A gas absorption cell, a gas concentration detection device and a method

Abstract

The present invention discloses a gas absorption cell, a gas concentration detection device and a method. The gas absorption cell includes an annular reflector, the annular reflector has a reflection cavity, and the shape of the reflection cavity is spherical or a part of a sphere. The gas concentration detection device includes a gas absorption cell, an input device and a receiving device. The input device is installed at the light input port; the receiving device is installed at the light receiving port. The beneficial effects of the present invention are as follows: the gas absorption cell provided by the present invention adopts a single annular reflector as an optical element, has high stability, is easy to install and debug, and increases the optical path of the laser beam by making the laser beam reflect multiple times in the reflection cavity, which is beneficial to reducing the volume of the reflection cavity and improving the gas detection sensitivity; the gas concentration detection method provided by the present invention adopts a focused beam instead of a traditional parallel beam, thereby overcoming the defect that the parallel beam of the traditional gas concentration detection device diverges when the optical path is long, thereby affecting the accuracy of gas concentration measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of gas detection, and in particular to a gas absorption cell, a gas concentration detection device and a method. Background Art

[0002] At present, the photoelectric technology that uses the infrared laser spectrum absorption principle to measure gas composition and concentration is becoming increasingly mature. Its core device is the gas absorption cell. At present, the gas absorption cell mainly adopts White cell and Herriott cell. Its characteristics are that the measuring gas chamber usually adopts multiple mirrors or reflectors to reflect the light path multiple times in the gas chamber to increase the optical path length, which makes the optical structure of the absorption cell complicated, increases the complexity of the production process and reduces the yield rate, is not conducive to large-scale production, is expensive, and is not conducive to debugging. The long-term reliability is not high. At the same time, the existing measuring gas chamber is large in size and requires more measuring gas.

[0003] In addition, existing gas measurement devices often use a method in which a parallel light beam is reflected multiple times in a gas chamber. Since existing lasers cannot output absolutely parallel laser beams, when the optical path is long, the laser beam will disperse, which seriously affects the accuracy of gas measurement. Summary of the invention

[0004] In view of this, it is necessary to provide a gas absorption cell with a small size, simple structure, and easy installation and debugging, as well as a gas content detection method that can overcome the disadvantage of low gas measurement accuracy under long optical path conditions.

[0005] The present invention provides a gas absorption cell, comprising an annular reflector,

[0006] The annular reflector has a reflective cavity, the shape of the reflective cavity is spherical or a part of a sphere, the annular reflector is provided with an air inlet and an air outlet connected to the reflective cavity, and the annular reflector is also provided with a light input port and a light receiving port connected to the reflective cavity.

[0007] The present invention also provides a gas concentration detection device, comprising the gas absorption cell, input device and receiving device provided by the present invention.

[0008] The input device is installed at the light input port, and is used to input a laser beam into the reflective cavity;

[0009] The receiving device is installed at the light receiving port, and is used to receive the laser light beam and detect the laser light beam.

[0010] The present invention also provides a gas concentration detection method, comprising the following steps:

[0011] S1. Prepare a gas concentration detection device provided by the present invention, and connect the gas inlet and the gas outlet to a gas source to be detected;

[0012] S2, inputting a laser beam into the reflection cavity through the input device, and focusing the laser beam to a focal point in the reflection cavity and then diverging, wherein the focal point is located at the midpoint of two reflections and does not pass through the spherical center of the reflection cavity;

[0013] S3. Receive the laser beam emitted from the receiving point after multiple reflections through the receiving device, and detect the laser beam to obtain the concentration of the gas to be measured.

[0014] Compared with the prior art, the technical solution proposed in the present invention has the following beneficial effects: the gas absorption cell provided by the present invention adopts a single annular reflector as an optical element, has high stability, is easy to install and debug, and increases the optical path of the laser beam by causing the laser beam to reflect multiple times in the reflection cavity, thereby facilitating reducing the volume of the reflection cavity and improving the gas detection sensitivity, thereby reducing the demand for the amount of gas to be detected; at the same time, the gas concentration detection method provided by the present invention adopts a focused beam instead of a traditional parallel beam, thereby effectively overcoming the defect that the parallel beam of a traditional gas concentration detection device diverges and affects the accuracy of gas concentration measurement when the optical path is long. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of an embodiment of a gas concentration detection device provided by the present invention;

[0016] Figure 2 yes Figure 1 The optical path diagram of the gas concentration detection device in the reflection cavity under the condition of short optical path;

[0017] Figure 3 yes Figure 1 The optical path diagram of the gas concentration detection device in the reflection cavity under the condition of long optical path;

[0018] In the figure: 1-annular reflector, 11-base, 12-cover plate, 101-air inlet, 102-air outlet, 103-light input port, 104-light receiving port, 111-lower screw hole, 121-upper screw hole, 21-first optical fiber, 31-second optical fiber. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] Please refer to Figure 1 The present invention provides a gas absorption cell, including an annular reflector 1, wherein the annular reflector 1 has a reflection cavity, wherein the reflection cavity is spherical or a part of a sphere. In this embodiment, the reflection cavity is a part of a sphere that is divided by two upper and lower parallel planes and is located in the middle. The annular reflector 1 is provided with an air inlet 101 and an air outlet 102 that are connected to the reflection cavity. The annular reflector 1 is also provided with a light input port 103 and a light receiving port 104 that are connected to the reflection cavity.

[0021] For further information, please refer to Figure 1 The annular reflector 1 includes a base 11 and a cover plate 12, the cover plate 12 is matched with the base 11 and is detachably connected, the light input port 103 and the light receiving port 104 are both located on the base 11, and the air inlet 101 and the air outlet 102 are both located on the cover plate 12. It should be pointed out that: in other embodiments, the light input port 103 and the light receiving port 104 can also be set at other positions besides the base 11, and these embodiments all fall within the protection scope of the present invention.

[0022] Preferably, please refer to Figure 1 A plurality of lower screw holes 111 are provided on the upper end surface of the base 11, and a plurality of upper screw holes 121 are provided on the cover plate 12, which are matched one by one with the lower screw holes 111; the gas absorption pool also includes a plurality of screw rods (not shown) which are matched one by one with the upper screw holes 121 and the lower screw holes 111 corresponding to the upper screw holes 121, and each of the screw rods is threadedly connected with the corresponding upper screw hole 121 and the corresponding lower screw hole 111.

[0023] For further information, please refer to Figure 1 , the annular reflector 1 is made of metal material or glass material. In this embodiment, the annular reflector 1 is made of metal material.

[0024] Preferably, please refer to Figure 1 The inner wall of the annular reflector 1 is mirror-optically polished and coated with a reflective film.

[0025] The present invention also provides a gas concentration detection device, including the gas absorption cell, an input device and a receiving device, wherein the input device is installed at the light input port 103, and the input device is used to input a laser beam into the reflection cavity; the receiving device is installed at the light receiving port 104, and the receiving device is used to receive the laser beam and detect the laser beam, so as to obtain the concentration of the gas to be detected in the gas absorption cell.

[0026] In one embodiment, the input device includes a light source and a lens assembly, wherein the light source is used to emit a laser beam; the lens assembly includes a plurality of lenses, each of which is disposed between the light source and the light input port 103 .

[0027] In another embodiment, please refer to Figure 1 The input device includes a light source and a first optical fiber 21, the light source is used to emit a laser beam; one end of the first optical fiber 21 is coupled to the light source, and the other end of the first optical fiber 21 is coupled to the light input port 103.

[0028] Furthermore, the receiving device includes a detector, which is installed at the light receiving port 104 and is used to detect the laser beam.

[0029] Preferably, the receiving device further comprises a second optical fiber 31 , one end of the second optical fiber 31 is coupled to the light receiving port 104 , and the other end of the second optical fiber 31 is coupled to the detector.

[0030] The present invention also provides a gas concentration detection method, comprising the following steps:

[0031] S1. Prepare the above-mentioned gas concentration detection device, and connect the gas inlet 101 and the gas outlet 102 to the gas source to be tested;

[0032] S2, inputting a laser beam into the reflection cavity through the input device, and focusing the laser beam to a focus in the reflection cavity and then diverging, wherein the focus is located at the midpoint of two reflections and does not pass through the spherical center of the reflection cavity; the laser beam is reflected back and forth by the inner wall of the reflection cavity, and the focus of each reflection also does not pass through the spherical center, and finally enters the light receiving port 104;

[0033] The angle of the input device can be adjusted to change the incident angle of the laser beam and thus control the optical path of the laser beam in the reflective cavity. Figure 2 In the case of short optical path, the laser beam has fewer reflections on the inner wall of the reflective cavity. Please refer to Figure 3 ,In the case of long optical path, the laser beam reflects on the inner wall of the ,reflection cavity more times.

[0034] S3. Receive the laser beam emitted from the receiving point after multiple reflections through the receiving device, and detect the laser beam to obtain the concentration of the gas to be measured.

[0035] In summary, the gas absorption cell provided by the present invention adopts a single annular reflector 1 as an optical element, which has high stability and is easy to install and debug. By making the laser light beam reflect multiple times in the reflection cavity, the optical path of the laser light beam is increased, which is beneficial to reduce the volume of the reflection cavity and reduce the demand for the amount of gas to be detected. At the same time, the gas concentration detection method provided by the present invention adopts a focused light beam instead of a traditional parallel light beam, which effectively overcomes the defect that the parallel light beam of the traditional gas concentration detection device diverges when the optical path is long, thereby affecting the accuracy of gas concentration measurement.

[0036] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A gas concentration detection device, characterized in that: It includes a gas absorption cell, an input device and a receiving device, The gas absorption cell comprises an annular reflector, the annular reflector has a reflection cavity, the shape of the reflection cavity is spherical or a part of a sphere, the annular reflector is provided with an air inlet and an air outlet communicated with the reflection cavity, the annular reflector is also provided with a light input port and a light receiving port communicated with the reflection cavity; the annular reflector comprises a base and a cover plate, the cover plate is matched with the base and is detachably connected, the light input port and the light receiving port are both located on the base, the air inlet and the air outlet are both located on the cover plate; the annular reflector is made of metal material or glass material; the inner wall of the annular reflector is optically polished and coated with a reflection film; The input device is installed at the light input port, and is used to input a laser beam into the reflective cavity. The laser beam is input into the reflective cavity through the input device, and the laser beam is first focused to a focus in the reflective cavity and then diverges, wherein the focus is located at the midpoint of two reflections and does not pass through the spherical center of the reflective cavity; The receiving device is installed at the light receiving port, and is used to receive the laser light beam and detect the laser light beam.

2. The gas concentration detection device according to claim 1, characterized in that: The upper end surface of the base is provided with a plurality of lower screw holes, and the cover plate is provided with a plurality of upper screw holes matching the lower screw holes one by one; The gas absorption cell further comprises a plurality of screw rods matched with the upper screw holes and the lower screw holes corresponding to the upper screw holes, and each of the screw rods is threadedly connected with the corresponding upper screw hole and the corresponding lower screw hole.

3. The gas concentration detection device according to claim 1, characterized in that: The input device includes a light source and a lens assembly, The light source is used to emit a laser beam; The lens assembly includes a plurality of lenses, and each of the lenses is arranged between the light source and the light input port.

4. The gas concentration detection device according to claim 1, characterized in that: The input device includes a light source and a first optical fiber, The light source is used to emit a laser beam; One end of the first optical fiber is coupled to the light source, and the other end of the first optical fiber is coupled to the light input port.

5. The gas concentration detection device according to claim 1, characterized in that: The receiving device comprises a detector, which is installed at the light receiving port and is used to detect the laser beam.

6. A gas concentration detection method, characterized in that: The steps include: S1. Prepare a gas concentration detection device as described in any one of claims 1 to 5, and connect the gas inlet and the gas outlet to a gas source to be detected; S2, inputting a laser beam into the reflection cavity through the input device, and focusing the laser beam to a focal point in the reflection cavity and then diverging, wherein the focal point is located at the midpoint of two reflections and does not pass through the spherical center of the reflection cavity; S3. Receive the laser beam emitted from the receiving point after multiple reflections through the receiving device, and detect the laser beam to obtain the concentration of the gas to be measured.

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