CN117233091A - Gas absorption cell with regular heptagon light path and corresponding laser sensor - Google Patents
Gas absorption cell with regular heptagon light path and corresponding laser sensor Download PDFInfo
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- CN117233091A CN117233091A CN202310755238.4A CN202310755238A CN117233091A CN 117233091 A CN117233091 A CN 117233091A CN 202310755238 A CN202310755238 A CN 202310755238A CN 117233091 A CN117233091 A CN 117233091A
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Abstract
The invention relates to a gas absorption tank with a regular heptagon light path, which comprises a light path main body, a light source and a detector, wherein the inner side of the light path main body is regular heptagon, so that the light path main body is provided with seven inner side surfaces, the light source and the detector are respectively arranged at two inner side surfaces spaced by three inner side surfaces from clockwise direction, first reflectors are arranged on the other five inner side surfaces, and laser beams emitted by the light source are received by the detector after being reflected by the first reflectors. The invention also discloses a corresponding laser sensor. By adopting the gas absorption cell with the regular heptagon light path, the technical requirements of light path processing and light path adjustment can be reduced under the condition of improving the light path, and the production efficiency can be improved.
Description
Technical Field
The invention relates to a gas absorption tank, in particular to a gas absorption tank with a regular heptagon light path and a corresponding laser sensor.
Background
The infrared absorption phenomenon of gases follows Lambert-Beer law, namely:
I(ν)＝I 0 (ν)·exp[-σ(ν)·c·L]；
wherein c is the gas volume concentration; v is the laser emission frequency (cm) -1 )；I 0 (v) and I (v) are the incident light intensity and the transmittance light intensity, respectively; sigma (v) is the spectral absorption cross section at frequency v; l is the gas absorption optical path; ratio I/I 0 1-I/I for transmittance 0 Is the absorption rate. Therefore, the expression of the absorptivity a is:
from the above expression we can see that for a gas of the same concentration c, the larger the gas absorption optical path L, the larger the absorption rate a, and a is exponentially varying with L. Therefore, in designing laser methane gas sensors, designers desire to use gas absorption cells with longer optical paths.
Usually, under laboratory conditions, a White cell or a Herriott cell or other gas absorption cell can be used to achieve an optical path of several meters or even tens of meters, but this requires very precise optical path adjustment and stable environmental conditions, which are difficult to use under engineering environmental conditions, and are also costly. Because the actual engineering conditions are much worse than the laboratory conditions, the gas absorption tank is required to be small enough, and the gas absorption tank is simple to assemble and adjust and low in price. Thus, under a number of limited conditions, the optical path length of commercially available laser methane sensor gas absorption cells is typically in the range of 50-90 mm.
The structure of the existing long-optical-path gas absorption cell has the characteristics of compact and small structure and long optical path, but has some problems in the structure. For example, since the laser beam is not an infinitely fine straight line, but has a light spot with a certain thickness (diameter is about phi 4.8 mm), the mounting seats of the light source and the detector interfere with the light path, and the reflector cannot be mounted on the same plane; because a plurality of reflectors are used, the requirements on the relative angles of the reflectors are very strict, the difficulty for processing parts is very high, and the cost is very high; the requirement on the assembly and adjustment of the optical path is very high, and the actual production is not facilitated. The existing gas absorption cell realizes a longer optical path through a complex space structure, and has the same problems of exquisite design, extremely high processing difficulty, strict tolerance requirement, complex optical path adjustment, extremely high cost and inapplicability to mass production.
Disclosure of Invention
In order to solve the problems, the invention provides a gas absorption cell with a regular heptagon light path structure, which can reduce the technical requirements of light path processing and light path adjustment under the condition of improving the light path and improve the production efficiency.
The invention provides a gas absorption tank with a regular heptagon light path, which comprises a light path main body, a light source and a detector, wherein the inner side of the light path main body is regular heptagon, so that the light path main body is provided with seven inner side surfaces, the light source and the detector are respectively arranged at two inner side surfaces spaced by three inner side surfaces from clockwise, first reflectors are arranged on the other five inner side surfaces, and laser beams emitted by the light source are received by the detector after being reflected by the first reflectors.
Preferably, from clockwise, the optical path main body has a first inner side, a second inner side, a third inner side, a fourth inner side, a fifth inner side, a sixth inner side, and a seventh inner side, the light source and the detector are respectively disposed at the second inner side and the sixth inner side, the first inner side, the third inner side, the fourth inner side, the fifth inner side, and the seventh inner side are respectively disposed with a first reflector, and the laser beam emitted by the light source is received by the detector after being reflected by the first reflector of the fifth inner side, the first reflector of the first inner side, the first reflector of the fourth inner side, the first reflector of the seventh inner side, and the first reflector of the third inner side.
Preferably, two mounting holes are formed in the bottom of the light path main body and are used for mounting the light source and the detector respectively, a reflector seat is arranged at the end of each mounting hole and is used for mounting a second reflector, the second reflector is mounted at 45 degrees, laser beams emitted by the light source are reflected by the second reflector and then are emitted to the first reflector on the fifth inner side surface, and the laser beams reflected by the first reflector on the third inner side surface enter the detector after being reflected by the second reflector.
Preferably, the direction of the laser beam emitted by the light source after being reflected by the second reflector forms an included angle of 51.45 degrees with the first reflector on the first inner side surface;
the center line of the first reflecting mirror of the third inner side and the center of the detector are parallel to the first reflecting mirror of the first inner side.
Preferably, the light source comprises a laser which emits laser light having a wavelength of 1653.7 nm.
Preferably, the first mirror or the second mirror is a gold-plated mirror or a dielectric film-plated mirror, and the dielectric film-plated mirror has the following film system structure:
Glass/(HL)^11/Air
wherein Glass represents a single-sided polished H-K9L optical Glass, air represents Air, and H represents TiO of quarter-wavelength optical thickness 2 Film layer, L represents one-fourth optical thickness of SiO 2 The film layer, the pattern 11, represents 11 repetitions of the film stack structure, the incident angle is 12.8 DEG, and the design wavelength is 1620nm.
Preferably, the light path main body is made of stainless steel or super hard aluminum.
Another aspect of the present invention provides a laser sensor, including the gas absorption cell having a regular heptagon light path.
Preferably, the sensor is a methane sensor.
The invention also provides a light path adjustment method, which comprises the following steps:
(1) The first reflecting mirror and the second reflecting mirror at the detector are well installed and fixed, and the light path adjustment is carried out;
(2) Aligning a green semiconductor laser with the wavelength of 532nm with a light source mounting hole, if the green light emission can be seen from the detector mounting hole, indicating that the light path is aligned, otherwise, calibrating the light path by finely adjusting the position of a reflection seat of the light source;
(3) Glue is used to fix the light source reflector base.
The gas absorption tank with the regular heptagon light path has the following advantages:
(1) The regular heptagon light path structure is rotationally symmetrical, the structure is simple, the processing precision is high, and the cost is low;
(2) The long optical path is realized in a smaller space, and the optical path of 145mm is realized in the diameter phi 30mm range, which is far longer than the optical path used by commercial laser methane gas sensors in the market;
(3) The whole foldback light path is in a plane, and the green light laser is used for adjusting the light path, so that the method is simple and easy to implement;
(4) The specially designed cut-off film reflecting lens has the characteristics of bicolor high reflection (532 nm is less than 1653.7 nm), high reflectivity and low coating cost.
Drawings
Fig. 1 is a view showing a structure of a regular heptagon light path of a gas absorption cell having the regular heptagon light path of the present invention.
Fig. 2 is a front view of a regular heptagon-shaped light path structure of a gas absorption cell provided with the regular heptagon-shaped light path of the present invention.
Fig. 3 is a perspective view showing the structure of a regular heptagon light path of the gas absorption cell with the regular heptagon light path of the present invention.
Fig. 4 is a view of a 45 ° mirror mount of a gas absorption cell with a regular heptagon optical path of the present invention.
FIG. 5 is a cross-sectional view of a gas absorption cell having a regular heptagon-shaped optical path according to the present invention.
FIGS. 6a to 6c are mirror spectrograms at an incident angle of 12.8℃for a gas absorption cell having a regular heptagon optical path according to the invention.
Detailed Description
In order to more clearly describe the technical contents of the present invention, a further description will be made below in connection with specific embodiments.
Before describing in detail embodiments that are in accordance with the present invention, it should be observed that relational terms, such as first and second, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
As shown in fig. 1 to 5, the embodiment of the gas absorption cell with a regular heptagon light path provided by the invention is particularly suitable for a methane laser sensor. The gas absorption cell comprises a light path main body 10, a light source 8 and a detector 9, wherein the light source comprises a laser which emits laser light with the wavelength of 1653.7 nm. The inner side of the optical path main body 10 is in a regular heptagon shape, and the outer side of the optical path main body can be in a round shape, so that the optical path main body has seven inner side surfaces. From the clockwise direction, the optical path main body is provided with a first inner side surface 1, a second inner side surface 2, a third inner side surface 3, a fourth inner side surface 4, a fifth inner side surface 5, a sixth inner side surface 6 and a seventh inner side surface 7. The light path main body can be made of stainless steel or super hard aluminum. The processing precision of the regular heptagon is high, and the cost is low.
The light source 2 and the detector 9 are respectively arranged at the second inner side surface 2 and the sixth inner side surface 6 of the three inner side surfaces at intervals, the light source is close to the second inner side surface 2 as much as possible, the detector is close to the sixth inner side surface as much as possible, the first inner side surface, the third inner side surface, the fourth inner side surface, the fifth inner side surface and the seventh inner side surface are respectively provided with a first reflecting mirror, the 5 reflecting mirrors can be directly adhered to the 5 inner side surfaces of the light path main body, and laser beams emitted by the light source are sequentially received by the detector after being reflected by the first reflecting mirror of the fifth inner side surface, the first reflecting mirror of the first inner side surface, the first reflecting mirror of the fourth inner side surface, the first reflecting mirror of the seventh inner side surface and the first reflecting mirror of the third inner side surface. That is, the laser beam emitted from the light source is folded back in the reflection plane of the heptagonal optical path body.
As shown in fig. 3 to 5, two mounting holes are formed at the bottom of the light path main body and are respectively used for mounting the light source and the detector, the mounting holes extend perpendicular to the reflecting plane, the end parts of the mounting holes are provided with a reflecting mirror seat 11 for mounting a second reflecting mirror, the second reflecting mirror is mounted at 45 degrees, and the second reflecting mirror can be directly bonded on the reflecting mirror seat relative to the reflecting plane at 45 degrees. The laser beam emitted by the light source enters from the first end of the reflector seat, is reflected by the second reflector, is emitted from the second end of the reflector seat and is emitted to the first reflector on the fifth inner side surface, and the laser beam reflected by the first reflector on the third inner side surface enters the detector after being reflected by the second reflector on the reflector seat of the detector. Therefore, the laser beam sequentially passes through the 7 times of reflection mirrors and then enters the detector, and the whole light path is free from shielding.
The light source can be composed of a laser and a corresponding reflector seat, and the reflector seat can be positioned in the light path main body; the detector has a similar structure, comprising an InGaAs detector and a corresponding mirror mount positionable in the optical path body. The reflector seat can be provided with a reflector on one hand and can be used for positioning the reflecting angles of the laser and the detector light source on the other hand.
The gas absorption cell realizes long optical path in a limited space, and in the gas cell with the diameter phi of 30mm, the effective optical path is 145mm, which is far larger than the optical path used by commercial laser methane gas sensors in the market. Meanwhile, the processing difficulty of the gas tank and the light path adjustment difficulty are reduced, and the method is suitable for batch production.
The direction of the laser beam emitted by the light source after being reflected by the second reflecting mirror forms an included angle of 51.45 degrees with the first reflecting mirror on the first inner side surface, and meanwhile, the emitted light can be led to point to the middle point of the reflecting mirror on the fifth inner side surface;
the center line of the first reflecting mirror of the third inner side and the center of the detector are parallel to the first reflecting mirror of the first inner side.
The first reflecting mirror or the second reflecting mirror is a gold-plated reflecting mirror or a reflecting mirror with a dielectric film, and the reflecting mirror with the dielectric film has the following film system structure:
Glass/(HL)^11/Air
wherein Glass represents a single-sided polished H-K9L optical Glass, air represents Air, and H represents TiO of quarter-wavelength optical thickness 2 Film layer, L represents one-fourth optical thickness of SiO 2 The film layer, the pattern 11, represents 11 repetitions of the film stack structure, the incident angle is 12.8 DEG, and the design wavelength is 1620nm.
As shown in fig. 6a to 6c below, under the incident condition of 12.8 degrees, the reflectivity at 1653.7nm and 532nm can reach 98% (the bicolor high-reflectivity film), which is equivalent to the reflectivity of the gold-plated reflector, and the reflective mirror has good reflection effect, the solid line is the reflectivity, and the dotted line is the transmittance spectrum curve. The dielectric filter does not use noble metal gold (Au), and the cost is lower.
The invention also provides a light path adjustment method, which comprises the following steps:
(1) The first reflecting mirror and the second reflecting mirror at the detector are well installed and fixed, and the light path adjustment is carried out;
(2) As shown in fig. 4, the green semiconductor laser with the wavelength of 532nm is aligned with the light source mounting hole, if the green light emission can be seen from the detector mounting hole, the light path is aligned, otherwise, the light path can be calibrated by fine-tuning the position of the reflector seat of the light source;
(3) Glue is used to fix the light source reflector base.
Normally, the processing precision of the regular heptagon is high, and the fine adjustment of the light source reflection seat is not needed.
The gas absorption tank with the regular heptagon light path has the following advantages:
(1) The regular heptagon light path structure is rotationally symmetrical, the structure is simple, the processing precision is high, and the cost is low;
(2) The long optical path is realized in a smaller space, and the optical path of 145mm is realized in the diameter phi 30mm range, which is far longer than the optical path used by commercial laser methane gas sensors in the market;
(3) The whole foldback light path is in a plane, and the green light laser is used for adjusting the light path, so that the method is simple and easy to implement;
(4) The specially designed cut-off film reflecting lens has the characteristics of bicolor high reflection (532 nm is less than 1653.7 nm), high reflectivity and low coating cost.
It is to be understood that the same or similar parts in the above embodiments may be referred to each other, and that in some embodiments, the same or similar parts in other embodiments may be referred to.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (8)
1. The utility model provides a possess gas absorption pond of regular heptagon light path, its characterized in that includes light path main part, light source, detector, the inboard of light path main part be regular heptagon for light path main part have seven medial surfaces, from clockwise, light source and detector set up respectively in two medial surfaces department of interval three medial surface, all set up first speculum with five remaining medial surfaces, the laser beam that the light source sent after the reflection of first speculum by the detector receive.
2. The gas absorption cell having a regular heptagon optical path according to claim 1, wherein the optical path main body has a first inner side, a second inner side, a third inner side, a fourth inner side, a fifth inner side, a sixth inner side, and a seventh inner side from clockwise direction, the light source and the detector are disposed at the second inner side and the sixth inner side, respectively, the first inner side, the third inner side, the fourth inner side, the fifth inner side, and the seventh inner side are each provided with a first mirror, and the laser beam emitted from the light source is received by the detector after passing through the first mirror of the fifth inner side, the first mirror of the first inner side, the first mirror of the fourth inner side, the first mirror of the seventh inner side, and the first mirror of the third inner side.
3. The gas absorption cell with the regular heptagon light path according to claim 2, wherein two mounting holes are formed in the bottom of the light path main body and are used for mounting the light source and the detector respectively, a reflector seat is arranged at the end of each mounting hole and is used for mounting a second reflector, the second reflector is mounted at 45 degrees, laser beams emitted by the light source are reflected by the second reflector and then are emitted to the first reflector of the fifth inner side surface, and laser beams reflected by the first reflector of the third inner side surface are reflected by the second reflector and then enter the detector.
4. The gas absorption cell with regular heptagon light path according to claim 3, wherein the direction of the laser beam emitted by the light source after being reflected by the second reflector forms an angle of 51.45 degrees with the first reflector on the first inner side;
the center line of the first reflecting mirror of the third inner side and the center of the detector are parallel to the first reflecting mirror of the first inner side.
5. The gas absorption cell having a regular heptagon-shaped optical path according to any of claims 1-4, wherein the light source comprises a laser that emits laser light having a wavelength of 1653.7 nm.
6. The gas absorbing cell with regular heptagon optical path as claimed in any one of claims 1 to 4, wherein the first or second mirror is a gold-plated mirror or a dielectric-coated mirror, and the dielectric-coated mirror has a film system structure as follows:
Glass/(HL)^11/Air
wherein Glass represents a single-sided polished H-K9L optical Glass, air represents Air, and H represents TiO of quarter-wavelength optical thickness 2 Film layer, L represents one-fourth optical thickness of SiO 2 The film layer, the pattern 11, represents 11 repetitions of the film stack structure, the incident angle is 12.8 DEG, and the design wavelength is 1620nm.
7. A laser sensor comprising the gas absorption cell having a regular heptagon-shaped optical path according to any of claims 1 to 6.
8. The laser sensor of claim 7, wherein the sensor is a methane sensor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310755238.4A CN117233091A (en) | 2023-06-26 | 2023-06-26 | Gas absorption cell with regular heptagon light path and corresponding laser sensor |
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| CN202310755238.4A CN117233091A (en) | 2023-06-26 | 2023-06-26 | Gas absorption cell with regular heptagon light path and corresponding laser sensor |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115452756A (en) * | 2022-09-26 | 2022-12-09 | 南瑞集团有限公司 | A detection device for decomposition components of sulfur hexafluoride |
| CN117825327A (en) * | 2023-12-26 | 2024-04-05 | 深圳市诺安智能股份有限公司 | Multi-gas laser sensor with equal optical path and high resolution and multi-gas detection method |
| CN119804337A (en) * | 2025-03-13 | 2025-04-11 | 大连易卓激光科技有限公司 | An adaptive laser methane sensor based on MEMS optical system |
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2023
- 2023-06-26 CN CN202310755238.4A patent/CN117233091A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115452756A (en) * | 2022-09-26 | 2022-12-09 | 南瑞集团有限公司 | A detection device for decomposition components of sulfur hexafluoride |
| CN117825327A (en) * | 2023-12-26 | 2024-04-05 | 深圳市诺安智能股份有限公司 | Multi-gas laser sensor with equal optical path and high resolution and multi-gas detection method |
| CN119804337A (en) * | 2025-03-13 | 2025-04-11 | 大连易卓激光科技有限公司 | An adaptive laser methane sensor based on MEMS optical system |
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