4-series laser gas sensor

Abstract

The utility model discloses a 4-series laser gas sensor, relates to the technical field of gas sensors, and solves the problem of poor detection sensitivity of a gas sensor in the prior art. The device comprises a shell, a laser and a detector are arranged in the shell, a plurality of reflecting surfaces are arranged in the shell, an optical cavity is formed among the reflecting surfaces, the reflecting surfaces are matched with the laser and the detector, and laser emitted by the laser can be reflected to the detector under the reflecting action of the reflecting surfaces. The laser is reflected between the reflecting surfaces and penetrates through the optical cavity for at least three times, and the optical cavity is communicated with the outside of the shell. The optical cavity is arranged, the internal space for containing and detecting the gas is provided, and the laser can be emitted by the laser, penetrates through the gas to be detected and is received by the detector, so that the gas to be detected can be detected by a laser absorption spectrum technology, and the detection precision, the sensitivity and the anti-interference capability are improved. And by increasing the laser optical path, the mirror surface utilization rate is improved, and miniaturization development is facilitated.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of gas sensor, especially a 4 series laser gas sensor. BACKGROUND

[0002] The 4 series gas sensor using the nondispersion infrared spectrum principle on the market at present, because its light source is wide spectrum light source, poor selectivity, is susceptible to other gas cross interference, optical path length is mostly in 5 centimeter range, and detection sensitivity is low. Laser absorption spectrum technology has been widely applied to industrial process control, environmental detection, safety detection and other fields due to the advantages of high selectivity, high resolution, high sensitivity, not being interfered by other gases. The product of laser absorption spectrum technology is large in size due to the limitation of optical cavity, and is not conducive to the use of portable and small-sized instruments and meters.

[0003] The Chinese invention patent with the publication number CN109883979A discloses a kind of adjustable long optical path infrared gas sensor and detection method, the gas sensor includes: mutually connected and mutually used light source module, adjustable long optical path connector and detection module;Light source module includes light source reflection cavity, infrared light source arranged in light source reflection cavity;Detection module includes detector condensing cavity, infrared detector arranged in detector condensing cavity. In the scheme, infrared detector generates voltage signal after receiving infrared light, and voltage signal is converted into corresponding gas concentration after being processed by detector signal processing circuit board.

[0004] The scheme also uses infrared light source, and detection sensitivity is poor, susceptible to other gas interference. In addition, in the scheme, infrared light can only be reflected twice when passing through the gas to be measured, so the overall size of the sensor is relatively large. And in the miniaturization trend, due to the low gas optical path length, it cannot meet the application of laser absorption spectrum technology, and cannot reduce the volume of optical cavity while ensuring detection sensitivity. UTILITY MODEL CONTENTS

[0005] In view of the deficiencies in the above background art, the utility model provides a 4 series laser gas sensor, which solves the problem of poor detection sensitivity of the gas sensor in the prior art.

[0006] The technical scheme of the utility model is as follows: a 4 series laser gas sensor, comprising a shell, a laser and a detector are arranged in the shell, a plurality of reflecting surfaces are arranged in the shell, an optical cavity is formed between the plurality of reflecting surfaces, the reflecting surfaces are arranged in cooperation with the laser and the detector, the laser emitted by the laser can be reflected to the detector under the reflection of the plurality of reflecting surfaces, the laser is reflected between the reflecting surfaces and passes through the optical cavity at least three times, and the optical cavity is in communication with the outside of the shell.

[0007] Preferably, the shell is a cylindrical shell, and a reflecting block is arranged on the shell, and the reflecting surface is arranged on the reflecting block.

[0008] Preferably, the reflecting surface comprises a first reflecting surface, a second reflecting surface, a third reflecting surface and a fourth reflecting surface arranged on the reflecting block, and the second reflecting surface and the third reflecting surface are arranged in parallel.

[0009] Preferably, the reflecting block is provided with a gas-permeable hole, and the gas-permeable hole is communicated between the optical cavity and the outside of the shell.

[0010] Preferably, the shell is provided with a signal circuit board, and the laser and the detector are arranged on the signal circuit board.

[0011] Preferably, the signal circuit board is connected with a power supply circuit board, the power supply circuit board is provided with a silk screen piece on the outside, and the power supply circuit board is provided with a pin, and the silk screen piece is fixedly connected with the power supply circuit board through the pin.

[0012] Preferably, the reflecting block and the shell are provided with a positioning column and a positioning hole in cooperation, and the positioning column and the positioning hole are inserted and connected.

[0013] Preferably, the first reflecting surface, the second reflecting surface, the third reflecting surface and the fourth reflecting surface comprise a coated reflecting surface or a mirror surface of a reflector.

[0014] The 4-system laser gas sensor has the advantages that: the optical cavity is arranged to provide an internal space for containing and detecting gas, the laser can emit laser, pass through the gas to be detected and be received by the detector, so that the laser absorption spectrum technology is used to detect the gas to be detected, the detection precision, the sensitivity and the anti-interference capability are improved, and the problem of low detection sensitivity of the 4-system gas sensor adopting the non-dispersive infrared spectrum principle in the prior art is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present application, the drawings used in the embodiments will be briefly introduced as follows: obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0016] Figure 1It is a cross section structure schematic view of the utility model;

[0017] Figure 2 It is an explosion structure schematic view of the utility model;

[0018] Figure 3 It is a light path schematic view inside the first reflecting block of the utility model;

[0019] Figure 4 It is a light path schematic view inside the second reflecting block of the utility model;

[0020] In the drawing: 1: shell, 2: laser, 3: detector, 4: reflecting block, 41: first reflecting surface, 42: second reflecting surface, 43: third reflecting surface, 44: fourth reflecting surface, 45: air hole, 46: waterproof and dustproof air permeable film, 5: signal circuit board, 6: bolt, 7: power supply circuit board, 8: silk screen, 9: pin, 10: positioning column. DETAILED DESCRIPTION

[0021] The technical scheme in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the utility model.

[0022] As shown in Figure 1 , 2 Embodiment 1, a 4 series laser gas sensor, comprising a shell 1, the shell 1 is provided with a laser 2 and a detector 3, the shell 1 is provided with a plurality of reflecting surfaces, the plurality of reflecting surfaces form an optical cavity, the optical cavity provides an internal space for containing and detecting gas. The reflecting surface is arranged in cooperation with the laser 2 and the detector 3, the laser emitted by the laser 2 can be reflected to the detector 3 under the reflection of the plurality of reflecting surfaces, the laser can emit laser, pass through the to-be-detected gas in the optical cavity and be received by the detector, so that the to-be-detected gas can be detected by laser absorption spectroscopy technology, improve the detection precision, sensitivity and anti-interference ability. The laser is reflected between the reflecting surfaces and passes through the optical cavity at least three times, the optical cavity is in communication with the outside of the shell 1, which is beneficial to the entry of the external to-be-detected gas. In the embodiment, the laser can be reflected multiple times by cooperating with the plurality of reflecting surfaces, in order to improve the optical path, the laser is reflected at least three times between the reflecting surfaces in the embodiment, thereby increasing the optical path of the laser, improving the mirror utilization rate of the reflecting surface, reducing the volume of the optical cavity under the condition of ensuring the detection sensitivity, thereby reducing the overall size of the sensor, and being beneficial to miniaturization development.

[0023] In use, the gas to be measured enters the optical cavity inside the shell, the laser emits laser light into the optical cavity, and the laser light passes through the optical cavity multiple times, thereby passing through the gas to be measured multiple times, increasing the optical path, and finally the laser light is reflected out of the optical cavity and irradiates on the detector, thereby realizing detection of the gas to be measured.

[0024] In embodiment 2, on the basis of embodiment 1, the shell 1 is a cylindrical shell, and the shell 1 is provided with a reflection block 4. The reflection surface is arranged on the reflection block 4, that is, the optical cavity is formed on the reflection block 4, and the reflection block and the optical cavity can be formed by machining a metal material or by a mold of a plastic material. The reflection surface includes a first reflection surface 41, a second reflection surface 42, a third reflection surface 43 and a fourth reflection surface 44 arranged on the reflection block 4, and the second reflection surface 42 and the third reflection surface 43 are arranged in parallel. In this embodiment, the first reflection surface is arranged obliquely, and is used for receiving the laser light emitted by the laser and reflecting the laser light to the second reflection surface. The laser light is reflected between the second reflection surface and the third reflection surface, and finally is reflected to the fourth reflection surface through the second reflection surface or the third reflection surface. The fourth reflection surface is arranged obliquely, so as to reflect the laser light irradiated thereon out of the optical cavity and be received by the detector.

[0025] In this embodiment, by adjusting the angles of the first reflection surface and the fourth reflection surface, according to the reflection principle of light, the incident angle of the laser light irradiated on the second reflection surface can be adjusted, and then the number of reflections between the second reflection surface and the third reflection surface is adjusted, so as to adjust the length of the optical path. As shown in Figure 3 , the laser light is reflected 7 times in total in the first reflection surface 41, the second reflection surface 42, the third reflection surface 43 and the fourth reflection surface 44. In the space with the size of ø20x16.6mm of the shell, the optical path of the laser light passing through the gas to be measured can reach more than 6cm, which meets the requirements of the gas detection accuracy. In addition, after adjusting the angles of the first reflection surface and the fourth reflection surface, as shown in Figure 4 , the laser light is reflected 13 times in total in the first reflection surface 41, the second reflection surface 42, the third reflection surface 43 and the fourth reflection surface 44. The optical path reaches more than 10cm, which further improves the sensitivity of the system detection, so as to adapt to the requirements of the optical path length in different gas detection occasions.

[0026] In this embodiment, as an optional solution to achieve reflection, the first reflective surface 41, the second reflective surface 42, the third reflective surface 43, and the fourth reflective surface 44 may include a coated reflective surface or a mirror surface of a reflector disposed on the reflective block 4. When using a coated reflective surface, the overall assembly process is simple. Metal reflective blocks require precision machining to achieve a highly flat reflective surface for reflection, or further coating processes to enhance the reflective surface's reflective capability. Plastic reflective blocks require coating the reflective surface after molding to give it reflective capability. When using a reflector, a reflective mirror of the corresponding size and specification is directly pasted onto the corresponding reflective surface using an adhesive method to achieve the reflection function.

[0027] In addition, the reflector block 4 is provided with a vent hole 45, which connects the optical cavity and the outside of the housing 1. By providing a vent hole, the gas to be measured from the outside can easily enter the optical cavity under the detection environment. As a further specific embodiment, the reflector block 4 is provided with a waterproof and dustproof breathable membrane 46 that cooperates with the vent hole 45. The waterproof and dustproof breathable membrane is made of conventional materials to prevent dust and moisture from entering the optical cavity and the housing, thus affecting the use of the sensor.

[0028] In Example 3, based on Example 2, a signal circuit board 5 is provided on the housing 1, and both the laser 2 and the detector 3 are fixedly mounted on the signal circuit board 5. In this example, the laser 2 can be a conventional laser with collimation function, and the detector 3 can be a conventional laser detector with focusing function.

[0029] For ease of connection, in this embodiment, the signal circuit board 5, housing 1, and reflector 4 are connected by bolts 6. Specifically, steps corresponding to the signal circuit board and reflector block can be provided at both ends of the housing, and the housing, signal circuit board, and reflector block are locked together by bolts. Additionally, in this embodiment, a positioning post 10 and a positioning hole are provided between the reflector block 4 and the housing 1, and the positioning post 10 and positioning hole are interlocked to achieve rapid positioning during assembly, improving assembly efficiency and accuracy, while avoiding the need to adjust the laser beam path emitted by the laser.

[0030] In a further specific embodiment, the signal circuit board 5 is fixedly connected to the power circuit board 7, which can be achieved using conventional bolt connections or snap-fit ​​connections. The power circuit board 7 has a silkscreened sheet 8 on its outer side and pins 9 on its surface. The silkscreened sheet 8 is fixedly engaged with the power circuit board 7 via the pins 9. In this embodiment, the pins 9 are soldered and fixed to the power circuit board 7, and the pins can transmit electrical signals and supply power. The signal circuit board 5 mainly consists of conventional circuits such as laser driver and temperature control circuits, and detector transimpedance amplification and filtering circuits. The power circuit board mainly consists of input / output circuits and microprocessor circuits.

[0031] In practical use, the microprocessor controls the laser to emit light covering the absorption peak wavelength of the gas "fingerprint" through the laser temperature control and drive circuit. The light is absorbed by the target gas that enters the interior through the vent holes of the waterproof and dustproof breathable membrane and optical cavity. After multiple reflections by the reflective surface inside the optical cavity, the light shines onto the detector. The detector's transimpedance amplification and filtering circuit converts the light into an electrical signal. The microprocessor extracts the harmonic information of the gas concentration information through lock-in amplification technology and calculates the concentration of the target gas through algorithm calculation, and then outputs the gas concentration signal to the outside.

[0032] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A 4-series laser gas sensor, characterized in that: Includes a housing (1), inside which is a laser (2) and a detector (3). Inside the housing (1) are several reflective surfaces, and between these reflective surfaces is an optical cavity. The reflective surfaces are configured in conjunction with the laser (2) and the detector (3). The laser emitted by the laser (2) can be reflected to the detector (3) by the reflection of the several reflective surfaces. The laser is reflected between the reflective surfaces and passes through the optical cavity at least three times. The optical cavity is connected to the outside of the housing (1).

2. The 4-series laser gas sensor according to claim 1, characterized in that: The housing (1) is a cylindrical housing, and a reflective block (4) is provided on the housing (1), with the reflective surface disposed on the reflective block (4).

3. The 4-series laser gas sensor according to claim 2, characterized in that: The reflective surface includes a first reflective surface (41), a second reflective surface (42), a third reflective surface (43) and a fourth reflective surface (44) disposed on the reflective block (4), and the second reflective surface (42) and the third reflective surface (43) are arranged in parallel.

4. The 4-series laser gas sensor according to claim 3, characterized in that: The reflector block (4) is provided with a vent hole (45), which connects the optical cavity and the outside of the housing (1).

5. The 4-series laser gas sensor according to claim 4, characterized in that: The reflective block (4) is provided with a waterproof and dustproof breathable membrane (46) that matches the vent (45).

6. The 4-series laser gas sensor according to any one of claims 2 to 5, characterized in that: The housing (1) is provided with a signal circuit board (5), and the laser (2) and detector (3) are both located on the signal circuit board (5).

7. The 4-series laser gas sensor according to claim 6, characterized in that: The signal circuit board (5), housing (1), and reflector (4) are connected by bolts (6).

8. The 4-series laser gas sensor according to claim 7, characterized in that: The signal circuit board (5) is connected to the power circuit board (7). The power circuit board (7) has a silkscreen sheet (8) on its outer side and pins (9) on its side. The silkscreen sheet (8) is fixedly connected to the power circuit board (7) through the pins (9).

9. The 4-series laser gas sensor according to claim 8, characterized in that: The reflector block (4) and the housing (1) are provided with a positioning post (10) and a positioning hole, and are connected by the positioning post (10) and the positioning hole.

10. The 4-series laser gas sensor according to claim 3, characterized in that: The first reflective surface (41), the second reflective surface (42), the third reflective surface (43) and the fourth reflective surface (44) include the coated reflective surface or the mirror surface of the reflector provided on the reflective block (4).

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