the sensor module.

[0006] By adopting the above technical solution, the base provides a stable support structure for the entire variable optical path gas measurement device, ensuring the stable installation of all components. The laser module is placed in the base, and the through hole on the base allows the laser beam to pass through smoothly, ensuring normal laser beam emission. The first housing and the base form a first accommodating cavity, which protects components such as the first reflector located within it and prevents external interference. The first reflector is positioned relative to the laser module, reflecting the laser beam emitted by the laser module and changing the propagation direction of the laser beam. In the gas cell assembly, the first and second fixing members are positioned opposite each other, and the gas cell cover is fixed between them to form a second accommodating cavity for accommodating the gas to be measured, providing a specific space for gas measurement. The support shaft is fixed to the first fixing member. On the first and second fixing components, a second and third reflecting mirror are sleeved on both ends of the support shaft, and the third reflecting mirror can rotate relative to the support shaft. The reflected optical path can be adjusted by adjusting the position of the light outlet relative to the second reflecting mirror, which can meet the optical path requirements of different gas measurements. The focusing lens tube is fixed on one side of the second fixing component, and its internal focusing lens can focus the laser beam that has been reflected and emitted from the light outlet. The sensor module is located at the end of the focusing lens tube away from the second fixing component, and can receive the focused laser beam to realize the detection of gas-related parameters. The circuit module is located in the base and electrically connected to the laser module and the sensor module, which can provide power support for the laser module and the sensor module and realize signal transmission to ensure the normal operation of the entire measurement process.

[0007] Optionally, the first housing is provided with a detachable adjustment cover for easy adjustment of the angle of the first reflector.

[0008] By adopting the above technical solution, a detachable adjustment cover is provided on the first housing to facilitate the adjustment of the angle of the first reflector. This allows the operator to easily adjust the angle of the first reflector to ensure the accuracy of the laser beam reflection path, thereby improving the measurement precision and accuracy of the variable optical path gas measuring device.

[0009] Optionally, the first housing is provided with an entrance window for the laser beam reflected by the first reflector to pass through and exit onto the second reflector; the second fixing member is provided with an exit window for the laser beam exiting through the light exit hole to pass through and exit onto the focusing lens.

[0010] By adopting the above technical solution, an entrance window is provided on the first housing, which allows the laser beam reflected by the first reflector to pass smoothly through and exit onto the second reflector, ensuring that the laser beam can accurately enter the gas cell assembly, and also ensuring the sealing of the first and second accommodating cavities; an exit window is provided on the second fixing member, which allows the laser beam emitted through the light exit hole to pass smoothly through and exit onto the focusing lens, ensuring that the laser beam can accurately exit from the gas cell assembly to the focusing lens, and further ensuring the sealing of the second accommodating cavity, which helps to improve the measurement accuracy of the variable optical path gas measuring device.

[0011] Optionally, it also includes: a sensor, one end of which is located in the first accommodating cavity, and the other end which passes through the first housing for sensing the temperature and pressure of the gas to be measured in the second accommodating cavity.

[0012] By adopting the above technical solution, the temperature and pressure data of the gas being measured can be obtained in real time, so that the measurement results can be accurately corrected and analyzed in the future.

[0013] Optionally, the first fixing member is provided with a first gas passage component that passes through the second accommodating cavity, and the gas pool cover is provided with a second gas passage component. The first gas passage component and the second gas passage component are used to input and output the gas to be measured into the second accommodating cavity.

[0014] By adopting the above technical solution, a first gas passage component that penetrates the second accommodating cavity is set on the first fixing component, and a second gas passage component is set on the gas pool cover. This enables the input and output of the gas to be measured into the second accommodating cavity, ensuring that the gas to be measured can smoothly enter and exit the gas pool, and ensuring that the optical path variable gas measuring device can perform gas measurement work normally.

[0015] Optionally, the focusing lens barrel is further provided with a pressure ring, a guide lens, and a lens spacer. The pressure ring is close to the second fixing member, the guide lens is located at the end of the pressure ring close to the second fixing member, the lens spacer is located at the end of the guide lens away from the pressure ring, and the focusing lens is located at the end of the lens spacer away from the guide lens.

[0016] By adopting the above technical solution, setting a pressure ring, a guide lens, and a lens spacer in a specific position inside the focusing lens barrel can provide good positioning and support for the focusing lens, ensuring the stable installation and accurate position of the focusing lens inside the focusing lens barrel. This ensures that the laser beam can be accurately focused onto the sensor module, thereby improving the accuracy of gas measurement.

[0017] Optionally, the sensor module includes: a rear cover covering the focusing lens barrel; and a sensor disposed inside the rear cover relative to the focusing lens, with a fixing groove on the edge of the sensor for radial adjustment by screws.

[0018] By adopting the above technical solution, the sensor can be protected by covering the focusing lens barrel with the rear cover. The sensor is positioned relative to the focusing lens to facilitate receiving the laser beam. The sensor edge is provided with a fixing groove for radial adjustment by screws, which can facilitate radial adjustment of the sensor to accurately align with the focusing lens to receive the laser beam, thereby improving the measurement accuracy of the gas measuring device.

[0019] Optionally, the focusing lens barrel is provided with a fixing hole relative to the second fixing member for screws to pass through and fix it.

[0020] By adopting the above technical solution, the focusing lens barrel and the second fixing component can be stably connected, ensuring the positional stability of the focusing lens barrel, which is beneficial to improving the accuracy of laser beam focusing and transmission.

[0021] In summary, this application includes at least one of the following beneficial technical effects:

[0022] 1. By setting a rotatable third reflecting mirror to adjust the position of the light outlet relative to the second reflecting mirror, the reflected optical path can be adjusted to flexibly cope with different concentration ranges, different types of gases and different measurement environments, and meet the requirements of high-precision measurement.

[0023] 2. A detachable adjustment cover is provided on the first housing to facilitate the adjustment of the angle of the first reflector, which allows the operator to easily adjust the angle of the first reflector to ensure the accuracy of the laser beam reflection path, thereby improving the measurement accuracy of the variable optical path gas measuring device;

[0024] 3. An entrance window is provided on the first housing, which allows the laser beam reflected by the first reflector to pass smoothly through and exit onto the second reflector, ensuring that the laser beam can accurately enter the gas cell assembly, and also ensuring the sealing of the first and second accommodating cavities; an exit window is provided on the second fixing member, which allows the laser beam emitted through the exit hole to pass smoothly through and exit onto the focusing lens, ensuring that the laser beam can accurately exit from the gas cell assembly to the focusing lens, and further ensuring the sealing of the second accommodating cavity, which helps to improve the measurement accuracy of the variable optical path gas measuring device. Attached Figure Description

[0025] Figure 1 This is a three-dimensional structural schematic diagram of a variable optical path gas measuring device disclosed in an embodiment of this application;

[0026] Figure 2 for Figure 1 A schematic diagram of the explosion structure of a variable optical path gas measuring device disclosed in the present invention;

[0027] Figure 3 for Figure 1 A cross-sectional structural schematic diagram of the variable optical path gas measuring device disclosed in China;

[0028] Figure 4 This is a schematic diagram of the optical path propagation during optical path measurement using a variable optical path gas measuring device disclosed in this application.

[0029] Figure 5 This is a schematic diagram of the optical path propagation during optical path measurement using a variable optical path gas measuring device disclosed in this application.

[0030] Figure 6 This is a schematic diagram of the optical path propagation during optical path measurement using a variable optical path gas measuring device disclosed in this application.

[0031] Explanation of reference numerals in the attached figures:

[0032] 10. Base; 11. Through hole; 20. Laser module; 30. First housing; 301. First accommodating cavity; 31. Adjustment cover; 32. Entrance window; 40. First reflector; 50. Gas pool assembly; 51. First fixing member; 511. First gas path member; 52. Second fixing member; 521. Exit window; 53. Gas pool cover; 531. Second accommodating cavity; 532. Second gas path member; 54. Support shaft; 55. Second reflector; 56. Third reflector; 561. Light exit hole; 60. Focusing lens barrel; 61. Focusing lens; 62. Pressure ring; 63. Guide lens; 64. Lens spacer; 65. Fixing hole; 70. Sensor module; 71. Back cover; 72. Sensor; 721. Fixing groove; 80. Circuit module; 90. Sensor. Detailed Implementation

[0033] The terminology used in the following embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” and “this” are intended to include the plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this application refers to and includes any or all possible combinations of one or more of the listed items.

[0034] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0035] The technical solutions of the embodiments of this application are described in detail below with reference to the accompanying drawings.

[0036] See Figure 1 and Figure 2The present application discloses a variable optical path gas measuring device, which includes a base 10, a laser module 20, a first housing 30, a first reflector 40, a gas cell assembly 50, a focusing lens tube 60, a sensor module 70, and a circuit module 80.

[0037] The laser module 20 is located in the base 10. The first housing 30 covers the upper end of the base 10 and forms a first accommodating cavity 301 with the base 10. The first reflector 40 is located in the first accommodating cavity 301 and is positioned relative to the laser module 20. The gas cell assembly 50 is located on the upper end of the base 10 and is positioned relative to the first housing 30. The focusing lens tube 60 is fixed on the side of the gas cell assembly 50 away from the first housing 30. The sensor module 70 is located at the end of the focusing lens tube 60 away from the gas cell assembly 50. The circuit module 80 is located in the base 10 and is electrically connected to the laser module 20 and the sensor module 70.

[0038] Specifically, the base 10 has a rectangular external structure and is used to house the laser module 20 and the circuit module 80 internally. A through hole 11 is provided on the base 10 corresponding to the laser module 20, allowing the laser beam emitted by the laser module 20 to pass through and be reflected by the first reflector 40. The through hole 11 can be circular, with dimensions sufficient to ensure the laser beam can pass through smoothly.

[0039] The laser module 20 is used to emit a laser beam and mainly consists of a laser emitter and related control circuitry. The laser emitter can be a semiconductor laser, which is characterized by its small size and high efficiency; or it can be a solid-state laser, which has a higher output power. The laser module 20 is fixed inside the base 10 by bolts or welding, ensuring that the emission port of the laser module 20 is aligned with the through hole 11 on the base 10, so that the laser beam can accurately pass through the through hole 11.

[0040] See Figure 2 and Figure 3 The first housing 30 is mounted on the upper end of the base 10, forming a first accommodating cavity 301. The first housing 30 is made of sheet metal and is detachable on one side for easy disassembly and assembly by operators to facilitate internal operations. A detachable adjustment cover 31 is provided on the first housing 30 to facilitate adjustment of the angle of the first reflector 40. This adjustment cover 31 can be fixed to the first housing 30 by clips or screws, allowing operators to easily open the adjustment cover 31 to fine-tune the angle of the first reflector 40, thereby ensuring the accurate reflection path of the laser beam. In addition, the first housing 30 is also provided with an entrance window 32, which is generally made of optical glass and has high transmittance. This window allows the laser beam reflected by the first reflector 40 to pass through and exit onto the second reflector 55.

[0041] The first reflecting mirror 40 is a plane reflecting mirror, using optical glass as a substrate and coated with a high-reflectivity metal film, such as a silver film or an aluminum film. The first reflecting mirror 40 is fixed in the first accommodating cavity 301 by a bracket. The bracket has an adjustable angle structure, which facilitates adjusting the angle of the reflecting mirror according to actual needs. The structure of the bracket is not limited.

[0042] See Figure 1 and Figure 2 The gas chamber assembly 50 is located on the upper end of the base 10, opposite to the first housing 30, and includes a first fixing member 51, a second fixing member 52, a gas chamber cover 53, a support shaft 54, a second reflector 55, and a third reflector 56. The first fixing member 51 and the second fixing member 52 are flanges and are positioned opposite each other. The first fixing member 51 is fixed to the outside of the first housing 30, typically using bolts. The gas chamber cover 53 is cylindrical, with one end fixed to the first fixing member 51 and the other end fixed to the second fixing member 52, forming a second accommodating cavity 531 for containing the gas to be measured. A first gas passage 511 is provided on the first fixing member 51, penetrating the second accommodating cavity 531, and a second gas passage 532 is provided on the gas chamber cover 53. The first gas passage 511 and the second gas passage 532 are used for inputting and outputting the gas to be measured into the second accommodating cavity 531. The first gas supply component 511 and the second gas supply component 532 can be pipe interfaces, which are connected to external gas supply and gas emission equipment via rubber or metal pipes.

[0043] See Figure 2 and Figure 3 The support shaft 54 ​​is located within the second accommodating cavity 531, and its two ends are respectively fixed to the first fixing member 51 and the second fixing member 52. The support shaft 54 ​​is made of corrosion-resistant materials such as stainless steel and is cylindrical in shape. Its function is to provide support and a base for the rotation of the second reflecting mirror 55 and the third reflecting mirror 56. The second reflecting mirror 55 and the third reflecting mirror 56 are located within the second accommodating cavity 531 and are respectively fitted onto the two ends of the support shaft 54. Both the second reflecting mirror 55 and the third reflecting mirror 56 are planar reflecting mirrors with a highly reflective metal film coated on their surfaces. The third reflecting mirror 56 is provided with a light-emitting aperture 561, and the third reflecting mirror 56 is rotatably mounted relative to the support shaft 54 ​​to adjust the position of the light-emitting aperture 561 relative to the second reflecting mirror 55, thereby adjusting the reflected optical path. The rotation of the third reflecting mirror 56 on the support shaft 54 ​​can be manually operated by disassembling the air chamber cover 53 or the focusing lens tube 60. Alternatively, in another embodiment, a bearing can be fitted onto the third reflecting mirror 56 and driven by a motor; this is not a limitation.

[0044] Further, see Figure 2 and Figure 3To sense the temperature and pressure in the second accommodating cavity 531 in real time, this embodiment also includes a sensor 90, one end of which is located in the first accommodating cavity 301, and the other end passes through the first housing 30 to contact the gas being measured for sensing the temperature and pressure of the gas being measured in the second accommodating cavity 531. It should be noted that both ends of the gas pool cover 53 are sealed, making the second accommodating groove a closed space for containing the gas being measured.

[0045] See Figure 1 , Figure 2 and Figure 3 The focusing lens barrel 60 is fixed to the side of the second fixing member 52 away from the first fixing member 51. Inside the focusing lens barrel 60 are a focusing lens 61, a retaining ring 62, a guide lens 63, and a lens spacer 64. The retaining ring 62, located near the second fixing member 52, is used to fix the guide lens 63. The retaining ring 62 is a ring-shaped metal component, fixed to the inner wall of the focusing lens barrel 60 by threads or snaps. The guide lens 63, located at the end of the retaining ring 62 near the second fixing member 52, guides the propagation direction of the laser beam and is shaped like a convex lens. The lens spacer 64, located at the end of the guide lens 63 away from the retaining ring 62, separates the guide lens 63 and the focusing lens 61, ensuring a suitable distance between them. The focusing lens 61, located at the end of the lens spacer 64 away from the guide lens 63, focuses the laser beam, after multiple reflections, onto the sensor module 70. The focusing lens 61 is also a convex lens, and its focal length is selected according to the actual measurement requirements. The focusing lens barrel 60 is provided with a fixing hole 65 relative to the second fixing member 52 for screws to pass through and fix, so as to ensure a firm connection between the focusing lens barrel 60 and the second fixing member 52.

[0046] See Figure 1 , Figure 2 and Figure 3 The sensor module 70 is located at the end of the focusing lens barrel 60 away from the second fixing member 52, and includes a rear cover 71 and a sensor 72. The rear cover 71 covers the focusing lens barrel 60 and protects the sensor 72. The rear cover 71 is generally made of plastic or metal. The sensor 72 is located inside the rear cover 71 relative to the focusing lens 61, and a fixing groove 721 for radial adjustment by screws is provided on the edge of the sensor 72. By adjusting the screws in the fixing groove 721, the position of the sensor 72 can be finely adjusted to ensure that the sensor 72 can accurately receive the focused laser beam.

[0047] See Figure 2 and Figure 3 The circuit module 80 is located in the base 10 and is electrically connected to the laser module 20 and the sensor module 70. The circuit module 80 mainly consists of a circuit board, power supply, signal processing circuit, etc., and is used to control the emission of the laser module 20 and the reception of signals from the sensor module 70, and to process and analyze the signals.

[0048] To more clearly illustrate that this embodiment can change the reflected optical path, please refer to the following description:

[0049] See Figures 4 to 6 This corresponds to three different optical path modes, which are schematic diagrams of the optical path of the laser beam after it radiates back and forth between the second reflector 55 and the third reflector 56, and then passes through the light exit hole 561, the guide lens 63, and the focusing lens 61 to reach the sensor module 70. Based on the different positions of the light exit hole 561, the number of times the laser beam radiates back and forth between the second reflector 55 and the third reflector 56 is different in different modes, which makes the effective optical path of the laser beam different.

[0050] In addition, the effective optical path can be calculated as follows:

[0051] Assuming the direction vector of the incident light is (x_0, y_0, 1), the opening position of the primary reflector is (x_0, y_0), the radii of curvature of the second reflector 55 and the third reflector 56 are R, the global coordinate system is set at the center of the vertex of the second reflector 55, and the distance between the vertices of the second reflector 55 and the third reflector 56 along the optical axis (direction of the support axis 54) is d, then the position of the principal ray of the laser beam on the second reflector 55 is... The focal position (x1, y1, z1) of the main laser beam and the third reflecting mirror 56 can be determined by solving the system of equations. To obtain.

[0052] Assuming the direction vector of the light beam after the first reflection by the third reflecting mirror 56 is (x_1, y_1, -1), it can be solved by the system of equations. To obtain.

[0053] Where (xq, yq, zq) are the symmetric coordinates of point (x1, y1, z1) about the normal of the third mirror 56, and the angle direction vector (x_1, y_1, 1) of the light rays reflected by the third mirror 56 can be calculated.

[0054] Through multiple iterations, the coordinates and direction vectors of each point on the second reflector 55 and the third reflector 56 can be calculated, thereby allowing the calculation of the effective optical path for each reflection.

[0055] The implementation principle of this embodiment is as follows: When it is necessary to measure gases of different concentration ranges, different types of gases, and gases under different measurement environments, the operator can adjust the position of the light-emitting aperture 561 relative to the second reflector 55 by rotating the third reflector 56, thereby changing the reflected optical path of the laser beam within the gas cell assembly 50. The laser beam is emitted from the laser module 20, passes through the through-hole 11 to the first reflector 40, is reflected, and enters the gas cell assembly 50 through the entrance window 32. It is reflected back and forth between the second reflector 55 and the third reflector 56, and finally passes through the light-emitting aperture 561, the exit window 521, the guide lens 63, and the focusing lens 61 before reaching the sensor module 70. The sensor module 70 converts the received laser signal into an electrical signal, transmits it to the circuit module 80 for processing and analysis, and obtains information such as the concentration of the measured gas. Compared with traditional gas measuring devices with fixed optical paths, this device can better adapt to various measurement needs, improve the accuracy and flexibility of measurement, and expand the application range of gas measuring devices.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A variable optical path gas measuring device, characterized in that, include: Base (10); A laser module (20) is located in the base (10), and the base (10) is provided with a through hole (11) for the laser beam to pass through, corresponding to the laser module (20). The first housing (30) is covered on the upper end of the base (10) and is used to form a first accommodating cavity (301) with the base (10). The first reflector (40) is located in the first accommodating cavity (301) and is positioned relative to the laser module (20) to reflect the laser beam; The gas chamber assembly (50) is located on the upper end of the base (10) opposite to the first housing (30), and includes a first fixing member (51), a second fixing member (52), a gas chamber cover (53), a support shaft (54), a second reflector (55), and a third reflector (56). The first fixing member (51) and the second fixing member (52) are arranged opposite to each other. The first fixing member (51) is fixed to the outside of the first housing (30). One end of the gas chamber cover (53) is fixed to the first fixing member (51), and the other end is fixed to the second fixing member (52) to form a second container for accommodating the gas to be measured. The second accommodating cavity (531) is provided with a support shaft (54) located inside the second accommodating cavity (531) and its two ends are fixed to the first fixing member (51) and the second fixing member (52) respectively. The second reflector (55) and the third reflector (56) are located inside the second accommodating cavity (531) and are respectively sleeved on the two ends of the support shaft (54). The third reflector (56) is provided with a light-emitting hole (561) and the third reflector (56) is rotatably arranged relative to the support shaft (54) to adjust the position of the light-emitting hole (561) relative to the second reflector (55) to adjust the reflected light path. A focusing lens barrel (60) is fixed to the side of the second fixing member (52) away from the first fixing member (51), and a focusing lens (61) is provided inside the focusing lens barrel (60). A sensor module (70) is disposed at one end of the focusing lens barrel (60) away from the second fixing member (52); The circuit module (80) is located in the base (10) and is electrically connected to the laser module (20) and the sensor module (70). The laser beam emitted by the laser module (20) is reflected by the first reflector (40) through the through hole (11). The reflected laser beam is reflected back and forth by the second reflector (55) and the third reflector (56) so that the reflected laser beam is reflected by the focusing lens (61) through the light outlet hole (561) and then by the sensor module (70).

2. The variable optical path gas measuring device according to claim 1, characterized in that, The first housing (30) is provided with a detachable adjustment cover (31) for easy adjustment of the angle of the first reflector (40).

3. The variable optical path gas measuring device according to claim 1, characterized in that, An entrance window (32) is provided on the first housing (30) for the laser beam reflected by the first reflector (40) to pass through and for the laser beam to be emitted onto the second reflector (55); The second fixing member (52) is provided with an exit window (521) for the laser beam emitted through the light exit hole (561) to pass through and emit the laser beam onto the focusing lens (61).

4. The variable optical path gas measuring device according to claim 1, characterized in that, Also includes: The sensor (90) has one end located in the first accommodating cavity (301) and the other end passing through the first housing (30) for sensing the temperature and pressure of the gas to be measured in the second accommodating cavity (531).

5. The variable optical path gas measuring device according to claim 1, characterized in that, The first fixing member (51) is provided with a first gas passage (511) that passes through the second accommodating cavity (531), and the gas pool cover (53) is provided with a second gas passage (532). The first gas passage (511) and the second gas passage (532) are used to input and output the gas to be measured into the second accommodating cavity (531).

6. The variable optical path gas measuring device according to claim 1, characterized in that, The focusing lens barrel (60) is also provided with a pressure ring (62), a guide lens (63), and a lens spacer (64). The pressure ring (62) is close to the second fixing member (52). The guide lens (63) is located at the end of the pressure ring (62) close to the second fixing member (52). The lens spacer (64) is located at the end of the guide lens (63) away from the pressure ring (62). The focusing lens (61) is located at the end of the lens spacer (64) away from the guide lens (63).

7. The variable optical path gas measuring device according to claim 1, characterized in that, The sensor module (70) includes: The rear cover (71) is mounted on the focusing lens tube (60); The sensor (72) is disposed inside the rear cover (71) relative to the focusing lens (61), and a fixing groove (721) for radial adjustment of the screw is provided on the edge of the sensor (72).

8. The variable optical path gas measuring device according to claim 1, characterized in that, The focusing lens tube (60) is provided with a fixing hole (65) relative to the second fixing member (52) for screws to pass through and fix it.

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