CN104914058A - Multi-component trace gas concentration measuring apparatus - Google Patents
Multi-component trace gas concentration measuring apparatus Download PDFInfo
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- CN104914058A CN104914058A CN201510274327.2A CN201510274327A CN104914058A CN 104914058 A CN104914058 A CN 104914058A CN 201510274327 A CN201510274327 A CN 201510274327A CN 104914058 A CN104914058 A CN 104914058A
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- semiconductor laser
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- beam splitter
- gas concentration
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Abstract
The invention discloses a multi-component trace gas concentration measuring apparatus, which belongs to the technical field of absorption spectroscopic measurement. The multi-component trace gas concentration measuring apparatus overcomes the problems of high cost and inaccurate measurement results of measuring apparatuses in the prior art. The measuring apparatus provided by the invention comprises a first semiconductor laser, a second semiconductor laser, a first fold mirror, a beam splitter, a collimating isolator, a mode matching mirror, a reflection resonant cavity, a photoelectric detector and a data processing module, wherein a laser beam emitted by the first semiconductor laser is transmitted to the first fold mirror by an optical fiber and reflected by the beam splitter, transmitted light and reflected light successively pass through the collimating isolator, the mode matching mirror and the reflection resonant cavity, then enter the photoelectric detector and are converted into electric signals which are sent to the data processing module for analysis. The multi-component trace gas concentration measuring apparatus has the advantages of low cost, convenience in maintenance of an optical path and small measurement errors.
Description
Technical field
The invention belongs to absorption spectroscopy field of measuring technique, be specifically related to a kind of many components trace gas concentration measurement mechanism.
Background technology
Theoretical according to spectral absorption, each molecule has corresponding multiple characteristic absorption peaks, and near characteristic absorption peak, molecule absorption is stronger.Different molecules is due to component and textural difference, and it rotates, vibrate and electronic spectrum is also had any different, and cause the distribution of the characteristic absorption peak of gas with various to be not quite similar, and the peak-to-peak absorption intensity of same gas different characteristic also has very big difference.The theoretical peak-to-peak distributional difference of feature based just of spectral absorption detects the concentration of gas with various.
Semiconductor laser can regulate within the specific limits continuously due to its wavelength, is very applicable to spectral absorption technology.The absorption intensity can measuring on the one hand different wave length place within the scope of characteristic absorption peaks come matching measure in error; Several absorption at a distance of nearer characteristic peak can be measured on the other hand, thus realize measurement of multi-components.The spacing of lattice that semiconductor laser changes Bragg grating in laser instrument by electric current and temperature variation carrys out adjusting wavelength, and the usual amplitude of variation of spacing of lattice is very little, and the wavelength coverage causing lasers A tunable to save is very little, is generally 5-20nm.So little scope is the detection demand that can not meet most of multicomponent gas concentration.When the spacing of the characteristic absorption peak of molecule several in multicomponent gas is comparatively large, single semiconductor laser just can not meet the detection demand of multicomponent gas concentration.
In addition, in spectral absorption technology, under raising clean background, the detection accuracy of gas to be measured has two kinds of ways feasible, one is select to be operated in absorb strong characteristic absorption peak place, and two is increase absorption distance.Owing to just securing when its characteristic absorption peak after selected gas to be measured, and the characteristic peak that background will be selected comparatively clean just more not easily, often can not meet and absorb strong requirement, and adopting so general increases absorption distance and improve detection accuracy.
Based on above-mentioned 2 considerations, many components trace gas concentration measurement mechanism of the prior art is generally made up of multiple semiconductor laser, multiple collimation isolator, multiple pattern match mirror, multiple reflection resonator cavity, multiple mirror of turning back, photodetector and data processing module, the light beam of each semiconductor laser is incident light electric explorer after a collimation isolator, a pattern match mirror, a reflection resonator cavity, a mirror of turning back successively, converts to enter data processing module after electric signal and carry out spectral analysis through photodetector.But, on the one hand, because the catoptron (reflectivity is generally more than 0.9999) and micro-displacement mechanism that reflect the high reflectance that resonator cavity uses are expensive, so cause installation cost high, on the other hand, because multiple reflection resonator cavity is sampled respectively, easily cause measuring error, cause testing result inaccurate.
Summary of the invention
The object of the invention is to solve that many components trace gas concentration measurement mechanism cost in prior art is high, the inaccurate technical matters of measurement result, a kind of many components trace gas concentration measurement mechanism is provided.
The technical scheme that the present invention solves the problems of the technologies described above employing is as follows.
Many components trace gas concentration measurement mechanism, comprise the first semiconductor laser, mirror turned back by the second semiconductor laser, beam splitter, first, collimation isolator, pattern match mirror, reflection resonator cavity, photodetector and data processing module;
Described first semiconductor laser and the second semiconductor laser are operated in n λ respectively
0, n λ
0/ 2 or n λ
0/ 4 reflectivity covered are in the wavelength coverage of more than 0.9999, and n is the equivalent refractive index of multi-layer mirror in reflection resonator cavity, λ
0for the centre wavelength of multi-layer mirror in reflection resonator cavity;
The light path trend of described device is: the light beam of the first semiconductor laser through Optical Fiber Transmission to beam splitter, through beam splitter transmission, the light beam of the second semiconductor laser to be turned back mirror through Optical Fiber Transmission to the first, turn back after mirror turns back through first, incident beam splitter also reflects through beam splitter, the transmitted light that beam splitter exports and reflected light are successively through collimation isolator, pattern match mirror and reflection resonator cavity after incident light electric explorer, photodetector converts the light signal of reception to electric signal and transfers to data processing module, data processing module is analyzed the electric signal received.
Further, described device also comprises second and to turn back mirror, and described light beam, after reflection resonator cavity, is first turned back through the second mirror of turning back, re-shoot photodetector.
Further, described photodetector is one, and responsiveness covers the operation wavelength of the first semiconductor laser and the second semiconductor laser; Or be two, and the responsiveness of a photodetector covers the operation wavelength of the first semiconductor laser, the responsiveness of another photodetector covers the operation wavelength of the second semiconductor laser, two photodetector parallel connections.
Compared with prior art, the invention has the beneficial effects as follows:
1, many components trace gas concentration measurement mechanism of the present invention adopts two semiconductor lasers, both can by having switched the mode of different laser instruments, measure several molecules that the spacing of characteristic absorption peak is far away, also by regulating single laser instrument, measure characteristic absorption peak at a distance of nearer several molecules, or the measuring error in matching characteristic absorption peaks scope;
2, many components trace gas concentration measurement mechanism light source position of the present invention is fixed, and is convenient to the maintenance of light path;
3, two semiconductor lasers are increased absorption distance by a reflection resonator cavity by many components trace gas concentration measurement mechanism of the present invention, both equipment cost was reduced, can ensure that again single sample just can obtain the concentration of multiple gases component, avoid the error that the factors such as gas flowing are brought.
Accompanying drawing explanation
Fig. 1 is that the reflectivity of the multi-layer mirror of reflection resonator cavity is with wavelength variations curve;
Fig. 2 is the structural representation of many components trace gas concentration measurement mechanism of the present invention;
In figure, the 101, first semiconductor laser, the 102, second semiconductor laser, 2, beam splitter, 3, first to turn back mirror, 4, collimation isolator, 5, pattern match mirror, 6, resonator cavity is reflected, 601, micro-displacement mechanism, 602, multi-layer mirror, 7, second turns back mirror, 8, photodetector, 9, data processing module.
Embodiment
The present invention is further illustrated below in conjunction with accompanying drawing.
As shown in Figure 2, many components trace gas concentration measurement mechanism of the present invention, mainly comprises: turn back mirror 3, collimation isolator 4, pattern match mirror 5, reflection resonator cavity 6, second of the first semiconductor laser 101, second semiconductor laser 102, beam splitter 2, first is turned back mirror 7, photodetector 8 and data processing module 9.Wherein, the service band of the first semiconductor laser 101 and the second semiconductor laser 102 can also can at different section high reflectance wave band at same section of high reflectance (it is that reflectivity is more than 0.9999 that the present invention defines high reflectance) wave band, arrange according to actual needs, for guaranteeing to increase absorption distance by same reflection resonator cavity 6, the first semiconductor laser 101 and the second semiconductor laser 102 are all operated in n λ
0, n λ
0/ 2 or n λ
0in/4 high reflectance wavelength coverages covered, n is the equivalent refractive index of multi-layer mirror 602 in reflection resonator cavity 6, λ
0for the centre wavelength of multi-layer mirror 602 in reflection resonator cavity 6; First semiconductor laser 101 launch light beam through Optical Fiber Transmission to beam splitter 2, incident collimation isolator 4 after beam splitter 2 transmission, the light beam that second semiconductor laser 102 is launched to be turned back mirror 3 to first through Optical Fiber Transmission, turn back after mirror 3 turns back through first, then reflex to collimation isolator 4 through beam splitter 2.In the present invention, collimation isolator 4 has two effects, and one is collimating effect, ensure the center of beam orthogonal by pattern match mirror 5, it two is buffer action, cuts off and is reflected back the beam path of returning with transmission through pattern match mirror 5, thus avoid in running order semiconductor laser damaged.Light beam is from incidence reflection resonator cavity 6 after pattern match mirror 5 outgoing, reflection resonator cavity 6 is made up of multi-layer mirror 602 more than two sides, and it is long to adjust chamber by micro-displacement mechanism 601 (as piezoelectric ceramics), realize resonance, the reflectivity requirements of the multi-layer mirror 602 in reflection resonator cavity 6 is very high, general more than 0.9999, this multi-layer mirror 602 is at basic wavelength n λ
0, basic wavelength n λ
0half-wavelength n λ
0/ 2 and basic wavelength n λ
0quarter-wave n λ
0the reflectivity at/4 places all more than 0.9999, and keeps high reflectance in certain wavelength width, as shown in Figure 1.The light beam incident light electric explorer 8 of reflection resonator cavity 6 outgoing, the service band of the wave band that the responsiveness of photodetector 8 is corresponding and the first semiconductor laser 101 and the second semiconductor laser 102 matches, the wave band corresponding due to the responsiveness of photodetector 8 is wider, adopt a photodetector 8 just can realize so general, when the first semiconductor laser 101 and the second semiconductor laser 102 service band can not a corresponding photodetector 8 time, two photodetectors 8 can be adopted in parallel, parallel way is prior art, as passed through fiber beam splitting, the responsiveness of a photodetector 8 is made to cover the operation wavelength of the first semiconductor laser 101, the responsiveness of another photodetector 8 covers the operation wavelength of the second semiconductor laser 102.Photodetector 8 converts the electric signal of reception to light signal, and through Optical Fiber Transmission to data processing module 9.Data processing module 9 is analyzed the light signal received, and calculates gas concentration.
In present embodiment, for ease of putting of each parts of device, the light beam of reflection resonator cavity 6 outgoing is first turned back through the second mirror 7 of turning back, and re-shoots photodetector 8.
Many components trace gas concentration measurement mechanism of present embodiment light path trend be: first semiconductor laser 101 launch light beam through Optical Fiber Transmission to beam splitter 2, after beam splitter 2 transmission, to turn back incident light electric explorer 8 after mirror 7 through collimation isolator 4, pattern match mirror 5, reflection resonator cavity 6 and second successively, photodetector 8 converts the light signal of reception to electric signal and transfers to data processing module 9, data processing module 9 is analyzed the electric signal received, and calculates each component concentration; Second semiconductor laser 102 launch light beam through Optical Fiber Transmission to mirror 3 of turning back, then after beam splitter 2 reflects, to turn back incident light electric explorer 8 after mirror 7 through collimation isolator 4, pattern match mirror 5, reflection resonator cavity 6 and second successively, photodetector 8 converts the light signal of reception to electric signal and transfers to data processing module 9, data processing module 9 is analyzed the electric signal received, and calculates each component concentration.
The course of work of many components trace gas concentration measurement mechanism of present embodiment is: reflection resonator cavity 6 takes out gaseous sample completely to be measured, according to the molecule determination individual features absorption peak of gas composition to be analyzed, and then select the laser works of service band within the scope of this, open laser instrument, measure a kind of concentration (selecting as required whether to regulate the wavelength of single laser instrument to realize length scanning function) of gas composition, after a kind of gasmetry completes, characteristic absorption peak according to the molecule of the lower a kind of gas composition measured is selected switched laser device or regulates single laser wavelength, when in multicomponent gas upper a kind of measure molecule characteristic absorption peak and lower a kind of spacing measuring the characteristic absorption peak of molecule larger, different laser instruments can be switched, when in multicomponent gas upper a kind of measure molecule characteristic absorption peak and lower a kind of spacing measuring the characteristic absorption peak of molecule less time, single laser instrument can be regulated.
Claims (3)
1. many components trace gas concentration measurement mechanism, comprises the first semiconductor laser (101), the second semiconductor laser (102), collimation isolator (4), pattern match mirror (5), reflection resonator cavity (6), photodetector (8) and data processing module (9);
It is characterized in that, also comprise beam splitter (2) and first and to turn back mirror (3);
Described first semiconductor laser (101) and the second semiconductor laser (102) are operated in n λ respectively
0, n λ
0/ 2 or n λ
0in the wavelength coverage of/4 reflectivity covered more than 0.9999, n is the equivalent refractive index of reflection resonator cavity (6) interior multi-layer mirror (602), λ
0for the centre wavelength of reflection resonator cavity (6) interior multi-layer mirror (602);
Described device light path trend be: the light beam that the first semiconductor laser (101) is launched through Optical Fiber Transmission to beam splitter (2), through beam splitter (2) transmission, the light beam launched of second semiconductor laser (102) to be turned back mirror (3) through Optical Fiber Transmission to the first, turn back after mirror (3) turns back through first, incident beam splitter (2) is also reflected through beam splitter (2), the reflected light that beam splitter (2) exports and transmitted light are successively through collimation isolator (4), pattern match mirror (5) and reflection resonator cavity (6) incident light electric explorer (8) afterwards, photodetector (8) converts the light signal of reception to electric signal and transfers to data processing module (9), data processing module (9) is analyzed the electric signal received.
2. many components trace gas concentration measurement mechanism according to claim 1, it is characterized in that, described device also comprises second and to turn back mirror (7), described light beam is after reflection resonator cavity (6), first turn back through the second mirror (7) of turning back, re-shoot photodetector (8).
3. many components trace gas concentration measurement mechanism according to claim 1, is characterized in that, described photodetector (8) is one, and responsiveness covers the operation wavelength of the first semiconductor laser and the second semiconductor laser; Or be two, and the responsiveness of a photodetector (8) covers the operation wavelength of the first semiconductor laser, the responsiveness of another photodetector (8) covers the operation wavelength of the second semiconductor laser, two photodetector parallel connections.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106841106A (en) * | 2016-12-12 | 2017-06-13 | 中国科学院光电研究院 | A kind of bi-component trace gas concentration measurement apparatus based on Research on Cavity Ring Down Spectroscopy |
| CN108333142A (en) * | 2017-01-19 | 2018-07-27 | 卡斯卡德技术控股有限公司 | Tightly coupled analyzer |
| CN111157470A (en) * | 2020-01-06 | 2020-05-15 | 武汉米字能源科技有限公司 | Method for simultaneously measuring contents of multi-component gases on line by multiple lasers |
| CN112362597A (en) * | 2020-11-16 | 2021-02-12 | 安徽中科瀚海光电技术发展有限公司 | Multi-path laser gas monitoring system and monitoring method |
| CN113008814A (en) * | 2021-02-22 | 2021-06-22 | 山东省科学院海洋仪器仪表研究所 | Device and method for detecting water vapor concentration by using dual lasers |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106841106A (en) * | 2016-12-12 | 2017-06-13 | 中国科学院光电研究院 | A kind of bi-component trace gas concentration measurement apparatus based on Research on Cavity Ring Down Spectroscopy |
| CN106841106B (en) * | 2016-12-12 | 2019-08-02 | 中国科学院光电研究院 | A kind of bi-component trace gas concentration measuring device based on Research on Cavity Ring Down Spectroscopy |
| CN108333142A (en) * | 2017-01-19 | 2018-07-27 | 卡斯卡德技术控股有限公司 | Tightly coupled analyzer |
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| CN111157470A (en) * | 2020-01-06 | 2020-05-15 | 武汉米字能源科技有限公司 | Method for simultaneously measuring contents of multi-component gases on line by multiple lasers |
| CN112362597A (en) * | 2020-11-16 | 2021-02-12 | 安徽中科瀚海光电技术发展有限公司 | Multi-path laser gas monitoring system and monitoring method |
| CN113008814A (en) * | 2021-02-22 | 2021-06-22 | 山东省科学院海洋仪器仪表研究所 | Device and method for detecting water vapor concentration by using dual lasers |
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