A reflective gas chamber for TDLAS gas detection

Abstract

The present invention relates to a reflective gas chamber for TDLAS gas detection, comprising a gas chamber shell, wherein a plurality of fixed reflectors, a coupling reflector, a light input hole, and a light output hole are distributed on the inner wall of the gas chamber shell. Light entering from the light input hole is reflected by the coupling reflector and the plurality of fixed reflectors in sequence and then emitted from the light output hole. The coupling reflector is mounted on the inner wall of the gas chamber shell via a coupling ferrule and a coupling pagoda sleeve. The coupling ferrule cooperates with the coupling pagoda sleeve so that the coupling reflector can adjust its relative position and relative angle relative to the optical axis of the light input hole before being fixed in the gas chamber shell. In the present invention, the path of light propagating in the gas chamber is a broken line, so that multiple light path reflections are achieved in a smaller-sized gas chamber shell to increase the optical path.

Description

Technical Field

[0001] The present invention relates to the field of gas component detection, and in particular to a reflective gas chamber for TDLAS gas detection, which is applied to a multi-gas real-time online detector. Background Art

[0002] TDLAS technology is based on a tunable diode laser and utilizes the "frequency-selective" properties of the gas molecules being measured to measure the characteristics of the gas being measured. This advantage successfully avoids interference from other gas components, making it the preferred solution for accurate, real-time online gas detection systems. It also features a fast response time, a low measurement limit, and the ability to simultaneously analyze multiple gas components, primarily including methane, carbon monoxide, carbon dioxide, oxygen, and ammonia. Consequently, particularly since the late 1990s, gas detection solutions and equipment based on TDLAS technology have mushroomed, and various measurement methods, including fixed test systems, distributed test systems, and telemetry test systems, have emerged in industrial applications.

[0003] Due to the working principle of TDLAS, the gas chamber is an indispensable optical component in the diffusion-type gas online measuring instrument. The stability, compactness, and manufacturability of the gas chamber optical path directly determine the performance, volume, and cost of the overall diffusion-type gas online measuring instrument. Currently, the reflective gas chamber used in the diffusion-type gas detector has the following problems: 1. The number of light path reflections in the gas chamber determines the light path stability. The more reflections, the more sensitive the light path stability. The fewer reflections, the higher the light path stability, but the larger the gas chamber volume. 2. The coupling method of the reflective lens in the gas chamber is complex, mostly 6-dimensional coupling, which has a complex manufacturing process, poor manufacturability, and high cost. 3. The coupling reflector in the gas chamber is mostly fixed by gluing. When the glued gas chamber works in an oil and gas environment for a long time, the fixing glue is prone to softening and decomposition, causing the coupling reflector to fall off and the gas chamber to fail to work normally. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned existing technologies and provide a reflective gas chamber for TDLAS gas detection to solve a series of technical defects existing in the existing gas chambers, such as the problem of balancing the number of reflections and the stability of the optical path, the problem of high-efficiency coupling manufacturability, and the problem of reliability in oil and gas environment applications.

[0005] The present invention provides a reflective gas chamber for TDLAS gas detection, comprising a gas chamber shell, wherein a plurality of fixed reflectors and coupling reflectors are distributed on the inner wall of the gas chamber shell, and a light entrance hole for light entry and a light exit hole for light exit are distributed on the gas chamber shell. The light entering from the light entrance hole is reflected by the coupling reflector and the plurality of fixed reflectors in sequence and then exits from the light exit hole; wherein the coupling reflector is mounted on the inner wall of the gas chamber shell through a coupling ferrule and a coupling pagoda sleeve, the coupling ferrule having an angled end face, the coupling reflector is fixed on the angled end face of the coupling ferrule, and the coupling ferrule cooperates with the coupling pagoda sleeve so that the coupling reflector can be adjusted in relative position and relative angle relative to the optical axis of the light entrance hole before being fixed in the gas chamber shell.

[0006] In the above technical solution, the number of the fixed reflectors is greater than or equal to 2.

[0007] In the above technical solution, a temperature and pressure sensor is further provided on the inner wall of the air chamber shell, and the temperature and pressure sensor is close to the light exit hole.

[0008] In the above technical solution, the coupling reflector, the coupling ferrule, the coupling pagoda sleeve, and the coupling welding surfaces of the air chamber shell all have circular structural metal parts. The coupling ferrule is inserted into the inner hole of the coupling pagoda sleeve and passes through the opening on the air chamber shell. The lower circular welding surface of the base of the coupling pagoda sleeve is flattened with the circular coupling welding surface outside the opening of the air chamber shell; thereby, the coupling ferrule has the adjustment function of moving along the XYZ axis and coaxial rotation during assembly.

[0009] In the above technical solution, the air chamber shell is outer-circuited with a diffusion-type sealing cover, and a molecular filtering structure is provided inside the diffusion-type sealing cover.

[0010] In the above technical solution, an entrance hole sealing light window is provided on the inner wall of the air chamber tube shell and located at the light entrance hole, the entrance hole sealing light window is non-perpendicular to the light incident from the light entrance hole, and the angle range between the light incident from the light entrance hole and the normal of the entrance hole sealing light window is greater than zero degree and less than or equal to sixty degrees; an exit hole sealing light window is provided on the inner wall of the air chamber tube shell and located at the light exit hole, the exit hole sealing light window is non-perpendicular to the light emitted from the entrance hole, and the angle range between the light emitted from the light exit hole and the normal of the exit hole sealing light window is greater than zero degree and less than or equal to sixty degrees.

[0011] In the above technical solution, the incident hole sealed light window and the exit hole sealed light window are both coated with AR dielectric film; or / and the fixed reflector 1, the fixed reflector 2 and the coupling reflector are all coated with HR dielectric film.

[0012] In the above technical solution, the light entrance hole sealed window and the light exit hole sealed window are both fixed to the inner wall of the gas chamber shell by welding or sintering solder.

[0013] In the above technical solution, the fixed reflector 1 and the fixed reflector 2 are both fixed to the inner wall of the air chamber shell by welding or sintering solder; the coupling reflector is fixed to the angled end face of the coupling core by welding or sintering solder.

[0014] In the above technical solution, the coupling reflector is non-perpendicularly arranged relative to the light incident from the light incident hole, and the angle between the light incident from the light incident hole and the normal of the coupling reflector is greater than zero degree and less than or equal to sixty degrees.

[0015] The present invention also provides a method for manufacturing a reflective gas cell for TDLAS gas detection, comprising the steps of:

[0016] Fix the first fixed reflector to the inner wall of the air chamber shell and locate it at the center bottom point of the M-shaped optical path; fix the second fixed reflector to the inner wall of the air chamber shell and locate it at the top point on the right side of the M-shaped optical path;

[0017] Fix the coupling reflector on the beveled end face of the coupling ferrule. After the coupling ferrule passes through the inner hole of the coupling pagoda sleeve, place it at the vertex on the left side of the M-shaped optical path.

[0018] The incident light passes through the light entrance hole at the bottom point on the left side of the M-shaped optical path in the air chamber shell and illuminates the opposite surface of the coupling reflector installed on the angled end face of the coupling ferrule;

[0019] The optical path coupling of the reflective gas chamber is achieved by the XYZ axis movement of the coupling ferrule and the coaxial rotation of the coupling ferrule. The incident light passes through the coupling reflector, fixed reflector 1 and fixed reflector 2 in sequence, and is finally coupled to the center of the light exit hole as the output light.

[0020] After the optical path is coupled, laser welding is used to penetrate the wall of the coupling pagoda sleeve to fix the coupling pagoda sleeve and the coupling ferrule;

[0021] Fix the coupling pagoda sleeve with the coupling ferrule fixed inside to the air chamber shell by laser welding;

[0022] Use caulking glue to fill the gap between the coupling pagoda sleeve and the air chamber shell, as well as the gap between the coupling ferrule and the coupling pagoda sleeve, to seal them;

[0023] Fix the temperature and pressure sensor inside the gas chamber shell, next to the light exit hole. And seal the tail of the temperature and pressure sensor with glue to prevent gas leakage between the temperature and pressure sensor and the gas chamber shell.

[0024] The diffusion sealing cover is crimped and fixed to the air chamber shell with a sealing ring to achieve the sealing of the air chamber and play a protective and isolating role for the internal optical components.

[0025] The beneficial effects of the present invention are as follows: in a reflective gas chamber for TDLAS gas detection of the present invention, the path of light propagation in the gas chamber is M-shaped. The M-shaped optical path realizes four reflections of the optical path at a smaller size, which means that the optical path is increased by about 4 times. According to the Lambert-Beer law, increasing the optical path can increase the amplitude of the gas absorption signal, thereby effectively improving the detection sensitivity; at the same time, since the M-shaped optical path structure has a low reflection density, the optical path stability is more stable and reliable in high and low temperature environments compared to a high-density reflective gas chamber.

[0026] The coupling reflector is fixed on the coupling ferrule, and the XYZ axis movement and coaxial rotation of the coupling ferrule can realize the precise coupling of the optical path of the reflective air chamber, and couple the incident light to the center of the light exit hole after multiple reflections; it avoids the XYZ axis and θ axis of the lens commonly used in the multi-reflective air chamber on the current market. X θ Y θ Z The six-dimensional coupling method greatly improves the coupling efficiency. At the same time, the coupling core and the coupling pagoda sleeve are made of stainless steel. This structure can be fixed after coupling by laser welding. While ensuring the reliability of fixation, it effectively improves the product's manufacturability and production efficiency, and greatly reduces costs.

[0027] The diffusion-type sealing cover has a macromolecular filtration structure inside, which can block dust and water vapor outside the sealing cover, while the gas can pass through the sealing cover normally into the air chamber.

[0028] Sealed light windows are added at the light entrance and exit holes, making the overall gas chamber structure a complete airtight sealed structure, which can effectively ensure that the measured gas will not leak through the gas chamber to the light source and control module, thereby improving the safety and reliability of the product. In addition, since the two sealed light windows are not placed perpendicular to the transmitted light, the angle between the transmitted light and the normal of the sealed light windows is between zero and sixty degrees. While avoiding the zero-point noise problem caused by light reflection caused by vertical incidence, it will not cause excessive optical path displacement due to too large an angle.

[0029] By fixing the mirrors by welding or sintering, the process of gluing the reflectors in conventional multi-reflective air chambers is avoided. When air chamber products with glued sealed light windows work in oil and gas environments for a long time, the fixing glue is prone to softening and decomposition, resulting in displacement or falling off of the sealed light window, causing the air chamber to malfunction. Welding or low-temperature sintering can meet more severe usage environments, thereby improving the product's range of use and reliability.

[0030] By soldering or sintering the material, the reflectors are secured by gluing, a common method used in conventional multi-reflector air chambers. This method, which uses glued reflectors for long-term operation in oil and gas environments, can cause the adhesive to soften and decompose, leading to reflector displacement or detachment, and thus malfunctioning. Soldering or low-temperature sintering can withstand harsher operating environments, extending the product's range of applications and reliability.

[0031] Because the coupling reflector and the incident light are not arranged perpendicularly, an M-shaped reflection light path can be formed. However, if the angle between the incident light and the normal of the coupling reflector is too large, the stability of the reflection chamber light path will be too sensitive to the angle. Due to the coupling and fixation during the product production process and the high and low temperature working environment of the product, slight displacements will occur between the components. Therefore, controlling the angle range between the light entering the light incident hole and the normal of the coupling reflector can control the sensitivity of the light path. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the structure of a reflective gas chamber for gas sensing in Example 1 of the present invention;

[0033] Figure 2 Schematic diagram of the structure of a reflective gas chamber for gas sensing in the second embodiment of the present invention;

[0034] Figure 3 Schematic diagram of the structure of a reflective gas chamber for gas sensing in Example 3 of the present invention;

[0035] Figure 4 This is a structural stereogram of the coupling pagoda sleeve and the coupling pin of the present invention;

[0036] Figure 5 It is a schematic diagram of the coupling structure and process in the present invention.

[0037] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0038] 1. Air chamber shell, 2. Fixed reflector 1, 3. Fixed reflector 2, 4. Coupling reflector, 5. Light incident hole, 6. Light exit hole, 7. Temperature and pressure sensor, 8. Coupling ferrule, 9. Coupling pagoda sleeve, 10. Diffusion sealing cover, 11. Sealed light window for incident hole, 12. Sealed light window for exit hole, 13. Solder. DETAILED DESCRIPTION

[0039] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0040] Example 1:

[0041] like Figure 1 As shown, a reflective gas chamber for gas sensing includes a gas chamber shell 1, on the inner wall of which a fixed reflector 1 2, a fixed reflector 2 3 and a coupling reflector 4 are distributed. The gas chamber shell 1 is distributed with a light entrance hole 5 for light entry and a light exit hole 6 for light exit. The light entering from the light entrance hole 5 is reflected by the coupling reflector 4, the fixed reflector 1 2 and the fixed reflector 2 3 in sequence and then exits from the light exit hole 6. The light path formed by the light passing through the light entrance hole 5, the coupling reflector 4, the fixed reflector 1 2, the fixed reflector 2 3 and the light exit hole 6 in sequence is an M-type light path.

[0042] Specifically, the fixed reflector 1 2 is fixed at the center bottom point M of the M-type optical path, the fixed reflector 2 3 is fixed at the vertex on either side of M of the M-type optical path, and the coupling reflector 4 is fixed at the vertex on the other side of M of the M-type optical path after coupling adjustment.

[0043] In this specific embodiment, a temperature and pressure sensor 7 is further provided on the inner wall of the air chamber shell 1 , and the temperature and pressure sensor 7 is close to the light exit hole 6 .

[0044] In this specific embodiment, the coupling reflector 4 is mounted on the inner wall of the air chamber housing 1 via a coupling ferrule 8 and a coupling turret 9. The coupling ferrule 8 has an angled end face, and the coupling reflector 4 is fixed to the angled end face of the coupling ferrule 8. The coupling ferrule 8 is welded within the coupling turret 9 after coupling adjustment, and the coupling turret 9 is welded and fixed to the air chamber housing 1. The coupling ferrule 8 has XYZ-axis movement and coaxial rotation functions. The coupling method of the M-type optical path is that through the XYZ-axis movement and coaxial rotation of the coupling ferrule 8, the light entering the light input hole 5 can be coupled to the center of the light output hole 6 after multiple reflections and output along the optical axis of the light output hole 6.

[0045] In this specific embodiment, the air chamber shell 1 is provided with a diffusion type sealing cover 10 on its outer shell, and a molecular filtering structure is provided inside the diffusion type sealing cover 10 .

[0046] In this specific embodiment, the mirror surface of the coupling reflector 4 is arranged in a non-perpendicular manner to the optical axis of the light incident hole 5, that is, the mirror surface of the coupling reflector 4 is arranged in a non-perpendicular manner relative to the light incident from the light incident hole 5, so that the angle range between the light incident from the light incident hole 5 and the normal of the coupling reflector 4 is greater than zero degrees and less than or equal to sixty degrees.

[0047] The process focus of this specific embodiment is to achieve optical path coupling of the reflective air chamber by XYZ axis movement of the coupling ferrule 8 and coaxial rotation of the coupling ferrule 8, so as to couple the incident light to the center of the light exit hole 5 after multiple reflections.

[0048] The coupling structure and process of the present invention are as follows Figure 4-5 As shown, the coupling reflector 4, the coupling ferrule 8, the coupling pagoda sleeve 9, and the coupling welding surfaces of the air chamber shell 1 are all circular structural metal parts. The coupling reflector 4 is fixed on the angled end face of the coupling ferrule 8. The coupling ferrule 8 slides through the inner hole of the coupling pagoda sleeve 9 and passes through the opening on the air chamber shell 1 to place the coupling reflector 4 inside the air chamber shell 1. Then, the lower circular welding surface of the base of the coupling pagoda sleeve 9 containing the coupling ferrule 8 is flattened with the circular coupling welding surface outside the opening of the air chamber shell 1. Among them, the outer diameter of the coupling ferrule 8 is matched with the inner diameter of the coupling pagoda sleeve 9, so that the two can fit tightly and enable the coupling ferrule 8 to move a certain distance along the Z axis. The inner diameter of the opening on the air chamber shell 1 for the coupling ferrule 8 to pass through is slightly larger than the outer diameter of the coupling ferrule 8, so that the coupling ferrule 8 can move a certain distance in any direction of the XY plane in the opening of the air chamber shell 1 and can rotate freely around the Z axis. The inner diameter of the opening on the air chamber shell 1 for the coupling ferrule 8 to pass through is much smaller than the base part of the coupling pagoda sleeve 9, so that when the coupling ferrule 8 moves to any extreme position in the opening of the air chamber shell 1, the base part of the coupling pagoda sleeve 9 can tightly seal the opening on the air chamber shell 1.

[0049] After assembly is complete, prepare to start coupling. The specific coupling adjustment method is as follows Figure 5 As shown in ABCD, the starting position before coupling is as follows Figure 5 By adjusting the XY relative position of the coupling pagoda sleeve 9 and the air chamber shell 1, the coupling pagoda sleeve 9 drives the internal coupling ferrule 8 to drive the XY movement of the coupling reflector 4, as shown in FIG. Figure 5 By sliding the coupling ferrule 8 relative to the upper and lower coupling pagoda sleeve 9, the coupling ferrule 8 moves in the Z direction relative to the air chamber shell 1, thereby driving the coupling reflector 4 to move in the Z direction, as shown in FIG. Figure 5As shown in C; since the coupling pagoda sleeve 9 and the coupling ferrule 8 are both coaxial rotating body structures, the coaxial rotation of the coupling pagoda sleeve 9 can drive the coaxial rotation of the coupling ferrule 8, which can drive the coaxial rotation of the coupling reflector 4. Since the coupling reflector 4 is fixed on the angled end face of the coupling ferrule 8, the coaxial rotation of the coupling ferrule 8 will change the angle of the angled end face relative to the incident light. Thereby, the position movement of the coupling reflector 4 in any XYZ direction and the angle change relative to the air chamber shell 1 are achieved, thereby completing the coupling. Its final coupling state may be as follows Figure 5 As shown in D.

[0050] Specifically, a method for preparing a reflective gas cell for gas sensing in this embodiment is as follows:

[0051] Step S1010: Fix the fixed reflector 1 2 on the inner wall of the air chamber housing 1 and located at the M center bottom point of the M-shaped optical path, and fix the fixed reflector 2 3 on the inner wall of the air chamber housing 1 and located at the M right side vertex of the M-shaped optical path.

[0052] Step S1020: Fix the coupling reflector 4 on the angled end face of the coupling ferrule 8. After the coupling ferrule 8 passes through the inner hole of the coupling pagoda sleeve 9, it is placed at the vertex on the left side of the M-shaped optical path to prepare for optical path coupling.

[0053] Step S1030: the incident light passes through the light incident hole 5 located at the bottom point on the left side of the M-shaped optical path in the air chamber shell 1 and irradiates the opposite surface of the coupling reflector 4 installed on the angled end face of the coupling ferrule 8.

[0054] Step S1040: By moving the coupling ferrule 8 along the XYZ axis and rotating the coupling ferrule 8 along the coaxial axis, the optical path coupling of the reflective air chamber is achieved, and the incident light passes through the coupling reflector 4, the fixed reflector 1 2, and the fixed reflector 2 3 in sequence, and is finally coupled to the center of the light exit hole 5 as the exit light.

[0055] Step S1050: After the optical paths are coupled, laser welding is performed on the tube wall of the coupling pagoda sleeve 9 to fix the coupling pagoda sleeve 9 and the coupling ferrule 8 by penetration welding.

[0056] Step S1060: Fix the coupling cone sleeve 9 with the coupling ferrule 8 fixed therein to the air chamber shell 1 by laser welding.

[0057] Step S1070: Use sealing glue to fill and seal the gap between the coupling pagoda sleeve 9 and the air chamber shell 1 and the gap between the coupling ferrule 8 and the coupling pagoda sleeve 9.

[0058] Step S1080: Fix the temperature and pressure sensor 7 in the air chamber housing 1, next to the light exit hole 6. Fill the tail of the temperature and pressure sensor 7 with glue to prevent gas leakage between the temperature and pressure sensor 7 and the air chamber housing 1.

[0059] Step S1090: crimping and fixing the diffusion type sealing cover 10 onto the air chamber shell 1 with a sealing ring to seal the air chamber and protect and isolate the internal optical components.

[0060] In a reflective gas chamber for gas sensing in the first embodiment of the present invention, external incident light passes through the light incident hole 5 and enters the reflective gas chamber. The light is then totally reflected by the coupling reflector 4, fixed reflector 1 2, and fixed reflector 2 3 in the reflective gas chamber, and finally outputted from the light exit hole 6. Since the coupling reflector 4 is fixed to the angled end face of the coupling ferrule 8, the coupling reflector 4 and the incident light are non-perpendicularly arranged. During coupling, the XYZ-axis movement of the coupling ferrule 8 and the coaxial rotation of the coupling ferrule 8 can realize the XZY three-dimensional movement of the coupling reflector 4 and the relative angle in three-dimensional space with the incident light. In this way, the optical path coupling can be performed accurately, and the light is totally reflected by the coupling reflector 4, fixed reflector 1 2, and fixed reflector 2 3 in sequence according to the design requirements, and finally outputted from the light exit hole 6. After the coupling is completed, the coupling ferrule 8, the coupling pagoda sleeve 9 and the air chamber shell 1 are fixed by a laser welding process, thereby fixing the relative position of the coupling reflector 4 in the optical path.

[0061] Example 2:

[0062] like Figure 2 As shown, the difference between Example 2 and Example 1 is that an entrance hole sealing light window 11 is further provided on the inner wall of the air chamber shell 1 and located at the light entrance hole 5, and the entrance hole sealing light window 11 is non-perpendicular to the light incident from the light entrance hole 5, and the angle range between the light incident from the light entrance hole 5 and the normal of the entrance hole sealing light window 11 is greater than zero degree and less than or equal to sixty degrees; an exit hole sealing light window 12 is provided on the inner wall of the air chamber shell 1 and located at the light exit hole 6, and the exit hole sealing light window 12 is non-perpendicular to the light emitted from the entrance hole 6, and the angle range between the light emitted from the light exit hole 6 and the normal of the exit hole sealing light window 12 is greater than zero degree and less than or equal to sixty degrees.

[0063] Compared with the first embodiment, the method for preparing a fully sealed reflective gas cell for gas sensing in the second embodiment is different in that:

[0064] Before step S1010, the method further includes:

[0065] Step S1004: fix the incident hole sealing light window 11 to the inner wall of the light incident hole 5 of the air chamber shell 1, and place it non-perpendicular to the incident light to prevent reflected light from entering the link system and causing optical noise.

[0066] Step S1005: Fix the exit hole sealing light window 12 to the inner wall of the light exit hole 6 of the air chamber shell 1, and place it non-perpendicular to the exit light to prevent reflected light from entering the link system and causing optical noise.

[0067] This second embodiment is achieved through the above steps. Based on the first embodiment, a sealed light window 11 for the entrance aperture and a sealed light window 12 for the exit aperture are added. While ensuring that incident light can smoothly penetrate the sealed light window 11 to enter the gas chamber and that exiting light can smoothly penetrate the sealed light window 12 to exit the gas chamber, this also achieves a sealed structure for the gas chamber, preventing gas from escaping from the light entrance aperture 5 and the light exit aperture 6. Therefore, this structure enables gas content measurement in pressurized gas pipelines. Furthermore, because the incident light, exiting light, and corresponding sealed light windows are not arranged perpendicularly, their reflected light does not return to the original optical link and generate optical noise in the optical system.

[0068] Example 3:

[0069] like Figure 3 As shown, the difference between Example 3 and Example 2 is that the incident hole sealed light window 11 and the exit hole sealed light window 12 are both fixed to the inner wall of the gas chamber shell 1 by welding or sintering solder 13. The fixed reflector 1 2 and the fixed reflector 2 3 are both fixed to the inner wall of the gas chamber shell 1 by welding or sintering solder 13; and the coupling reflector 4 is fixed to the angled end face of the coupling ferrule 8 by welding or sintering solder 13.

[0070] Further optionally, the incident hole sealed light window 11 and the exit hole sealed light window 12 are both coated with an AR dielectric film; the fixed reflector 1 2 , the fixed reflector 2 3 and the coupling reflector 4 are all coated with an HR dielectric film.

[0071] Specifically, compared with the first embodiment, the method for preparing a reflective gas cell for gas sensing with high reliability in the third embodiment has the following differences:

[0072] Before step S1010, the method further includes:

[0073] Step S1001: The fixed reflector 1 2 , the fixed reflector 2 3 and the coupling reflector 4 are all coated with HR dielectric film to increase light reflectivity.

[0074] Step S1002: AR dielectric films are coated on both the incident hole sealing window 11 and the exit hole sealing window 12 to increase light transmittance.

[0075] Step S1003: Pre-treating the surfaces of the fixed reflector 1 2, the fixed reflector 2 3, the coupling reflector 4, the incident hole sealed light window 11 and the exit hole sealed light window 12 for fixing to meet the requirements of low-temperature brazing or glass sintering process.

[0076] Step S1004: The incident hole sealing light window 11 is placed inside the light incident hole 5 of the gas chamber shell 1 through solder 13 (the solder 13 is brazing material or glass solder), low-temperature brazing (low-temperature brazing when the solder 13 is brazing material) or glass sintering (glass sintering when the solder 13 is glass solder), and is placed non-perpendicular to the incident light to prevent reflected light from entering the link system and causing optical noise.

[0077] Step S1005: The exit hole sealed light window 12 is soldered (the solder 13 is brazing material or glass solder) at a low temperature (low temperature brazing when the solder 13 is brazing material) or glass sintered (glass sintered when the solder 13 is glass solder) on the inner side of the light exit hole 6 of the air chamber shell 1, and is placed non-perpendicular to the exiting light to prevent reflected light from entering the link system and causing optical noise.

[0078] Furthermore, in step S1010 and step S1020, the fixing methods of the fixed reflector 1 2, the fixed reflector 2 3, and the coupling reflector 4 can be respectively selected as low temperature brazing or glass sintering.

[0079] In this third embodiment, based on the second embodiment, the reflectivity of the reflector and the transmittance of the sealed light window can be further improved, the irregular reflected light within the reflective air chamber can be reduced, and the optical noise of the optical system can be reduced. The lens fixing process of low-temperature brazing or glass sintering can meet the requirements of more severe operating environments, thereby improving the product's usability and reliability. This avoids the problem of softening and decomposition of the fixing glue when traditional reflective air chamber products with glued-in reflectors are used in oil and gas environments for a long time, which may cause the reflector to shift or fall off.

[0080] Example 4:

[0081] In the above-mentioned first, second, and third embodiments, the incident light is reflected three times within the air chamber, forming an M-shaped optical path. On this basis, the number of fixed reflectors can be further increased, that is, N fixed reflectors can be provided within the air chamber housing 1, so that the incident light undergoes more refractions within the air chamber before reaching the exit hole, thereby further extending the propagation path of the incident light within the air chamber. Here, N is greater than or equal to 3, for example, 3, 4, 5, 6, 7, 8, 9, or 10. Since the light path reflection is symmetrical with respect to the optical axis of the fixed reflectors, the alignment and adjustment of the light path after multiple reflections can be achieved by periodically and symmetrically staggering multiple fixed reflectors by adjusting the position and angle of the coupling reflector 4.

[0082] In the above-mentioned first, second and third embodiments, the incident hole and the reflection hole are arranged on the same side of the air chamber shell 1. Those skilled in the art will appreciate that in this embodiment, the incident hole and the reflection hole can also be arranged on different sides of the air chamber shell 1.

[0083] Those skilled in the art will understand that, in the description of this specification, reference to the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0084] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. Those skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A reflective gas cell for TDLAS gas detection, characterized by: The invention comprises an air chamber shell (1), wherein a fixed reflector 1, a fixed reflector 2 and a coupling reflector (4) are distributed on the inner wall of the air chamber shell (1), and a light entrance hole (5) for light entry and a light exit hole (6) for light exit are distributed on the air chamber shell (1), and the light entering from the light entrance hole (5) is reflected by the coupling reflector (4), the fixed reflector 1 and the fixed reflector 2 in sequence and then exits from the light exit hole (6); wherein the The coupling reflector (4) is mounted on the inner wall of the air chamber shell (1) via a coupling ferrule (8) and a coupling pagoda sleeve (9); the coupling ferrule (8) has an oblique end face; the coupling reflector (4) is fixed on the oblique end face of the coupling ferrule (8); the coupling ferrule (8) and the coupling pagoda sleeve (9) cooperate so that the coupling reflector (4) can be adjusted in relative position and relative angle relative to the optical axis of the light incident hole (5) before being fixed in the air chamber shell; The coupling reflector (4), the coupling insert (8), the coupling pagoda sleeve (9), and the coupling welding surface of the air chamber shell (1) all have circular structural metal parts. The coupling insert (8) is inserted into the inner hole of the coupling pagoda sleeve (9) and passes through the opening on the air chamber shell (1). The lower circular welding surface of the base of the coupling pagoda sleeve (9) is pressed flat against the circular coupling welding surface outside the opening of the air chamber shell (1); thereby, the coupling insert (8) has the adjustment function of moving along the XYZ axis and coaxial rotation during assembly.

2. The reflective gas cell for TDLAS gas detection according to claim 1, characterized in that: A temperature and pressure sensor (7) is also provided on the inner wall of the air chamber shell (1), and the temperature and pressure sensor (7) is close to the light exit hole (6).

3. The reflective gas cell for TDLAS gas detection according to claim 1, characterized in that: The air chamber shell (1) is provided with a diffusion-type sealing cover (10) on its outer shell, and a molecular filtering structure is provided inside the diffusion-type sealing cover (10).

4. The reflective gas cell for TDLAS gas detection according to claim 1, characterized in that: An entrance hole sealing light window (11) is provided on the inner wall of the air chamber shell (1) and located at the light entrance hole (5), the entrance hole sealing light window (11) is non-perpendicular to the light incident from the light entrance hole (5), and the angle between the light incident from the light entrance hole (5) and the normal of the entrance hole sealing light window (11) is greater than zero and less than or equal to sixty degrees; an exit hole sealing light window (12) is provided on the inner wall of the air chamber shell (1) and located at the light exit hole (6), the exit hole sealing light window (12) is non-perpendicular to the light emitted from the light exit hole (6), and the angle between the light emitted from the light exit hole (6) and the normal of the exit hole sealing light window (12) is greater than zero and less than or equal to sixty degrees.

5. The reflective gas cell for TDLAS gas detection according to claim 4, characterized in that: The incident hole sealed light window (11) and the exit hole sealed light window (12) are both plated with an AR dielectric film; Or / and, the fixed reflector 1, the fixed reflector 2 and the coupling reflector (4) are all coated with HR dielectric films.

6. The reflective gas cell for TDLAS gas detection according to claim 4, characterized in that: The incident hole sealed light window (11) and the exit hole sealed light window (12) are both fixed on the inner wall of the air chamber tube shell (1) by welding or sintering the solder (13).

7. The reflective gas cell for TDLAS gas detection according to claim 2, characterized in that: The first fixed reflector and the second fixed reflector are both fixed to the inner wall of the air chamber shell (1) by welding or sintering the solder (13); the coupling reflector (4) is fixed to the oblique end face of the coupling ferrule (8) by welding or sintering the solder (13); the coupling reflector (4) is non-perpendicular to the light incident from the light incident hole (5), and the angle between the light incident from the light incident hole (5) and the normal of the coupling reflector (4) is greater than zero and less than or equal to sixty degrees.

8. A method for manufacturing a reflective gas cell for TDLAS gas detection, characterized in that Including steps: Step S1010: Fix the first fixed reflector to the inner wall of the air chamber housing and located at the center bottom point M of the M-shaped optical path; fix the second fixed reflector to the inner wall of the air chamber housing and located at the top point on the right side of M of the M-shaped optical path; Step S1020: Fix the coupling reflector on the angled end face of the coupling ferrule. After the coupling ferrule passes through the inner hole of the coupling cone, place it at the vertex on the left side of the M-shaped optical path. Step S1030: directing the incident light through the light entrance hole located at the bottom point on the left side of the M-shaped optical path in the air chamber housing and irradiating the opposite surface of the coupling reflector mounted on the angled end face of the coupling ferrule; Step S1040: By moving the coupling ferrule along the XYZ axes and rotating the coupling ferrule along the same axis, optical path coupling of the reflective gas chamber is achieved, and the incident light passes through the coupling reflector, the first fixed reflector, and the second fixed reflector in sequence, and is finally coupled to the center of the light exit hole as the exit light. Step S1050: After the optical paths are coupled, laser welding is performed on the tube wall of the coupling pagoda sleeve to fix the coupling pagoda sleeve and the coupling ferrule by penetration welding; Step S1060: Fix the coupling pagoda sleeve with the coupling ferrule fixed therein to the air chamber shell by laser welding; Step S1070: Fill the gaps between the coupling pagoda sleeve and the air chamber shell, and the gaps between the coupling ferrule and the coupling pagoda sleeve with sealing glue to seal them; Step S1080: Fix the temperature and pressure sensor in the air chamber housing, next to the light exit hole, and seal the tail of the temperature and pressure sensor with glue to prevent gas leakage between the temperature and pressure sensor and the air chamber housing; Step S1090: crimping and fixing the diffusion sealing cover to the air chamber shell with a sealing ring to seal the air chamber and protect and isolate the internal optical components.

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