CN117191742A - Three-optical-path multi-pass absorption tank - Google Patents
Three-optical-path multi-pass absorption tank Download PDFInfo
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- CN117191742A CN117191742A CN202311174388.2A CN202311174388A CN117191742A CN 117191742 A CN117191742 A CN 117191742A CN 202311174388 A CN202311174388 A CN 202311174388A CN 117191742 A CN117191742 A CN 117191742A
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- mirror
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- concave mirror
- circular concave
- pass
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- 238000010521 absorption reaction Methods 0.000 title claims abstract description 18
- 230000003287 optical effect Effects 0.000 claims abstract description 12
- 238000002310 reflectometry Methods 0.000 claims abstract description 5
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 239000007789 gas Substances 0.000 abstract description 21
- 238000012544 monitoring process Methods 0.000 abstract description 11
- 238000005516 engineering process Methods 0.000 description 6
- 238000000862 absorption spectrum Methods 0.000 description 4
- 239000003570 air Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000035945 sensitivity Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 239000012080 ambient air Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000000041 tunable diode laser absorption spectroscopy Methods 0.000 description 1
Abstract
The invention is mainly used in the field of atmospheric trace polluted gas monitoring, and mainly relates to a three-optical-path multi-pass absorption cell, which comprises a circular concave mirror (1), a circular plane mirror (2) and a lens barrel (3), wherein the radius of curvature of the circular concave mirror (1) and the radius of curvature of the mirror surface are 2390mm, the diameters of the mirror surface and the mirror surface of the circular plane mirror (2) are 100mm, the distance between the circular concave mirror (1) and the mirror surface curvature (2) is 50cm, the reflectivity of both the two mirror surfaces is not less than 98%, light entering the multi-pass cell from the hole of the circular concave mirror (1) enters the multi-pass cell at the angles of (0.12,0.31), (0.12,0.49) and (0.12,0.68), and after the multi-pass cell is subjected to multi-reflection, the corresponding optical paths of 20.5m,42.5m and 64.5m can be obtained. The invention realizes that three gases can be measured simultaneously in one multi-way pool, improves the utilization rate of the multi-way pool and has lower cost.
Description
Technical Field
The invention relates to a three-optical path multi-pass absorption cell, in particular to a multi-pass cell for monitoring atmospheric trace polluted gas.
Background
Trace amount of polluted gas affects the quality of the ambient air and causes great harm to human health and ecological environment. Therefore, continuous efforts are made to monitor the atmospheric trace polluted gas, new monitoring methods and technologies are continuously developed, and powerful scientific and technical guarantees are provided for monitoring and treating the atmospheric trace polluted gas.
Tunable diode laser absorption spectroscopy technology in optical monitoring methods is one of the commonly used methods for trace contaminant gas monitoring, and has been favored by researchers for many years and is continuously innovated. According to the fingerprint characteristics of the gas to be detected in different wave bands, the tunable diode laser absorption spectrum technology basically has corresponding available lasers from the visible wave band to the mid-infrared wave band. However, lasers for monitoring trace polluted gas often have only one wave band, so that the requirement of one laser for measuring various gases is difficult to meet, especially in a mid-infrared wave band, the cost of the laser is high, the fiber collimation technology is not mature in the wave band, if various gases are to be monitored, each laser corresponds to one optical multi-pass cell, and the monitoring cost is greatly increased. In recent years, in order to improve detection sensitivity and reduce system volume, multi-way absorption cells of various shapes are continuously appeared, and the multi-way absorption cells are widely applied to trace gas monitoring and achieve higher detection sensitivity. However, most of the multipass cells are bi-spherical systems, and only one optical path is used, and only one gas is measured. The novel multi-way absorption cell is explored, so that the multi-way cell can be used for simultaneously measuring various gases, and the method has very important significance for reducing the cost, improving the sensitivity and developing a portable tunable diode laser absorption spectrum system. The invention provides a circular concave mirror and a circular plane mirror structure under the research background, realizes that three light beams with different incident angles enter a multipass cell from the same incident hole, and are reflected back and forth between the circular concave mirror and the circular plane mirror, respectively realizes optical paths of 20.5m,42.5m and 64.5m under the condition of 50cm base length, and has important significance for promoting the development and application of a tunable diode laser absorption spectrum technology in trace pollution gas monitoring. .
Disclosure of Invention
The invention provides a three-optical path multi-way absorption cell, which aims at reducing cost, improving optical path and realizing simultaneous measurement of various gases, realizes the monitoring of three trace polluted gases by a tunable diode laser absorption spectrum technology, and overcomes the defect that one multi-way cell can only use a single light source to measure one trace gas.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: the three-optical path multi-way absorption cell consists of a circular concave mirror (1), a circular plane mirror (2) and a lens cone (3), wherein the diameter of the circular concave mirror (1) is 100mm, the curvature radius is 2490 mm, the reflectivity is not less than 98%, the center of the circular concave mirror (1) is taken as the origin of coordinates, and the circular concave mirror is taken as the origin of coordinatesThe mirror surface of the mirror (1) isx-yAnd a hole (4) with the diameter of 3.4mm is formed on the circular concave mirror plane (0, 42), and the diameter of a light spot passing through the hole (4) is not more than 3mm.
The diameter of the circular plane mirror (2) is 100mm, the reflectivity is not less than 98%, the circle center of the circular plane mirror (2) is used as the origin of coordinates, and the circular plane mirror (2) is used as the origin of coordinatesx′-yThe 'plane' is formed by opening a hole (5) with the diameter of 3.4mm on the circular plane mirror (5.5, 41), and the diameter of a light spot passing through the hole (4) is not more than 3mm.
The three-optical path multi-way absorption cell is characterized in that the inner diameter of a lens barrel connected with a circular concave mirror (1) and a circular plane mirror (3) is 100mm, the length of the lens barrel is 50cm, an air inlet hole (6) and an air outlet hole (7) are formed in positions, close to 30 mm of the circular concave mirror (1) and the circular plane mirror (2) respectively, on two sides of the lens barrel, and the circular concave mirror (1) and the circular plane mirror (2) are connected and fixed through the lens barrel (3).
The three incident light beams of the three-optical-path multi-pass absorption cell can enter from the opening (4) of the circular concave mirror (1) and also can enter from the opening (5) of the circular plane mirror (2). The diameters of the opening (4) and the opening (5) are determined to be 3.4 and mm, so as to prevent the quality of the laser beam from being influenced by the smaller diameter of the opening when the laser beam enters and exits the multi-pass cell.
Drawings
FIG. 1 is a schematic view of the basic structure of the present invention
1. Round concave mirror 2, round plane mirror 3, lens barrel 4, incident light hole 5, emergent light hole 6, air inlet hole 7, air outlet hole
In FIG. 2, the distribution of light spots in the multipass cell is 64.5m, the left is the distribution of light spots on the concave mirror and the position of the holes, and the right is the distribution of light spots on the plane mirror and the position of the holes
FIG. 3 is a graph showing the distribution of light spots in a multipass cell with an optical path length of 42.5m, with the left side showing the distribution of light spots on the concave mirror and the position of the holes, and the right side showing the distribution of light spots on the plane mirror and the position of the holes
FIG. 4 is a plot of the light spot distribution in a multipass cell at an optical path length of 20.5m, with the light spot distribution and aperture position on the concave mirror on the left and the light spot distribution and aperture position on the plane mirror on the right
Description of the embodiments
The vertex of the circular concave mirror is taken as the origin of coordinates, an x-y-z coordinate system is established, and a vertical plane is set asx-yA plane for fixing the holes (0, 42) of the circular concave mirror (1) tozThe point 50cm on the axis is the origin of coordinates to be perpendicular tozShaft establishmentx′-y' plane, inx′-yA circular plane mirror (2) is arranged on the plane, so that the hole (5) of the circular plane mirror coincides with the point of the coordinates (5.5, 41), and then a lens cone (3) is arranged, so that the lens cone is tightly connected with the circular concave mirror (1) and the circular plane mirror (2) to form the three-optical path multi-pass cell.
When the polluted gas is measured, firstly, three different gases are filled in a three-optical-path multi-pass cell, then three lasers with different wavelengths are selected, the wavelengths output by the lasers and the three gases filled in the three-optical-path multi-pass cell respectively correspond to strong absorption lines, the light spots output by the lasers are shaped, the diameters of the light spots are smaller than 1mm, then the light spots enter the three-optical-path multi-pass cell from a light-passing hole (4) of a circular concave mirror (1), and the incidence angles of three light beams are regulated, so that the incidence directions of the three light beams are relative to each otherxShaft and method for producing the sameyThe deflection angles of the shafts respectively satisfy (0.12) o ，0.31 o ）、（0.12 o ，0.49 o ) Sum (0.12) o ，0.68 o ) The light is reflected back and forth by the round concave mirror (1) and the round plane mirror (2) in the three-optical-path multi-pass cell, respectively reaches optical paths of 20.5m,42.5m and 64.5m, and then is emitted from the hole (5), and the emitted light is detected by a detector arranged behind the multi-pass cell.
Claims (6)
1. A three-optical path multi-way absorption cell is characterized by comprising a round concave mirror (1), a round plane mirror (2) and a lens cone (3), wherein the round concave mirror (1) and the round plane mirror (2) are respectively arranged at two sides of the lens cone (3), and the reflectivity of the round concave mirror and the round plane mirror is not less than 98%.
2. The three-optical path multi-pass absorption cell according to claim 1, wherein the circular plane mirror (2) and the circular concave mirror (1) are placed on two sides of the lens barrel (3) in different orders, and the positions of the circular plane mirror (2) and the circular concave mirror (1) are determined and then fixed by the lens barrel (3).
3. The three-optical path multi-pass absorption cell according to claim 1, wherein the diameter of the circular plane mirror (2) and the diameter of the circular concave mirror (1) are 100mm, the radius of curvature of the circular concave mirror (1) is 2390mm, and the length of the lens barrel (3) connecting and fixing the circular concave mirror (1) and the circular plane mirror (2) is 50 cm.
4. The three-path multi-pass absorption cell according to claim 1, wherein the center of the circular concave mirror (1) is used as the origin of coordinates, and the mirror surface is used as the mirror surfacex-yThe surface is provided with a hole (4) with the diameter of 3.4mm at the coordinates of (0, 42), the center of the round plane mirror (2) is taken as the origin of coordinates, and the mirror surface is taken as the mirror surfacex′-yThe' face is provided with a hole (5) with the diameter of 3.4mm at the (5.5, 41) coordinate, and the diameter of the light beam entering the multi-pass cell is not more than 3mm.
5. A three-path, multi-pass absorption cell according to claim 1, wherein the reflectivity of the circular plane mirror (2) and the circular concave mirror (1) is not less than 98% and is set according to the wavelength of the laser used to measure the gas.
6. A three-path, multi-pass absorption cell according to claim 1, wherein the light enters the multi-pass cell from the aperture (4) of the circular concave mirror (1), the light beam being directed againstxShaft and method for producing the sameyThe deflection angles of the shafts were 0.12 respectively o ，0.31 o When the corresponding optical path is 20.5m, the light beam is relative toxShaft and method for producing the sameyThe deflection angles of the shafts were 0.12 respectively o ，0.49 o When the corresponding optical path is 42.5m, the light beam is relative toxShaft and method for producing the sameyThe deflection angles of the shafts were 0.12 respectively o ，0.68 o The corresponding optical path length was 64.5m.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311174388.2A CN117191742A (en) | 2023-09-13 | 2023-09-13 | Three-optical-path multi-pass absorption tank |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311174388.2A CN117191742A (en) | 2023-09-13 | 2023-09-13 | Three-optical-path multi-pass absorption tank |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117191742A true CN117191742A (en) | 2023-12-08 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311174388.2A Pending CN117191742A (en) | 2023-09-13 | 2023-09-13 | Three-optical-path multi-pass absorption tank |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117191742A (en) |
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2023
- 2023-09-13 CN CN202311174388.2A patent/CN117191742A/en active Pending
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