CN115615919A - Optical cavity ring-down trace gas measurement system based on triangular annular cavity - Google Patents

Optical cavity ring-down trace gas measurement system based on triangular annular cavity Download PDF

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CN115615919A
CN115615919A CN202210683489.1A CN202210683489A CN115615919A CN 115615919 A CN115615919 A CN 115615919A CN 202210683489 A CN202210683489 A CN 202210683489A CN 115615919 A CN115615919 A CN 115615919A
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cavity
ring
triangular
gas
light
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李晓梅
阎杰
江康
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Anhui Wanyi Science and Technology Co Ltd
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Anhui Wanyi Science and Technology Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N2021/0106—General arrangement of respective parts
    • G01N2021/0112—Apparatus in one mechanical, optical or electronic block
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
    • G01N2021/391—Intracavity sample
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/061—Sources
    • G01N2201/06113—Coherent sources; lasers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/063—Illuminating optical parts
    • G01N2201/0636—Reflectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/06—Illumination; Optics
    • G01N2201/066—Modifiable path; multiple paths in one sample
    • G01N2201/0668—Multiple paths; optimisable path length

Abstract

The invention discloses an optical cavity ring-down trace gas measuring system based on a triangular ring cavity, which comprises an optical path module, an air path module, a data acquisition module and a control module, wherein the optical path module is used for forming a closed triangular optical path for detecting gas concentration, the air path module is used for introducing sample gas to be detected into the triangular optical path of the optical path module, the data acquisition module is used for acquiring ring-down time of light in a cavity environment and a gas absorption environment, and the control module is used for controlling the optical path module, the air path module and the data acquisition module.

Description

Optical cavity ring-down trace gas measurement system based on triangular annular cavity
Technical Field
The invention belongs to the technical field of gas monitoring, and particularly relates to a cavity ring-down trace gas measuring system based on a triangular annular cavity.
Background
The gas spectral measurement method mainly comprises a tunable semiconductor laser absorption spectrum technology, a photoacoustic spectrum technology, a cavity enhanced absorption spectrum technology, a Fourier infrared spectrum technology, a non-dispersive infrared technology, a differential absorption spectrum technology, an off-axis integral cavity technology, a cavity ring-down spectrum technology and the like. The cavity ring-down spectroscopy technology is a high-precision measurement technology based on a ring-down cavity, and laser is coupled into a resonant cavity through mode matching to realize coherent growth by the ring-down cavity with high fineness of two or more high-reflector groups, so that the absorption optical path is increased. When the laser is cut off rapidly, the detector detects the attenuation of the light intensity, and the cavity ring-down time is obtained through exponential fitting. The ring-down time is related to the reflectivity, cavity length and gas absorption of the cavity mirror, and the concentration of the gas to be measured can be inverted by measuring the ring-down time difference of the gas, wherein the ring-down time is shown in the following formula:
Figure BDA0003696890020000011
in the above formula, C is the concentration of the gas to be measured, C is the speed of light, and is the absorption cross section of the gas to be measured at a specific absorption peak, tau and tau 0 Respectively ring down times with gas absorption and cavity.
The cavity that rings down among the prior art is most for the linear type ring down and rings down the cavity, and the high-order mode is difficult to be inhibited, and the SNR that rings down the signal is not high, and cavity structures is longer, and the inhomogeneous increase that can arouse the error of sample excitation simultaneously to sum up, this application now provides a cavity ring down trace gas measurement system based on triangle annular chamber and solves the problem that the aforesaid appeared.
Disclosure of Invention
In order to solve the above-mentioned deficiencies in the prior art, the present invention provides an optical cavity oscillation trace gas measurement system based on a triangular ring cavity, so as to solve the problems in the background art.
The technical scheme adopted by the invention for solving the technical problems is as follows: the utility model provides an optical cavity rings down trace gas measurement system based on triangle annular chamber, includes light path module, gas circuit module, data acquisition module and control module, the light path module is used for forming the closed triangle light path that detects gas concentration, the gas circuit module is used for to wait to detect sample gas to the inside letting in of triangle light path of light path module, the data acquisition module is arranged in gathering the time of ring down of light in the cavity environment with have the gas absorption environment, control module is used for controlling light path module, gas circuit module and data acquisition module.
Preferably, the optical path module comprises a triangular annular cavity, a front cavity optical path and a rear cavity optical path, the cavity of the triangular annular cavity is preferably made of invar steel with small thermal expansion coefficient, low thermal conductivity coefficient, low hardness and high performance, the diameters of two end ports of the cavity are different, an air inlet through which sample gas to be detected can be introduced and an air outlet corresponding to the air inlet are arranged on the cavity of the triangular annular cavity, the planar positions of the air inlet and the air outlet are at least 2cm away from the first high-reflection mirror, the second high-reflection mirror and the third high-reflection mirror, so that adverse effects caused by airflow on the reflection efficiency of the first high-reflection mirror, the second high-reflection mirror and the third high-reflection mirror are avoided, the triangular annular cavity comprises the first high-reflection mirror, the second high-reflection mirror and the third high-reflection mirror, the reflectivities of the first high-reflection mirror, the second high-reflection mirror and the third high-reflection mirror are all greater than 99.99%, the first high-reflection mirror, the second high-reflection mirror and the third high-reflection mirror are arranged inside a cavity of the triangular annular cavity in a triangular mode, the first high-reflection mirror and the second high-reflection mirror preferably adopt plane mirrors and are bonded to one side end face of the cavity of the triangular annular cavity, the third high-reflection mirror preferably adopts a spherical mirror and is bonded to the other side end face of the cavity of the triangular annular cavity, an included angle between the first high-reflection mirror and the second high-reflection mirror is preferably designed to be an included angle of 88.768 degrees, the third high-reflection mirror is preferably arranged at a perpendicular bisector of a connecting line of central points of the first high-reflection mirror and the second high-reflection mirror, glue for bonding the first high-reflection mirror, the second high-reflection mirror and the third high-reflection mirror preferably adopts epoxy resin glue, air tightness of the cavity is ensured, s-linear polarized light entering the triangular annular cavity is reflected to the surface of the second high-reflection mirror through the first high-reflection mirror and then reflected to the surface of the third high-reflection mirror, the third high-reflection mirror reflects the light beam to the surface of the first high-reflection mirror, and the first high-reflection mirror reflects the light beam reflected by the third high-reflection mirror to the surface of the second high-reflection mirror to form a closed triangular light beam; the laser comprises a laser, a first reflector and a polarization beam splitter, the laser is used for outputting light beams, the laser can adopt a DFB continuous wave laser and has good monochromaticity, the line width of the laser can be generally within 1MHz, the wavelength can be adjusted, and the laser has very high side mode suppression ratio; the optical path behind the cavity comprises a 1/4 glass slide and a second reflecting mirror, the 1/4 glass slide is used for converting s-linear polarized light into circularly polarized light or elliptically polarized light and converting the circularly polarized light or elliptically polarized light into P-linear polarized light, the second first reflecting mirror reflects the light to the focusing mirror and focuses the light on the end face of the photoelectric detector, the s-linear polarized light output by the triangular annular cavity passes through the 1/4 glass slide, the 1/4 glass slide converts the s-linear polarized light into circularly polarized light or elliptically polarized light, the circularly polarized light or elliptically polarized light returns after being reflected by the second reflecting mirror and then passes through the 1/4 glass slide, and the 1/4 glass slide converts the circularly polarized light or elliptically polarized light into P-linear polarized light without interference with the forward traveling wave.
More preferably, the optical path module still includes optical platform, optical path and triangle annular optical cavity all set up on optical platform behind light path, the chamber before the chamber, and optical platform prefers to adopt tungsten copper to make, and it has characteristics such as hardness height, thermal expansion coefficient are low, the thermal conductivity is good.
More preferably, the optical path still includes before the chamber first collimating mirror, matching mirror and second collimating mirror, the beam waist size of laser instrument output beam can adopt first collimating mirror or first collimating mirror and second collimating mirror to adjust jointly, and the light beam after the regulation passes through matching mirror, makes the beam waist of light beam and the beam waist phase-match of triangle annular chamber, and the collimation principle according to gaussian beam of the lens parameter of first collimating mirror and the accurate diameter of second determines.
More preferably, the optical path before the cavity further includes a prism, and the prism is used for adjusting the spatial position of the light beam, adjusting the angle of the light beam input into the triangular ring cavity, adjusting the angle of the light beam entering into the triangular ring cavity, and ensuring that the angle of the incident light beam meets the condition of forming a closed optical path.
More preferably, the data acquisition module includes a photodetector and a focusing mirror, the photodetector is used for acquiring ring-down time of light in a cavity environment and a gas absorption environment, light reflected by the second reflecting mirror is focused on the end face of the photodetector by the focusing mirror, the photodetector can be connected with an acquisition card arranged outside through a data line, and the acquisition card is used for storing and transmitting detected data.
More preferably, the gas circuit module includes air pump, two proportional valves, primary filter and secondary filter, the intake pipe route of air pump is opened and shut of one of them proportional valve control route, the air inlet pipeline of air pump runs through primary filter and secondary filter, be connected with the air inlet of triangle annular chamber, the gas outlet pipeline of air pump is connected with the gas outlet of triangle annular chamber, the play gas pipe route of air pump is opened and shut of another proportional valve control route, the air pump provides power for waiting to detect sample gas business turn over triangle annular chamber, the opening and shutting of the air inlet pipeline of two proportional valve control air inlet pumps, primary filter and secondary filter the sample gas.
More preferably, the control module comprises a laser driver, a cavity temperature controller and an electrical shutoff device, the laser is controlled by the laser driver to operate, the cavity temperature controller is used for controlling the temperature inside the cavity of the triangular annular cavity, and the electrical shutoff device controls the shutoff of the laser.
From the above, the invention has the following beneficial effects: according to the invention, laser is circularly reflected in the ring-down cavity through the triangular annular cavity, so that an effective absorption path is increased, and the lower limit of measurement is improved; because the incident light and the return light of the triangular cavity are in different directions and no feedback is provided for the light source, the frequency fluctuation is reduced, the coupling of the optical cavity is improved, the baseline noise is reduced, and the absolute sensitivity is improved. Meanwhile, because the light in the cavity is composed of traveling waves instead of standing waves, the uniformity of the light intensity in the cavity is improved, and therefore errors caused by nonuniform excitation of the sample are reduced.
Drawings
FIG. 1 is a schematic block diagram of a cavity ring-down trace gas analysis system based on a triangular ring cavity according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of an optical path structure of a cavity ring-down trace gas analysis system based on a triangular ring cavity according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of beam matching for a cavity ring-down trace gas analysis system based on a triangular ring cavity according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a triangular annular cavity of a cavity ring-down trace gas analysis system based on the triangular annular cavity according to an embodiment of the present invention.
In the reference symbols: 1. a cavity front light path; 2. a triangular annular cavity; 3. a cavity back optical path; 4. an optical platform; 5. a data acquisition module; 6, a gas circuit module; 7. a laser driver; 8. an electrical shutoff; 9. a cavity temperature controller; 11. a laser; 12. a first collimating mirror; 13. a second collimating mirror; 14. matching the glasses; 15. a first reflecting mirror; 16. a polarizing beam splitter; 17. a prism; 201. a first high-reflection mirror; 202. a second high-reflection mirror; 203. a third high-reflection mirror; 204. an air outlet; 205. an air inlet; 31.1/4 glass slide; 32. a second reflector; 33. a focusing mirror; 51. and a light detector.
Detailed Description
The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, for the convenience of description, only the portions related to the present invention are shown in the drawings.
Example one
Referring to fig. 1-4, a cavity ring-down trace gas measurement system based on a triangular ring cavity comprises a light path module, a gas path module 6, a data acquisition module 5 and a control module, wherein the light path module is used for forming a closed triangular light path for detecting gas concentration, the light path module comprises a triangular ring cavity 3, a cavity front light path 1 and a cavity rear light path 3, the cavity front light path 1 comprises a laser 11, a first collimating mirror 12, a second collimating mirror 13, a matching mirror 14, a first reflecting mirror 15, a polarization beam splitter 16 and a prism 17, the laser 11 emits a gaussian light beam, the beam waist size of the light beam is changed after passing through the first collimating mirror 12 and the second collimating mirror 13, the beam waist of the light beam is matched with the beam waist of the triangular ring cavity 3 after passing through the matching mirror 14, the light beam reaches the polarization beam splitter 16 after being reflected by the first reflecting mirror 15, the polarization beam splitter 16 separates s-linear polarized light from p-polarized light, and s-polarized light is injected into the triangular ring cavity.
The triangular annular cavity 3 comprises a first high-reflection mirror 201, a second high-reflection mirror 202 and a third high-reflection mirror 203, the first high-reflection mirror 201, the second high-reflection mirror 202 and the third high-reflection mirror 203 are arranged inside the cavity of the triangular annular cavity 3 in a triangular mode, the first high-reflection mirror 201 and the second high-reflection mirror 202 are preferably flat mirrors and are bonded to one side end face of the cavity of the triangular annular cavity 3, the third high-reflection mirror 203 is preferably a spherical mirror, the third high-reflection mirror 203 is bonded to the other side end face of the cavity of the triangular annular cavity 3, s-polarized light entering the triangular annular cavity 3 is reflected to the surface of the second high-reflection mirror 202 through the first high-reflection mirror 201 and then reflected to the surface of the third high-reflection mirror 203, the third high-reflection mirror 203 reflects the light beam to the surface of the first high-reflection mirror 201, and the first high-reflection mirror 201 reflects the light beam reflected by the third high-reflection mirror 203 to the surface of the second high-reflection mirror 202 to form a closed triangular light beam.
The cavity back light path 3 comprises a 1/4 glass slide 31 and a second reflecting mirror 32, s-linear polarized light which penetrates through the triangular ring cavity 3 passes through the surface of the 1/4 glass slide 31 and is converted into circularly polarized light to reach the second reflecting mirror 32, the second reflecting mirror 32 reflects the s-linear polarized light back to the triangular ring cavity 3, on the way, after passing through the other side surface of the 1/4 glass slide 31, the 1/4 glass slide 31 converts circularly polarized light into p-linear polarized light which is injected into the triangular ring cavity 3 again, the p-linear polarized light is the same in principle, a reverse circulation closed light path opposite to the direction of the s-linear polarized light is formed in the triangular ring cavity 3, and meanwhile, when the p-linear polarized light penetrates through the polarization beam splitter 16, the p-linear polarized light can be refracted by the polarization beam splitter 16, and interference on a light source can not be generated.
The cavity of the triangular annular cavity 3 is provided with an air inlet 205 capable of introducing sample gas to be detected and an air outlet 204 corresponding to the air inlet 205, the air circuit module 6 is used for introducing the sample gas to be detected into the triangular optical path of the optical path module, the air circuit module 6 comprises an air pump, two proportional valves, a primary filter and a secondary filter, an air inlet pipe of the air pump is controlled by one of the proportional valves to open and close the passage, an air inlet pipeline of the air pump penetrates through the primary filter and the secondary filter and is connected with the air inlet 205 of the triangular annular cavity 3, the gas outlet pipeline of air pump is connected with the gas outlet 204 of triangle annular chamber 3, the outlet duct way of air pump is controlled by another proportional valve and is opened and shut, the air pump is for waiting to detect sample gas business turn over triangle annular chamber 3 and provide power, one-level filter and second grade filter are filtered sample gas, the air pump is for detecting the triangle annular chamber 3 that finishes of discharging of sample gas, the air pump will wait to detect sample gas and inject into triangle annular chamber 3 through the air inlet 205 of triangle annular chamber 3 inside, the air pump can be discharged the gas outlet 204 of triangle annular chamber 3 with the inside gas in triangle annular chamber 3.
Data acquisition module 5 is used for collecting the ring-down time of light in cavity environment and having the gas absorption environment, data acquisition module 5 includes photoelectric detector 51 and focusing mirror 33, photoelectric detector 51 collects the ring-down time of light in cavity environment and having the gas absorption environment, the light that second reflector 32 reflects is focused on photoelectric detector 51's terminal surface by focusing mirror 33, photoelectric detector 51 can pass through the data line with the collection card of locating the outside and be connected, the collection card is used for storing and transmitting the data that detect, after the good data of record, calculate the concentration of the gas to be measured through following formula:
Figure BDA0003696890020000051
where C is the concentration of the gas to be measured, C is the speed of light, τ and τ 0 The absorption cross section of the gas to be measured at a specific absorption peak and the ring-down time when the gas is absorbed and the cavity is formed respectively.
Example two
The first high-reflection mirror 201 and the second high-reflection mirror 202 are preferably plane mirrors and are bonded to one side end face of the cavity of the triangular annular cavity 3, the third high-reflection mirror 203 is preferably a spherical mirror, the third high-reflection mirror 203 is bonded to the other side end face of the cavity of the triangular annular cavity 3, the included angle between the first high-reflection mirror 201 and the second high-reflection mirror 202 is preferably designed to be 88.768 degrees, and the third high-reflection mirror 203 is preferably arranged at the perpendicular bisector of the connecting line of the central points of the first high-reflection mirror 201 and the second high-reflection mirror 202.
The beam waist radius of the gaussian beam output by the laser 11 is determined by the fiber diameter of the output optical fiber, which is very small, while the beam waist radius and position of the gaussian beam in the triangular ring cavity 3 are determined by the long side and short side of the triangular closed optical path and the curvature radius R of the spherical high-reflection mirror, and the beam waist position of the gaussian beam in the cavity is located at the middle position between the input plane mirror 701 and the output plane mirror 702.
It should be noted that, in the present application, the embodiments and features of the embodiments may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
The foregoing description is only exemplary of the preferred embodiments of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention according to the present application is not limited to the embodiments with specific combinations of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.
Besides the technical features described in the specification, other technical features are known to those skilled in the art, and are not described herein again in order to highlight the innovative features of the present invention.

Claims (10)

1. An optical cavity ring-down trace gas measurement system based on a triangular annular cavity, comprising:
the optical path module is used for forming a closed triangular optical path for detecting the concentration of the gas;
the gas path module (6), the gas path module (6) is used for introducing the sample gas to be detected into the triangular light path of the light path module;
a data acquisition module (5), wherein the data acquisition module (5) is used for acquiring the ring-down time of light in a cavity environment and a gas absorption environment; and
and the control module is used for controlling the light path module, the gas path module (6) and the data acquisition module (5).
2. The cavity ring-down trace gas measurement system based on the triangular ring cavity of claim 1, wherein the optical path module comprises:
triangle ring chamber (3), be equipped with gas outlet (204) that can let in gas inlet (205) and correspond with gas inlet (205) that await measuring the appearance gas on the cavity of triangle ring chamber (3), triangle ring chamber (3) include:
the three-dimensional ring cavity comprises a first high-reflection mirror (201), a second high-reflection mirror (202) and a third high-reflection mirror (203), wherein the first high-reflection mirror (201), the second high-reflection mirror (202) and the third high-reflection mirror (203) are arranged inside a cavity of the triangular ring cavity (3) in a triangular mode;
a pre-cavity light path (1), the pre-cavity light path (1) comprising:
a laser (11), the laser (11) for outputting a light beam;
a first mirror (15), the first mirror (15) for changing the optical path direction of the light beam passing through the matching mirror (14); and
a polarizing beam splitter (16), said polarizing beam splitter (16) for separating s-linearly polarized light and p-linearly polarized light;
a post-cavity light path (3), the post-cavity light path (3) comprising:
a 1/4 glass plate (31), the 1/4 glass plate (31) is used for converting s-linear polarized light into circularly polarized light or elliptically polarized light and converting the circularly polarized light or elliptically polarized light into P-linear polarized light;
and the second reflector (32) is used for reflecting the light beams output by the triangular ring cavity (3) back to the interior of the triangular ring cavity (3).
3. The cavity ring-down trace gas measurement system based on the triangular ring-shaped cavity according to claim 2, wherein the optical path module further comprises an optical platform (4), and the cavity front optical path (1), the cavity rear optical path (3) and the triangular ring-shaped cavity are all arranged on the optical platform (4).
4. The cavity ring-down trace gas measurement system based on the triangular ring cavity as claimed in claim 2, wherein the cavity front optical path (1) further comprises the first collimating mirror (12), and the first collimating diameter is used for changing the beam waist size of the output beam of the laser (11); and
a matching lens (14), the matching lens (14) being used to adjust the beam waist of the first collimating lens (12).
5. The cavity ring-down trace gas measurement system based on the triangular ring cavity according to claim 4, wherein the cavity front optical path (1) further comprises a second collimating mirror (13), and the second collimating mirror (13) and the first collimating mirror (12) are used in cooperation for changing the beam waist size of the output beam of the laser (11).
6. The cavity ring-down trace gas measurement system based on the triangular annular cavity according to claim 2, wherein the cavity front light path (1) further comprises a prism (17), and the prism (17) is used for adjusting the spatial position of the light beam and adjusting the angle of the light beam input into the triangular annular cavity (3).
7. The cavity ring-down trace gas measurement system based on the triangular ring cavity according to claim 2, wherein the first high-reflection mirror (201) and the second high-reflection mirror (202) are both planar high-reflection mirrors, the third high-reflection mirror (203) is a spherical high-reflection mirror, and an included angle between the first high-reflection mirror (201) and the second high-reflection mirror (202) is 85-90 °.
8. The cavity ring-down trace gas measurement system based on the triangular annular cavity according to claim 2, wherein the data acquisition module (5) comprises:
a photodetector (51), the photodetector (51) for collecting a ring down time of light in a cavity environment and a gas-absorbing environment; and
and a focusing mirror (33), wherein the light reflected by the second reflecting mirror (32) is focused on the end face of the photoelectric detector (51) by the focusing mirror (33).
9. The optical cavity ring-down trace gas measurement system based on the triangular annular cavity according to claim 2, wherein the gas path module (6) comprises a gas pump, two proportional valves, a primary filter and a secondary filter, a gas inlet pipe of the gas pump controls opening and closing of a passage by one of the proportional valves, a gas inlet pipe of the gas pump penetrates through the primary filter and the secondary filter and is connected with a gas inlet (205) of the triangular annular cavity (3), a gas outlet pipe of the gas pump is connected with a gas outlet (204) of the triangular annular cavity (3), and opening and closing of the passage is controlled by the other proportional valve.
10. The cavity ring-down trace gas measurement system based on the triangular annular cavity of claim 9, wherein the control module comprises:
the laser driver (7) is used for controlling the laser (11) to operate by the laser driver (7);
the cavity temperature controller (9), the cavity temperature controller (9) is used for controlling the cavity internal temperature of the triangular annular cavity (3); and
an electrical shut-off (8), the electrical shut-off (8) controlling the switching off of the laser (11).
CN202210683489.1A 2022-06-16 2022-06-16 Optical cavity ring-down trace gas measurement system based on triangular annular cavity Pending CN115615919A (en)

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