Laser module structure and air quality sensor

Abstract

The invention discloses a laser module structure and an air quality sensor, and the laser module structure comprises a housing which is provided with an air flow channel, a first accommodation cavity and a second accommodation cavity, the air flow channel allows to-be-detected gas to pass through, the first accommodation cavity is provided with a first channel communicated with the air flow channel, and the second accommodation cavity is provided with a second channel communicated with the air flow channel; the laser transmitter is arranged in the first accommodating cavity; the emission lens is arranged in the first accommodating cavity and is configured to focus the laser emitted by the laser emitter to the airflow channel to form a laser focus; the photoelectric sensor is arranged in the second accommodating cavity; the receiving lens is arranged on the second channel and is configured to receive scattered light generated when particles of the to-be-detected gas in the gas flow channel pass through the laser focus and focus the scattered light to the photoelectric sensor. According to the laser module structure, the scattered light receiving efficiency is improved, enough high signal feedback can be provided at low concentration, and high-precision and miniaturized PM2.5 detection is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a laser module structure and an air quality sensor. BACKGROUND

[0002] The principle of the laser module of the current PM2.5 air quality sensor is to generate Mie scattering by laser irradiation of particulate matter, and to receive the scattered light signal by a photodiode and to inverse the particulate concentration. However, the scattered light of the laser module in the related art directly irradiates the photodiode, and the photodiode only collects a small part of the scattered light or conducts the scattered light through a long distance medium, resulting in large energy loss of the scattered light, reduction of the effective signal received by the photosensitive device, and insufficient sensitivity of low concentration detection, which limits the measurement accuracy of the sensor. SUMMARY

[0003] The present application aims to at least solve one of the above technical problems in the technical field. To this end, the present application aims to provide a laser module structure and an air quality sensor, which improves the reception efficiency of scattered light and can provide high signal feedback at low concentration, thereby realizing high-precision and miniaturized PM2.5 detection.

[0004] To achieve the above-mentioned purpose, an embodiment of the present application provides a laser module structure, comprising:

[0005] a housing having an airflow channel, a first accommodating cavity and a second accommodating cavity, the airflow channel being configured to pass the gas to be detected, the first accommodating cavity having a first channel communicating with the airflow channel, and the second accommodating cavity having a second channel communicating with the airflow channel;

[0006] a laser emitter arranged in the first accommodating cavity;

[0007] a transmitting lens arranged in the first accommodating cavity and configured to focus the laser emitted by the laser emitter to the airflow channel to form a laser focal point;

[0008] a photoelectric sensor arranged in the second accommodating cavity;

[0009] a receiving lens arranged on the second channel and configured to receive the scattered light generated when the particulate matter of the gas to be detected in the airflow channel passes through the laser focal point, and focus the scattered light to the photoelectric sensor.

[0010] According to the laser module structure of the embodiment of the present application, the physical isolation of the first accommodating cavity and the second accommodating cavity can eliminate the interference of stray light from the structure; the first channel and the second channel are respectively used as a laser incident port and a scattered light receiving port, the aperture can be customized according to the size of the lens, air flow turbulence caused by an excessively large opening is avoided, and the stability of the gas flow rate is ensured; and the structure is compact, no additional optical path folding is required, and the small-sized sensor requirement is met; the emission lens condenses and enhances the laser focal point energy, the receiving lens directionally captures the scattered light, the sensing sensitivity is improved, the low-concentration particulate matter detection is met, and the scattered light received after the receiving lens is 5.3 times that of the receiving lens.

[0011] In addition, the laser module structure according to the above-mentioned embodiment of the present application can also have the following additional technical features:

[0012] Optionally, the emission lens is arranged in the first accommodating cavity close to the first channel, and the optical axis of the emission lens is collinear with the central axis of the first channel; the receiving lens is arranged in the second channel close to one side of the airflow channel, and the optical axis of the receiving lens is collinear with the central axis of the second channel; the central axis of the first channel and the central axis of the second channel are perpendicular to each other.

[0013] Optionally, the emission lens has two opposite curved surfaces, one of which is inserted into the first channel.

[0014] Further, the laser module structure further comprises an emission lens barrel arranged in the first accommodating cavity, one end of the emission lens barrel is provided with a radial necking portion, the radial necking portion is provided with a through hole communicating with the inside of the emission lens barrel, the laser emitter is arranged in the emission lens barrel, the emission lens is sleeved on the radial necking portion, and the other curved surface of the emission lens is inserted into the through hole.

[0015] Further, the emission lens is assembled on the emission lens barrel by the first fixing glue.

[0016] Optionally, the second channel is radially expanded at one end towards the second accommodating cavity to form a clamping groove, the receiving lens is clamped in the clamping groove, and has a receiving end surface extending from the second channel to the airflow channel and a curved surface facing the photoelectric sensor.

[0017] Optionally, the housing has a third channel that communicates with the airflow channel and is coaxially arranged with the first channel. The third channel is provided with a reflective sheet, which is configured to unidirectionally reflect light passing through the airflow channel and entering the third channel back into the third channel, thereby blocking light in the third channel from entering the airflow channel in the opposite direction.

[0018] Furthermore, the reflector is tilted on the housing and covers the end of the third channel away from the airflow channel. The end of the third channel that communicates with the airflow channel is provided with a constricted through hole. The inner diameter of the constricted through hole is smaller than the inner diameter of the third channel, and the tilt angle of the reflector is matched with the axis of the constricted through hole to block the light in the third channel from entering the airflow channel in the opposite direction.

[0019] Furthermore, the receiving lens is assembled to the second channel using a second adhesive; the reflector is assembled to the housing using a third adhesive.

[0020] In another aspect, the present invention also proposes an air quality sensor comprising:

[0021] Circuit board;

[0022] In the laser module structure described above, the laser emitter is coupled to the circuit board, and the photoelectric sensor is coupled to the circuit board, converting the optical signal into an electrical signal.

[0023] According to the air quality sensor of the present invention, the laser module structure described above improves the measurement accuracy of the sensor and provides sufficiently high signal feedback even at low concentrations. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a laser module structure according to an embodiment of the present invention;

[0025] Figure 2 This is an exploded view of the laser module structure according to an embodiment of the present invention;

[0026] Figure 3 This is a perspective view of the laser module structure according to an embodiment of the present invention;

[0027] Figure 4 for Figure 3 AA section view;

[0028] Figure 5 This is a comparison diagram of light received with and without a receiving lens according to an embodiment of the present invention.

[0029] Label Explanation:

[0030] The housing 100, airflow channel 110, first receiving cavity 120, first channel 121, second receiving cavity 130, second channel 131, slot 132, third channel 140, and constricted through hole 141;

[0031] Laser emitter 200;

[0032] 300mm emission lens;

[0033] Photoelectric sensor 400;

[0034] Receiver lens 500;

[0035] The emitting lens tube 600 and the radial constriction section 610;

[0036] First fixing adhesive 710, second fixing adhesive 720, third fixing adhesive 730;

[0037] 800 reflector. Detailed Implementation

[0038] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0039] The following is in conjunction with the appendix Figures 1-4 The structure of the laser module according to an embodiment of the present invention is described in detail.

[0040] An air quality sensor for detecting PM2.5 can include a device containing a laser light source and a photoelectric sensor. The laser light source can emit laser light into the detection area to form a laser focus. In this detection area, when particulate matter of the gas to be detected passes through the laser focus, Mie scattering occurs. The scattered light passes through a receiving lens and enters the photoelectric sensor, where it is converted into an electrical signal. The circuit board uses the electrical signal converted by the photoelectric sensor to fit the concentration of dust.

[0041] like Figure 1 and Figure 2 As shown, the laser module structure according to an embodiment of the present invention includes a housing 100, a laser emitter 200, an emitting lens 300, a photoelectric sensor 400, and a receiving lens 500.

[0042] Specifically, the housing 100 has an airflow channel 110, a first receiving cavity 120, and a second receiving cavity 130. The airflow channel 110 allows the gas to be detected to pass through. The first receiving cavity 120 has a first channel 121 communicating with the airflow channel 110, and the second receiving cavity 130 has a second channel 131 communicating with the airflow channel 110. The airflow channel 110, the first receiving cavity 120, and the second receiving cavity 130 in the housing 100 can all be integrally formed during the manufacturing of the housing 100. The gas in the airflow channel 110 can flow from... Figure 1 The airflow enters through the opening of the airflow channel 110 and exits from the opposite end that is coaxial with the opening.

[0043] A laser emitter 200 is disposed within a first receiving cavity 120; an emitting lens 300 is disposed within the first receiving cavity 120 and configured to focus the laser emitted by the laser emitter 200 onto the airflow channel 110 to form a laser focal point; when the laser emitter 200 emits laser light, the laser light is focused by the emitting lens 300 and passes through the first channel 121, forming a laser focal point in the airflow channel 110; when the laser focal point contacts particulate matter in the gas being detected, light scattering occurs, thus the concentration of particulate matter such as dust in the gas can be captured and detected. The laser emitter 200 can be configured to emit laser light of a predetermined wavelength.

[0044] The photoelectric sensor 400 is disposed within the second receiving cavity 130; the photoelectric sensor 400 may include photosensitive devices such as photodiodes, photoelectric integrated circuit diodes, phototransistors, photomultiplier tubes, or phototransistors.

[0045] A receiving lens 500 is disposed on the second channel 131 and configured to receive scattered light generated when particulate matter in the gas to be detected from the gas flow channel 110 passes through the laser focus, and to focus the scattered light onto the photoelectric sensor 400. The photoelectric sensor 400 can be configured to receive the scattered light generated when particulate matter in the gas to be detected, focused by the receiving lens 500, passes through the laser focus, and to convert the received scattered light into an electrical signal. Thus, the electrical signal can represent the characteristics of the scattered light. The electrical signal can be used (e.g., by a processor or circuitry of a computing device) to detect dust in the gas to be detected, at least in part, based on the scattering of the scattered light. For example, the photoelectric sensor 400 can generate an electrical signal associated with the number of particles, the size of the particles, and the concentration of the particles.

[0046] The receiving lens 500 can be arranged on the second channel 131 facing the photoelectric sensor 400, so that the scattered light can be focused towards the photoelectric sensor 400. In this way, most of the scattered light can be collected and focused onto the photoelectric sensor 400, thereby increasing the signal strength received by the photoelectric sensor 400 and thus improving the sensing sensitivity.

[0047] Therefore, according to an embodiment of the present invention, a laser module structure can eliminate stray light interference structurally through the physical isolation of the first receiving cavity 120 and the second receiving cavity 130; the first channel 121 and the second channel 131 serve as the laser inlet and the scattered light receiving outlet, respectively, and the aperture can be customized according to the lens size to avoid airflow turbulence caused by excessively large openings and ensure stable gas flow rate; moreover, the structure is compact, requiring no additional optical path folding, and is suitable for miniaturized sensor requirements; the emitting lens 300 focuses and enhances the laser focal energy, and the receiving lens 500 directionally captures the scattered light, improving sensing sensitivity and adapting to low-concentration particulate matter detection; the scattered light that can be received after adding the receiving lens 500 is 5.3 times that without the receiving lens, such as... Figure 5 As shown.

[0048] According to one or more embodiments of the present invention, the emitting lens 300 is disposed within the first receiving cavity 120 near the first channel 121, and the optical axis of the emitting lens 300 is collinear with the central axis of the first channel 121, to ensure that the laser light, after being focused by the emitting lens, accurately enters the airflow channel 110 along the channel axis. The receiving lens 500 is disposed within the second channel 131 on one side near the airflow channel 110, and the optical axis of the receiving lens 500 is collinear with the central axis of the second channel 131, to ensure that the scattered light is efficiently focused along the axis by the receiving lens 500 to the photoelectric sensor 400, avoiding spot shift or energy loss due to lens eccentricity. The central axis of the first channel 121 and the central axis of the second channel 131 are perpendicular to each other. Understandably, the first channel 121 and the second channel 131 are set at a 90° angle. For example, the central axis of the first channel 121 is in the horizontal direction, and the central axis of the second channel 131 is in the vertical direction. In this way, the laser incident direction and the scattered light receiving direction are at a 90° right angle, effectively separating the direct laser and the scattered light, reducing the interference of the incident light on the photoelectric sensor 400, and ensuring that the scattered light is captured by the receiving lens 500 at the optimal angle (the vertical direction has the highest scattering intensity); thus significantly improving the optical alignment accuracy. In addition, the emitting lens 300 is close to the first channel 121, shortening the transmission distance of the laser in the cavity and increasing the energy density of the laser focus after focusing; the receiving lens 500 is close to the airflow channel 110, shortening the transmission path of the scattered light, improving the light energy utilization rate, and enhancing the detection capability of weak signals (such as scattered light from low-concentration PM2.5 particles); thus improving detection efficiency and sensitivity.

[0049] According to one or more embodiments of the present invention, the emitting lens 300 has two opposing curved surfaces, one of which is inserted into the first channel 121. Thus, the two opposing curved surfaces reduce the size of the focused laser spot, increase the laser focus energy density, and enhance the intensity of light scattered by particles; the insertion of the lens portion into the first channel 121 reduces the transmission distance of the laser from the lens to the airflow channel 110, reduces light energy loss, and simultaneously avoids stray reflections of the beam within the receiving cavity.

[0050] Preferably, the laser module structure further includes an emitting lens tube 600 disposed within the first receiving cavity 120. One end of the emitting lens tube 600 has a radially constricted portion 610, and the radially constricted portion 610 has a through hole communicating with the inside of the emitting lens tube 600. The laser emitter 200 is disposed within the emitting lens tube 600, and the emitting lens 300 is fitted onto the radially constricted portion 610, with the other curved surface of the emitting lens 600 inserted into the through hole. In this way, the emitting lens tube 600 provides a rigid mounting reference for the laser emitter 200. The through hole in the radially constricted portion 610 and the lens insertion cooperate to achieve coaxial positioning of the emitting lens 300 and the laser emitter 200, ensuring that the laser is accurately focused along a preset path onto the airflow channel 110. The constricted portion reduces the diameter of the through hole, allowing only the focused beam to pass through the first channel 121, blocking stray reflected light from entering the first channel 121 and subsequently into the airflow channel 110. Furthermore, the laser emitter 200 is pre-installed in the emitting lens tube 600 and the lens is then integrated into the first receiving cavity 120. The constricted part is fitted with a structure to achieve positioning and reduce calibration procedures. The curved surface of the lens is inserted into a perforation to form a radial limit, which is fixed in conjunction with the emitting lens tube 600. Under vibration conditions, the lens displacement is reduced and the optical stability is improved.

[0051] Furthermore, the emitting lens 300 is mounted on the emitting lens barrel 600 using a first fixing adhesive 710. The first fixing adhesive 710 can be a UV fixing adhesive.

[0052] According to one or more embodiments of the present invention, the second channel 131 expands radially at one end toward the second receiving cavity 130 to form a slot 132. The receiving lens 500 is mounted in the slot 132 and has a receiving end face extending from the second channel 131 toward the airflow channel 110 and a curved surface toward the photoelectric sensor 400. Thus, the slot 132 formed by the radial expansion of the second channel 131 forms a radial rigid constraint on the receiving lens 500 (in conjunction with the collinear optical axis design), ensuring that the central axis of the lens has a small axial deviation from the second channel 131. The scattered light can be accurately projected onto the center of the photosensitive surface of the photoelectric sensor 400 after being focused by the receiving lens 500. The receiving end face extends from the second channel 131 toward the airflow channel 110, making the optical surface of the receiving lens 500 closer to the area where the scattered light is generated, reducing the propagation loss of the scattered light in the air medium. Especially for weak scattered signals (such as PM1.0 ultrafine particles), it can effectively capture low-intensity light signals and improve detection sensitivity. In addition, the curved surface of the receiving lens 500 facing the photoelectric sensor 400 serves as the main optical surface, which can converge the scattered light from multiple angles to the photosensitive surface of the photoelectric sensor 400; while the extended end face serves as the incident surface, ensuring that the scattered light is incident on the receiving lens 500 at a near-vertical angle, reducing Fresnel reflection loss; the curved surface serves as the exit surface for synchronous focusing, improving the overall light energy transmission efficiency.

[0053] According to one or more embodiments of the present invention, the housing 100 has a third channel 140, which communicates with the airflow channel 110 and is coaxially arranged with the first channel 121. A reflector 800 is provided on the third channel 140, configured to unidirectionally reflect light passing through the airflow channel 110 and entering the third channel 140 back into the third channel 140, thereby blocking light within the third channel 140 from re-entering the airflow channel 110. Thus, by coaxially arranging the third channel 140 with the first channel 121, it is ensured that the remaining laser light passing through the airflow channel 110 propagates in a straight line, preventing the laser from obliquely striking the non-optical inner wall of the housing 100 and reducing stray light; and the light entering the third channel 140 is reflected by the reflector 800 within the third channel 140. In other words, the third channel 140 effectively absorbs the light passing through the airflow channel 110, blocking the light from re-entering the airflow channel 110, preventing stray light interference with detection, and ensuring that the stray light received by the photoelectric sensor 400 is less than 130 nW in the absence of particles. By reducing stray light, the receiving lens 500 can accurately capture the weak light signals scattered by particles.

[0054] Preferably, the reflector 800 is obliquely disposed on the housing 100 and covers the end of the third channel 140 away from the airflow channel 110. The end of the third channel 140 communicating with the airflow channel 110 has a constricted through-hole 141. The inner diameter of the constricted through-hole 141 is smaller than the inner diameter of the third channel 140, and the tilt angle of the reflector 800 matches the axis of the constricted through-hole 141 to block light from entering the airflow channel 110 from the third channel 140. That is, as... Figure 4 As shown, the reflector 800 is tilted so that incident light (propagating along the axis of the third channel) enters the surface of the reflector 800 at a non-perpendicular angle, thus reflecting the light to the inner wall and bottom surface of the third channel 140. The constricted through-hole 141 allows light to smoothly enter the third channel 140, while the inner wall of the third channel 140, except for the area of ​​the constricted through-hole 141, prevents the light reflected by the tilted reflector 800 from entering the airflow channel 110 in the opposite direction. This collects stray light within the third channel 140, preventing stray light from interfering with detection. Preferably, the tilt angle of the reflector 800 can be 55° between the reflector 800 and the axis of the third channel 140, thus cooperating with the constricted through-hole 141 to prevent the light reflected by the tilted reflector 800 from entering the airflow channel 110 in the opposite direction.

[0055] Preferably, the receiving lens 500 is mounted to the second channel 131 using a second adhesive 720. The reflector 800 is mounted to the housing 100 using a third adhesive 730. The second adhesive 720 and the third adhesive 730 can be UV adhesives.

[0056] According to one or more embodiments of the present invention, an air quality sensor is also provided, comprising a circuit board and the aforementioned laser module structure. The laser emitter 200 of the laser module structure is coupled to the circuit board, and the photoelectric sensor 400 is coupled to the circuit board, converting optical signals into electrical signals. This air quality sensor, through the aforementioned laser module structure, improves the sensor's measurement accuracy and provides sufficiently high signal feedback even at low concentrations. The connection relationship between the circuit board and the laser emitter 200 and photoelectric sensor 400 can employ existing technology and will not be described in detail here.

[0057] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0058] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0059] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0060] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0061] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0062] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A laser module structure, characterized by, include: The housing has an airflow channel, a first receiving cavity, and a second receiving cavity. The airflow channel is for the gas to be detected to pass through. The first receiving cavity has a first channel communicating with the airflow channel, and the second receiving cavity has a second channel communicating with the airflow channel. The laser emitter is disposed within the first receiving cavity; An emitting lens is disposed within the first receiving cavity and configured to focus the laser emitted by the laser emitter onto the airflow channel to form a laser focal point; A photoelectric sensor is disposed within the second accommodating cavity; A receiving lens is disposed on the second channel and configured to receive scattered light generated when particulate matter of the gas to be detected in the airflow channel passes through the laser focal point, and to focus the scattered light onto the photoelectric sensor.

2. The laser module structure of claim 1, wherein, The emitting lens is disposed within the first receiving cavity near the first channel, and the optical axis of the emitting lens is collinear with the central axis of the first channel; the receiving lens is disposed within the second channel near the airflow channel, and the optical axis of the receiving lens is collinear with the central axis of the second channel; the central axis of the first channel and the central axis of the second channel are perpendicular to each other.

3. The laser module structure of claim 1, wherein the laser module structure is configured to be mounted on a circuit board. The emitting lens has two opposing curved surfaces, one of which is inserted into the first channel.

4. The laser module structure of claim 3, wherein the laser module structure is configured to be mounted on a circuit board. It also includes a emitting lens tube disposed in the first receiving cavity. One end of the emitting lens tube is provided with a radially constricted portion. The radially constricted portion is provided with a through hole communicating with the inside of the emitting lens tube. The laser emitter is disposed in the emitting lens tube. The emitting lens is sleeved on the radially constricted portion, and the other curved surface of the emitting lens is inserted into the through hole.

5. The laser module structure of claim 4, wherein the laser module structure is configured to be mounted on a circuit board. The emitting lens is assembled onto the emitting lens tube by a first fixing adhesive.

6. The laser module structure of claim 1, wherein, The second channel expands radially at one end toward the second receiving cavity to form a slot, the receiving lens is mounted in the slot, and has a receiving end face extending from the second channel toward the airflow channel and a curved surface toward the photoelectric sensor.

7. The laser module structure of claim 1, wherein the laser module structure is configured to be mounted on a circuit board. The housing has a third channel that communicates with the airflow channel and is coaxially arranged with the first channel. The third channel is provided with a reflector that is configured to unidirectionally reflect light passing through the airflow channel and entering the third channel back into the third channel, thereby blocking light in the third channel from entering the airflow channel in the opposite direction.

8. The laser module structure of claim 7, wherein the laser module structure is configured to be mounted on a circuit board. The reflector is tilted on the housing and covers the end of the third channel away from the airflow channel. The end of the third channel that communicates with the airflow channel is provided with a constricted through hole. The inner diameter of the constricted through hole is smaller than the inner diameter of the third channel, and the tilt angle of the reflector is matched with the axis of the constricted through hole to block the light in the third channel from entering the airflow channel in the opposite direction.

9. The laser module structure of claim 8, wherein the laser module structure is configured to be mounted on a circuit board. The receiving lens is assembled to the second channel by a second fixing adhesive; the reflector is assembled to the housing by a third fixing adhesive.

10. An air quality sensor, characterized by, include: Circuit board; The laser module structure of any one of claims 1-9, the laser emitter coupled to the circuit board, the optoelectronic sensor coupled to the circuit board and converting optical signals into electrical signals.

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