Multi-spectrum single-gas-chamber multi-gas custom detection method and multi-spectrum single-gas-chamber multi-gas custom detection system

Abstract

The invention relates to the technical field of spectrum detection, in particular to a multi-spectrum single-gas-chamber multi-gas self-defined detection method and system.The surface of a cavity mirror of an integral cavity is subjected to regional film coating according to detection requirements, multiple annular reflection regions and a circular reflection region are formed through film coating, the central wavelengths reflected by different reflection regions are different, and the central wavelengths are different; corresponding to absorption peaks of different gases, in order to overcome the limitation of a detector on a detection wave band and optimize a detection light path, a central light beam turning structure is arranged on a light path of an emergent end of the integral cavity and is used for changing the propagation direction of transmission light of a circular reflecting region, so that the transmission light enters a second detection device; the transmission light of the annular reflection area is incident to the first detection device, the problem that the detection spectrum of a traditional detection system is limited by the response range of a single detector is solved, and the detection system can detect and cover a wide range from short waves to long waves by customizing the working spectrum of the two detection devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of spectrum detection, and in particular relates to a multi-spectral single-gas chamber multi-gas custom detection system. Background Art

[0002] The off-axis integral cavity output spectrum technology is to construct a resonant cavity structure, and allow the laser beam to destroy the transverse mode resonance in an off-axis manner, and perform multiple reflections between two cavity mirrors to achieve an optical air chamber structure that increases the optical path. This air chamber structure can achieve an extremely long effective absorption optical path within a limited cavity mirror space, and the weak energy signal transmitted each time the laser beam reaches the cavity mirror rear mirror is the final detection signal.

[0003] The advantage of the traditional off-axis integrating cavity structure is that the off-axis design has strong resistance to external interference and a long effective absorption optical path, which can improve the detection accuracy. Its optical structure is simple and clear, consisting of two cavity mirrors on the front and back. And a high-reflection dielectric film is usually coated on the surface of the cavity mirror to increase the effective absorption optical path.

[0004] However, due to the limitations of existing dielectric film coating technology, the high-reflection area of ​​the coating layer is relatively narrow. When the reflectivity is as high as 99.99% or above, the wavelength width effectively covered by the dielectric film is generally within tens of nanometers. The wavelength distribution of the gas absorption peak is determined by the valence bond structure of molecules and atoms. Usually, the main absorption peak position distribution is relatively dispersed, which also leads to the fact that an optically designed integral cavity can only meet the detection of one quantitative gas type. Even if some existing instruments can meet the detection of multiple gases, they also use the frequency-broadband absorption peak of the gas. Therefore, the range and detection accuracy of multiple gases cannot be customized.

[0005] At present, there are two main methods for realizing multi-gas detection. The first method is to simply add multiple integrating cavities. This method can realize customized detection accuracy and measurement range of multiple gases, but the relative cost will increase significantly. The second method is to select appropriate characteristic spectrum bands to realize the measurement of multiple gases within the same measurement band. This method requires that the appropriate gas components happen to exist within the same wavelength coverage range, and the absorption intensity is also appropriate. This method is difficult to implement and requires that the response wavelength of the detector must cover the selected gas absorption peak wavelength range. However, when the gas components to be detected have different absorption peak wavelengths, especially when these wavelengths cover a wide range from short waves to long waves, the detector cannot meet the detection needs of all gases. For example, the detection gas contains both gases with longer absorption peak wavelengths such as carbon dioxide and gases with shorter absorption peak wavelengths such as ammonia. At this time, the response wavelength of the detector is difficult to cover the absorption peak wavelength range of these two gases, resulting in the inability to detect these two gases through the same integrating cavity. Therefore, this method has great limitations and is not universal.

[0006] In summary, a consensus has been reached at the current stage of research, and there is an urgent need to design a detection system that can realize multi-gas detection and meet the customized detection range accuracy. Summary of the invention

[0007] In view of this, the present invention aims to provide a multi-spectral band single-chamber multi-gas customized detection system. Through the design of a zoned coating process, an off-axis integrating cavity that can realize simultaneous detection of multiple spectral bands is obtained, so that a single cavity can realize customized optical path and range detection of multiple gases, solving the problem in the prior art that a single integrating cavity can only detect gases in a specific band. In addition, the present invention designs a central light beam deflection structure to change the propagation path of part of the light beam without destroying the outer ring detection structure, so that light beams with large differences in wavelength ranges are incident on different detectors. By adapting different detectors to light of different wavelengths, the detection system can be suitable for detecting mixed gases with large differences in absorption peak wavelengths.

[0008] To achieve the above object, the technical solution created by the present invention is implemented as follows: The present invention provides a multi-spectral single-gas chamber multi-gas custom detection method, comprising the following steps: According to the absorption peaks of different gas components in the sample gas to be tested, all gas components are divided into a first gas component set and a second gas component set, and a first detection device whose response range covers the absorption peaks of gas components in the first gas component set is selected, and a second detection device whose response range covers the absorption peaks of gas components in the second gas component set is selected; A plurality of annular reflection films having absorption peaks equal to different gas components in the first gas component set are respectively plated on the cavity mirror of the integrating cavity to form a plurality of annular reflection areas; coherent light having a wavelength equal to the central wavelength of each annular reflection area is respectively incident on the corresponding annular reflection area, and the gas components in the first gas component set are detected without aliasing disturbance by using the first detection device; A circular reflection film covering the absorption peaks of gas components in the second gas component set is plated inside the annular reflection area with the smallest inner diameter to form a circular reflection area; a light beam covering the absorption peaks of all gas components in the second gas component set is incident on the circular reflection area, and a central light beam deflection structure is provided to adjust the optical propagation direction of the light beam transmitted from the circular reflection area, so that the light beam transmitted from the circular reflection area is directed toward the second detection device, and the gas components in the second gas component set are detected by the second detection device.

[0009] Preferably, the first detection device is a single-point detector, a linear array detector, a planar array detector or a spectrometer.

[0010] Preferably, the light beam covering the absorption peaks of all gas components in the second gas component set is coherent light.

[0011] Preferably, when the light beam covering the absorption peaks of all gas components in the second gas component set is incoherent light, the second detection device is a spectrometer, and the spectrometer is used to perform channel-by-channel detection on different gas components in the second gas component set.

[0012] The invention provides a multi-spectral single-gas chamber multi-gas custom detection system, comprising: a light source, a gas absorption cell, a first detection device and a second detection device; The gas absorption cell comprises: an integrating cavity and a central beam deflection structure; a front cavity mirror and a rear cavity mirror are arranged in the integrating cavity, a plurality of annular reflection areas are arranged on the opposite surfaces of the front cavity mirror and the rear cavity mirror, a circular reflection area is arranged inside the annular reflection area with the smallest inner diameter, and different reflection areas reflect different central wavelengths, corresponding to the absorption peaks of different gas components; The light source is used to provide light beams of different wavelengths, and the light beams of different wavelengths are correspondingly irradiated on different reflection areas; The central beam deflection structure is located on the optical path of the output end of the integrating cavity. The light transmitted from the annular reflection area is incident on the first detection device. The central beam deflection structure changes the propagation direction of the light transmitted from the circular reflection area to make it incident on the second detection device.

[0013] Preferably, the front cavity mirror and the rear cavity mirror are both plano-concave lenses, and a plurality of annular reflective films are plated on the concave surfaces of the front cavity mirror and the rear cavity mirror to form a plurality of annular reflective areas, and different annular reflective films reflect different central wavelengths.

[0014] Preferably, a circular reflective film is plated on the circular area within the annular reflective film with the smallest inner diameter on the front cavity mirror and the rear cavity mirror to form a circular reflective area, and the central wavelength reflected by the circular reflective film is different from that of all the annular reflective films.

[0015] Preferably, the light beams provided by the light source to illuminate the annular reflection area and the circular reflection area are both coherent lights.

[0016] Preferably, the light beam provided by the light source and irradiated onto the circular reflective area includes incoherent light of multiple wavelength bands.

[0017] Preferably, a plurality of collimators are further provided at the front end of the air chamber, and light beams of different wavelengths emitted by the light source are incident on different collimators, and the transmission angle of the light beam is changed by adjusting the angle of the collimator.

[0018] Preferably, the transmitted light of different annular reflection areas is detected by time-division multiplexing technology.

[0019] Preferably, it also includes: a pressure closed-loop measurement and control device for monitoring the air pressure in the inner chamber, a mass flow controller and a tunable air pump for controlling the flow rate of the sample gas to be measured, and a processor for processing the data collected by the detector.

[0020] Compared with the prior art, the invention can achieve the following beneficial effects: The present invention adopts a regional coating method to create multiple reflection zones on a single cavity mirror, each reflection zone corresponds to a different gas absorption peak, so that it can realize the detection of multiple gases in the same integral cavity structure, thereby improving the detection range and flexibility of the system.

[0021] The present invention designs a central beam deflection structure so that the circular reflection area can be compatible with coherent light and incoherent light, overcoming the drawback of the traditional detection system that relies on coherent light. More importantly, the present invention can customize multiple gas detections through a single cavity, and the detection light corresponding to the circular reflection area and the annular reflection area is incident into different detection devices through the central beam deflection structure, overcoming the problem that the detection spectrum of the traditional detection system is limited by the response range of a single detector. By customizing the working spectrum of the two detection devices, the detection system of the present invention can detect a wide range from short waves to long waves. When there are different gases with extremely different absorption peak bands in the mixed gas, the detection system of the present invention is still applicable, while the detection spectrum of the traditional detection system is not only limited by the reflection spectrum range of the integral cavity coating, but also by the response wavelength of the detector. Therefore, it is impossible to detect different gases with extremely different absorption peak bands. The detection system of the present invention has the advantages of wide detection spectrum, simple optical path structure, and high flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 is a structural block diagram of a multi-spectral single-gas chamber multi-gas custom detection system provided according to an embodiment of the present invention; Figure 2 is a diagram showing the coating distribution of a cavity mirror provided in an embodiment of the present invention; Figure 3 is a schematic diagram of the spot of a light beam on a cavity mirror provided in an embodiment of the present invention; Figure 4 is an overall structural diagram of a gas absorption cell provided according to an embodiment of the present invention; Figure 5 is a structural exploded diagram of the light-incoming end of a gas absorption cell provided in accordance with an embodiment of the present invention; Figure 6 It is a structural explosion diagram of the light-emitting end of the gas absorption cell provided according to an embodiment of the present invention.

[0023] Reference numerals include: DFB laser group 11, laser driver 12, laser temperature controller 13, one-way isolator 14; Gas absorption cell 2, front cavity mirror 21, front cavity mirror mounting seat 211, front cavity mirror pressing ring 212; Rear cavity mirror 22; Central reflector 23, central reflector mounting seat 231; Focusing mirror 24, focusing mirror mounting seat 241; Air chamber 25, first air pipe connector 251, second air pipe connector 252, mounting pad 253, support frame 254, bottom plate 255; A first collimator 26, a first collimator mounting seat 261, and a first collimator gasket 262; A second collimator 27, a second collimator mounting seat 271, and a second collimator gasket 272; A third collimator 28 and a third collimator mounting seat 281; Sunshade 29; A first annular reflection area A, a second annular reflection area B, and a circular reflection area C; Pressure closed-loop measurement and control device 31, mass flow controller 32, tunable air pump 33; A first detection device 4; The second detection device 5; FPGA6, a first data acquisition module 61, a second data acquisition module 62, and a communication interface 63. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the invention clearer, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the invention and do not constitute a limitation to the invention. Similar components in different embodiments use associated similar component numbers. In the following embodiments, many detailed descriptions are to enable the invention to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other components, materials, and methods. In some cases, some operations related to the invention are not shown or described in the specification, in order to avoid the core part of the invention being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0025] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to form various implementation methods. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a necessary sequence, unless otherwise specified that a certain sequence must be followed.

[0026] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0027] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0028] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0029] See also Figure 1In one embodiment of the present invention, a multi-spectral single-chamber multi-gas custom detection system is provided. By optimizing the off-axis integrating cavity and the detection optical path, a single cavity can realize custom detection of multiple gases according to the detection requirements. Under the premise of ensuring the advantage of the long optical path of the integrating cavity, the function of self-selected detection accuracy and detection range of multiple gas components is realized, and it can be applied to the detection of two components with large absorption peak band differences in the gas. Specifically, the detection system includes: a light source, a gas absorption cell 2, a gas flow controller, a detection device and a processor, wherein the gas absorption cell 2 is the detection area of ​​the sample gas to be tested, which mainly includes: an integrating cavity and a central beam deflection structure, and a front cavity mirror 21 and a rear cavity mirror 22 are arranged in the integrating cavity, and the front cavity mirror 21 and the rear cavity mirror 22 are both plano-concave lenses and the concave surfaces are both facing the inside of the integrating chamber. It can be understood that the concave surfaces of the front cavity mirror 21 and the rear cavity mirror 22 are a set of opposite surfaces. In order to form a stable cavity structure, the concave surfaces of the front cavity mirror 21 and the rear cavity mirror 22 are coated with a high-reflection film, and the coating distribution forms of the two are the same.

[0030] See also Figure 2 The concave surfaces of the front cavity mirror 21 and the rear cavity mirror 22 are both designed with regional coating, which divides the concave surface into several annular areas, and each annular area is coated with a high-reflection film with high reflectivity for light of different wavelengths. The reflection films on different annular areas reflect different central wavelengths, corresponding to the absorption peaks of different gases, and multiple annular reflection areas are formed after coating. Correspondingly, inside the annular reflection area with the smallest inner diameter is a circular area, which is also coated with high-reflection films of different wavelengths to form a circular reflection area. The circular reflection area and the annular reflection area are collectively referred to as the reflection area. The specific number of coating times and the division of the reflection area depend on the number of components of the sample gas to be tested. It can be understood that the sample gas to be tested is a mixture of multiple different gases, and different gases correspond to different absorption peaks. Accordingly, it is necessary to select different bands of detection light corresponding to the absorption peaks of different gases. In order to increase the action path between the detection light and the sample gas to be measured, it is necessary to plate high-reflection films corresponding to different wavelength bands of light on the concave surfaces of the front cavity mirror 21 and the rear cavity mirror 22. The detection light beams of different wavelength bands are reflected multiple times between the corresponding reflection areas on the front cavity mirror 21 and the rear cavity mirror 22, such as Figure 3 That is, the spot of the detection light on the concave surface during multiple reflections. Since a small part of the light beam will be transmitted out of the integrating cavity for each reflection, when the energy of the detection light beam decays to a certain extent, the condition of continuing to reflect in the integrating cavity will no longer be met. At this time, the detection light beam will be transmitted out of the integrating cavity, thereby realizing the detection of the transmitted light. This design increases the action optical path of the detection light and the sample gas to be measured, and improves the detection accuracy.

[0031] In the embodiment of the present invention, only two annular reflection areas are taken as an example, and a first annular reflection area A, a second annular reflection area B and a circular reflection area C are formed on the front cavity mirror 21 and the rear cavity mirror 22 by coating. The outer diameter of the first annular reflection area A is Indicates that the outer diameter of the second annular reflection area B is Indicates that the diameter of the circular reflection area C is expressed as The first annular reflection area A is to The second annular reflection area B is to The circular reflection area C is After coating, the first annular reflection area A has a central wavelength of high reflectivity. The second annular reflection area B has a central wavelength of high reflectivity. The central wavelength of the circular reflection area C with high reflectivity is .

[0032] When the sample gas to be tested is detected, the flow rate and other parameters of the sample gas to be tested need to be controlled, so the gas absorption cell 2 needs to provide a closed space for the sample gas to be tested and provide debugging, installation and support structures for the optical lens group. Figure 4 The gas absorption cell 2 is provided with a sealed gas chamber 25, the bottom of which is fixedly mounted on a bottom plate 255 through a mounting pad 253 and a support frame 254, so as to achieve stable support of the gas chamber 25. In addition, a first gas pipe connector 251 and a second gas pipe connector 252 are respectively provided at both ends of the gas chamber 25, and the first gas pipe connector 251 and the second gas pipe connector 252 are respectively used to connect the input pipeline and the output pipeline of the sample gas to be tested. Correspondingly, in order to accurately control the flow rate of the sample gas to be tested, the air chamber 25 is also provided with a pressure closed-loop measurement and control device 31, a mass flow controller 32, and an adjustable air pump 33 which are electrically connected to the controller. The output end of the mass flow controller 32 is connected to the input pipeline of the sample gas to be tested. The sample gas to be tested enters from the input end of the mass flow controller 32, passes through the mass flow controller 32, and enters the air chamber 25 from the first air pipe connector 251. The pressure closed-loop measurement and control device 31 and the adjustable air pump 33 are connected to the input pipeline of the sample gas to be tested of the air chamber 25 in sequence. The pressure closed-loop measurement and control device 31 is used to measure the air pressure in the air chamber 25, and then control the output flow rate of the sample gas to be tested through the adjustable air pump 33. Among them, the pressure closed-loop measurement and control device 31 and the adjustable air pump 33 are both controlled by a controller. In an embodiment of the present invention, in order to realize multi-line parallel control, the controller adopts FPGA6. FPGA6 can control the pressure closed-loop measurement and control device 31 to measure the air pressure in the air chamber 25 in real time, and control the adjustable air pump 33 to adjust the output flow rate of the sample gas to be tested, maintain the air pressure in the air chamber 25 stable, and ensure the stability of the detection conditions.

[0033] See also Figure 5 The front cavity mirror 21 is arranged at the front end of the air chamber 25, and is fixed to the front cavity mirror mounting seat 211 through the front cavity mirror pressing ring 212. The front cavity mirror mounting seat 211 is installed at the front end opening of the air chamber 25. The rear cavity mirror 22 is arranged at the rear end of the air chamber 25, and its installation method is the same as that of the front cavity mirror 21. In addition, a plurality of collimation components are provided at the front end of the air chamber 25. Specifically, there are three collimation components corresponding to the detection light beams incident on the first annular reflection area A, the second annular reflection area B and the circular reflection area C, namely, a first collimator 26, a second collimator 27 and a third collimator 28. The first collimator 26 is used to collimate the detection light beam irradiated on the first annular reflection area A. The first collimator 26 is installed on the first collimator mounting seat 261 through the first collimator gasket 262. The first collimator mounting seat 261 is installed at the front end of the air chamber 25, and the incident angle of the detection light beam after passing through the first collimator 26 can be adjusted by adjusting the first collimator gasket 262. The angle adjustment makes the detection light beam incident on the first annular reflection area A in an off-axis form. After the incident angle is fine-tuned, the light spot distribution of the detection light beam on the first annular reflection area A is spherical or ellipsoidal, and is only distributed within the outermost annular range, and does not interfere with other internal mirror ranges. Similarly, the second collimator 27 is used to collimate the detection beam irradiated to the second annular reflection area B. The second collimator 27 is mounted on the second collimator mounting seat 271 through the second collimator gasket 272. The second collimator mounting seat 271 is also mounted at the front end of the gas chamber 25, and the incident angle of the detection beam after passing through the second collimator 27 can be adjusted by adjusting the second collimator gasket 272. The angle adjustment allows the detection beam to be incident on the second annular reflection area B in an off-axis form. After the incident angle is fine-tuned, the light spot distribution presented by the detection beam on the second annular reflection area B is spherical or ellipsoidal. The third collimator 28 is used to collimate the detection beam irradiated to the circular reflection area C. Since the circular reflection area C is at the center of the cavity mirror, the third collimator 28 can be directly mounted at the front end of the gas chamber 25 through the third collimator mounting seat 281.

[0034] Correspondingly, the first collimator 26, the second collimator 27 and the third collimator 28 correspond to detection beams of different wavelengths respectively. See also Figure 6, the rear cavity mirror 22 is arranged at the rear end of the air chamber 25, and the rear cavity mirror 22 is installed at the rear end of the air chamber 25 through the rear cavity mirror pressure ring, the central reflector 23 is connected to the rear end of the air chamber 25 through the central reflector mounting seat 231, and the focusing mirror 24 is connected to the rear end of the central reflector mounting seat 231 through the focusing mirror mounting seat 241. The rear end of the focusing mirror 24 is also provided with a light shielding cover 29 for shielding the interference of ambient light. The rear end of the air chamber 25 is the detection end. After multiple reflections in the integrating cavity, the detection beam is transmitted by the rear cavity mirror 22 and emitted to the detection device. It can be understood that the detection beam is provided by the light source. In the embodiment of the present invention, the light source adopts the DFB laser group 11. The DFB laser group 11 can provide a detection beam of corresponding wavelength according to the absorption peaks of different gas components in the sample gas to be measured. In order to prevent the detection light beams of different wavelengths provided by the DFB laser group 11 from generating reflected echoes that affect the light source signal, a one-way isolator 14 is also provided at the output end of the DFB laser group 11. The one-way isolator 14 is located on the optical path between the DFB laser group 11 and the collimator. In the embodiment of the present invention, the cavity mirror is divided into a first annular reflection area A, a second annular reflection area B and a circular reflection area C, so the one-way isolator 14 is provided on the optical path of the detection light beam directed to the above three reflection areas.

[0035] Furthermore, the DFB laser group 11 is controlled and modulated by FPGA6. A laser driver 12 and a laser temperature controller 13 controlled by FPGA6 are arranged at the front end of the DFB laser group 11. FPGA6 controls the laser driver 12 and the laser temperature controller 13 by outputting a WMS modulation signal to control the output of lasers with different wavelengths in the DFB laser group 11 and to perform temperature control on the lasers, thereby enabling lasers with different wavelengths in the DFB laser group 11 to respectively scan the absorption peaks of different gas components in the center of the sample gas to be tested.

[0036] See also Figure 6 , the detection beam provided by the DFB laser group 11 is transmitted by the rear cavity mirror 22 arranged at the rear end of the gas chamber 25 after multiple reflections in the integrating cavity, and continues to be emitted to the detection device. A focusing mirror 24 is arranged at the rear end of the gas chamber 25. The focusing mirror 24 is installed at the rear end of the gas chamber 25 through a focusing mirror mounting seat 241. The focusing mirror 24 is used to converge the detection beam to facilitate its imaging on the detection device at the rear end. Specifically, during the reflection process of the detection beam in the integrating cavity, the detection beams of different wavelengths need to be irradiated to the corresponding reflection areas on the cavity mirror. This process is achieved by adjusting the angles of the first collimator 26 and the second collimator 27. Taking the detection beam irradiated to the first annular reflection area A as an example, the first annular reflection area A is used to detect a gas component in the sample gas to be tested, such as methane gas, whose absorption peak wavelength is 1651nm. Correspondingly, the DFB laser group 11 provides a corresponding detection beam, which is only distributed in the outermost first annular reflection area A, that is, Figure 2 In to Similarly, the second annular reflection area B is used to detect another gas component in the sample gas to be tested, such as carbon dioxide, whose absorption peak wavelength is 2004nm. The DFB laser group 11 provides a corresponding detection beam, which is only distributed in the second annular reflection area B, that is, Figure 2 In to Similarly, according to actual detection requirements, the number and range of the annular coating areas on the front cavity mirror 21 and the rear cavity mirror 22 can be adjusted, and the DFB laser group 11 can be adjusted accordingly.

[0037] The detection light beams transmitted from the first annular reflection area A and the second annular reflection area B are directly irradiated on the first detection device 4 through the focusing lens 24. The first detection device 4 can be a single-point detector, a linear array detector, a planar array detector or a spectrometer. To avoid interference from ambient light, a light shield 29 is also provided at the rear end of the gas chamber 25. The first detection device 4 is used to receive the detection light beams corresponding to the annular reflection areas. The first detection device 4 transmits the response information to the FPGA 6, obtains the detection information of the gas through the FPGA 6, and transmits the detection information to the outside through the communication interface 63.

[0038] In order to realize the detection of different gas components, the response range of the first detection device 4 needs to be able to cover the absorption peaks of different gas components detected by the annular reflection area. In other words, the response range of the first detection device 4 needs to cover the central wavelength of the high-reflection film on the annular reflection area (the first annular reflection area A and the second annular reflection area B). However, no matter which detector is selected for the first detection device 4, its response range is limited, so the response range of the first detection device 4 will limit the high-reflection film plated on the annular reflection area, that is, the response range of the first detection device 4 will limit the wavelength of the gas that can be detected by the annular reflection area. For example, the first annular reflection area A and the second annular reflection area B detect methane gas and carbon dioxide respectively, then the response range of the first detection device 4 needs to cover 1651nm-2004nm, at this time, the first detection device 4 can use an indium gallium arsenic detector, and the response wavelength range of the indium gallium arsenic detector is 760nm-2400nm, so the freedom of model selection of the first detection device 4 is limited. In order to clarify whether the response information obtained on the first detection device 4 is specifically methane gas or carbon dioxide, the detection light beam transmitted through the annular reflection area needs to be detected using time-division multiplexing technology, that is, the DFB laser group 11 is controlled to provide detection light beams of different bands under different clock signals. Then, the response information obtained on the first detection device 4 can be determined whether it is methane gas or carbon dioxide based on the clock signal.

[0039] It has been explained above that the gas components that the annular reflection area can match and detect will be limited by the response range of the first detection device 4. Therefore, when the gas components that need to be detected by the detection system have absorption peaks corresponding to long infrared waves, ultraviolet bands (range 150-400nm), or even X-rays, no detector response range can simultaneously cover such ultra-long spectrum bands. Therefore, at this time, even if the wavelength of the detection beam output by the DFB laser group 11 and the coating on the cavity mirror can be adjusted, the first detection device 4 cannot respond to these bands, so it is impossible to achieve effective detection of this part of the band. For example, when there are gases such as ammonia, hydrogen sulfide, nitrogen oxides and sulfides in the sample gas to be tested, it is impossible to achieve simultaneous detection of the six gases of methane, carbon dioxide, ammonia, hydrogen sulfide, nitrogen oxides and sulfides only by the first detection device 4. For example, to overcome the above structure's reliance on the detection beam being coherent light, and the detection band being limited by the corresponding range of the first detection device 4, in an embodiment of the present invention, a central beam deflection structure is additionally provided at the rear end of the air chamber 25. The central beam deflection structure is designed to change the transmission path of the detection beam transmitted by the circular reflection area C. In an embodiment of the present invention, the main functional component of the central beam deflection structure is the central reflector 23, and its specific surface shape can be a concave mirror, a plane mirror, an off-axis parabolic mirror, and can be a full reflector or a half reflector. The central reflector 23 is installed on the optical path between the rear cavity mirror 22 and the first detection device 4 through the central reflector mounting seat 231, and can be arranged before or after the focusing mirror 24. The central reflector 23 reflects the detection light beam transmitted by the circular reflection area C to the second detection device 5. The second detection device 5 can be a single-point detector, a linear array detector, a planar array detector or a spectrometer as needed. In order to improve the detection band of the second detection device 5, the second detection device 5 is usually preferably a spectrometer. The spectrometer can realize the detection of multiple bands of light through multi-channel spectral analysis.

[0040] When there are gases such as ammonia, hydrogen sulfide, nitrogen oxides and sulfides in the sample gas to be tested, the response range of the first detection device 4 can cover methane gas and carbon dioxide, so the corresponding high-reflection film with the central wavelength corresponding to the absorption peak of methane gas and carbon dioxide is coated on the first annular reflection area A and the second annular reflection area B, and the methane gas and carbon dioxide components in the sample gas to be tested can be detected by the first detection device 4 through time-sharing multiplexing technology. When the sample gas to be tested contains other gas components, different bands can be used to select the most appropriate gas absorption peaks for detection of different gases, so as to realize multi-spectrum multi-gas component simultaneous detection with multiple gas components, self-selected range, self-selected accuracy and self-selected absorption optical path. As for the gas components that cannot be covered by the corresponding range of the first detection device 4, such as ammonia, hydrogen sulfide, nitrogen oxides and sulfides, they can be detected through the circular reflection area C, and the DFB laser group 11 provides detection light beams corresponding to the above-mentioned gases. At this time, since the rear end reflects this part of the light beam to the second detection device 5 through the central reflector 23 instead of shooting to the first detection device 4 along the original optical path, the detection light beam irradiated on the circular reflection area C can be either coherent light or incoherent light, and the detection range of the detection system is also expanded from the original response range of the second detection device 5 to the response range of the second detection device 5 and the first detection device 4, which greatly improves the spectrum that the detection system can detect. The multi-spectral band single-chamber multi-gas customized detection system shown in the embodiment of the present invention can simultaneously detect methane, carbon dioxide, ammonia, hydrogen sulfide, nitrogen oxides and sulfides through a single integrating cavity. The detection of the above six gases is only an example given in the embodiment of the present invention. According to the detection requirements, that is, the components of the sample gas to be detected, the DFB laser group 11, the coating on the front cavity mirror 21 and the rear cavity mirror 22 that meet the requirements, and the models of the second detection device 5 and the first detection device 4 can be selected. It is possible to achieve multi-spectral and multi-gas component simultaneous detection of more gas components, self-selected ranges, self-selected accuracy, and self-selected absorption optical path through an integrating cavity.

[0041] Furthermore, since the circular reflection area C is used to detect multiple gases, the light source that provides the detection beam for the circular reflection area C should be a wide-band light source. However, when the wide-band light source is used in conjunction with the first detection device 4 of the spectrometer for detection, the independence and accuracy of the detection may be lost due to the mutual overlap of the gas absorption peaks. Therefore, the embodiment of the present invention also proposes to realize the interactive calibration and correction of multiple detection gases in a single detection system by coherent light detection in conjunction with the annular reflection area. Specifically, the first annular reflection area A and the second annular reflection area B are coherent light, and each reflection area only detects one gas, so the two gases detected by the first annular reflection area A and the second annular reflection area B have extremely high detection accuracy, that is, the two gases are known gas concentrations without disturbance at this time, and the two detection results can be used to correct the gas detected by the circular reflection area C. The two gases detected by the first annular reflection area A and the second annular reflection area B are detected by the circular reflection area C, and the concentrations of the gases detected by the first annular reflection area A and the second annular reflection area B are analyzed by the second detection device 5. The methane and carbon dioxide concentrations obtained by the second detection device 5 are then compared with the methane and carbon dioxide concentrations obtained by the first detection device 4, so as to correct the concentrations of other gases detected by the second detection device 5. By using the known gas concentration as a correction factor, the error in measuring the concentration of unknown gas is reduced, thereby improving the detection accuracy and reliability of the detection system for simultaneously detecting multiple gases.

[0042] As a feasible embodiment, the circular reflection area C can also be designed without coating, or with a unified coating design as the second annular reflection area B, that is, the high-reflection film coated on the circular reflection area C and the second annular reflection area B is the same. In this case, the concave surfaces of the front cavity mirror 21 and the rear cavity mirror 22 are simplified into two reflection area designs, and two gases with different absorption peaks can be detected. At this time, the central reflector 23 and the second detection device 5 can be removed, and the central reflector 23 can be adjusted to simultaneously reflect the detection light projected by the circular reflection area C and the second annular reflection area B. When the central reflector 23 and the second detection device 5 are removed, the detection system will have two limitations. One is that the detection beam provided by the light source must be coherent light, and the other is that the response wavelength range of the first detection device 4 must simultaneously cover the absorption peak of the detection gas of the first annular reflection area A, and the absorption peak of the detection gas of the circular reflection area C and the second annular reflection area B. This design will greatly limit the requirements for the light source and the model selection of the first detection device 4. Moreover, a single detection device of this design cannot achieve a response over a very large spectral band, so it is difficult to detect multiple gases simultaneously, especially when there are gas components with greatly different absorption peak wavelengths in the sample gas to be tested.

[0043] In another embodiment of the present invention, a multi-spectral single-chamber multi-gas custom detection method is provided, which can perform high-precision detection of mixed gases with self-selected wavelength, self-selected optical path, and self-selected accuracy according to the components of the sample gas to be detected. The specific process is as follows: First, the gas components in the sample gas to be tested are grouped according to their absorption peaks, and all gas components in the sample gas to be tested are divided into a first gas component set and a second gas component set based on the corresponding bands of the absorption peaks. Under normal circumstances, the absorption peaks of the gas components in the same set are relatively close, and according to the absorption peak coverage bands of the gas components in the first gas component set and the second gas component set, a first detection device 4 whose response range can completely cover the absorption peaks of the gas components in the first gas component set is selected, and a second detection device 5 whose response range can completely cover the absorption peaks of the gas components in the second gas component set is selected. For example, if the gas components in the sample gas to be tested include six gases, namely methane, carbon dioxide, ammonia, hydrogen sulfide, nitrogen oxides and sulfides, according to the absorption peaks of each gas component, methane and carbon dioxide are divided into the first gas component set, and ammonia, hydrogen sulfide, nitrogen oxides and sulfides are divided into the second gas component set. According to the principle that the response band of the detection device needs to cover the absorption peak of its detection gas, the first detection device 4 uses an indium gallium arsenide detector. The second detection device 5 needs to perform channel detection on ammonia, hydrogen sulfide, nitrogen oxides and sulfides, so the second detection device 5 can use a spectrometer with full band coverage. Accordingly, annular reflection films corresponding to the absorption peaks of methane and carbon dioxide in the first gas component set are respectively plated on the concave surfaces of the front cavity mirror 21 and the rear cavity mirror 22 in the integrating cavity, forming the first annular reflection area A and the second annular reflection area B in the multi-spectral single-chamber multi-gas custom detection system, and the light source is controlled to provide a detection beam equal to the central wavelength of the first annular reflection area A and the second annular reflection area B, respectively. The detection beam is coherent light, and the detection beam is incident on the first detection device 4 after being emitted from the integrating cavity. The detection information is collected by the first detection device 4. In order to clarify whether the detection information of methane or carbon dioxide obtained on the first detection device 4 is the detection information, the detection beam transmitted by the first annular reflection area A and the second annular reflection area B can be time-divided and non-aliased disturbance detection can be performed by time-division multiplexing technology.

[0044] As for ammonia, hydrogen sulfide, nitrogen oxides and sulfides, a circular reflection film covering the absorption peaks of ammonia, hydrogen sulfide, nitrogen oxides and sulfides in the second gas component set is plated in the inner area of ​​the second annular reflection area B to form a circular reflection area C. It can be understood that a circular reflection film covering the absorption peaks of ammonia, hydrogen sulfide, nitrogen oxides and sulfides in the second gas component set means that the circular reflection film has a reflective effect on the detection beam used to detect ammonia, hydrogen sulfide, nitrogen oxides and sulfides. The light source is controlled to provide a detection beam covering the absorption peaks of all gas components in the second gas component set, and the detection beam is incoherent light. According to the detection requirements, the detection beam can also use coherent light.

[0045] In order to ensure that the detection light beam transmitted by the circular reflection area C can be detected by another detection end and to increase the detectable band range, a central reflector 23 is set on the propagation light path of the detection light beam transmitted by the circular reflection area C, and the light path propagation direction of the detection light beam transmitted by the circular reflection area C is adjusted so that this part of the detection light beam is directed to the second detection device 5. Since the second detection device 5 needs to detect ammonia, hydrogen sulfide, nitrogen oxides and sulfides at the same time, the second detection device 5 needs to use a spectrometer to realize the channel detection of ammonia, hydrogen sulfide, nitrogen oxides and sulfides in the second gas component set through the spectrometer. In short, the above is only a preferred embodiment of this specification and is not used to limit the protection scope of this specification. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this specification should be included in the protection scope of this specification.

[0046] The systems, devices, modules or units described in one or more of the above embodiments may be implemented by a computer chip or entity, or by a product having a certain function. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0047] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0048] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0049] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A multi-spectral single-chamber multi-gas custom detection method, characterized by: According to the absorption peaks of different gas components in the sample gas to be tested, all gas components are divided into a first gas component set and a second gas component set, and a first detection device whose response range covers the absorption peaks of gas components in the first gas component set is selected, and a second detection device whose response range covers the absorption peaks of gas components in the second gas component set is selected; A plurality of annular reflection films having absorption peaks of different gas components in the first gas component set are respectively plated on the cavity mirrors of the integrating cavity to form a plurality of annular reflection areas; Coherent light having a wavelength equal to the center wavelength of each annular reflection area is incident on the corresponding annular reflection area, and a first detection device is used to perform non-aliasing disturbance detection on the gas components in the first gas component set; A circular reflection film covering the absorption peaks of gas components in the second gas component set is plated inside the annular reflection area with the smallest inner diameter to form a circular reflection area; a light beam covering the absorption peaks of all gas components in the second gas component set is incident on the circular reflection area, and a central light beam deflection structure is provided to adjust the optical propagation direction of the light beam transmitted from the circular reflection area, so that the light beam transmitted from the circular reflection area is directed toward the second detection device, and the gas components in the second gas component set are detected by the second detection device.

2. The multi-spectral single-chamber multi-gas custom detection method according to claim 1, characterized in that: The first detection device is a single-point detector, a linear array detector, a planar array detector or a spectrometer.

3. The multi-spectral single-chamber multi-gas custom detection method according to claim 1, characterized in that: The light beam covering the absorption peaks of the gas components in the second gas component set is coherent light or incoherent light.

4. The multi-spectral single-chamber multi-gas custom detection method according to claim 1, characterized in that: When the light beam covering the absorption peaks of all gas components in the second gas component set is incoherent light, the second detection device is a spectrometer, and the spectrometer is used to perform channel-by-channel detection on different gas components in the second gas component set.

5. A multi-spectral single-chamber multi-gas custom detection system, characterized in that: include: A light source, a gas absorption cell, a first detection device and a second detection device; The gas absorption cell comprises: an integrating cavity and a central beam deflection structure; A front cavity mirror and a rear cavity mirror are arranged in the integrating cavity. A plurality of annular reflection areas are arranged on the opposite surfaces of the front cavity mirror and the rear cavity mirror. A circular reflection area is arranged inside the annular reflection area with the smallest inner diameter. The central wavelengths reflected by different reflection areas are different, corresponding to the absorption peaks of different gas components. The light source is used to provide light beams of different wavelengths, and the light beams of different wavelengths are correspondingly irradiated on different reflection areas; The central beam deflection structure is located on the optical path of the output end of the integrating cavity. The light transmitted from the annular reflection area is incident on the first detection device. The central beam deflection structure changes the propagation direction of the light transmitted from the circular reflection area to make it incident on the second detection device.

6. The multi-spectral single-chamber multi-gas custom detection system according to claim 5, characterized in that: The front cavity mirror and the rear cavity mirror are both plano-concave lenses. A plurality of annular reflection films are plated on the concave surfaces of the front cavity mirror and the rear cavity mirror to form a plurality of annular reflection areas. Different annular reflection films reflect different central wavelengths.

7. The multi-spectral single-chamber multi-gas custom detection system according to claim 6, characterized in that: A circular reflective film is plated on the circular area within the annular reflective film with the smallest inner diameter on the front cavity mirror and the rear cavity mirror to form a circular reflective area. The central wavelength reflected by the circular reflective film is different from that of all the annular reflective films.

8. The multi-spectral single-chamber multi-gas custom detection system according to claim 5, characterized in that: The light beams provided by the light source and irradiated on the annular reflection area and the circular reflection area are both coherent lights.

9. The multi-spectral single-chamber multi-gas custom detection system according to claim 5, characterized in that: The light source provides a light beam irradiated on the circular reflecting area, which includes incoherent lights of multiple wavelength bands.

10. The multi-spectral single-chamber multi-gas custom detection system according to claim 5, characterized in that: A plurality of collimators are also provided at the front end of the air chamber. Light beams of different wavelengths emitted by the light source are incident on different collimators, and the transmission angle of the light beams is changed by adjusting the angle of the collimator.

11. The multi-spectral single-chamber multi-gas custom detection system according to claim 5, characterized in that: A focusing mirror is also provided on the optical path of the output end of the integrating cavity.

12. The multi-spectral single-chamber multi-gas custom detection system according to claim 10, characterized in that: The front cavity mirror is installed at the front end of the air chamber through the front cavity mirror pressure ring and fixed through the front cavity mirror mounting seat; the collimator is connected to the front cavity mirror mounting seat through the collimator mounting seat, and a collimator gasket is provided between the collimator mounting seat and the front cavity mirror mounting seat, and the angle of the collimator can be adjusted through the collimator gasket; The rear cavity mirror is installed at the rear end of the air chamber through the rear cavity mirror pressure ring, the central beam deflection structure is connected to the rear end of the air chamber through the central reflector mounting seat, the focusing mirror is connected to the rear end of the central reflector mounting seat through the focusing mirror mounting seat, and the rear end of the focusing mirror is also provided with a light shielding cover for blocking ambient light interference.

13. The multi-spectral single-chamber multi-gas custom detection system according to claim 5, characterized in that: The transmitted light from different annular reflection areas is detected by time-division multiplexing technology.

14. The multi-spectral single-chamber multi-gas custom detection system according to claim 5, characterized in that: It also includes: a pressure closed-loop measurement and control device for monitoring the air pressure in the inner chamber, a mass flow controller and a tunable air pump for controlling the flow of the sample gas to be measured, and a processor for processing the data collected by the detector.

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