A coaxial multi-wavelength self-stabilized laser for real-time detection of multi-component gases

Abstract

The present invention relates to a coaxial multi-wavelength self-stabilized laser for real-time detection of multi-component gases, comprising a laser tube housing and a light output component. The laser tube housing includes N TO lasers, N TO detectors and a coaxial light combining and splitting optical path component, where N is a natural number greater than or equal to 2. The coaxial light combining and splitting optical path component includes a plurality of optical filters. While part of the laser light emitted by the N TO lasers is input into the corresponding TO detectors after reflection and / or transmission, the remaining part of the laser light emitted by the N TO lasers is input from N directions, then combined and focused and output to the light output component. Each of the TO detectors has a reference gas chamber and correspondingly detects the change in the output light wavelength of one TO laser. The present invention is particularly applicable to fixed, portable, and telemetry TDLAS gas detection systems for real-time on-line detection of multiple gases.

Description

Technical Field

[0001] The present invention relates to the field of TDLAS gas detection, and in particular to a coaxial multi-wavelength self-stabilizing laser based on TDLAS technology for a multi-gas real-time online detector. Background Art

[0002] TDLAS technology (Tunable Diode Laser Absorption Spectroscopy) is based on a tunable diode laser and utilizes the "frequency selection" characteristics of the measured gas molecules to achieve the measurement of the characteristics of the measured gas. This technology successfully avoids the interference of other irrelevant gas components and has become the preferred solution for current online gas detection systems with high precision and real-time requirements. At the same time, it has a fast response speed, a low measurement threshold, and can analyze multiple gas components simultaneously, mainly including gases such as methane, carbon monoxide, carbon dioxide, oxygen, and ammonia. Since the late 1990s, gas detection solutions and devices based on TDLAS technology have emerged in large numbers, and various measurement methods such as fixed test systems, distributed test systems, and telemetry test systems have appeared in the industrial application field.

[0003] Due to the working principle of TDLAS technology, the absorption wavelengths corresponding to different gas components are different. Therefore, in actual applications, if multiple gas components need to be measured, multiple lasers with different central wavelengths need to be used for spectral scanning, and multiple detectors need to be correspondingly set to detect the laser signals of the corresponding wavelengths; or the central wavelength of a laser is tuned in a time-sharing manner to correspond to the absorption wavelengths of different measured gas components, and a spectral analyzer is used for reception or multiple detectors are correspondingly set for reception. Therefore, most of the current industrial online gas detectors are detectors for single gas components, such as methane detectors, acetylene detectors, and oxygen detectors, and it is difficult to detect multiple gas components with the same device.

[0004] Currently, the existing devices for real-time online detection of multi-component gases have the following main technical problems:

[0005] 1. For different gas components to be measured, the lasers are different, the detectors are different, and the gas chambers are different. The optical paths of the multi-component gas real-time online detector formed are separated, and its cost is high, almost equal to the sum of the costs of several separate detectors. Moreover, it has a large volume, a loose structure, poor structural reliability, poor portability, and is not conducive to inspection and maintenance.

[0006] 2. As the core component of a TDLAS gas detector and the "frequency selection" characteristics of gas molecules, a multi-gas measurement necessarily requires a laser with multiple wavelengths. However, there is currently no integrated laser for multi-gas real-time online detectors on the market, let alone a coaxial multi-wavelength self-stabilizing laser. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a coaxial multi-wavelength self-stabilizing laser aiming at the deficiencies of the above-mentioned prior art, so as to solve a series of technical problems such as the completely independent measurement optical paths for each gas in existing multi-gas real-time online detectors, low integration, complex structure, high manufacturing cost, and poor reliability.

[0008] The present invention provides a coaxial multi-wavelength self-stabilizing laser for real-time detection of multi-component gases, including a laser housing and a light output component. The laser housing includes N TO lasers, N TO detectors, and a coaxial light combining and splitting optical path component, where N is a natural number greater than or equal to 2; the laser emitted by each TO laser has at least one typical wavelength, and the typical wavelengths of each TO laser are different from each other, and each or several typical wavelengths correspond to the typical absorption line or absorption spectrum peak of a certain gas; the coaxial light combining and splitting optical path component includes multiple filter plates. While part of the laser emitted by the N TO lasers is input to the corresponding TO detector after reflection and / or transmission, the remaining part of the laser emitted by the N TO lasers is input from N directions, then combined and bundled and output to the light output component; each TO detector has a reference gas chamber inside and correspondingly detects the change in the output light of a TO laser; the typical absorption line or absorption spectrum peak of the reference gas filled in the corresponding reference gas chamber corresponds to the typical wavelength of the corresponding TO laser; the light spots of the N TO lasers are all incident on the focus of the light output component after being reflected and / or transmitted by the filter plates of the coaxial light combining and splitting optical path component; the light output component collimates the combined and bundled light beam and emits it from the coaxial multi-wavelength self-stabilizing laser, and the combined and bundled light beam is a composite light beam for measuring different gas components.

[0009] In the above technical solution, each of the multiple filter plates is made by coating both sides. One side is a semi-transparent and semi-reflective film with a specific wavelength, that is, it partially reflects and partially transmits light in the first specific wavelength range and completely transmits light with other wavelengths outside the first specific wavelength range; the other side is a total reflection film with a specific wavelength, that is, it completely reflects light in the second specific wavelength range and completely transmits light with other wavelengths outside the second specific wavelength range.

[0010] In the above technical solution, any one of the multiple filter plates is made by single-sided coating. The single-sided coating is a semi-transmissive and semi-reflective film with a specific wavelength, that is, it partially reflects and partially transmits light within a specific wavelength range, and completely transmits light with other wavelengths outside the specific wavelength range.

[0011] In the above technical solution, the TO laser is a laser device with a semiconductor refrigeration module in coaxial packaging.

[0012] In the above technical solution, the main optical axis of one of the TO lasers is coaxial with the main optical axis of the light output component, and the main optical axes of the remaining TO lasers are perpendicular to the main optical axis of the light output component; the coaxial light combining optical path component is located on the main optical axis of the light output component.

[0013] In the above technical solution, the light output component is a collimating lens or an optical fiber connector or an optical fiber fixed at the light output port position of the laser package.

[0014] In the above technical solution, the laser package includes three TO lasers and three TO detectors. The coaxial light combining and splitting optical path component includes three filter plates; the first TO laser is coupled and fixed on one side of the laser package opposite to the light output port of the laser package, the second TO laser is coupled and fixed on one side perpendicular to the light output port of the laser package; the third TO laser is coupled and fixed on one side perpendicular to the light output port of the laser package and is located on the opposite side of the second TO laser; the first TO detector 1 is coupled and fixed beside the third TO laser on the same side, and is distributed at a 90-degree angle with the first TO laser; the second TO detector is coupled and fixed beside the third TO laser on the same side, and is distributed at a 90-degree angle with the first TO laser and is distributed in an opposite direction to the second TO laser; the third TO detector is coupled and fixed on the same side of the second TO laser, and is distributed at a 90-degree angle with the first TO laser and is distributed in an opposite direction to the third TO laser; the first filter plate is fixed at the intersection of the main optical axes of the first and second TO lasers and is at a 45-degree angle relative to both the first and second TO lasers; the second filter plate is fixed at the intersection of the main optical axes of the third TO laser and the first TO laser and is at a 45-degree angle relative to both the first and third TO lasers; the first filter plate and the second filter plate are distributed in a V shape; the third filter plate is coaxial with the main optical axes of the first TO laser and the light output component and is at a 45-degree angle relative to the first TO laser, and is distributed in a V shape with the second filter plate.

[0015] In the above technical solution, an output optical isolator is further included; the output optical isolator is fixed inside the laser package, located between the third filter plate and the light output component, and is coaxial with the main optical axis of the first TO laser.

[0016] In the above technical solution, the first, second, and third TO detectors detect the changes in the central wavelengths of the light beams emitted by the first, second, and third TO lasers, and respectively control the temperatures of the first, second, and third TO lasers to thereby keep the central wavelengths of the emitted light beams stable.

[0017] In the above technical solution, 1 - 99% of the light emitted by each TO laser is received by the corresponding TO detector. Preferably, 50% of the light is received by the corresponding TO detector.

[0018] The present invention also provides a method for manufacturing a coaxial multi - wavelength self - stabilizing laser for real - time detection of multi - component gases, including:

[0019] Step S1010: Fix a light output isolator at the light outlet of the laser housing.

[0020] Step S1020: Fix a first filter at the intersection of the main optical axes of the first TO laser and the second TO laser. The first filter is at a 45 - degree angle with respect to both the first and second TO lasers.

[0021] Step S1030: Fix a second filter at the intersection of the main optical axes of the third TO laser and the first TO laser. The second filter is at a 45 - degree angle with respect to both the first and third TO lasers, and the first filter and the second filter are in a figure - eight distribution.

[0022] Step S1040: Fix a third filter coaxially with the main optical axis of the first TO laser and the light output component 5. The third filter is at a 45 - degree angle with respect to the first TO laser and is in a figure - eight distribution with the second filter.

[0023] Step S1050: Align the first TO laser with the light output component for coupling. The first TO laser couples the Z - axis, and the light output component couples the XY - axes. After coupling, the first TO laser is welded and fixed to the laser housing, and the light output component is welded and fixed to the laser housing; the first TO laser, the light output component, and the light output isolator are kept coaxial.

[0024] Step S1060: Align the second TO laser with the light output component for coupling. The second TO laser couples the XYZ - axes. After coupling, the second TO laser is welded and fixed to the laser housing.

[0025] Step S1070: Align the third TO laser with the light output component for coupling. The third TO laser couples the XYZ - axes. After coupling, the third TO laser is welded and fixed to the laser housing.

[0026] Step S1080: The first TO detector is aligned with the XYZ axes of the third filter. After the coupling is completed, it is fixed on one side perpendicular to the light output port of the laser housing, on the laser housing beside the third TO laser on the same side, and is distributed at a 90-degree angle to the first TO laser.

[0027] Step S1090: The second TO detector is aligned with the XYZ axes of the first filter. After the coupling is completed, it is fixed on another side of the laser housing beside the third TO laser on the same side, is distributed at a 90-degree angle to the first TO laser, and is distributed in an opposite direction to the second TO laser.

[0028] Step S1100: The third TO detector is aligned with the XYZ axes of the second filter. After the coupling is completed, it is fixed on another side of the laser housing beside the second TO laser on the same side, is distributed at a 90-degree angle to the first TO laser, and is distributed in an opposite direction to the third TO laser.

[0029] The beneficial effects of the present invention are as follows:

[0030] Multiple highly integrated TO packaged lasers that output different wavelengths are integrated in a single laser housing. Through one or more filters placed at a 45-degree angle, multiple laser beams with different wavelengths from different directions are combined in wavelength and in beam, and output from a single output port. The combined laser beam is output externally, laying a foundation for the integration and unification of the optical paths in a multi-component gas real-time detector, enabling the overall optical path to be integrated. Through the structural arrangement of the present invention, wavelength combination and beam combination can be achieved for two or more lasers with arbitrary wavelengths, truly realizing a multi-wavelength coaxial laser product. By distributing the TO lasers at a 90-degree angle to each other in pairs, the volume of the coaxial multi-wavelength laser is greatly reduced. At the same time, the completely aligned focal spots enable the fiber or collimating lens to couple to their focal points, so that two output modes, namely fiber remote output or parallel light spatial output, of the multi-wavelength laser can be realized, greatly improving the usability and application scope of the product.

[0031] By adding an output isolator between the light output component and the third filter, the reflected light in the internal optical path of the laser and the peripheral optical link cannot be reflected back into the laser chip resonator cavity, thereby avoiding the problem of large errors in gas concentration measurement caused by unstable output power, non-linearity, and mode hopping of the DFB laser.

[0032] By integrating a TO-packaged detector with a reference gas chamber inside a coaxial multi-wavelength laser and effectively using dielectric films with different coatings on both sides of the filter, the output beam of all TO lasers is split into two parts inside the coaxial multi-wavelength laser. One part enters the corresponding detector with a reference gas chamber for active wavelength feedback real-time calibration, and the other part is output as a measurement beam. Without adding extra optical components, the coaxial multi-wavelength laser is upgraded to a coaxial multi-wavelength self-stabilized laser. This effectively improves the usability of the product in the application environment of high-precision industrial gas detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the coaxial dual-wavelength laser in Embodiment 1 of the present invention

[0034] Figure 2 Schematic diagram of the coaxial triple-wavelength laser in Embodiment 2 of the present invention

[0035] Figure 3 Schematic diagram of the coaxial triple-wavelength self-stabilized laser in Embodiment 3 of the present invention

[0036] The list of components represented by each reference numeral in the drawings is as follows: TO laser 1, TO laser 2, filter 1 3, laser housing 4, light output assembly 5, TO laser 3 6, filter 2 7, light output isolator 8, TO detector 1 9, TO detector 2 10, TO detector 3 11, filter 3 12. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The principles and features of the present invention will be described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. The present invention will be described below with reference to the accompanying drawings.

[0038] Embodiment 1:

[0039] The present invention provides a coaxial multi-wavelength laser for real-time detection of multi-component gases, as Figure 1 shown, which includes TO laser 1, TO laser 2, filter 1 3, laser housing 4, and light output assembly 5.

[0040] The light output assembly 5 is a collimating lens fixed at the light output port of the laser housing 4, or can also be an optical fiber connector to connect the output optical fiber, or can be an optical fiber.

[0041] The TO laser is a coaxial packaged laser with a semiconductor refrigeration function.

[0042] The wavelengths of the detection lasers output by the TO laser 1 and the TO laser 2 are different, that is, the output light wavelengths of the TO laser 1 and the TO laser 2 are respectively applicable to measuring two different types of gases. Typically, the TO laser 1 and the TO laser 2 respectively emit laser detection signals with different peak wavelengths, and each peak wavelength corresponds to one or more typical absorption spectral lines or absorption spectral peaks of a certain gas component. For example, when detecting CH4 (methane) gas, 1654 nm is correspondingly used; when detecting CO / CO2 (carbon monoxide / carbon dioxide) gas, 1580 / 2004 / 2327 / 2330 / 2680 nm is correspondingly used; when detecting O2 (oxygen) gas, 760 / 761 / 763 nm is correspondingly used; when detecting H2S (hydrogen sulfide) gas, 1590 nm is correspondingly used; when detecting HCN (hydrogen cyanide) gas, 1540 nm is correspondingly used, and so on. The above gas types and corresponding wavelength values are only illustrative, and the gas types that can be detected by the present invention and the detection wavelengths used are not limited to the above examples.

[0043] The filter 1 can reflect light of the first wavelength and transmit light of a non-first wavelength (such as light of the second wavelength), or transmit light of the first wavelength and reflect light of a non-first wavelength (such as light of the second wavelength). Typically, the filter 1 is made by double-sided coating. Its first surface is coated with a first film layer, and its second surface is coated with a second film layer; wherein, the first film layer is an AR antireflection film, and this AR antireflection film is an enhanced transmission film for the first wavelength, and this first wavelength corresponds to the central wavelength of a certain typical absorption spectrum of the first measured gas; wherein, the second film layer is a narrowband total reflection film, and this narrowband total reflection film is a total reflection film for the second wavelength, and this second wavelength corresponds to the central wavelength of a certain typical absorption spectrum of the second measured gas; thus, the laser beam with the first wavelength emitted by the TO laser 1 is input from the first direction to the filter 1 placed at a 45-degree angle, and can pass through the front and back surfaces of the filter 1 and reach the light output component 5. The laser beam with the second wavelength emitted by the TO laser 2 is input from the second direction to the reflection surface of the filter 1 placed at a 45-degree angle for total reflection. After the optical path is turned by 90 degrees, it also reaches the light output component 5.

[0044] Those skilled in the art know that there can be other choices for the coating method of the filter 1. For example, it can be selected that the AR antireflection film is for the second wavelength and the narrowband total reflection film is for the first wavelength. These selection changes can be selected and combined by those skilled in the art based on the technical concept of the present invention. According to the performance parameters of the first film layer and the second film layer made by double-sided coating of the filter 1, a reasonable selection can be made for the wavelength spacing between the two wavelengths in the composite beam so that it meets the optical wavelength isolation range index of the first film layer and the second film layer.

[0045] The preparation method of the coaxial multi-wavelength laser for multi-component gas real-time detection based on the TDLAS technology in this embodiment is as follows:

[0046] Step S110: Glue and fix the first filter 3 inside the laser housing 4 at the intersection of the main optical axes of the two TO lasers, and it is at a 45-degree angle relative to both TO lasers.

[0047] Step S120: Align the first TO laser 1 with the light output component 5 for coupling. The first TO laser 1 is coupled along the Z-axis, and the light output component 5 is coupled along the XY-axis. After the coupling is completed, weld and fix the first TO laser 1 to the laser housing 4, and weld and fix the light output component 5 to the laser housing 4. The first TO laser 1 and the light output component 5 are kept coaxial.

[0048] Step S130: Align the second TO laser 2 with the light output component 5 for coupling. The second TO laser 2 is coupled along the XYZ-axes. After the coupling is completed, weld and fix the second TO laser 2 to the laser housing 4.

[0049] In this embodiment, by first coupling the first TO laser 1 and then coupling the second TO laser 2, the light spots of the two lasers are made to coincide, and the focal points coincide, thereby achieving the design purpose of wave combination and beam combination.

[0050] Embodiment 2:

[0051] The present invention provides a coaxial multi-wavelength laser for multi-component gas real-time detection, as Figure 2 shown, including the first TO laser 1, the second TO laser 2, the third TO laser 6, the first filter 3, the second filter 7, the laser housing 4, the light output component 5, and the light output isolator 8. Compared with Embodiment 1, this Embodiment 2 adds the third TO laser 6 and the second filter 7.

[0052] The wavelengths of the detection lasers output by the first TO laser 1, the second TO laser 2, and the third TO laser 6 are all different, that is, the output light wavelengths of the first TO laser 1, the second TO laser 2, and the third TO laser 6 are respectively suitable for measuring three different types of gases. Based on this, those skilled in the art can know that each TO laser outputs an optical signal of one wavelength, and the number of TO lasers corresponds to the number of typical wavelengths in the output light; the number of filters is associated with the number of TO lasers. Preferably, the number of filters is one less than the number of TO lasers.

[0053] The second filter 7 is similar to the first filter 3 and can also be fabricated by double-sided coating. One side of the second filter 7 is an AR antireflection film for the output laser wavelengths of the TO laser 1 and the TO laser 2. The other side is a narrowband total reflection film for the output laser wavelength of the TO laser 3. Therefore, the laser beams output by the TO laser 1 and the TO laser 2 can pass through the front and back surfaces of the second filter 7 placed at a 45-degree angle and reach the optical output component 5. The laser beam output by the TO laser 3 is totally reflected at the reflecting surface of the second filter 7 placed at a 45-degree angle. After the optical path is turned by 90 degrees, it reaches the optical output component 5.

[0054] In this embodiment, an optical isolator is added at the light output port. The optical isolator can optically isolate the reflected light from the coupling end face of the optical output component 5 and the reflected light in the optical link of the gas in-line measuring instrument, greatly reducing the problems of unstable output power, non-linearity, and mode hopping of the DFB laser chip in the TO package due to the reflection problem in the front optical path. Thereby increasing the stability of the detection system.

[0055] The preparation method of the multi-component gas real-time detection coaxial multi-wavelength laser based on the TDLAS technology in this embodiment is as follows:

[0056] Step S210: Glue or weld and fix the optical isolator 8 at the light output port inside the laser housing 4, between the second filter 7 and the optical output component 5, and coaxial with the main optical axis of the TO laser 1.

[0057] Step S220: Glue and fix the first filter 3 inside the laser housing 4 at the intersection of the main optical axes of the TO laser 1 and the TO laser 2, and at a 45-degree angle relative to both TO lasers.

[0058] Step S230: Glue and fix the second filter 7 inside the laser housing 4 at the intersection of the main optical axes of the TO laser 3 and the TO laser 1, and at a 45-degree angle relative to both TO lasers, and the first filter 3 and the second filter 7 are distributed in a figure-eight shape.

[0059] Step S240: Align the TO laser 1 with the optical output component 5 for coupling. The TO laser 1 couples the Z axis, and the optical output component 5 couples the XY axes. After the coupling is completed, the TO laser 1 is welded and fixed to the laser housing 4, and the optical output component 5 is welded and fixed to the laser housing 4. The TO laser 1, the optical output component 5, and the optical isolator 8 are kept coaxial.

[0060] Step S250: Align the TO laser 2 with the optical output component 5 for coupling. The TO laser 2 couples the XYZ axes. After the coupling is completed, the TO laser 2 is welded and fixed to the laser housing 4.

[0061] Step S260: The TO laser three 6 is aligned with the optical output component 5 for coupling. For the XYZ axes of the coupling of the TO laser three 6, after the coupling is completed, the TO laser three 6 is welded and fixed to the laser housing 4.

[0062] Embodiment Three:

[0063] The present invention provides a multi-component gas real-time detection coaxial multi-wavelength self-stabilizing laser, as Figure 3 shown, including a TO laser one 1, a TO laser two 2, a TO laser three 6, a filter one 3, a filter two 7, a filter three 12, a laser housing 4, an optical output component 5, an output optical isolator 8, a TO detector one 9, a TO detector two 10, and a TO detector three 11. Compared with Embodiment Two, this Embodiment Three adds a TO detector one 9, a TO detector two 10, a TO detector three 11, and a filter three 12.

[0064] Among them, the wavelengths of the detection lasers output by the TO laser one 1, the TO laser two 2, and the TO laser three 6 are all different, that is, the output light wavelengths of the TO laser one 1, the TO laser two 2, and the TO laser three 6 are respectively applicable to measuring three different types of gases. Based on this, those skilled in the art can know that each TO laser outputs an optical signal of one wavelength, and the number of TO lasers corresponds to the number of typical wavelengths in the output light; the number of filters is associated with the number of TO lasers. Preferably, the number of filters is the same as the number of TO lasers.

[0065] The TO detector is a TO detector with a reference gas chamber, and the gas filled in the TO detector one 9 is the reference gas corresponding to the wavelength of the TO laser one 1; the gas filled in the TO detector two 10 is the reference gas corresponding to the wavelength of the TO laser two 2. The gas filled in the TO detector three 11 is the reference gas corresponding to the wavelength of the TO laser three 6.

[0066] The filter 1 3, the filter 2 7, and the filter 3 12 are all made by coating both sides. One side is a semi-transmissive and semi-reflective film with a specific wavelength, that is, light within a specific wavelength range is partially reflected and partially transmitted, and light of other wavelengths is completely transmitted; the other side is a fully transmissive film within a specific wavelength range, that is, light within a specific wavelength range is completely transmitted. For example, the light beam emitted by the TO laser 1 passes through the filter 1 3 and the filter 2 7, and part of the light is reflected at a 90-degree angle on the semi-transmissive and semi-reflective surface of the filter 3 12 into the TO detector 1 9 as a reference beam, and the remaining part of the light passes through the filter 3 12 and is output to the optical output assembly 5 as a measurement beam. Similarly, part of the light beam emitted by the TO laser 2 enters the TO detector 2 10 arranged oppositely through the semi-transmissive and semi-reflective surface of the filter 1 3 as a reference beam, and the remaining part of the light beam is reflected by the filter 1 3 and the optical path changes by 90 degrees, passes through the filter 2 7 and the filter 3 12, and is output to the optical output assembly 5 as a measurement beam. Part of the light beam emitted by the TO laser 3 enters the TO detector 3 11 with an opposite design through the semi-transmissive and semi-reflective surface of the filter 2 7 as a reference beam, and the remaining part of the light beam is reflected by the filter 2 7 and the optical path changes by 90 degrees, passes through the filter 3 12, and is output to the optical output assembly 5 as a measurement beam.

[0067] Those skilled in the art know that under certain optical performance requirements, the filter 1 3, the filter 2 7, and the filter 3 12 can also be made by single-sided coating. Its first surface is coated with a first film layer, and its second surface may not have an optical coating or only be coated with a protective film layer with non-specific optical properties; among them, the first film layer is a semi-transmissive and semi-reflective film with a specific wavelength, that is, light within a specific wavelength range is partially reflected and partially transmitted, and light of other wavelengths is completely transmitted.

[0068] Specifically, TO laser one 1 is coupled and fixed on the side of the laser housing 4 opposite to the light output port. TO laser two 2 is coupled and fixed on the side perpendicular to the light output port of the laser housing 4. TO laser three 6 is coupled and fixed on the side perpendicular to the light output port of the laser housing 4, on the opposite side of TO laser two 2. Filter one 3 is glued and fixed inside the laser housing 4, at the intersection of the main optical axes of TO laser one 1 and TO laser two 2, and is at a 45-degree angle relative to both TO laser one 1 and TO laser two 2. Filter two 7 is glued and fixed inside the laser housing 4, at the intersection of the main optical axes of TO laser three 6 and TO laser one 1, and is at a 45-degree angle relative to both TO laser three 6 and TO laser one 1. Filter one 3 and filter two 7 are distributed in a V shape. The light output component 5 is fixed at the light output port of the laser housing 4 after coupling the three TO lasers. The linear distances between TO laser one 1 and TO laser two 2 relative to the center of filter one 3 and between TO laser three 6 and filter two 7 are the same. TO laser one 1 and TO laser two 2 are distributed at a 90-degree angle. TO laser one 1 and TO laser three 6 are distributed at a 90-degree angle, and the spot foci of the three TO lasers after passing through filter one 3 coincide. The output optical isolator 8 is glued and fixed inside the laser housing 4, between filter three 12 and the light output component 5, and is coaxial with the main optical axis of TO laser one 1.

[0069] TO detector one 9 is coupled and fixed beside the same side of TO laser three 6, and is distributed at a 90-degree angle with TO laser one 1. TO detector two 10 is coupled and fixed beside the other side of the same side of TO laser three 6, is distributed at a 90-degree angle with TO laser one 1, and is distributed in an opposite direction to TO laser two 2. TO detector three 11 is coupled and fixed on the same side of TO laser two 2, is distributed at a 90-degree angle with TO laser one 1, and is distributed in an opposite direction to TO laser three 6. Part of the light emitted by TO laser one 1 passes through filter one 3, filter two 7, and filter three 12 and is output to the focus of the light output component 5. Another part of the light is reflected by filter three 12 and enters TO detector one 9. Part of the light emitted by TO laser two 2 passes through filter one 1 and enters TO detector two 10. Another part of the light is reflected by filter one 3, passes through filter two 7 and three 12, and then reaches the focus of the light output component 5. Part of the light emitted by TO laser three 6 passes through filter two 7 and enters TO detector three 11. Another part of the light is reflected by filter two 7, passes through filter three 12, and then reaches the focus of the light output component 5.

[0070] Those skilled in the art know that the transmission and reflection ratios of the semi-transmissive and semi-reflective film can be adjusted within the range of 1-99% according to actual needs. Generally speaking, among the light emitted by each TO laser, approximately 1-50% of the light is received by the corresponding TO detector, and preferably 30-70% of the light is received by the corresponding TO detector.

[0071] In this way, while multiple TO lasers are combined and beam-combined in the laser housing, a part of the light from each TO laser enters the corresponding TO detector. Since the corresponding measured gas is filled in the TO detector, the external module can find the displacement of the central wavelength of the laser output by each TO laser according to the first harmonic of the absorption curve, and then feedback it to the TEC thermoelectric cooler of each TO laser. By actively adjusting the TEC temperature control points inside each TO laser, the self-stabilization function of the output wavelength of each TO laser is completed.

[0072] The preparation method of the multi-component gas real-time detection coaxial multi-wavelength self-stabilizing laser based on the TDLAS technology in this embodiment is as follows:

[0073] Step S1010: Glue or weld and fix the optical isolator 8 at the light output port inside the laser housing 4, between the third filter 11 and the light output component 5, and coaxial with the main optical axis of the first TO laser 1.

[0074] Step S1020: Glue and fix the first filter 3 inside the laser housing 4 at the intersection of the main optical axes of the first TO laser 1 and the second TO laser 2, and it is at a 45-degree angle relative to both TO lasers.

[0075] Step S1030: Glue and fix the second filter 7 inside the laser housing 4 at the intersection of the main optical axes of the third TO laser 6 and the first TO laser 1, and it is at a 45-degree angle relative to both TO lasers. And the first filter 3 and the second filter 7 are distributed in a V shape.

[0076] Step S1040: Glue and fix the third filter 12 inside the laser housing 4, coaxial with the main optical axes of the first TO laser 1 and the light output component 5, and it is at a 45-degree angle relative to the first TO laser 1, and is distributed in a V shape with the second filter 7.

[0077] Step S1050: Align the first TO laser 1 with the light output component 5 for coupling. The first TO laser 1 couples the Z axis, and the light output component 5 couples the XY axes. After the coupling is completed, the first TO laser 1 is welded and fixed to the laser housing 4, and the light output component 5 is welded and fixed to the laser housing 4. The first TO laser 1, the light output component 5, and the optical isolator 8 are kept coaxial.

[0078] Step S1060: The TO laser two 2 is aligned with the optical output component 5 for coupling. The TO laser two 2 is coupled with the XYZ axes. After the coupling is completed, the TO laser two 2 is welded and fixed to the laser housing 4.

[0079] Step S1070: The TO laser three 6 is aligned with the optical output component 5 for coupling. The TO laser three 6 is coupled with the XYZ axes. After the coupling is completed, the TO laser three 6 is welded and fixed to the laser housing 4.

[0080] Step S1080: The TO detector one 9 is aligned with the filter three 12 for coupling the XYZ axes. After the coupling is completed, it is glued and fixed on one side perpendicular to the light output port of the laser housing 4, on the laser housing 4 beside the same side of the TO laser three 6, and is distributed at a 90-degree angle with the TO laser one 1.

[0081] Step S1090: The TO detector two 10 is aligned with the filter one 3 for coupling the XYZ axes. After the coupling is completed, it is glued and fixed on the other side beside the same side of the TO laser three 6 on the laser housing 4, is distributed at a 90-degree angle with the TO laser one 1, and is distributed in an opposite direction to the TO laser two 2.

[0082] Step S1100: The TO detector three 11 is aligned with the filter two 7 for coupling the XYZ axes. After the coupling is completed, it is glued and fixed on the other side beside the same side of the TO laser two 2 on the laser housing 4, is distributed at a 90-degree angle with the TO laser one 1, and is distributed in an opposite direction to the TO laser three 6.

[0083] Although the above Embodiments 1 to 3 exemplarily illustrate the real-time on-line detection of two different gas components or three different gas components by coaxially combining two TO lasers and coaxially combining three TO lasers, those skilled in the art know that based on the basic technical concept of the present invention, by using the adopted method, combinations of four, five, six, seven, eight, nine, ten or even more TO detectors can also be realized to achieve the real-time on-line detection of four, five, six, seven, eight, nine, ten or even more different gas components. That is, the present invention can combine N TO lasers to achieve the real-time on-line detection of M different gas components, where N is a natural number greater than 2 and M is less than or equal to N.

[0084] The reader should understand that in the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection 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 can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0085] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0086] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A coaxial multi-wavelength self-stabilizing laser for real-time detection of multi-component gases, comprising a laser tube housing and a light output component, characterized in that: The laser housing includes three TO lasers, three TO detectors, and a coaxial light combining and splitting optical path assembly; The laser emitted by each TO laser has at least one typical wavelength, and the typical wavelengths of each TO laser are different from each other. Each one or several typical wavelengths correspond to the typical absorption line or absorption spectrum peak of a certain gas; The coaxial light combining and splitting optical path assembly includes three filters. While part of the laser emitted by the three TO lasers is input into the corresponding TO detector after reflection and / or transmission, the remaining parts of the laser emitted by the three TO lasers are input from three directions, combined and bundled, and then output to the light output assembly; Each TO detector has a reference gas chamber and correspondingly detects the change in the output light of a TO laser; the typical absorption line or absorption spectrum peak of the reference gas filled in the corresponding reference gas chamber corresponds to the typical wavelength of the corresponding TO laser; The light spots of the three TO lasers are incident on the focus of the light output assembly after being reflected and / or transmitted by the filters of the coaxial light combining and splitting optical path assembly; The light output assembly collimates the combined and bundled light beam and emits it from the coaxial multi-wavelength self-stabilizing laser. The combined and bundled light beam is a composite light beam for measuring different gas components; Among them, the three TO lasers are the first TO laser, the second TO laser, and the third TO laser. The first TO laser is coupled and fixed on one side of the laser housing opposite to the light output port of the laser housing. The second TO laser is coupled and fixed on one side perpendicular to the light output port of the laser housing; the third TO laser is coupled and fixed on one side perpendicular to the light output port of the laser housing and is located on the opposite side of the second TO laser; The three TO detectors are the first TO detector, the second TO detector, and the third TO detector. The first TO detector is coupled and fixed beside the same side of the third TO laser and is distributed at a 90-degree angle to the first TO laser; the second TO detector is coupled and fixed beside the other side of the same side of the third TO laser, is distributed at a 90-degree angle to the first TO laser, and is distributed in a facing direction to the second TO laser; the third TO detector is coupled and fixed on the same side of the second TO laser, is distributed at a 90-degree angle to the first TO laser, and is distributed in a facing direction to the third TO laser; The three filters are the first filter, the second filter, and the third filter. The first filter is fixed at the intersection of the main optical axes of the first and second TO lasers and is at a 45-degree angle relative to both the first and second TO lasers; the second filter is fixed at the intersection of the main optical axes of the third TO laser and the first TO laser and is at a 45-degree angle relative to both the first and third TO lasers; the first filter and the second filter are distributed in a V shape; the third filter is coaxial with the main optical axis of the first TO laser and the light output assembly and is at a 45-degree angle relative to the first TO laser and is distributed in a V shape with the second filter; The multi-component gas real-time detection coaxial multi-wavelength self-stabilizing laser further includes an output optical isolator; the output optical isolator is fixed inside the laser housing, located between the third filter and the optical output component, and is coaxial with the main optical axis of the first TO laser.

2. The coaxial multi-wavelength self-stabilizing laser for real-time detection of multi-component gases according to claim 1, wherein: Each of the three filters is made by coating both sides, one side is a semi-transmissive and semi-reflective film with a specific wavelength, that is, it partially reflects and partially transmits light within the first specific wavelength range, and fully transmits light with other wavelengths outside the first specific wavelength range; the other side is a total reflection film with a specific wavelength, that is, it totally reflects light within the second specific wavelength range, and fully transmits light with other wavelengths outside the second specific wavelength range.

3. A coaxial multi-wavelength self-stabilizing laser for real-time detection of multi-component gases according to claim 1, characterized in that: Any one of the three filters is made by coating one side, and the single-sided coating is a semi-transmissive and semi-reflective film with a specific wavelength, that is, it partially reflects and partially transmits light within a specific wavelength range, and fully transmits light with other wavelengths outside the specific wavelength range.

4. The coaxial multi-wavelength self-stabilized laser for real-time detection of multi-component gases according to claim 1, wherein: The TO laser is a laser device with a semiconductor refrigeration module in coaxial packaging.

5. A coaxial multi-wavelength self-stabilizing laser for real-time detection of multi-component gases according to claim 1, characterized in that: Among the three TO detectors, the main optical axis of one TO laser is coaxial with the main optical axis of the optical output component, and the main optical axes of the remaining TO lasers are perpendicular to the main optical axis of the optical output component; the coaxial light combining optical path component is located on the main optical axis of the optical output component; the optical output component is a collimating lens or an optical fiber connector or an optical fiber fixed at the light output port position of the laser housing.

6. The coaxial multi-wavelength self-stabilizing laser for real-time detection of multi-component gases according to claim 1, wherein: The first, second, and third TO detectors respectively detect the central wavelength changes of the light beams emitted by the first, second, and third TO lasers, and respectively control the temperatures of the first, second, and third TO lasers to keep the central wavelengths of their emitted light beams stable.

7. A coaxial multi-wavelength self-stabilizing laser for real-time detection of multi-component gases according to claim 6, characterized in that: 1 - 99% of the light emitted by each TO laser is received by the corresponding TO detector.

8. A coaxial multi-wavelength self-stabilizing laser for real-time detection of multi-component gases according to claim 7, characterized in that 50% of the light emitted by each TO laser is received by the corresponding TO detector.

9. A method for fabricating a multi-component gas real-time detection coaxial multi-wavelength self-stabilized laser as described in any one of claims 1-8, characterized in that Including: Step S1010: Fix the output optical isolator at the light port of the laser housing. Step S1020: Fix the first filter at the intersection of the main optical axes of the first TO laser and the second TO laser, and the first filter is at a 45-degree angle relative to both the first and second TO lasers. Step S1030: Fix the second filter at the intersection of the main optical axes of the third TO laser and the first TO laser, the second filter is at a 45-degree angle relative to both the first and third TO lasers, and the first filter and the second filter are in a V-shaped distribution. Step S1040: Fix and set the third filter at the position where the main optical axis of the first TO laser is coaxial with the optical output component 5, the third filter is at a 45-degree angle relative to the first TO laser, and is in a V-shaped distribution with the second filter. Step S1050: Align the first TO laser with the optical output component for coupling. The first TO laser couples the Z axis, and the optical output component couples the XY axis. After the coupling is completed, the first TO laser is welded and fixed to the laser housing, and the optical output component is welded and fixed to the laser housing; the first TO laser, the optical output component, and the output optical isolator remain coaxial. Step S1060: Align the second TO laser with the optical output assembly for coupling, couple the XYZ axes of the second TO laser. After coupling is completed, weld and fix the second TO laser to the laser housing; Step S1070: Align the third TO laser with the optical output assembly for coupling, couple the XYZ axes of the third TO laser. After coupling is completed, weld and fix the third TO laser to the laser housing; Step S1080: Align the first TO detector with the third filter and couple the XYZ axes. After coupling is completed, fix it on one side perpendicular to the light output port of the laser housing, on the same side of the laser housing as the third TO laser, and distributed at a 90-degree angle to the first TO laser; Step S1090: Align the second TO detector with the first filter and couple the XYZ axes. After coupling is completed, fix it on the other side of the laser housing on the same side as the third TO laser, distributed at a 90-degree angle to the first TO laser, and distributed in an opposite direction to the second TO laser; Step S1100: Align the third TO detector with the second filter and couple the XYZ axes. After coupling is completed, fix it on the other side of the laser housing on the same side as the second TO laser, distributed at a 90-degree angle to the first TO laser, and distributed in an opposite direction to the third TO laser.

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