CN211877754U - Hyperspectral system for gas concentration detection - Google Patents
Hyperspectral system for gas concentration detection Download PDFInfo
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- CN211877754U CN211877754U CN201921886055.1U CN201921886055U CN211877754U CN 211877754 U CN211877754 U CN 211877754U CN 201921886055 U CN201921886055 U CN 201921886055U CN 211877754 U CN211877754 U CN 211877754U
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Abstract
The utility model discloses a high spectrum system that gas concentration detected, the light that the light source sent forms the parallel light that has the settlement numerical aperture after the collimating mirror collimation, incide the objective in optical absorption chamber, and go on turning back many times between the objective in optical absorption chamber and the field lens, through turning back many times, the light after being absorbed by the gas in the optical absorption chamber incides to the beam splitting board of two optical path interference structure, the light of inciding to the beam splitting board is divided into two the tunnel by 1:1, is reflected to the plane mirror by the beam splitting board all the way, is reflected to the beam splitting board through the plane mirror, is transmitted to the convergent mirror by the beam splitting board; the other route beam splitting plate transmits to the cube corner reflector, is reflected to the beam splitting plate by the cube corner reflector, and is finally reflected to the converging mirror by the beam splitting plate; the converging mirror converges the two paths of light rays and images the light rays onto the detector. The utility model discloses there are high spectral resolution and high flux's advantage, can obtain higher SNR's high resolution spectral data, finally promote detecting system's concentration detection limit.
Description
Technical Field
The utility model belongs to the technical field of photoelectric detection, a hyperspectral system that gas concentration detected is related to.
Background
The optical absorption spectroscopy is a gas concentration detection method, the spectrum acquisition of gas is the basic and key technology for concentration inversion by the optical absorption spectroscopy, and the resolution of the gas absorption spectroscopy determines the type number and detection limit of the detectable gas.
At present, in the conventional absorption spectroscopy method for detecting the gas concentration, an optical absorption cavity is mostly adopted to increase the optical path of the gas, and the detection capability (detection limit) of the low-concentration gas is improved by increasing the optical path of the light in the gas. And obtaining the characteristic absorption spectrum of the target gas at the output aperture of the absorption cavity by using an optical fiber spectrometer, and inverting the concentration of the gas by using an optical absorption spectrum technology.
The working principle of fiber optic spectrometers is based on grating dispersive spectroscopy. The slit light is spatially separated according to wavelength by using the dispersion capability of the grating and is received by a linear array detector. The photosensitive units at different positions on the linear array detector receive energy with different wavelengths, and finally the spectrum of the gas in the range of the whole wave band is obtained. The optical fiber spectrometer is limited by the grating dispersion light splitting principle, and has spectral line bending and limited wavelength precision; limited by grating performance and light splitting capacity, the spectral resolution of a grating spectral system is limited; in addition, its slit width directly affects the spectral resolution of the instrument. Therefore, to obtain higher spectral resolution, the slit width needs to be made narrow. This greatly affects the luminous flux of the whole system, and spectral signals with higher signal-to-noise ratio cannot be obtained, so that the detection capability of the system on gas absorption spectrum is lower.
The optical absorption cavity is filled with gas to be measured. After light rays emitted by the light source are collimated, parallel light enters the input aperture of the optical absorption cavity, and is emitted out in the exit aperture of the optical absorption cavity after being reflected for multiple times by the objective lens and the field lens; and the light is received by the optical fiber probe at the exit aperture of the optical absorption cavity and is transmitted to the optical fiber spectrometer. The light entering the optical fiber spectrometer is limited in the spectrometer by the slit, enters the grating by the collimating mirror, and is converged on the linear array detector by the condenser lens after being split by the grating.
The disadvantages of the conventional gas detection spectroscopy system:
1. in order to use the fiber optic spectrometer, the light input aperture of the absorption cavity is very small, and the light flux of the system is limited, so that the detection limit of the gas concentration is influenced.
2. The output aperture of the absorption cavity is also very small, the emergent light is conducted by the optical fiber, and the luminous flux is limited by the aperture of the optical fiber; the luminous flux and the light energy utilization rate are low; the spectral sensitivity of the system is reduced to some extent.
3. The principle of grating dispersion spectroscopy in fiber optic spectrometers determines the inevitable disadvantage of line bending and uses slits in the spectrometer whose width is inversely proportional to the spectral resolution, and therefore their spectral accuracy and luminous flux are limited.
4. The spectral resolution of the whole fiber spectroscopic system is low (about 1nm at the highest), and the detection limit of the types and the concentrations of the detectable gases is limited.
Disclosure of Invention
Objects of the invention
The utility model aims at: the hyperspectral system for gas concentration detection is provided, so that the luminous flux of the system is increased, and gas absorption spectrum data with high spectral resolution can be acquired.
(II) technical scheme
In order to solve the technical problem, the utility model provides a hyperspectral system that gas concentration detected, it includes light source, collimating mirror, optical absorption chamber, two light path interference structures, convergent mirror and detector, the optical absorption chamber includes the relative objective and the field lens that arrange of plane of reflection, two light path interference structures include plane mirror, cube corner mirror and beam splitter plate; the light emitted by the light source is collimated by the collimating lens to form parallel light with a set numerical aperture, the parallel light is incident to the objective lens of the optical absorption cavity, multiple turning is performed between the objective lens and the field lens of the optical absorption cavity, the light absorbed by gas in the optical absorption cavity is incident to the beam splitting plate of the dual-optical-path interference structure through the multiple turning, the light incident to the beam splitting plate is divided into two paths by the ratio of 1:1, one path is reflected to the plane reflecting mirror by the beam splitting plate, is reflected to the beam splitting plate by the plane reflecting mirror, and is transmitted to the converging mirror by the beam splitting plate; the other route beam splitting plate transmits to the cube corner reflector, is reflected to the beam splitting plate by the cube corner reflector, and is finally reflected to the converging mirror by the beam splitting plate; the converging lens converges the two paths of light rays and images the light rays onto the detector; and obtaining interference light signals with alternate light and shade, which change along with the movement of the cube corner, at each pixel point of the detector, performing denoising and direct current removal pretreatment on the signals of the pixel points, and performing Fourier transform to obtain the absorption spectrum of the gas.
(III) advantageous effects
The hyperspectral system for detecting the gas concentration has the advantages of high spectral resolution and high flux, high-resolution spectral data with high signal-to-noise ratio can be obtained, the concentration detection limit of the detection system is finally improved, the concentration of gas with low concentration can be detected, and the number of types of detectable gas can be increased.
Drawings
FIG. 1 is a schematic diagram of a hyperspectral system for gas detection.
In the figure, 1-surface light source, 2-collimating lens, 3-objective lens, 4-field lens, 5-cube corner reflector, 6-plane reflector, 7-beam splitting plate, 8-converging lens and 9-detector.
Detailed Description
In order to make the objects, contents, and advantages of the present invention clearer, the following description of the embodiments of the present invention will be made in detail with reference to the accompanying drawings and examples.
The patent provides a spectrum system for detecting gas concentration, which uses a multi-optical-path optical absorption cavity to increase the optical path of light in gas to be detected and improve the signal-to-noise ratio so as to improve the detection limit and detection precision of the gas concentration; the spectrum acquisition system of the system adopts a double-light-path interference device to acquire an interference signal of target gas, wherein one path of reflector can move to generate a series of variable optical path differences, and Fourier transform is utilized to acquire an absorption spectrum of the target gas.
The utility model discloses combine optics absorption chamber and high spectrum detection device organically, form integrated device, optics absorption chamber increases the number of times of turning back of light in gas in order to increase the optical path, improves gaseous absorption spectrum SNR to reach the purpose that improves gas concentration detection limit. The emergent light rays of the optical absorption cavity are interfered by a double-path structure, the cube corner reflector which reflects one path of light rays moves to generate a variable optical path difference, and the gas absorption spectrum is obtained through Fourier transformation of interference signals. In the whole device, no slit is used for limiting, so that the integral luminous flux of the system is improved, the signal to noise ratio of the whole device system is further improved, and the purposes of improving the gas concentration detection precision and the detection limit are achieved. The optical path difference of the whole system is increased by moving a path of cube corner reflector for reflecting light in the interference device, so that the spectral reflectivity of the system is improved, and a high-resolution spectrum is obtained. In addition, compared with the grating light splitting principle of the traditional fiber spectrometer, the fiber spectrometer has the advantages of interference light splitting, no spectral line bending and lower cost.
As shown in fig. 1, the hyperspectral system for gas concentration detection of the present invention includes a light source, a collimating mirror, an optical absorption cavity, a dual-optical-path interference structure, a converging mirror and a detector, wherein the optical absorption cavity includes an objective lens and a field lens with reflecting surfaces arranged oppositely, and the dual-optical-path interference structure includes a plane mirror, a cube-corner mirror and a beam splitter plate; the light emitted by the light source is collimated by the collimating lens to form parallel light with a set numerical aperture, the parallel light is incident to the objective lens of the optical absorption cavity, multiple turning is performed between the objective lens and the field lens of the optical absorption cavity, the light absorbed by gas in the optical absorption cavity is incident to the beam splitting plate of the dual-optical-path interference structure through the multiple turning, the light incident to the beam splitting plate is divided into two paths by the ratio of 1:1, one path is reflected to the plane reflecting mirror by the beam splitting plate, is reflected to the beam splitting plate by the plane reflecting mirror, and is transmitted to the converging mirror by the beam splitting plate; the other route beam splitting plate transmits to the cube corner reflector, is reflected to the beam splitting plate by the cube corner reflector, and is finally reflected to the converging mirror by the beam splitting plate; the converging mirror converges the two paths of light rays and images the light rays onto the detector.
Wherein, the light source is a surface light source or a wide slit light source; the beam splitting plate is a semi-transparent semi-reflecting mirror.
The parallel light with the same incident angle is imaged to the same point of the image surface of the converging mirror to form interference, and the optical path difference of the two paths of light rays changes along with the difference of the incident angles. In addition, the cube corner reflector is arranged on the controllable linear displacement platform and can linearly move along the optical axis of the emergent ray of the optical absorption cavity. The optical path difference for each image point may change as the cube corner mirror moves. The utility model discloses can require use point detector, linear array detector or area array detector according to system cost.
Therefore, interference light signals with alternate light and shade which change along with the movement of the cube corner (optical path difference along with the change of time) can be obtained at each pixel point of the detector. The signals of the pixel points are preprocessed by denoising, DC removal and the like, and Fourier transform is carried out, so that the absorption spectrum of the gas can be obtained. If a linear array detector or an area array detector is used, interference optical signals of a plurality of pixel points can be obtained and subsequent denoising, direct current removing and Fourier transform processing can be carried out, so that the luminous flux, the detection sensitivity and the spectral precision of the whole system can be increased. The spectral resolution of interference spectroscopy system is directly proportional with the optical path difference, the utility model discloses well adoption cube corner reflector that removes produces variable optical path difference, can acquire very large range optical path difference interference signal. Therefore, the utility model discloses a system has high spectral resolution's characteristic.
The included angle between the beam splitting plate and the optical axis of the emergent ray of the optical absorption cavity is 45 degrees, the included angle between the plane reflector and the beam splitting plate is 45 degrees, and the cube corner reflector is arranged on the linear displacement platform and can move along the direction of the optical axis of the emergent ray of the optical absorption cavity.
In specific implementation, the collimating mirror can adopt a spherical mirror or a long-focus lens (f is 75 mm); the optical absorption cavity can adopt White type or modified White type Chernin multi-optical path optical absorption cavity; the converging lens adopts a concave spherical reflector or a converging lens; using a detector to receive light and shade alternate interference signals on the image surface of the convergent mirror, which change along with the movement of the cube corner reflector; the interference signal obtained by the detector is preprocessed by direct current removal, apodization and the like, and is subjected to Fourier transform, so that the absorption spectrum of the gas can be obtained.
The utility model discloses a spectral resolution ratio calculation process as follows:
the moving range of the cube corner reflector is 2cm, and the maximum optical path difference of the system is L which is 2 cm:
wave number resolution of
The wavelength resolution for 300nm is: λ ═ λ2Δv＝0.0045nm
The spectral resolution of general grating spectroscopy system is about 0.1nm, the utility model discloses the spectral resolution of system is higher than about two orders of magnitude.
The utility model discloses it is different with traditional optical absorption chamber and fiber optic spectrometer's split type device. In the traditional gas detection device, an optical fiber spectrometer for dispersing and splitting light by utilizing an optical fiber connection grating is arranged behind an emergent aperture of an optical absorption cavity; and the utility model combines the optical absorption cavity and the double-path interference to form an integrated device. The surface light source can be used before the incident aperture of the absorption cavity, and the slit of the whole device without limiting luminous flux has the advantages of high flux and high signal-to-noise ratio. The detection limit of the gas concentration can be improved. The utility model discloses an optical path difference change range of device is big, and the removal of accessible cube corner reflector obtains the great optical path difference along with time change, has high spectral resolution's advantage.
Compared with the prior art, the utility model has no slit limitation and secondary collimation, and has the advantages of high flux and high sensitivity; interference signals with different optical path differences are obtained by utilizing an interference principle, and Fourier transform is carried out to obtain a gas absorption spectrum, so that the defect of spectral line bending of the traditional grating light splitting is overcome, and the method has the advantage of low cost; the optical path difference has a large variation range and has the advantage of high spectral resolution; the single-point, linear array and area array detectors can be used optionally, and the cost can be reduced to a certain extent.
The device provided by the patent avoids the defect that the slit width of a grating spectrometer is inversely proportional to the spectral resolution, and eliminates the slit in the whole system so as to improve the luminous flux and the sensitivity of the system; by adopting the principle of interference light splitting, grating light splitting is not needed, and spectral line bending caused by grating light splitting is avoided; the variable range of the optical path difference is increased through the movable cube corner reflector, and the spectral resolution of the system is improved; compared with the grating, the interference light splitting device can also reduce the cost; the whole system is of an integrated design and is more compact.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be considered as the protection scope of the present invention.
Claims (10)
1. A hyperspectral system for gas concentration detection is characterized by comprising a light source, a collimating mirror, an optical absorption cavity, a dual-light-path interference structure, a converging mirror and a detector, wherein the optical absorption cavity comprises an objective lens and a field lens, the reflecting surfaces of the objective lens and the field lens are arranged oppositely, and the dual-light-path interference structure comprises a plane reflecting mirror, a cube corner reflecting mirror and a beam splitting plate; the light emitted by the light source is collimated by the collimating lens to form parallel light with a set numerical aperture, the parallel light is incident to the objective lens of the optical absorption cavity, multiple turning is performed between the objective lens and the field lens of the optical absorption cavity, the light absorbed by gas in the optical absorption cavity is incident to the beam splitting plate of the dual-optical-path interference structure through the multiple turning, the light incident to the beam splitting plate is divided into two paths by the ratio of 1:1, one path is reflected to the plane reflecting mirror by the beam splitting plate, is reflected to the beam splitting plate by the plane reflecting mirror, and is transmitted to the converging mirror by the beam splitting plate; the other route beam splitting plate transmits to the cube corner reflector, is reflected to the beam splitting plate by the cube corner reflector, and is finally reflected to the converging mirror by the beam splitting plate; the converging lens converges the two paths of light rays and images the light rays onto the detector; and obtaining interference light signals with alternate light and shade, which change along with the movement of the cube corner, at each pixel point of the detector, performing denoising and direct current removal pretreatment on the signals of the pixel points, and performing Fourier transform to obtain the absorption spectrum of the gas.
2. The hyperspectral system for gas concentration detection according to claim 1, wherein the light source is a surface light source or a wide slit light source.
3. The hyperspectral system of gas concentration detection according to claim 1, wherein the beam splitting plate is a half-mirror.
4. The hyperspectral system for gas concentration detection according to claim 1, wherein parallel light with the same incident angle is imaged on the same point on the image surface of the converging mirror to form interference, and the optical path difference of the two paths of light changes with the difference of the incident angles.
5. The hyperspectral system for gas concentration detection according to claim 1, wherein the cube corner reflector is arranged on the controllable linear displacement platform and moves linearly along the optical axis of the emergent ray of the optical absorption cavity, and the optical path difference of each image point changes along with the movement of the cube corner reflector.
6. The hyperspectral system for gas concentration detection as claimed in claim 1, wherein the detector is a point detector, a line detector or an area detector.
7. The hyperspectral system for gas concentration detection according to claim 1, wherein the angle between the beam splitting plate and the optical axis of the emergent light of the optical absorption cavity is 45 degrees, and the angle between the plane mirror and the beam splitting plate is 45 degrees.
8. The hyperspectral system for gas concentration detection according to claim 1, wherein the collimating mirror is a spherical mirror or a long-focus lens.
9. The hyperspectral system of gas concentration detection according to claim 1, wherein the optical absorption cavity is a White-type or modified White-type Chernin multipass optical absorption cavity.
10. The hyperspectral system for gas concentration detection according to claim 1, wherein the converging mirror is a concave spherical mirror or a converging lens.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110849829A (en) * | 2019-11-05 | 2020-02-28 | 苏州智曜科技有限公司 | Hyperspectral system for gas concentration detection |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110849829A (en) * | 2019-11-05 | 2020-02-28 | 苏州智曜科技有限公司 | Hyperspectral system for gas concentration detection |
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| Date | Code | Title | Description |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20210409 Address after: Room 10, no.228412, West Ring Road, Wujiang District, Jiangsu Province Patentee after: SUZHOU MINGKUN TECHNOLOGY Co.,Ltd. Address before: Room 410, building 10, 1188, West 2nd Ring Road, Shengze Town, Wujiang District, Suzhou City, Jiangsu Province Patentee before: Suzhou Zhiyao Technology Co.,Ltd. |
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| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20201106 |