Small infrared gas sensor with long optical path and low loss

Abstract

The utility model discloses a small infrared gas sensor with long optical path and low loss in the technical field of infrared gas sensors, which comprises an optical gas chamber and a signal acquisition circuit module, a plurality of edge plane reflecting surfaces and one or more optical path extension plane reflecting surfaces are arranged on the inner wall of the optical gas chamber, and the optical path extension plane reflecting surfaces are arranged on the inner wall of the optical gas chamber. The light path extension plane reflecting surface is positioned on one side opposite to the edge plane reflecting surfaces, and is used for receiving light rays of one edge plane reflecting surface and reflecting the light rays to the other edge plane reflecting surface, so that the light rays penetrate through the middle area of the optical gas chamber, and the light path length of the light rays in the optical gas chamber is increased. The optical gas chamber is compact in structure, light rays can be reflected for multiple times, the limited space in the optical gas chamber is efficiently utilized, the space utilization rate is improved, miniaturization design is facilitated, the optical path can be increased, and light energy loss caused by reflection can be reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to infrared gas sensor technical field, specifically, it is a long light path, low loss small infrared gas sensor. BACKGROUND

[0002] Infrared gas sensor utilizes the relationship between gas concentration and absorption light intensity (Lambert-Beer law), has response speed fast, measurement precision height, service life long etc. advantage, is widely used in petroleum chemical industry, metallurgical industry, industry mining etc. field. According to Lambert Beer law, the optical path length of sensor determines the detection range of sensor, and low range needs longer optical path gas chamber, and high range needs shorter optical path gas chamber. In order to be able to detect low concentration gas, the optical path of the infrared gas sensor is increased by various methods in the prior art.

[0003] For example, the patent with publication number CN117030610A discloses a gas sensor, which sequentially sets a first off-axis parabolic surface, a plurality of elliptical reflecting surfaces, a parabolic reflecting surface and a second off-axis parabolic surface inside the shell. The light emitted by the light source is incident and reflected on the surfaces in sequence, which improves the optical path structure of the existing gas sensor and increases the optical path. However, it is obvious that the optical path does not pass through the space in the middle of the shell, and the optical path design of this sensor wastes a lot of internal space.

[0004] In order to make full use of the internal space of the sensor, some sensors also design the optical path to pass through the middle area, for example, the patent with publication number CN114910417A discloses a compact and efficient gas sensor chamber structure, which is composed of a concave mirror, a first plane mirror placed at 45 degrees, a second plane mirror placed at 45 degrees, and a third plane mirror whose mirror surface is orthogonal to the incident light of the gas chamber. The first plane mirror, the second plane mirror and the third plane mirror are all arranged opposite to the concave mirror. This optical path structure can make full use of the space inside the gas chamber, but the transverse structure of this sensor is relatively long, resulting in a large volume of the entire sensor. This type of gas chamber structure is not suitable for the application of small volume sensors.

[0005] Some sensors also choose to design multiple reflections in the optical path design in order to make the most of the space inside the gas chamber and increase the optical path length, for example, the patent with publication number CN110361355A discloses a spiral gas concentration detection device, which has a spiral slot in the reflection chamber, so that the light forms multiple reflections inside the spiral slot, which can make use of the space inside the gas chamber and increase the optical path length. However, in this type of structure, the light reflects many times in the spiral slot, and each reflection has a certain loss of light energy, which results in a lot of light energy loss during gas detection.

[0006] Therefore, there is a need for a sensor structure that can fully utilize the space in the optical chamber, reduce light energy loss, and achieve miniaturized design. Utility model content

[0007] In order to overcome the deficiencies of the prior art, the utility model provides a long optical path, low loss small infrared gas sensor, its structure is compact, can utilize the design of optical chamber light path extension plane reflection surface makes light multiple reflection, efficient use of the limited space in the optical chamber, in order to improve space utilization, improve optical path and reduce the light energy loss caused by reflection, simultaneously, the utility model can reduce the size of the whole sensor, is favorable to miniaturized design.

[0008] The utility model technical scheme is as follows:

[0009] A long optical path, low loss small infrared gas sensor, including optical chamber and signal acquisition circuit module, the optical chamber is hollow structure, the signal acquisition circuit module includes infrared light source and detector, the top of infrared light source and the detector is located inside the optical chamber, its characterized in that,

[0010] The inner wall of the optical chamber is provided with a plurality of edge plane reflection surfaces, one or more light path extension plane reflection surfaces, the light path extension plane reflection surface is located on the opposite side of the edge plane reflection surface, the light path extension plane reflection surface is used to receive the light of one edge plane reflection surface and reflect it to another edge plane reflection surface, so that the light passes through the middle region of the optical chamber to increase the light path length of the light in the optical chamber.

[0011] According to the utility model of the above scheme, its characterized in that, the edge plane reflection surface includes but is not limited to first edge plane reflection surface, second edge plane reflection surface, third edge plane reflection surface, fourth edge plane reflection surface, the light path extension edge plane reflection surface is located on the opposite side of the second edge plane reflection surface, the third edge plane reflection surface, so that the light of the third edge plane reflection surface reflected to the light path extension plane reflection surface, the light of the light path extension plane reflection surface reflected to the second edge plane reflection surface passes through the middle region in the optical chamber.

[0012] According to the utility model of the above scheme, its characterized in that, the inner wall of the optical chamber is further provided with an incident parabolic reflector and an exit parabolic reflector, the incident parabolic reflector corresponds to the position of the infrared light source, and is used to receive the light of the infrared light source and collimate the light to be incident on the edge plane reflection surface, and the exit parabolic reflector corresponds to the position of the detector, and is used to receive the light of the edge plane reflection surface or the light path extension plane reflection surface and focus the light to be incident on the detector.

[0013] Further, the exit parabolic reflector includes but is not limited to a first exit parabolic reflector and a second exit parabolic reflector, both of which are located at the detector, and the first exit parabolic reflector is used to receive the light rays of the edge plane reflector or the light path extension plane reflector and reflect them to the second exit parabolic reflector, and the second exit parabolic reflector is used to receive the light rays of the first exit parabolic reflector and focus them to the detector.

[0014] Further, the focal point of the first exit parabolic reflector and the focal point of the second exit parabolic reflector are located on the same longitudinal axis.

[0015] Further, the outer side of the incident parabolic reflector and the outer side of the second exit parabolic reflector are connected with the inner wall of the optical chamber, the inner side of the incident parabolic reflector and the inner side of the second exit parabolic reflector are both directed to the hollow area of the optical chamber, and the inner concave surface of the incident parabolic reflector is arranged opposite to the inner concave surface of the second exit parabolic reflector.

[0016] Further, the two ends of the light path extension plane reflector are respectively connected with the inner side of the incident parabolic reflector and the inner side of the second exit parabolic reflector.

[0017] According to the above-mentioned scheme, the optical chamber is provided with a gas hole, and the gas hole is in communication with the internal space of the optical chamber.

[0018] According to the above-mentioned scheme, the utility model further includes a cover plate, which is located between the optical chamber and the signal acquisition circuit module, and is used to isolate the signal acquisition circuit of the signal acquisition circuit module from the inside of the optical chamber.

[0019] According to the above-mentioned scheme, the cover plate is provided with a first cover plate via hole and a second cover plate via hole, the first cover plate via hole corresponds to the position of the infrared light source, and is used to allow the top end of the infrared light source to pass through and extend into the optical chamber; the second cover plate via hole corresponds to the position of the detector, and is used to allow the top end of the detector to pass through and extend into the optical chamber.

[0020] The utility model has the advantages that:

[0021] The edge plane reflecting surface can not only increase the utilization ratio of space, effectively increase the optical path length, but also can reduce the reflection times as much as possible to reduce the energy loss of light reflection when propagating the light rays forward.

[0022] In addition, the light path extension plane reflecting surface is arranged at the connecting position of the two parabolic reflecting surfaces distributed in opposite directions, so that the light path extension plane reflecting surface and the parabolic reflecting surface are matched with each other to form a stable optical gas chamber structure, and the matching of the reflecting surfaces can fully utilize the space for layout, realize the miniaturization design of the gas detection sensor, and make the structure more stable. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural exploded view of the infrared gas sensor in the utility model;

[0024] Figure 2 is a schematic view of the optical gas chamber part of the infrared gas sensor in the utility model;

[0025] Figure 3 is a theoretical light path diagram of the infrared gas sensor in the utility model;

[0026] Figure 4 is a light path tracking diagram of the infrared gas sensor in the utility model;

[0027] Figure 5 is a light path tracking diagram of an infrared gas sensor in the prior art;

[0028] Figure 6 is a light path diagram of another infrared gas sensor in the prior art.

[0029] In the drawings, each reference numeral is:

[0030] 1, optical gas chamber; 101, incident parabolic reflecting surface; 102, first edge plane reflecting surface; 103, second edge plane reflecting surface; 104, third edge plane reflecting surface; 105, fourth edge plane reflecting surface; 106, light path extension plane reflecting surface; 107, first exit parabolic reflecting surface; 108, second exit parabolic reflecting surface;

[0031] 2, cover plate; 201, first cover plate via hole; 202, second cover plate via hole;

[0032] 3, signal acquisition circuit module; 301, infrared light source; 302, detector; 303, signal acquisition circuit board. DETAILED DESCRIPTION

[0033] The utility model is further described below in combination with the drawings and embodiments:

[0034] As Figures 1 to 4 The utility model discloses in order to make full use of the structure in optical chamber, to improve the space utilization, and as far as possible reduce the light reflection times, reduce the light loss, propose a long optical path, low loss small -size infrared gas sensor, its utilization optical chamber's design improves the space utilization of sensor, and reduces the loss, can realize the miniaturization design of sensor simultaneously.

[0035] The long optical path, low loss small -size infrared gas sensor includes optical chamber 1 and signal acquisition circuit module 3. Optical chamber 1 is hollow structure, is used to provide the space of light and gas action. The top of optical chamber 1 is equipped with gas hole, and the gas hole is communicated with the internal space of optical chamber 1, can utilize the gas hole to make the outside gas enter optical chamber 1, or make the gas in optical chamber 1 flow out.

[0036] Signal acquisition circuit module 3 includes infrared light source 301 and detector 302, and the top of infrared light source 301 and detector 301 is located inside optical chamber 1. The light emitted by infrared light source 301 is received by detector 302 after interacting with the gas in optical chamber 1, and detector 302 outputs an electrical signal representing the gas concentration detection result. Signal acquisition circuit module 3 further includes a signal acquisition circuit board 303, and infrared light source 301 and detector 302 are arranged on the signal acquisition circuit board 303. The signal acquisition circuit board 303 is used to control the light emission of infrared light source 301, receive the signal of detector 302, and send the signal to a remote terminal. Preferably, the infrared light source 301 uses a blackbody radiation infrared light source, which has high emissivity, wide wavelength range, precise temperature control, small size, high output power and other advantages, and is less affected by external interference factors.

[0037] The long optical path, low loss small -size infrared gas sensor further includes a cover plate 2, which is located at the lower end opening of the optical chamber 1 and between the optical chamber 1 and the signal acquisition circuit module 3, and is used to isolate the internal space of the optical chamber 1 from the signal acquisition circuit of the signal acquisition circuit module 3. The cover plate 2 is provided with a first cover plate via hole 201 and a second cover plate via hole 202. The first cover plate via hole 201 corresponds to the position of the infrared light source 301, and is used for the top end of the infrared light source 301 to pass through and extend into the optical chamber 1. The second cover plate via hole 202 corresponds to the position of the detector 302, and is used for the top end of the detector 302 to pass through and extend into the optical chamber 1.

[0038] The inner wall of the optical chamber 1 is provided with a plurality of edge plane reflecting surfaces, and one or more light path extension plane reflecting surfaces are located on the opposite side of the edge plane reflecting surfaces, the light path extension plane reflecting surface is used for receiving the light of one edge plane reflecting surface and reflecting it to another edge plane reflecting surface, so that the light passes through the middle region of the optical chamber 1 to increase the light path length of the light in the optical chamber 1. The light path extension plane reflecting surface can cooperate with the opposite edge plane reflecting surface, fully utilize the space in the middle part of the optical chamber 1, increase the light path length, and then the sufficient action of the optical chamber 1 and the light of the gas to be measured can be realized, and the precision of the gas detection is improved.

[0039] As shown in Figure 2 、 Figure 3 In one specific embodiment, the edge plane reflecting surface includes a first edge plane reflecting surface 102, a second edge plane reflecting surface 103, a third edge plane reflecting surface 104, and a fourth edge plane reflecting surface 105, and the light path extension plane reflecting surface 106 is located on the opposite side of the second edge plane reflecting surface 103 and the third edge plane reflecting surface 104, so that the light reflected by the third edge plane reflecting surface 104 to the light path extension plane reflecting surface 106 and the light reflected by the light path extension plane reflecting surface 106 to the second edge plane reflecting surface 103 passes through the middle region in the optical chamber 1. In other embodiments, the number of edge plane reflecting surfaces can be increased or decreased, and the utility model is not limited thereto.

[0040] The inner wall of the optical chamber 1 is also provided with an incident parabolic reflecting surface 101 and an exit parabolic reflecting surface, the incident parabolic reflecting surface 101 corresponds to the position of the infrared light source 301, which is used to receive the light of the infrared light source 301 and collimate it to be incident to the edge plane reflecting surface; the exit parabolic reflecting surface corresponds to the position of the detector 302, which is used to receive the light of the edge plane reflecting surface or the light path extension plane reflecting surface and focus it to be incident to the detector 302.

[0041] In this embodiment, the exit parabolic reflecting surface includes a first exit parabolic reflecting surface 107 and a second exit parabolic reflecting surface 108, the first exit parabolic reflecting surface 107 and the second exit parabolic reflecting surface 108 are both located at the detector 302, and the first exit parabolic reflecting surface 107 is used to receive the light of the edge plane reflecting surface (or the light path extension plane reflecting surface in other embodiments) and reflect it to the second exit parabolic reflecting surface 108, and the second exit parabolic reflecting surface 108 is used to receive the light of the first exit parabolic reflecting surface 107 and focus it to be incident to the detector 302. Preferably, the first exit parabolic reflecting surface 107 and the second exit parabolic reflecting surface 108 are confocal planes, that is, the focal point of the first exit parabolic reflecting surface 107 and the focal point of the second exit parabolic reflecting surface 108 are located on the same longitudinal axis.

[0042] As Figure 3 , Figure 4 shown, in the embodiment, the incident parabolic reflector 101, the first edge plane reflector 102, the second edge plane reflector 103, the third edge plane reflector 104, the fourth edge plane reflector 105, the exit parabolic reflector, and the light path extension plane reflector 106 are sequentially connected to form a ring and are located on the outer side wall of the optical chamber 1. The light emitted by the infrared light source 301 passes through the incident parabolic reflector 101, the first edge plane reflector 102, the third edge plane reflector 104, the light path extension plane reflector 106, the second edge plane reflector 103, the fourth edge plane reflector 105, the first exit parabolic reflector 107, and the second exit parabolic reflector 108 in sequence and is received by the detector 302.

[0043] In the infrared gas sensor, the more the number of reflections, the greater the light loss, so the light path extension plane reflector of the embodiment can reduce the number of light reflections as much as possible while ensuring the full use of the optical chamber space and increasing the optical path. Specifically, the outer side of the incident parabolic reflector 101 and the outer side of the second exit parabolic reflector 108 are connected with the inner wall of the optical chamber, the inner side of the incident parabolic reflector 101 and the inner side of the second exit parabolic reflector 108 are directed to the hollow area of the optical chamber, and the inner concave surface of the incident parabolic reflector 101 is arranged opposite to the inner concave surface of the second exit parabolic reflector 108.

[0044] Preferably, the two ends of the light path extension plane reflector are connected with the inner side of the incident parabolic reflector 101 and the inner side of the second exit parabolic reflector 108, respectively. In addition, in order to enable the light path extension plane reflector 106 to receive the light of the third edge plane reflector 104 and reflect it to the second edge plane reflector 103, the light path extension plane reflector 106 in the utility model is provided with an included angle between the inner side of the incident parabolic reflector 101, which is greater than 90 degrees, so that the light of the third edge plane reflector 104 to the light path extension plane reflector 106 and the light of the light path extension plane reflector 106 to the second edge plane reflector 103 can pass through the middle part of the optical chamber as much as possible and act on the gas entering from the gas hole. In other embodiments, the angle of the light path extension plane reflector can also be adjusted according to different light paths, which will not be described here.

[0045] To make fuller use of light and increase the accuracy of light transmission, in this invention, the infrared light source 301 is located at the focal point of the incident parabolic reflector 101. This allows the incident parabolic reflector 101 to transmit the light emitted by the infrared light source 301 from its bottom position upwards to the middle region of the optical chamber 1, collimating the light into parallel light and reflecting it to the first edge plane reflector 102. The light path extension plane reflector 106 receives the light from the third edge plane reflector 104 and reflects it to the second edge plane reflector 103. Furthermore, the light path extension plane reflector 106 can fully utilize the space within the optical chamber 1, ensuring that the third edge plane reflector... The light rays reflected from the light-emitting surface 104 to the light-path extension plane reflector 106, and the light rays reflected from the light-path extension plane reflector 106 to the second edge plane reflector 103, can pass through the central region inside the optical chamber 1, making full use of this region to increase the optical path length and avoid the stacking of light rays. The first exiting parabolic reflector 107 is used to focus the light rays reflected from the fourth edge plane reflector 105 and reflect them to the second exiting parabolic reflector 108. The detector 302 is located at the focal point of the second exiting parabolic reflector 108, so that the light rays reflected from the second exiting parabolic reflector 108 can be reflected to the bottom of the optical chamber 1 and focused at the detector 302.

[0046] like Figure 5 , Figure 6 The optical path states for light reflection in optical air cells in two existing technologies are given. Figure 5 In the illustrated embodiment, the light undergoes multiple reflections and accumulates at the edge of the optical chamber, while the space in the central region of the optical chamber remains unused, resulting in wasted space. Figure 6 In the embodiment shown, light is reflected from the right arc surface to the left middle reflective surface, then reflected back to the right arc surface, and then reflected again to the detector. In order to ensure the light effect, the lateral volume of the entire optical chamber is maximized. The increase in chamber volume directly affects the response time of the sensor, and the internal space utilization is also low. In addition, the structural size of the entire optical chamber is large, so it cannot be applied to small-size designs.

[0047] like Figure 3 , Figure 4 As shown, the optical chamber design of the mid-infrared gas sensor of this utility model can make full use of the internal space of the optical chamber to achieve multiple cross reflections, increase the optical path length of a single reflection, and thus increase the total optical path length; and the number of reflections is less compared to the spiral chamber channel, reducing reflection loss.

[0048] In one embodiment, it is applied to products of the same external dimensions (standard 7 series). Figure 6The optical gas chamber structure shown and the optical gas chamber structure of the utility model can realize 6cm optical path length, while the utility model can realize 10cm optical path length, and the whole optical path length is greatly improved.

[0049] It should be understood that the above description can be improved or changed by those skilled in the art, and all these improvements and changes shall belong to the protection scope of the appended claims of the utility model.

[0050] The utility model patent is described above in combination with the drawings, obviously, the implementation of the utility model patent is not limited by the above-mentioned mode, as long as various improvements are made by adopting the method concept and technical scheme of the utility model patent, or the concept and technical scheme of the utility model patent is directly applied to other occasions without improvement, all are within the protection scope of the utility model.

Claims

1. A long optical path, low loss, small infrared gas sensor, comprising an optical gas chamber and a signal acquisition circuit module, the optical gas chamber is a hollow structure, the signal acquisition circuit module comprises an infrared light source and a detector, the top end of the infrared light source and the detector is located inside the optical gas chamber, characterized in that, a plurality of edge plane reflecting surfaces and one or more light path extension plane reflecting surfaces are arranged on the inner wall of the optical gas chamber, the light path extension plane reflecting surface is located on the opposite side of the edge plane reflecting surface, the light path extension plane reflecting surface is used for receiving the light of one edge plane reflecting surface and reflecting it to another edge plane reflecting surface, so that the light passes through the middle area of the optical gas chamber to increase the optical path length of the light in the optical gas chamber. The edge plane reflecting surface comprises a first edge plane reflecting surface, a second edge plane reflecting surface, a third edge plane reflecting surface and a fourth edge plane reflecting surface, the light path extension plane reflecting surface is located on the opposite side of the second edge plane reflecting surface and the third edge plane reflecting surface, so that the light reflected by the third edge plane reflecting surface to the light path extension plane reflecting surface and the light reflected by the light path extension plane reflecting surface to the second edge plane reflecting surface pass through the middle area of the optical gas chamber.

2. The long optical path, low loss, compact infrared gas sensor of claim 1, wherein, The inner wall of the optical gas chamber is also provided with an incident parabolic reflecting surface and an exit parabolic reflecting surface, the incident parabolic reflecting surface corresponds to the position of the infrared light source, which is used to receive the light of the infrared light source and collimate it to the edge plane reflecting surface; the exit parabolic reflecting surface corresponds to the position of the detector, which is used to receive the light of the edge plane reflecting surface or the light path extension plane reflecting surface and focus it to the detector.

3. The long optical path, low loss, compact infrared gas sensor of claim 1, wherein, The exit parabolic reflecting surface comprises a first exit parabolic reflecting surface and a second exit parabolic reflecting surface, the first exit parabolic reflecting surface and the second exit parabolic reflecting surface are both located at the detector, and the first exit parabolic reflecting surface is used to receive the light of the edge plane reflecting surface or the light path extension plane reflecting surface and reflect it to the second exit parabolic reflecting surface, the second exit parabolic reflecting surface is used to receive the light of the first exit parabolic reflecting surface and focus it to the detector.

4. The long optical path, low loss, compact infrared gas sensor of claim 3, wherein, The focal point of the first exit parabolic reflecting surface and the focal point of the second exit parabolic reflecting surface are located on the same longitudinal axis.

5. The long optical path, low loss, compact infrared gas sensor of claim 4, wherein, The outer side of the incident parabolic reflecting surface and the outer side of the second exit parabolic reflecting surface are connected with the inner wall of the optical gas chamber, the inner side of the incident parabolic reflecting surface and the inner side of the second exit parabolic reflecting surface are both directed to the hollow area of the optical gas chamber, and the inner concave surface of the incident parabolic reflecting surface and the inner concave surface of the second exit parabolic reflecting surface are arranged oppositely.

6. The long optical path, low loss, compact infrared gas sensor of claim 4, wherein, The two ends of the light path extension plane reflecting surface are respectively connected with the inner side of the incident parabolic reflecting surface and the inner side of the second exit parabolic reflecting surface.

7. The long optical path, low loss, compact infrared gas sensor of claim 6, wherein, The top of the optical gas chamber is provided with a gas hole, which is in communication with the internal space of the optical gas chamber.

8. The long optical path, low loss, compact infrared gas sensor of claim 1, wherein, ​ 9. The long optical path, low loss, compact infrared gas sensor of claim 1, wherein, Further comprising a cover plate between the optical chamber and the signal acquisition circuit module, for isolating the inside of the optical chamber from the signal acquisition circuit of the signal acquisition circuit module.

10. The long optical path, low loss, compact infrared gas sensor of claim 9, wherein, The cover plate is provided with a first cover plate via hole and a second cover plate via hole, the first cover plate via hole corresponds to the position of the infrared light source, and the top end of the infrared light source passes through the first cover plate via hole and extends into the optical chamber; the second cover plate via hole corresponds to the position of the detector, and the top end of the detector passes through the second cover plate via hole and extends into the optical chamber.

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