A gas sensor and alarm

Abstract

The application provides a gas sensor and alarm for improving the accuracy of the gas sensor in detecting the gas component. The gas sensor comprises a laser emitter, a photodetector and a first scattering sheet arranged between the laser emitter and the photodetector, the distance from the laser emitter to the first scattering sheet is greater than the distance from the first scattering sheet to the photodetector, and the first scattering sheet comprises a first rough surface. The laser emitted by the laser emitter transmits through the first rough surface of the first scattering sheet and enters the light inlet of the photodetector. The first rough surface of the first scattering sheet scatters the laser emitted by the laser emitter once. The gas sensor introduces more scattering in the transmission path of the laser emitted by the laser emitter, reduces the wavelength correlation of the optical path loss, and makes the pollution in the environment unable to cause obvious fluctuation of the optical path, thereby improving the accuracy of the gas sensor in detecting the gas component of the target gas.

Description

Technical Field

[0001] This application relates to the field of optics, and more particularly to a gas sensor and alarm. Background Technology

[0002] With the continuous development of technology, the exploration of extreme environments is also progressing. The gas composition in extreme environments is one of the important indicators of whether those environments are safe. Based on the characteristic that different gases have different absorption spectra, after a laser passes through a gas with a complex composition, the gas components included in the complex gas can be determined by analyzing the laser light from the transmitting and receiving ends. This is the tunable diode laser absorption spectroscopy (TDLAS) gas sensing technology.

[0003] However, in harsh environments such as manholes, the presence of dust and other impurities makes it impossible for TDLAS gas sensing technology to accurately analyze the gas composition in the environment. Utility Model Content

[0004] This application provides a gas sensor and alarm to improve the accuracy of gas sensor in detecting gas components.

[0005] In a first aspect, this application provides a gas sensor, including: a laser emitter, a photodetector, and a first scattering plate. The first scattering plate is disposed between the laser emitter and the photodetector, and the distance from the laser emitter to the first scattering plate is greater than the distance from the first scattering plate to the photodetector. The first scattering plate includes a first rough surface. Laser light emitted by the laser emitter passes through the first rough surface of the first scattering plate and enters the light inlet of the photodetector. The first rough surface of the first scattering plate is used to perform primary scattering of the laser light emitted by the laser emitter. In some scenarios where the size of the gas laser is critical, such as in handheld gas sensors, the laser emitter and photodetector should be small-sized devices. The laser emitter can be a laser diode (LD), and the photodetector can be a photodiode (PD).

[0006] In this embodiment, a first scattering plate is positioned between the laser emitter and the photodetector. This introduces more scattering into the laser transmission path emitted to the photodetector, causing the laser emitted by the laser emitter to undergo at least one scattering in the target gas. This interrupts the possible interference paths between the laser emitter and the first scattering plate, or between the first scattering plate and the photodetector, or both. Furthermore, because the first scattering plate introduces some light loss into the gas sensor, the light loss caused by contamination in harsh environments has a limited impact on the optical signal compared to the light loss introduced by the first scattering plate. In other words, contamination in harsh environments cannot cause significant fluctuations in the optical path, thus not affecting the accuracy of the gas sensor in detecting the gas composition of the target gas, thereby improving the accuracy of the gas sensor in detecting the gas composition of the target gas.

[0007] In one possible implementation of the first aspect, the angle between the normal of the first scattering sheet and the laser emitted by the laser emission sensor is a first angle, which is greater than 5° and less than 75°.

[0008] In this embodiment, by setting the angle region between the normal of the first scattering sheet and the laser emitted by the LD, the situation where the specular reflection of the first scattering sheet reflects the laser emitted by the LD back to the light inlet of the LD can be effectively avoided due to the small angle between the normal of the first scattering sheet and the laser emitted by the LD. The first angle being less than 75° can reduce the laser range that cannot enter the PD after being scattered by the first scattering sheet, effectively ensuring the power of the light received by the PD and reducing unnecessary light loss.

[0009] In one possible implementation of the first aspect, the first rough surface is the surface of the first scattering sheet facing the photodetector. For example, when a laser emitter emits a first laser to the photodetector, the first laser passes through the first rough surface of the first scattering sheet and enters the light inlet of the photodetector. The exit surface of the first laser in the first scattering sheet is referred to as the surface of the first scattering sheet facing the photodetector, i.e., the first rough surface.

[0010] In this embodiment, a first rough surface is disposed on the surface of the first scattering sheet facing the photodetector, and the distance between the first scattering sheet and the photodetector is less than the distance between the first scattering sheet and the laser emitter. This effectively shortens the distance between the scattering initiation point and the light inlet of the photodetector. Using the first rough surface for scattering within a smaller spatial range effectively reduces optical path loss between the laser emitter's light outlet and the photodetector's light inlet, thereby significantly improving the accuracy of the gas sensor in detecting gas components.

[0011] In one possible implementation of the first aspect, the first scattering sheet further includes a second rough surface located between the light outlet of the LD and the first rough surface. That is, the first scattering sheet comprises two rough surfaces, and the laser emitted from the laser emitter is scattered by the two rough surfaces of the first scattering sheet before entering the photodetector. The second rough surface can be a surface with a particle size greater than or equal to 500 mesh and less than or equal to 4000 mesh, and the first scattering sheet needs to have a certain thickness, for example, greater than 1 mm, to create a gap between the first and second rough surfaces to achieve primary scattering (in specific implementations, the first and second rough surfaces can also be two non-parallel planes), which is not limited here.

[0012] In this embodiment, by using a scatterer with two rough surfaces to scatter the laser, a stronger scattering capability can be provided to the gas sensor. Since there is still a certain distance between the two rough surfaces, better light homogenization can also be provided, which helps to better eliminate stray light and thus improve the measurement stability of the gas sensor.

[0013] In one possible implementation of the first aspect, the first scattering sheet further includes a smooth surface located between the light outlet of the LD and the first rough surface, the smooth surface being opposite to the first rough surface. The smooth surface has a particle size greater than or equal to 10,000 particles, and the first scattering sheet needs to have a certain thickness, for example, greater than 1 mm, to ensure a certain gap exists between the first rough surface and the smooth surface.

[0014] In this embodiment, by setting one surface of the first scattering sheet as a smooth surface, when the gas sensor is applied to a water immersion scenario, the rough surface of the first scattering sheet will be filled with water stains after being immersed in water in an unsealed environment, thus becoming a smooth surface. The solution provided in this application sets one surface of the first scattering sheet as a smooth surface, which can reduce the impact of environmental factors on the working state of the gas sensor and further improve the reliability of the gas sensor in detecting the composition of the target gas in scenarios such as manholes where water immersion may occur.

[0015] In one possible implementation of the first aspect, the gas sensor further includes a window, the distance between the window and the emission vertex of the laser emitter is greater than 1 mm, the window is disposed between the laser emitter and the first scattering sheet, and the laser emitted by the laser emitter passes through the window and the first scattering sheet in sequence and enters the light inlet of the photodetector.

[0016] In this embodiment, by adding a window to the gas sensor and placing the window between the laser emitter and the first scattering sheet, environmental contamination of the laser emitter's light outlet is effectively blocked. By increasing the straight-line distance between the dirt and the laser emitter, the proportion of dirt in the laser irradiation area is reduced, thereby reducing the impact of dirt on the optical path and the impact of environmental dirt on the gas sensor's performance.

[0017] In one possible implementation of the first aspect, the gas sensor further includes a second scattering sheet;

[0018] The second scattering plate is disposed between the laser emitter and the photodetector. The distance from the light outlet of the laser emitter to the second scattering plate is greater than the distance from the second scattering plate to the light inlet of the photodetector. The second scattering plate includes a third rough surface, which is opposite to the light inlet of the photodetector. The second scattering plate is adjacent to the first scattering plate and has a certain distance between them, which is greater than 1 mm.

[0019] In this embodiment, by adding a second scattering sheet, the scattering in the optical path between the laser emitter and the photodetector is increased, thereby improving the uniform light effect of the gas sensor in the optical path between the laser emitter and the photodetector, and enabling the gas sensor to have a better stray elimination effect.

[0020] In one possible implementation of the first aspect, the first scattering sheet includes a dispensing area and a frosted area, the inner contour of the dispensing area being connected to the outer contour of the frosted area, and the dispensing area being a smooth plane. The second scattering sheet has a similar design and shape to the first scattering sheet, and will not be described further here.

[0021] In this embodiment, compared to the case of single-sided frosted glass, a smooth adhesive application area is added to the first scattering sheet. This solves the problem that when adhesive is applied to bond the first scattering sheet and the second support module, the high surface tension of the adhesive makes it difficult for the adhesive to fully penetrate into every gap connecting the first scattering sheet and the second support module, thus limiting the contribution of adhesive to the airtightness of the cavity formed by the first scattering sheet and the second support module. In the solution provided in this application, the adhesive application area of ​​the first scattering sheet is bonded to the second support module, allowing the adhesive to fully bond the adhesive application area of ​​the first scattering sheet and the second support module, thereby improving the airtightness of the cavity obtained by bonding the first scattering sheet and the second support module.

[0022] In one possible implementation of the first aspect, the gas sensor further includes a first lens disposed between the laser emitter and a target scattering sheet, the target scattering sheet being the scattering sheet closest to the laser emitter in the gas sensor. The first lens may be a convex lens or a concave lens. In distance applications, the first lens may also be a lens at the light outlet of the laser emitter; this is not a limitation.

[0023] In this embodiment, the diameter of the laser spot emitted by the laser emitter on the target scattering sheet is adjusted by adding a first lens between the target scattering sheet and the laser emitter. While ensuring the scattering efficiency of the target scattering sheet, there is no need to adjust the size of the gas sensor. This improves the detection effect of the gas sensor and also meets the size requirements of the gas sensor, making the gas sensor practical in specific scenarios.

[0024] In one possible implementation of the first aspect, the gas sensor further includes a second lens disposed between the photodetector and a preset scattering sheet, wherein the preset scattering sheet is the scattering sheet in the gas sensor that is closest to the photodetector, and the second lens includes a convex lens or a concave lens.

[0025] In this embodiment, the numerical aperture of the laser received by the photodetector is adjusted by adding a second lens between the preset scattering sheet and the photodetector. This ensures the photodetector's laser reception efficiency without requiring adjustment of the gas sensor's size. It improves the gas sensor's detection performance while also meeting the gas sensor's size requirements, making the gas sensor practical in specific scenarios.

[0026] In one possible implementation of the first aspect, the particle size of the rough surface is greater than or equal to 500 mesh and less than or equal to 4000 mesh. For example, the particle size of the first rough surface can be 500 mesh, 1000 mesh, 1500 mesh, 2000 mesh, 3000 mesh, or 4000 mesh. The rough surface includes a first rough surface and a second rough surface.

[0027] In this embodiment, by reasonably setting the particle size of the rough surface, the scattering efficiency of the first scattering sheet in the optical path from the laser emitter to the photodetector is ensured, thereby ensuring the uniform light effect of the first scattering sheet in the optical path from the laser emitter to the photodetector. This prevents stray light in the environment from having a significant impact on the laser received by the photodetector, thereby improving the accuracy of the gas sensor in detecting the gas composition of the target gas.

[0028] In one possible implementation of the first aspect, the laser emitted by the laser emitter has a wavelength of 1640nm-1660nm, 1670nm-1690nm, or 1515nm-1538nm. Wherein, 1640nm-1660nm is the gas absorption wavelength range for methane, 1670nm-1690nm is the gas absorption wavelength range for ethane, and 1515nm-1538nm is the gas absorption wavelength range for acetylene.

[0029] In this embodiment, the laser wavelength emitted by the laser emitter can be set according to specific testing requirements to adapt to different gas density testing environments. Combined with the first scattering sheet added to the gas sensor, it can effectively adapt to the measurement target under different gas environments. When measuring the gas density of methane, ethane, or acetylene in the environment, it eliminates the risk of generating MPI interference fringes in the gas sensor and improves the gas sensor's resistance to dirt, thereby improving the accuracy and reliability of measuring the gas density of methane in the environment.

[0030] In one possible implementation of the first aspect, the gas sensor further includes a first support module and a second support module. The first support module is a hollow block structure with an opening. A laser emitter is disposed inside the first support module, and the laser emitted by the laser emitter is emitted through the opening of the first support module. The second support module is a hollow block structure with an opening. A photodetector is disposed inside the second support module, and the photodetector receives the laser emitted by the laser emitter through the opening of the second support module.

[0031] In this embodiment, the gas sensor includes a first support module and a second support module, which provide support for the laser emitter and the photodetector, respectively. Since both the first and second support modules are hollow block structures with openings, the laser emitter is disposed inside the first support module, and the photodetector is disposed inside the second support module. The laser emitted by the laser emitter exits through the opening in the first support module, and the photodetector receives the laser emitted by the laser emitter through the opening in the second support module, thus providing effective support for the placement of the laser emitter and photodetector in the gas sensor.

[0032] In one possible implementation of the first aspect, a first scattering sheet covers the opening of the second support module to form a cavity, and a first rough surface is the surface close to the photodetector. When the first scattering sheet includes both a first rough surface and a smooth surface, the first rough surface is the surface inside the cavity, and the smooth surface is the surface outside the cavity.

[0033] In this embodiment, by covering the opening of the second support module with the first scattering sheet to form a cavity, and making the first rough surface closer to the PD, it can be ensured that the scattering effect of the first rough surface is not affected by environmental conditions during the operation of the gas sensor. This further ensures the reliability of the solution provided in water immersion scenarios. Moreover, when the first scattering sheet includes both a rough surface and a smooth surface, the solution provided in this application can effectively simulate the water immersion environment in manhole scenarios, reducing the impact of environmental factors on the working state of the gas sensor, and further improving the reliability of the gas sensor in detecting the composition of the target gas in scenarios such as manholes where water immersion may occur.

[0034] In one possible implementation of the first aspect, the laser emitter includes an LD, a fiber laser combined with a fiber cavity, or a spatial solid-state laser, and the photodetector includes a PD, a gain-enhanced avalanche diode, or a photoresistor based on photosensitive properties.

[0035] Secondly, this application provides an alarm device including a gas sensor, wherein the gas sensor is the gas sensor shown in the first aspect or any possible embodiment of the first aspect.

[0036] The beneficial effects shown in the second aspect are similar to those in the first aspect or any possible implementation of the first aspect, and will not be repeated here. Attached Figure Description

[0037] Figure 1 A schematic diagram of the structure of a gas sensor provided in this application;

[0038] Figure 2 Another structural schematic diagram of the gas sensor provided in this application;

[0039] Figure 3 Another structural schematic diagram of the gas sensor provided in this application;

[0040] Figure 4 Another structural schematic diagram of the gas sensor provided in this application;

[0041] Figure 5 Another structural schematic diagram of the gas sensor provided in this application;

[0042] Figure 6 Another structural schematic diagram of the gas sensor provided in this application;

[0043] Figure 7 Another structural schematic diagram of the gas sensor provided in this application;

[0044] Figure 8 A schematic diagram of the structure of the first scattering sheet provided in this application;

[0045] Figure 9 Another structural schematic diagram of the gas sensor provided in this application;

[0046] Figure 10 A schematic diagram of the spectrum of the gas absorption line provided in this application;

[0047] Figure 11 A schematic diagram of the structure of the alarm provided in this application. Detailed Implementation

[0048] This application provides a gas sensor and alarm to improve the accuracy of gas component detection by the gas sensor in harsh environments.

[0049] The embodiments of this application will now be described with reference to the accompanying drawings. Those skilled in the art will recognize that, with technological advancements and the emergence of new scenarios, the technical solutions provided in the embodiments of this application are equally applicable to similar technical problems.

[0050] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of units is not necessarily limited to those units, but may include other units not explicitly listed or inherent to those processes, methods, products, or apparatuses. Additionally, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can be expressed as: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.

[0051] With the continuous development of science and technology, the exploration of extreme environments is also ongoing. The gas composition in extreme environments is one of the important indicators for analyzing the safety of those environments. Different gas molecules undergo transitions and absorb photons at different wavelengths. For example, when a beam of light with a wavelength of 1651 nm passes through a gas containing methane molecules, a dip appears at the absorption peak of the methane gas in the received spectrum due to the absorption effect of the methane molecules. The intensity of this dip determines the concentration of methane gas.

[0052] However, most extreme environments contain impurities such as condensation, water stains, and dust. The stray gas caused by these impurities can significantly reduce the detection accuracy of gas sensors, or even render them inoperable.

[0053] To address the above issues, this application proposes incorporating a scattering plate into a gas sensor. This scattering plate is positioned between a laser emitter and a photodetector, with the distance from the scattering plate to the laser emitter's output port being greater than the distance from the scattering plate to the photodetector's input port. The scattering plate includes a rough surface, through which the laser emitted by the laser emitter passes and enters the photodetector's input port. By utilizing the scattering plate to create scattering, the influence of contaminants on the absorption amplitude of the laser by the target gas is reduced, thereby improving the gas sensor's performance in harsh environments. The laser emitter can be a laser diode (LD) based on semiconductor materials, a fiber laser combined with an optical fiber cavity, or a spatial solid-state laser. For example, the laser diode can be a Fabry-Perot laser diode (FD-LD), a distributed feedback semiconductor laser (DFB-LD), or a distributed Bragg reflector semiconductor laser (DBR-LD), etc., capable of wavelength tuning within specific wavelength ranges (e.g., 1640nm-1660nm, 1670nm-1690nm, or 1515nm-1538nm). Photodetectors can be photodiodes (PDs) based on the photoelectric effect, avalanche photodiodes (APDs) with gain, photoresistors based on photosensitive properties, pyroelectric detectors, or any other optoelectronic devices that can convert the intensity of an optical signal into an electrical signal.

[0054] To facilitate a clear understanding of the structure of the gas sensor provided in this application, we will first combine it with... Figure 1 This application describes one possible implementation of the gas sensor. The gas sensor provided in this application uses a DFB-LD laser emitter and a PD photodetector as an example. In practical applications, depending on the usage scenario, the laser emitter and photodetector can also be other optoelectronic devices; this is not a limitation.

[0055] The gas sensor 100 includes an LD 110 (i.e., a laser emitter 110), a PD 120 (i.e., a photodetector 120), and a first scattering sheet 130.

[0056] The first diffuser 130 is disposed between the LD110 and the PD120, and the distance from the light outlet of the LD110 to the first diffuser 130 is greater than the distance from the first diffuser 130 to the light inlet of the PD120. The first diffuser 130 includes a first rough surface 131.

[0057] The laser emitted by LD110 passes through the target gas, the first rough surface 131, and the target gas in sequence before entering the light inlet of PD120.

[0058] For example, the first diffuser 130 can also be the light inlet lens of the PD120. For instance, if the light inlet lens of the PD120 is a glass plate, the light inlet lens of the PD120 can be ground into frosted glass. There are no restrictions here.

[0059] It should be understood that Figure 1 The first rough surface 131 shown is the surface of the first scattering sheet 130 near PD120. In the solution proposed in this application, the first rough surface 131 can be either the surface of the first scattering sheet 130 near PD120 or the surface of the first scattering sheet 130 near LD110. Figure 1 The description is for illustrative purposes only. In actual applications, the settings can be adapted to specific application scenarios, and there are no restrictions here.

[0060] In this embodiment, a first scattering plate is disposed in the optical path between the LD and PD, and the first scattering plate is disposed at the end closer to the PD. More scattering is introduced into the laser transmission path emitted to the LD, causing the laser emitted by the LD to undergo at least one scattering in the target gas. This interrupts the possible interference optical path between the LD and the first scattering plate, or between the first scattering plate and the PD, or both. Furthermore, since the first scattering plate introduces a certain amount of optical loss into the gas sensor, the optical loss caused by contamination in harsh environments has a limited impact on the optical signal compared to the optical loss introduced by the first scattering plate. In other words, contamination in harsh environments cannot cause significant fluctuations in the optical path, thus not affecting the accuracy of the gas sensor in detecting the gas composition of the target gas, thereby improving the accuracy of the gas sensor in detecting the gas composition of the target gas.

[0061] Optionally, the first rough surface 131 can be as follows: Figure 1 The surface of the first scattering sheet 130 facing the PD120 is shown. In the gas sensor 100, when the LD110 emits a first laser towards the PD120, the first laser passes through the first scattering sheet 130 and enters the light inlet of the PD120. The exit surface of the first laser in the first scattering sheet 130 is called the surface of the first scattering sheet 130 near the PD120, or the surface of the first scattering sheet 130 facing the PD120, which in this application is also the first rough surface.

[0062] In this embodiment, a first rough surface is disposed on the surface of the first scattering sheet facing the PD, and the distance between the first scattering sheet and the PD is less than the distance between the first scattering sheet and the LD. This effectively shortens the distance between the scattering initiation point and the light inlet of the PD. Utilizing the first rough surface for scattering within a smaller spatial range can effectively reduce optical path loss between the light outlet of the LD and the light inlet of the PD, thereby effectively improving the accuracy of the gas sensor in detecting gas components.

[0063] Optionally, the particle size of the first rough surface 131 can be any value between 500 mesh and 4000 mesh. For example, the particle size of the first rough surface 131 can be 500 mesh, 1000 mesh, 1500 mesh, 2000 mesh, 2500 mesh, 3000 mesh, 3500 mesh or 4000 mesh, without any limitation.

[0064] In this embodiment, the scattering efficiency of the first scattering sheet in the optical path from LD to PD is ensured by the particle size of the first rough surface, thereby ensuring the uniform light effect of the first scattering sheet in the optical path from LD to PD, so that stray light in the environment cannot have a significant impact on the laser received by the PD, thereby improving the accuracy of the gas sensor in detecting the gas composition of the target gas.

[0065] In one possible implementation, in order to ensure that the first scattering sheet 130 fully exerts its scattering effect, the laser emitted by the LD110 produces a spot diameter on the first scattering sheet 130 that is greater than 1 mm and less than 20 mm. It should be understood that the spot diameter mentioned here is only an example. In actual application scenarios, the spot size can be adaptively adjusted according to the distance between the LD110 and the first scattering sheet 130 in the gas sensor 100. No limitation is made here.

[0066] In this embodiment, by limiting the minimum spot diameter of the laser emitted by the LD on the first scattering sheet, the scattering efficiency of the first scattering sheet can be effectively ensured. The first scattering sheet can be fully utilized to create more scattering paths in the target gas, reducing the wavelength dependence of the PD light collection efficiency. This effectively reduces the wavelength dependence of light loss caused by contamination in the gas sensor in harsh environments, further improving the gas sensor's resistance to dirt and thus enhancing the reliability of the gas sensor in detecting the composition of the target gas.

[0067] In one possible implementation, based on the positional relationship between the first scatterer 130 and the LD 110, the laser emitted by the LD 110 may be reflected by the first scatterer 130 and then enter the LD 110 again from its exit port. To eliminate this possibility, the angle between the normal of the first scatterer 130 and the laser emitted by the LD 110 is a first angle, which is greater than 5°, and to ensure the power of the light received by the PD 120, this first angle also needs to be less than 75°. Specifically, the normal of the first scatterer 130 can be the normal of the first rough surface 131.

[0068] It should be understood that the description of the range of the first angle setting here is only an example. In specific implementation scenarios, the first angle can be 10°, 20° or 30°. The first angle can be set to any degree between 5° and 75° according to the needs of the implementation scenario. There is no restriction here.

[0069] In this embodiment, the angle between the normal of the first rough surface of the first scattering sheet and the laser emitted by the LD is set to be in the range of 5° to 75°. An angle greater than 5° can effectively prevent the laser emitted by the LD from being reflected by the first scattering sheet and then entering the LD from the light outlet. An angle less than 75° can effectively ensure the power of the light received by the PD end and reduce unnecessary light loss.

[0070] In one possible implementation, the first scattering sheet 130 may consist of a rough surface and a smooth surface; that is, the first scattering sheet includes a first rough surface 131 and a smooth surface 132. The first scattering sheet 130 can be positioned in the gas sensor as follows: Figure 2 As shown.

[0071] That is, the smooth surface 132 is located between the light outlet of the LD110 and the first rough surface 131, and the smooth surface 132 is opposite to the first rough surface 131. The normal direction of the smooth surface 132 and the normal direction of the first rough surface 131 can coincide or have a certain angle. However, the angle between the normal direction of the smooth surface 132 and the laser emission axis of the LD must be within the range of 5° to 75°, and the angle between the normal direction of the first rough surface 131 and the laser emission axis of the LD must be within the range of 5° to 75°.

[0072] Optionally, the smooth surface 132 is a surface with a particle size greater than or equal to 10,000 mesh. For example, the particle size of the smooth surface 132 can be 10,000 mesh, 10,500 mesh, or 11,000 mesh, etc., and there is no limitation here.

[0073] When applied to specific implementation scenarios, gas sensors can, for example... Figure 3As shown, the gas sensor 100 may further include a first support module 140 and a second support module 150. The first support module 140 is a hollow block structure with an opening. An LD 110 is disposed inside the first support module 140, and the laser emitted by the LD 110 exits through the opening of the first support module 140. The second support module 150 is a hollow block structure with an opening. A PD 120 is disposed inside the second support module 150, and the PD 120 receives the laser emitted by the LD 110 through the opening of the second support module 150. Figure 3 It can be seen that the first scattering sheet 130 covers the opening of the second support module 150, so that the second support module 150 and the first scattering sheet 130 form a sealed cavity. And the first rough surface 131 is the surface close to PD120, and the smooth surface 132 is the surface close to LD110.

[0074] Application of the scheme proposed in this application, such as Figure 3 As shown, in the gas sensor provided by this application, the first rough surface is the surface inside the cavity, while the smooth surface is the surface exposed to the detection environment. This can effectively simulate the water immersion environment in a manhole scenario, reduce the impact of environmental factors on the working state of the gas sensor, and further improve the reliability of the gas sensor in detecting the composition of the target gas in scenarios such as manhole scenarios where water immersion may occur.

[0075] In one possible implementation, based on the foregoing Figure 2 The gas sensor, the smooth surface 132 can also be located between the light inlet of PD120 and the first rough surface 131, without limitation.

[0076] To improve the scattering capability of the gas sensor, this application also proposes, based on the aforementioned Figure 1 The gas sensor shown in this application proposes that the first scattering plate 130 may further include a second rough surface 133, which is disposed between the light outlet of the LD110 and the first rough surface 131. The specific structure of the gas sensor 100 is as follows: Figure 4 As shown.

[0077] Optionally, the first scattering sheet 130 can be a frosted glass sheet, a hazy scattering plastic sheet, or a laminated / laminated glass sheet, etc., and there are no restrictions here.

[0078] Optionally, the outer contour of the first scattering sheet 130 can be square, circular, polygonal or irregular in shape, without limitation.

[0079] Optionally, the surface shape of the first scattering sheet 130 can be a plane or a curved surface. When the first rough surface 131 and the second rough surface 133 are curved surfaces, the first rough surface 131 and the second rough surface 133 can have the same curvature or different curvatures. The first rough surface 131 and the second rough surface 133 can have the same surface shape or different surface shapes, which is not limited here.

[0080] Optionally, the normal direction of the second rough surface 133 may coincide with or have a certain angle with the normal direction of the first rough surface 131, but the angle between the normal direction of the smooth surface 132 and the axis of the LD laser emission must be within the range of 5° to 75°, and the angle between the normal direction of the first rough surface 131 and the axis of the LD laser emission must be within the range of 5° to 75°.

[0081] The particle size of the second rough surface 133 can be any value between 500 mesh and 4000 mesh. For example, the particle size of the second rough surface 133 can be 500 mesh, 1000 mesh, 1500 mesh, 2000 mesh, 2500 mesh, 3000 mesh, 3500 mesh or 4000 mesh, without any limitation.

[0082] Optionally, the thickness of the first scattering sheet 130 is greater than 1 mm, that is, the distance between the first rough surface 131 and the second rough surface 133 is greater than 1 mm. For example, the first rough surface 131 and the second rough surface 133 are parallel, and the distance between the first rough surface 131 and the second rough surface 133 is 1.5 mm, which is not limited here.

[0083] In such Figure 4 In the gas sensor shown, the laser scattering is achieved by using a scatterer with two rough surfaces, which provides a stronger scattering capability. Since there is still a certain distance between the two rough surfaces, it can also provide better light homogenization, which helps to better eliminate stray light and thus improve the measurement stability of the gas sensor.

[0084] Based on the foregoing Figure 1 , Figure 2 or Figure 4 The gas sensor shown is designed for use in relatively dirty measurement environments. Therefore, the LD (Digital Light Diode) needs some protection to reduce the impact of environmental contamination on the emitted beam. Based on this idea, this application proposes adding a window between the LD and the first scattering plate, specifically as follows... Figure 5 As shown.

[0085] Depend on Figure 5 It can be seen that the gas sensor 100 also includes a window 160, which is connected to the emission vertex of the LD 110 (e.g., Figure 5The distance between the black dots shown is greater than 1 mm. The window is positioned between the first diffuser 130 of the LD110. The laser emitted by the LD110 passes sequentially through the window 160 and the first diffuser 130 into the light inlet of the PD120. The emission vertex of the LD110 varies slightly depending on the shape of its emitting lens. For example, when the laser is emitted from the LD110 and the emitting lens is a convex lens, the intersection of the laser emission axis and the convex surface of the convex lens is taken as the emission vertex of the LD110; that is, the vertex of the LD110 emitting lens is taken as the emission vertex of the LD110. Similarly, when the emitting lens of the LD110 is a plane mirror, the intersection of the laser emission axis and the plane mirror is taken as the emission vertex of the LD110. When the emitting lens of the LD110 is a concave lens, the determination of the emission vertex is similar to that when the LD110 emitting lens is a convex lens, and will not be elaborated further here.

[0086] For example, the gas sensor can be as follows: Figure 6 As shown, the gas sensor 100 includes an LD 110, a PD 120, a first diffuser 130, a first support module 140, a second support module 150, and a window 160.

[0087] The first scattering plate 130 is disposed between the LD110 and the PD120, and the distance from the light outlet of the LD110 to the first scattering plate 130 is greater than the distance from the first scattering plate 130 to the light inlet of the PD120. The first scattering plate 130 includes a first rough surface 131. The laser emitted by the LD110 passes through the target gas, the first rough surface 131 and the target gas in sequence before entering the light inlet of the PD120.

[0088] The first support module 140 is a hollow block structure with an opening. The LD 110 is disposed inside the first support module 140, and the laser emitted by the LD 110 exits through the opening of the first support module 140. The second support module 150 is also a hollow block structure with an opening. The PD 120 is disposed inside the second support module 150, and the PD 120 receives the laser emitted by the LD 110 through the opening of the second support module 150. A first scattering sheet 130 covers the opening of the second support module 150, forming a sealed cavity with the second support module 150. The first rough surface 131 is the surface near the PD 120, and the smooth surface 132 is the surface near the LD 110.

[0089] The window 160 covers the opening of the first support module 140, so that the first support module 150 and the window 160 form a sealed cavity.

[0090] Optionally, since the first scattering sheet 130 covers the opening of the second support module 150, based on the aforementioned Figure 1 The angle between the normal of the first scatterer 130 and the laser emitted by the LD110 is defined as a first angle, which is greater than 5° and less than 75°. Figure 6 In the scenario shown, the normal of the plane containing the opening of the second support module 150 is parallel to the normal of the first scatterer 130. That is, the angle between the normal of the plane containing the opening of the second support module 150 and the laser emitted by the LD110 is also the first angle, which is not restricted here.

[0091] Similarly, since window 160 covers the opening of the first support module 140, the angle between the normal of window 160 and the laser emitted by LD110 can be the same as the first angle, and there is no restriction here.

[0092] In this embodiment, by adding a window to the gas sensor and placing the window between the LD and the first scattering sheet, the environmental contamination of the LD's light output port is effectively blocked. By increasing the straight-line distance between the dirt spot and the emission focus, the impact of dirt on the optical path is reduced, and the impact of environmental dirt on the working performance of the gas sensor is reduced.

[0093] Since the more scattering occurs in the optical path between the LD and PD in the gas sensor provided in this application, the better the uniformity of the transmitted laser light between the LD and PD can be achieved. Based on this idea, this application proposes that the gas sensor may further include a second scattering plate, the position of which in the gas sensor can be as follows: Figure 7 As shown.

[0094] The gas sensor 100 also includes a second diffuser 170, which is disposed between the LD 110 and the PD 120. The distance from the light outlet of the LD 110 to the second diffuser 170 is greater than the distance from the second diffuser 170 to the light inlet of the PD 120. The second diffuser 170 includes a third rough surface 171, which is opposite to the light inlet of the PD 120. The second diffuser 170 is adjacent to the first diffuser 130.

[0095] Optionally, the relative positions of the second scatterer 170 and the first scatterer 130 can be parallel or non-parallel, and the distance between the first scatterer 130 and the second scatterer 170 can also be adjusted according to the actual situation, without any restrictions.

[0096] Optionally, the particle size of the first rough surface 131, the second rough surface 133, and the third rough surface 171 is 500 mesh, 1000 mesh, or 1500 mesh. The particle size of the first rough surface 131 can be any value between 500 mesh and 4000 mesh, and there is no restriction here.

[0097] Optionally, the outer contour shape and surface type of the second scatterer 170 are similar to the possible outer contour shape and surface type of the first scatterer 130. For details, please refer to the above description of the first scatterer 130, which will not be repeated here.

[0098] It should be understood that, in specific implementations, the particle sizes of the first rough surface 131, the second rough surface 133, and the third rough surface 171 can be the same or different. There are no restrictions here. In specific implementations, the particle sizes should be set according to the specific implementation scenario. There are no restrictions here.

[0099] It should be understood that Figure 7 The positional relationship between the first scattering plate 130 and the second scattering plate 170 shown is for illustrative purposes only. In specific application scenarios, the first scattering plate 130 can be closer to the PD120 relative to the second scattering plate 170, and the first scattering plate 130 can also be further away from the PD120 relative to the second scattering plate 170 (that is, in the case of...). Figure 7 In the scenario shown, the first scatterer 130 can be located to the left or to the right of the second scatterer 170. The specific settings can be adjusted according to the specific application scenario, and there are no restrictions here.

[0100] In this embodiment, by setting a second scattering sheet 170, the scattering in the optical path between the LD and PD is increased, thereby improving the uniform light effect of the gas sensor in the optical path between the LD and PD and enabling the gas sensor to have a better stray elimination effect.

[0101] It should be noted that the diffusers involved in this application are all diffusers with high light transmittance, and their specific light transmittance is not limited here.

[0102] Based on the foregoing Figures 1 to 7 The gas sensor shown has a diffuser whose shape and area division can be as follows: Figure 8 As shown, the first scattering sheet 130 includes a dispensing area 134 and a frosted area 131 (since the frosted area 131 has a similar function and shape to the first rough surface 131, it can be understood that the frosted area 131 is another way of describing the first rough surface 131). The inner contour of the dispensing area 134 is connected to the outer contour of the frosted area 131, and the dispensing area 134 is a smooth plane.

[0103] It should be understood that the description of the shape of the diffuser and the division of the shapes of each region here is only an example. In specific implementations, the outer contour of the dispensing area 134 can also be a circle, rectangle, triangle or irregular polygon, etc., and the outer contour of the frosted area 131 can also be a circle, rectangle, triangle or irregular polygon, etc., and there is no correlation between the outer contour shape of the dispensing area 134 and the outer contour shape of the frosted area 131. In specific implementations, adjustments can be made according to specific needs, and no restrictions are imposed here.

[0104] The structure of the gas sensor 100 is as described above. Figure 3 As shown, the connection between the second support module 150 and the first scattering sheet 130 is achieved by dispensing adhesive in the dispensing area 134 and the bonding surface of the second support module 150, so that the first scattering sheet 130 covers the second support module 150, and the first scattering sheet 130 and the second support module 150 form a cavity.

[0105] In this embodiment, compared to the case of single-sided frosted glass, a smooth adhesive application area is added to the first scattering sheet. This solves the problem that when adhesive is applied to bond the first scattering sheet and the second support module, the high surface tension of the adhesive makes it difficult for the adhesive to fully penetrate into every gap connecting the first scattering sheet and the second support module, thus limiting the contribution of adhesive to the airtightness of the cavity formed by the first scattering sheet and the second support module. In the solution provided in this application, the adhesive application area of ​​the first scattering sheet is bonded to the second support module, allowing the adhesive to fully bond the adhesive application area of ​​the first scattering sheet and the second support module, thereby improving the airtightness of the cavity obtained by bonding the first scattering sheet and the second support module.

[0106] In the solution provided in this application, to fully achieve the purpose of scattering the laser emitted by the LD and ensure that the diameter of the laser spot generated on the target scattering sheet by the LD is greater than 1 mm, since the emission angle of the LD is difficult to change, and the size of the gas sensor is also difficult to adjust significantly to ensure portability, this application proposes to add a first lens between the LD and the target scattering sheet. The first lens can be a convex lens or a concave lens. The target scattering sheet is the scattering sheet closest to the LD in the gas sensor. For example, when the diameter of the laser spot on the first scattering sheet is less than 1 mm, the first lens can be a concave lens. When the laser spot on the first scattering sheet completely covers the first scattering sheet, the first lens can be a convex lens.

[0107] In this embodiment, the diameter of the laser spot emitted by the LD on the target scattering sheet is adjusted by adding a first lens between the target scattering sheet and the LD. While ensuring the scattering efficiency of the target scattering sheet, there is no need to adjust the size of the gas sensor. This improves the detection effect of the gas sensor and also meets the size requirements of the gas sensor, making the gas sensor practical in specific scenarios.

[0108] Furthermore, similar to the aforementioned situation, since the optical path propagating through the scatterer is difficult to control and the size of the gas sensor is also difficult to adjust significantly, in order to ensure that the numerical aperture of the laser received by the PD meets expectations, a second lens can be added between the PD and the preset scatterer. The second lens includes a convex lens or a concave lens, and the preset scatterer is the scatterer in the gas sensor that is closest to the PD.

[0109] It should be understood that there are no restrictions on the curvature of the first and second lenses here. In specific real-time scenarios, the curvature can be set according to the specific scenario, and there are no restrictions here.

[0110] In this embodiment, the numerical aperture of the laser received by the PD is adjusted by adding a first lens between the preset diffuser and the PD. While ensuring the PD's laser reception efficiency, there is no need to adjust the size of the gas sensor. This improves the detection effect of the gas sensor and also meets the size requirements of the gas sensor, making the gas sensor practical in specific scenarios.

[0111] It should be understood that the first or second lens here can be a single lens or a combination of multiple lenses; there is no limitation here.

[0112] Based on the above description of the first lens and the second lens, the gas sensor 100 provided in this application may further include a first lens 180 and a second lens 190, the positions of the first lens 180 and the second lens 190 in the gas sensor 100 being as follows: Figure 9 As shown. In Figure 9 In the scenario shown, the gas sensor 100 contains only one scattering sheet, the first scattering sheet 110. Therefore, the target scattering sheet and the preset scattering sheet in the aforementioned scheme are both the first scattering sheet 110, and no restriction is imposed here. Figure 9 The diagram only illustrates one possible configuration of the first lens 180 and the second lens 190. In specific implementation scenarios, the configuration can be combined with specific implementation methods, and no restrictions are imposed here.

[0113] The structure of the gas sensor provided in this application has been described above. The laser emitted by the LD will now be discussed in conjunction with its application scenarios. Since the operation of a gas sensor is based on the absorption capacity of different gases for photons of specific wavelengths, the laser emitted by the LD in the gas sensor provided in this application will vary depending on the target gas.

[0114] In one possible implementation, the target gas includes methane, acetylene, or ethane, without limitation.

[0115] Adaptive, the laser wavelength emitted by the LD is included in the gas absorption wavelength range of methane, acetylene, or ethane.

[0116] based on Figure 10 The gas absorption lines shown indicate that methane has multiple absorption peaks in the range of 1640nm-1660nm, acetylene has multiple absorption peaks in the range of 1515nm-1538nm, and ethane has multiple absorption peaks in the range of 1670nm-1690nm.

[0117] That is, the absorption wavelength range of methane is 1640nm-1660nm, the gas absorption wavelength range of ethane is 1670nm-1690nm, and the absorption wavelength range of acetylene is 1515nm-1538nm. Therefore, this application proposes that, based on measurement requirements, the laser wavelength emitted by the LD110 in the gas sensor 100 can be set to 1640nm-1660nm, 1670nm-1690nm, or 1515nm-1538nm.

[0118] Specifically, when measuring the density of methane, the laser wavelength emitted by the LD110 can be set to the absorption wavelength of methane, for example, 1677.60 nm, 1674.47 nm, 1653.73 nm, 1650.94 nm, and 1648.24 nm; when measuring the density of acetylene, the laser wavelength emitted by the LD110 can be set to the absorption wavelength of acetylene, for example, 1535.63 nm, 1534.10 nm, 1521.07 nm, and 1519.14 nm; and when measuring the density of ethane, the laser wavelength emitted by the LD110 can be set to the gas absorption wavelength of ethane, for example, 1680 nm and 1675.94 nm.

[0119] It should be understood that the absorption wavelengths of methane, acetylene, and ethane mentioned here are all based on... Figure 10 The schematic diagram of the gas absorption line shown indicates that, in specific implementations, depending on the specific usage environment, the wavelength of the target laser can be adjusted by up to 1 nm to adapt to the specific usage scenario; no restrictions are imposed here.

[0120] Based on the gas sensor described above, this application also provides an alarm device; please refer to [link / reference]. Figure 11 The alarm 1100 includes a gas sensor 100, which is related to the aforementioned Figures 1 to 9 Similar to any gas sensor, alarm 1100 is used to issue an alarm when gas sensor 100 detects an abnormal concentration of the target gas. For example, alarm 1100 may emit an audible or flashing alarm signal when the gas sensor detects that the concentration of the target gas is greater than a threshold; there is no limitation on this.

[0121] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0122] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0123] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0124] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

Claims

1. A gas sensor, characterized in that, Includes a laser emitter, a photodetector, and a first scattering sheet; The first scattering sheet is disposed between the laser emitter and the photodetector. The distance from the light outlet of the laser emitter to the first scattering sheet is greater than the distance from the first scattering sheet to the light inlet of the photodetector. The first scattering sheet includes a first rough surface. The laser emitted by the laser emitter passes through the first rough surface of the first scattering sheet and enters the light inlet of the photodetector.

2. The gas sensor according to claim 1, characterized in that, The angle between the normal of the first scattering sheet and the laser emitted by the laser emitter is a first angle, which is greater than 5° and less than 75°.

3. The gas sensor according to claim 1 or 2, characterized in that, The first rough surface is the surface of the first scattering sheet facing the photodetector.

4. The gas sensor according to claim 1 or 2, characterized in that, The first scattering sheet further includes a second rough surface, which is located between the light outlet of the laser emitter and the first rough surface.

5. The gas sensor according to claim 1 or 2, characterized in that, The first scattering sheet further includes a smooth surface, which is located between the light outlet of the laser emitter and the first rough surface, and the smooth surface is opposite to the first rough surface.

6. The gas sensor according to claim 1 or 2, characterized in that, The gas sensor also includes a window, the distance between the window and the emission vertex of the laser emitter is greater than 1 mm, the window is disposed between the laser emitter and the first scattering sheet, and the laser emitted by the laser emitter passes through the window and the first scattering sheet in sequence and enters the light inlet of the photodetector.

7. The gas sensor according to claim 1 or 2, characterized in that, The gas sensor also includes a second scattering plate; The second scattering sheet is disposed between the laser emitter and the photodetector. The distance from the light outlet of the laser emitter to the second scattering sheet is greater than the distance from the second scattering sheet to the light inlet of the photodetector. The second scattering sheet includes a third rough surface, which is opposite to the light inlet of the photodetector. The second scattering sheet is adjacent to the first scattering sheet.

8. The gas sensor according to claim 1 or 2, characterized in that, The first scattering sheet includes a dispensing area and a frosted area, wherein the inner contour of the dispensing area is connected to the outer contour of the frosted area, and the dispensing area is a smooth plane.

9. The gas sensor according to claim 1 or 2, characterized in that, The gas sensor further includes a first lens, which is disposed between the laser emitter and the target scattering sheet. The target scattering sheet is the scattering sheet in the gas sensor that is closest to the laser emitter. The first lens includes a convex lens or a concave lens.

10. The gas sensor according to claim 1 or 2, characterized in that, The gas sensor further includes a second lens, which is disposed between the photodetector and a preset scattering sheet. The preset scattering sheet is the scattering sheet in the gas sensor that is closest to the photodetector. The second lens includes a convex lens or a concave lens.

11. The gas sensor according to claim 1 or 2, characterized in that, The rough surface has a particle size greater than or equal to 500 mesh and less than or equal to 4000 mesh, and the rough surface includes the first rough surface.

12. The gas sensor according to claim 5, characterized in that, The particle size of the smooth surface is greater than or equal to 10,000 mesh.

13. The gas sensor according to claim 1 or 2, characterized in that, The laser emitter emits laser wavelengths including 1640nm-1660nm, 1670nm-1690nm, or 1515nm-1538nm.

14. The gas sensor according to claim 1 or 2, characterized in that, The gas sensor further includes a first support module and a second support module. The first support module is a hollow block structure with an opening. The laser emitter is disposed inside the first support module, and the laser emitted by the laser emitter is emitted through the opening of the first support module. The second support module is a hollow block structure with an opening. The photodetector is disposed inside the second support module, and the photodetector receives the laser emitted by the laser emitter through the opening of the second support module.

15. The gas sensor according to claim 14, characterized in that, The first scattering sheet covers the opening of the second support module.

16. The gas sensor according to claim 1 or 2, characterized in that, The laser emitter includes a laser diode (LD), a fiber laser combined with an optical fiber cavity, or a spatial solid-state laser, and the photodetector includes a photodiode (PD), a gain avalanche diode, or a photoresistor based on photosensitive properties.

17. An alarm device, characterized in that, Includes a gas sensor, wherein the gas sensor is the gas sensor described in any one of claims 1 to 16.

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