Laser gas sensor

Abstract

The utility model discloses a laser gas sensor, which relates to the field of optics, and comprises a sensor body, a gas outlet chamber, a gas inlet and a gas outlet, the plurality of reflecting mirrors comprise a first reflecting mirror, a second reflecting mirror and a third reflecting mirror, the first reflecting mirror and the second reflecting mirror are arranged on the sensor body and are arranged at intervals in the first direction, the third reflecting mirror is arranged on the first reflecting mirror, and reflecting surfaces of the first reflecting mirror and the third reflecting mirror are planes and have included angles; the reflecting surface of the second reflecting mirror is a concave surface; the circuit board is arranged on the sensor body, and the laser transmitter and the laser receiver are both connected with the circuit board. Therefore, the third reflecting mirror is arranged on the first reflecting mirror, and the reflecting surfaces of the first reflecting mirror and the third reflecting mirror are planes and have included angles, so that the reflection times of laser can be increased, the structural size of the laser gas sensor can be reduced, the utilization rate of an optical mirror surface can be improved, and the optical path volume ratio can be increased.

Description

Technical Field

[0001] The utility model relates to the field of optics, in particular to a laser gas sensor. Background Art

[0002] In related technologies, in order to improve the sensitivity of a laser gas sensor, most of them use an optical multi-pass absorption cell to make the laser reflect multiple times within a limited volume to achieve a longer optical path and stronger absorption. However, the existing laser gas sensors are not reasonably designed, and the structural size of the laser gas sensor is large and the utilization rate of the optical mirror is low, resulting in a reduction in the optical path volume ratio. Summary of the Utility Model

[0003] The utility model aims to at least solve one of the technical problems existing in the prior art. For this purpose, an object of the utility model is to provide a laser gas sensor with a high optical path volume ratio.

[0004] The laser gas sensor according to the utility model includes: a sensor body that defines a gas chamber; a plurality of reflectors, the plurality of reflectors including: a first reflector, a second reflector, and a third reflector. The first reflector and the second reflector are both provided on the sensor body and are spaced apart along a first direction. The third reflector is provided on the first reflector. The reflecting surfaces of the first reflector and the third reflector are both flat and have an included angle. The reflecting surface of the second reflector is concave; a circuit board, a laser emitter, and a laser receiver. The circuit board is provided on the sensor body. The laser emitter and the laser receiver are both connected to the circuit board. The laser emitter is used to emit a laser beam into the gas chamber. The laser beam can be reflected multiple times by the plurality of reflectors in the gas chamber. The laser receiver is used to receive the laser beam after being reflected multiple times.

[0005] According to the laser gas sensor of the utility model, by providing the third reflector on the first reflector and making the reflecting surfaces of the first reflector and the third reflector both flat and having an included angle, the number of reflections of the laser can be increased, thereby reducing the structural size of the laser gas sensor and improving the utilization rate of the optical mirror, which is beneficial to increasing the optical path volume ratio.

[0006] In some examples of the utility model, the first reflector has a first through hole and a second through hole. The laser emitter corresponds to the first through hole, and the laser receiver corresponds to the second through hole.

[0007] In some examples of the utility model, the third reflector is located at a position where the laser beam reaches the first reflector after being reflected once or three times by the second reflector.

[0008] In some examples of the present utility model, the first reflector has a mounting groove, and at least a part of the third reflector is disposed in the mounting groove.

[0009] In some examples of the present utility model, a part of the reflecting surface of the third reflector is coplanar with the reflecting surface of the first reflector.

[0010] In some examples of the present utility model, the first through hole and the second through hole are arranged at intervals in the second direction. Along the second direction, and from the first through hole to the second through hole, the reflecting surface of the third reflector gradually inclines away from the second reflector.

[0011] In some examples of the present utility model, the focal length of the second reflector is f, and the perpendicular distance between the center of the second reflector and the first reflector is D, satisfying the relational expression: 0.95f ≤ D ≤ 1.05f.

[0012] In some examples of the present utility model, at least a part of the first reflector is disposed in the gas chamber, and / or at least a part of the second reflector is disposed in the gas chamber.

[0013] In some examples of the present utility model, the laser gas sensor further includes: insulating members. The number of the insulating members is two. Both of the two insulating members are disposed on the circuit board and have mounting surfaces. The mounting surfaces form an included angle with the reflecting surface of the first reflector. The laser emitter and the laser receiver are respectively disposed on the mounting surfaces of the two insulating members.

[0014] In some examples of the present utility model, the reflecting surfaces of the first reflector, the second reflector and the third reflector are all coated with high-reflection dielectric films.

[0015] The additional aspects and advantages of the present utility model will be partly given in the following description, partly will become obvious from the following description, or will be understood through the practice of the present utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and / or additional aspects and advantages of the present utility model will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, in which:

[0017] Figure 1 is an exploded view of the laser gas sensor according to an embodiment of the present utility model;

[0018] Figure 2 is an optical path diagram (with the third reflector provided) of the laser gas sensor according to an embodiment of the present utility model;

[0019] Figure 3is the optical path diagram of the laser gas sensor according to the embodiment of the present invention (the third reflector is not provided);

[0020] Figure 4 is the spot distribution diagram on the first reflector of the laser gas sensor according to the embodiment of the present invention.

[0021] Reference numerals:

[0022] Laser gas sensor 100;

[0023] Circuit board 1; Laser emitter 2; Laser receiver 3; Insulating member 4;

[0024] Sensor body 5; Gas chamber 51; First reflector 6; First through hole 601; Second through hole 602; Mounting groove 603;

[0025] Third reflector 7; Second reflector 8; Cross screw 9; Wiring harness 10. Specific embodiments

[0026] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where 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 by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as limiting the present invention.

[0027] Below, refer to Figures 1 - 4 to describe the laser gas sensor 100 according to the embodiment of the present invention.

[0028] As Figures 1 - 3 shown, the laser gas sensor 100 according to the embodiment of the present invention includes: a sensor body 5, a plurality of reflectors, a circuit board 1, a laser emitter 2, and a laser receiver 3.

[0029] The sensor body 5 defines a gas chamber 51; the plurality of reflectors include: a first reflector 6, a second reflector 8, and a third reflector 7. The first reflector 6 and the second reflector 8 are both provided on the sensor body 5 and are spaced apart along a first direction (i.e., Figure 2 the X direction shown), the third reflector 7 is provided on the first reflector 6, the reflecting surfaces of the first reflector 6 and the third reflector 7 are both flat and have an included angle, and the reflecting surface of the second reflector 8 is concave; the laser emitter 2 and the laser receiver 3 are both connected to the circuit board 1. The laser emitter 2 is used to emit a laser beam into the gas chamber 51, and the laser beam can be reflected multiple times by the plurality of reflectors in the gas chamber 51, and the laser receiver 3 is used to receive the laser beam after being reflected multiple times.

[0030] Among them, the sensor body 5 defines a gas chamber 51. As some embodiments of the present application, the laser gas sensor 100 can be used to detect the gas concentration. The gas can be, but is not limited to, gases such as methane, carbon monoxide, and carbon dioxide. As some embodiments of the present application, the gas in the gas chamber 51 is methane. The sensor body 5 is connected to the circuit board 1. The connection manner between the sensor body 5 and the circuit board 1 can be, but is not limited to, clamping, bolt connection, etc. As some embodiments of the present application, the circuit board 1 and the sensor body 5 are connected by means of bolt connection.

[0031] The plurality of reflectors include a first reflector 6, a second reflector 8, and a third reflector 7. The first reflector 6 is connected to the sensor body 5. The connection manner between the first reflector 6 and the sensor body 5 can be, but is not limited to, clamping, bonding, etc. As some embodiments of the present application, the first reflector 6 and the sensor body 5 are connected by means of bonding. The second reflector 8 is connected to the sensor body 5. The connection manner between the second reflector 8 and the sensor body 5 can be, but is not limited to, clamping, bonding, etc. As some embodiments of the present application, the second reflector 8 and the sensor body 5 are connected by means of bonding. The first reflector 6 and the second reflector 8 are spaced apart along the first direction (i.e., Figure 2 the X direction shown).

[0032] The first reflector 6 is connected to the third reflector 7. The connection manner between the first reflector 6 and the third reflector 7 can be, but is not limited to, clamping, bonding connection, etc. As some embodiments of the present application, the first reflector 6 and the third reflector 7 are connected by means of bonding. The reflecting surface of the first reflector 6 is a plane, the reflecting surface of the third reflector 7 is a plane, the reflecting surface of the second reflector 8 is a concave surface, and the reflecting surfaces of the first reflector 6 and the third reflector 7 have an included angle. The size of the included angle can be, but is not limited to, 10 degrees, 15 degrees, 20 degrees, etc. As some embodiments of the present application, the included angle between the reflecting surfaces of the first reflector 6 and the third reflector 7 is 15 degrees.

[0033] As some embodiments of the present application, both the first reflector 6 and the second reflector 8 can be bonded to the sensor body 5 by epoxy resin AB glue, and the third reflector 7 can be bonded to the first reflector 6 by epoxy resin AB glue.

[0034] The laser emitter 2 is connected to the circuit board 1. As some embodiments of the present application, the laser emitter 2 and the laser receiver 3 are respectively connected to the circuit board 1 by means of electrical connection.

[0035] The laser emitter 2 is capable of emitting a laser beam towards the gas chamber 51. The laser beam can be reflected multiple times by a plurality of reflectors within the gas chamber 51. The laser receiver 3 is used to receive the laser beam after multiple reflections. It can be understood that the gas within the gas chamber 51 can absorb the laser. The laser receiver 3 can receive the laser emitted by the laser emitter 2 and reflected by a plurality of reflectors, so that the circuit board 1 can detect the concentration of the gas.

[0036] It should be noted that the reflection surface area of the third reflector 7 is much smaller than that of the first reflector 6. The reflection surfaces of the first reflector 6 and the third reflector 7 are both flat, and moreover, there is an included angle between the reflection surface of the first reflector 6 and the reflection surface of the third reflector 7. This enables the laser beam emitted by the laser emitter 2 to be reflected multiple times by a plurality of reflectors, thereby increasing the optical path of the laser gas sensor 100. It can be understood that, as Figure 3 shown, if the third reflector 7 is not provided, the laser beam will exit the gas chamber 51 through the first through hole 601 of the first reflector 6 after being reflected four times by the second reflector 8, and coincides with the main beam position of the incident beam and has the opposite direction, that is, the beam enters through the first through hole 601 of the first reflector 6 and exits through the first through hole 601 of the first reflector 6. In this way, it is not only difficult to distinguish the incident beam and the reflected beam, but also the optical path of the laser gas sensor 100 is short, resulting in low sensitivity of the laser gas sensor 100. Moreover, the laser beam path cannot be effectively adjusted, resulting in a reduction in the use reliability of the laser gas sensor 100.

[0037] However, in the present application, as Figure 2 shown, by providing the third reflector 7, the number of reflections of the laser beam between a plurality of reflectors can be increased. Moreover, the laser beam will finally exit the gas chamber 51 through the second through hole 602 of the first reflector 6, so that the incident beam and the reflected beam can be clearly distinguished. Moreover, the optical path of the laser gas sensor 100 is long, which can improve the sensitivity of the laser gas sensor 100. And, it is convenient to replace the third reflector 7 to adjust the laser beam path, which is beneficial to improving the use reliability of the laser gas sensor 100.

[0038] As some embodiments of the present application, the circuit board 1 is fixed to the sensor body 5 by a cross screw 9.

[0039] As some embodiments of the present application, the circuit board 1 is connected to a wire harness 10 to supply power to the circuit board 1 and enable information transmission.

[0040] Thus, by providing the third reflector 7 on the first reflector 6 and making the reflecting surfaces of the first reflector 6 and the third reflector 7 both planar and having an included angle, the number of reflections of the laser can be increased, thereby reducing the structural size of the laser gas sensor 100, improving the utilization rate of the optical mirror surface, and thus being conducive to increasing the optical path volume ratio.

[0041] In some embodiments of the present invention, as Figure 3 and Figure 4 shown, the first reflector 6 has a first through hole 601 and a second through hole 602, the laser emitter 2 corresponds to the first through hole 601, and the laser receiver 3 corresponds to the second through hole 602.

[0042] Among them, the first reflector 6 has a first through hole 601 and a second through hole 602, and the first through hole 601 and the second through hole 602 are spaced along the second direction (i.e., Figure 2 the Y direction shown), the laser emitter 2 is correspondingly arranged with the first through hole 601, and the laser receiver 3 is correspondingly arranged with the second through hole 602. That is to say, the laser beam emitted by the laser emitter 2 enters the gas chamber 51 through the first through hole 601, and after being reflected by multiple reflectors, the laser beam exits through the second through hole 602 and is received by the laser receiver 3.

[0043] By making the first reflector 6 have a first through hole 601 and a second through hole 602, and by making the laser emitter 2 correspond to the first through hole 601 and the laser receiver 3 correspond to the second through hole 602, the laser beam can be avoided, so that the laser beam emitted by the laser emitter 2 enters the gas chamber 51, and the laser beam after multiple reflections can be received by the laser receiver 3. Moreover, the routes of the laser beam entering and exiting the gas chamber 51 can be made non-overlapping, which is conducive to clearly distinguishing the incident beam and the reflected beam.

[0044] In some embodiments of the present invention, as Figure 3 and Figure 4 shown, the third reflector 7 is located at the position where the laser beam reaches the first reflector 6 after being reflected by the second reflector 8 once or three times.

[0045] Among them, when the laser beam enters the gas chamber 51 through the first through hole 601, it will first hit the second reflector 8, and the second reflector 8 reflects the laser beam towards the first reflector 6. This is the first reflection of the second reflector 8, and the third reflector 7 can be arranged at the position where the laser beam reaches the first reflector 6 after being reflected by the second reflector 8 once.

[0046] Alternatively, when the laser beam enters the gas chamber 51 through the first through hole 601, it will first hit the second mirror 8. The second mirror 8 reflects the laser beam towards the first mirror 6. This is the first reflection of the second mirror 8. The first mirror 6 reflects the laser beam towards the second mirror 8. When the laser beam reaches the second mirror 8, the second mirror 8 reflects the laser beam towards the first mirror 6 again. This is the second reflection of the second mirror 8. The first mirror 6 reflects the laser beam towards the second mirror 8. When the laser beam reaches the second mirror 8, the second mirror 8 reflects the laser beam towards the first mirror 6 again. This is the third reflection of the second mirror 8. The third mirror 7 can be arranged at the position where the laser beam reaches the first mirror 6 after being reflected three times by the second mirror 8.

[0047] By arranging the third mirror 7 at the position where the laser beam reaches the first mirror 6 after being reflected once or three times by the second mirror 8, the installation position of the third mirror 7 can be made reasonable, and multiple reflections of the laser beam can be achieved, so as to increase the optical path of the laser gas sensor 100 and improve the utilization rate of the optical mirror surface, which is beneficial to increasing the optical path volume ratio and improving the sensitivity of the laser gas sensor 100.

[0048] In some embodiments of the present utility model, as Figure 3 shown, the first mirror 6 has a mounting groove 603, and at least a part of the third mirror 7 is arranged in the mounting groove 603.

[0049] Among them, the first mirror 6 has a mounting groove 603, and at least a part of the third mirror 7 is arranged in the mounting groove 603. That is to say, a part of the third mirror 7 is arranged in the mounting groove 603, or the whole of the third mirror 7 is arranged in the mounting groove 603.

[0050] By arranging at least a part of the third mirror 7 in the mounting groove 603, it is convenient to install the third mirror 7, and the installation of the third mirror 7 can be made firm, the probability of the third mirror 7 moving can be reduced, and thus the use reliability of the laser gas sensor 100 can be improved.

[0051] In some embodiments of the present utility model, a part of the reflecting surface of the third mirror 7 is coplanar with the reflecting surface of the first mirror 6.

[0052] Among them, a part of the reflecting surface of the third mirror 7 is coplanar with the reflecting surface of the first mirror 6. As some embodiments of the present application, along the second direction (i.e., Figure 2 the Y direction shown), the upper end of the reflecting surface of the third mirror 7 is coplanar with the reflecting surface of the first mirror 6, or the lower end of the reflecting surface of the third mirror 7 is coplanar with the reflecting surface of the first mirror 6, or a part of the reflecting surface between the upper end and the lower end of the reflecting surface of the third mirror 7 is coplanar with the reflecting surface of the first mirror 6.

[0053] By making a part of the reflecting surface of the third mirror 7 coplanar with the reflecting surface of the first mirror 6, the setting position of the reflecting surface of the third mirror 7 can be made reasonable, which is beneficial to increasing the number of reflections of the laser beam between multiple mirrors, and thus beneficial to improving the sensitivity of the laser gas sensor 100.

[0054] In some embodiments of the present invention, as Figure 3 and Figure 4 shown, the first through hole 601 and the second through hole 602 are arranged at intervals along the second direction (i.e., Figure 2 the Y direction shown), along the second direction (i.e., Figure 2 the Y direction shown), and from the first through hole 601 to the second through hole 602, the reflecting surface of the third mirror 7 gradually tilts away from the second mirror 8.

[0055] Among them, along the second direction (i.e., Figure 2 the Y direction shown), and from the first through hole 601 to the second through hole 602, the reflecting surface of the third mirror 7 gradually tilts away from the second mirror 8, that is to say, along the second direction (i.e., Figure 2 the Y direction shown), and from the second through hole 602 to the first through hole 601, the reflecting surface of the third mirror 7 gradually tilts towards the second mirror 8.

[0056] Such a setting can make the inclination angle between the normal of the reflecting surface of the third mirror 7 and the normal of the reflecting surface of the first mirror 6 an acute angle, so that the optical path of the laser gas sensor 100 can be increased, which is beneficial to improving the sensitivity of the laser gas sensor 100.

[0057] In some embodiments of the present invention, the focal length of the second mirror 8 is f, and the vertical distance between the center of the second mirror 8 and the first mirror 6 is D, satisfying the relationship: 0.95f ≤ D ≤ 1.05f.

[0058] Among them, the focal length of the second mirror 8 is f, and the vertical distance between the center of the second mirror 8 and the first mirror 6 is D. f and D can satisfy the relationship: 0.95f ≤ D ≤ 1.05f, that is, the vertical distance D between the center of the second mirror 8 and the first mirror 6 can be any value between 0.95f and 1.05f. For example, the vertical distance D between the center of the second mirror 8 and the first mirror 6 can be, but is not limited to, 0.95f, 1.00f, 1.05f, etc. As some embodiments of the present application, the vertical distance D between the center of the second mirror 8 and the first mirror 6 can be 1.00f.

[0059] By making the vertical distance D between the center of the second mirror 8 and the first mirror 6 can be any value between 0.95f and 1.05f, the vertical distance D between the center of the second mirror 8 and the first mirror 6 can be approximately equal to or equal to the focal length of the second mirror 8, so that a confocal optical system can be constructed. Such a setting can improve the utilization rate of the optical mirror surface, which is beneficial to increasing the optical path volume ratio and improving the reliability of the laser gas sensor 100.

[0060] In some embodiments of the present invention, at least part of the first mirror 6 is disposed in the gas chamber 51, and / or at least part of the second mirror 8 is disposed in the gas chamber 51.

[0061] Among them, at least part of the first mirror 6 being disposed in the gas chamber 51 can be understood as part of the first mirror 6 being disposed in the gas chamber 51, or all of the first mirror 6 being disposed in the gas chamber 51. At least part of the second mirror 8 being disposed in the gas chamber 51 can be understood as part of the second mirror 8 being disposed in the gas chamber 51, or all of the second mirror 8 being disposed in the gas chamber 51.

[0062] At least part of the first mirror 6 is disposed in the gas chamber 51, and / or at least part of the second mirror 8 is disposed in the gas chamber 51, that is to say, at least part of the first mirror 6 is disposed in the gas chamber 51, or at least part of the second mirror 8 is disposed in the gas chamber 51, or at least part of the first mirror 6 is disposed in the gas chamber 51, and at least part of the second mirror 8 is disposed in the gas chamber 51.

[0063] By making at least part of the first mirror 6 disposed in the gas chamber 51, and / or at least part of the second mirror 8 disposed in the gas chamber 51, the positions of the first mirror 6 and the second mirror 8 can be reasonably set, which is beneficial to the structural compactness of the laser gas sensor 100 and the miniaturized design of the laser gas sensor 100.

[0064] In some embodiments of the present invention, as Figure 1 shown, the laser gas sensor 100 further includes: insulating members 4. The number of insulating members 4 is two. Both insulating members 4 are disposed on the circuit board 1 and have mounting surfaces. The mounting surfaces have an included angle with the reflecting surface of the first mirror 6. The laser emitter 2 and the laser receiver 3 are respectively disposed on the mounting surfaces of the two insulating members 4.

[0065] Among them, the laser gas sensor 100 further includes insulating members 4. The number of insulating members 4 is two. Both insulating members 4 are connected to the circuit board 1. The connection manner between the insulating members 4 and the circuit board 1 can be but not limited to snap connection, bolt connection, etc. As some embodiments of the present application, the insulating members 4 are connected to the circuit board 1 by snap connection.

[0066] Both of the two insulating parts 4 have mounting surfaces. The mounting surfaces of the two insulating parts 4 and the reflecting surface of the first mirror 6 both have an included angle, and the magnitude of the included angle can be, but is not limited to, 15 degrees, 30 degrees, 45 degrees, etc. The laser emitter 2 and the laser receiver 3 are respectively arranged on the mounting surfaces of the two insulating parts 4, and the connection manners of the laser emitter 2 and the laser receiver 3 with the two insulating parts 4 can be, but are not limited to, bolt connection, snap connection, bonding, etc. As some embodiments of the present application, the laser emitter 2 and the laser receiver 3 are connected to the mounting surface by bonding. Both of the two insulating parts 4 can have avoidance through holes, and the pins of the laser emitter 2 and the laser receiver 3 can pass through the corresponding avoidance through holes of the insulating parts 4 and be soldered to the circuit board 1.

[0067] As some embodiments of the present application, the insulating part 4 can be constructed as bakelite.

[0068] By making the mounting surface and the reflecting surface of the first mirror 6 have an included angle, the laser beam emitted by the laser emitter 2 into the gas chamber 51 can have a certain inclination angle, and moreover, the laser receiver 3 can receive the laser beam with a certain inclination angle, which can make the laser emitter 2 and the laser receiver 3 be reasonably arranged, be beneficial to increasing the number of reflections of the laser beam between multiple mirrors, can improve the utilization rate of the optical mirror surface, and thus is beneficial to increasing the optical path volume ratio.

[0069] In some embodiments of the present invention, the reflecting surfaces of the first mirror 6, the second mirror 8 and the third mirror 7 are all coated with a high-reflection dielectric film.

[0070] Among them, the high-reflection dielectric film is a thin film material with a high reflectivity, which can reflect most of the light within a specific wavelength range, can significantly improve the reflectivity, make the laser beam lose less during reflection, thereby increasing the optical path length and the number of interactions between the laser beam and the gas, improving the sensitivity and accuracy of measurement. In addition, it can maintain a stable optical path and will not cause the weakening of the laser beam signal due to reflection loss. As some embodiments of the present application, a gold film can be selected as the high-reflection dielectric film of the first mirror 6, the second mirror 8 and the third mirror 7. The gold film can also increase the corrosion resistance and wear resistance of the first mirror 6, the second mirror 8 and the third mirror 7, can effectively reduce the degree of surface corrosion of the first mirror 6, the second mirror 8 and the third mirror 7 by the gas, and extend the service life of the laser gas sensor 100.

[0071] By coating the reflecting surfaces of the first mirror 6, the second mirror 8, and the third mirror 7 with a high-reflection dielectric film, the loss during reflection of the first mirror 6, the second mirror 8, and the third mirror 7 can be reduced, which is beneficial to improving the sensitivity and service reliability of the laser gas sensor 100. Moreover, such a setting can increase the corrosion resistance and wear resistance of the first mirror 6, the second mirror 8, and the third mirror 7, effectively reduce the degree of gas corrosion on the surfaces of the first mirror 6, the second mirror 8, and the third mirror 7, and extend the service life of the laser gas sensor 100.

[0072] It should be noted that, as Figure 4 shown, the introduction of the third mirror 7 changes the position of the even-numbered reflection light spots on the first mirror 6, while the position of the odd-numbered reflection light spots remains unchanged. Therefore, the light beam reflected four times by the second mirror 8 will not exit from the first through-hole 601, thus realizing multiple reflections. Figure 4 FIG. is the light spot distribution diagram on the first mirror 6 after multiple reflections. Among them, after the second mirror 8 is reflected (4n + 1) times, the light spots located at the same position are denoted as P1; after the second mirror 8 is reflected (4n + 3) times, the light spots located at the same position are denoted as P3; after the second mirror 8 is reflected (4n + 2) times, the light spot positions are denoted as P2, P6, P10, etc. The light spots after the second mirror 8 is reflected (4n + 2) times are along the same straight line as the first through-hole 601 and the second through-hole 602, and this straight line is denoted as L2; after the second mirror 8 is reflected (4n + 4) times, the light spot positions are denoted as P4, P8, P12, etc. The light spots after the second mirror 8 is reflected (4n + 4) times are on the same straight line, and this straight line is denoted as L4; L2 and L4 are parallel to each other, and the interval between adjacent light spots on the straight line is obtained from the following formula:

[0073] ΔP = tan(2θ) * f

[0074] where, ΔP is the interval between adjacent light spots, θ is the inclination angle between the normal of the third mirror 7 and the normal of the first mirror 6, and f is the focal length of the second mirror.

[0075] The laser beam enters the gas chamber 51 through the first through-hole 601 and exits from the second through-hole 602 after multiple reflections. Let the input beam diameter of the first through-hole 601 be R0 and the divergence angle be B0; the beam diameter reaching the first mirror 6 after the second mirror 8 is reflected once is R1 and the divergence angle is B1; the beam diameter reaching the first mirror 6 after the second mirror 8 is reflected twice is R2 and the divergence angle is B2; the beam diameter reaching the first mirror 6 after the second mirror 8 is reflected three times is R3 and the divergence angle is B3; then the following relationship exists:

[0076] R1 = R3, B1 = B3

[0077] R0 = R2, B0 = B2

[0078] That is, after an even number of reflections by the second mirror 8, the beam diameter and divergence angle reaching the first mirror 6 are the same as those of the input beam; after an odd number of reflections by the second mirror 8, the beam diameter and divergence angle reaching the first mirror 6 are the same.

[0079] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0080] In the description of the present invention, the "first feature" and "second feature" may include one or more of such features.

[0081] In the description of the present invention, the meaning of "a plurality" is two or more.

[0082] In the description of the present invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween.

[0083] In the description of the present invention, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature.

[0084] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0085] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A laser gas sensor, characterized in that: include: a sensor body, the sensor body defining an outlet chamber; A plurality of reflectors, the plurality of reflectors comprising: a first reflector, a second reflector and a third reflector, the first reflector and the second reflector are both disposed on the sensor body and spaced apart along a first direction, the third reflector is disposed on the first reflector, the reflective surfaces of the first reflector and the third reflector are both planes and have an angle, and the reflective surface of the second reflector is a concave surface; A circuit board, a laser transmitter and a laser receiver, wherein the circuit board is arranged on the sensor body, the laser transmitter and the laser receiver are both connected to the circuit board, the laser transmitter is used to transmit a laser beam to the air chamber, the laser beam can be reflected multiple times by the multiple reflectors in the air chamber, and the laser receiver is used to receive the laser beam after being reflected multiple times.

2. The laser gas sensor according to claim 1, characterized in that: The first reflector has a first through hole and a second through hole, the laser transmitter corresponds to the first through hole, and the laser receiver corresponds to the second through hole.

3. The laser gas sensor according to claim 1, characterized in that: The third reflecting mirror is located at a position where the laser beam reaches the first reflecting mirror after being reflected once or three times by the second reflecting mirror.

4. The laser gas sensor according to claim 1, characterized in that: The first reflector has a mounting groove, and at least a portion of the third reflector is disposed in the mounting groove.

5. The laser gas sensor according to claim 1, characterized in that: A portion of the reflective surface of the third reflector is coplanar with the reflective surface of the first reflector.

6. The laser gas sensor according to claim 2, characterized in that: The first through holes and the second through holes are arranged at intervals along a second direction. Along the second direction and from the first through holes to the second through holes, the reflecting surface of the third reflector gradually tilts toward a direction away from the second reflector.

7. The laser gas sensor according to claim 1, characterized in that: The focal length of the second reflector is f, and the vertical distance between the center of the second reflector and the first reflector is D, satisfying the relationship: 0.95f≤D≤1.05f.

8. The laser gas sensor according to claim 1, characterized in that: At least a portion of the first reflector is disposed within the air chamber, and / or at least a portion of the second reflector is disposed within the air chamber.

9. The laser gas sensor according to claim 1, characterized in that: Also includes: Insulating member, the number of the insulating members is two, the two insulating members are both arranged on the circuit board and have a mounting surface, the mounting surface and the reflecting surface of the first reflector have an angle, and the laser transmitter and the laser receiver are respectively arranged on the mounting surfaces of the two insulating members.

10. The laser gas sensor according to any one of claims 1 to 8, characterized in that: The reflective surfaces of the first reflector, the second reflector and the third reflector are all coated with a high reflective dielectric film.

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