CN101968441A - New-type gas detection system based on fiber interferometer - Google Patents
New-type gas detection system based on fiber interferometer Download PDFInfo
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- CN101968441A CN101968441A CN 201010281866 CN201010281866A CN101968441A CN 101968441 A CN101968441 A CN 101968441A CN 201010281866 CN201010281866 CN 201010281866 CN 201010281866 A CN201010281866 A CN 201010281866A CN 101968441 A CN101968441 A CN 101968441A
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Abstract
The invention discloses a new-type gas detection system based on a fiber interferometer, which belongs to the gas detection technical field, is composed of a semiconductor laser, an isolator, 1*2 coupler, a gas room, common optical fibers and a phase demodulating system, and is characterized in that a tail optical fiber of the semiconductor laser is accessed into the isolator; the output end of the isolator is connected with the common optical fiber; the other end of the common optical fiber is connected with the input end of the 1*2 coupler; the two same directional output ends of the 1*2 coupler are respectively connected with two common optical fibers; one of the common optical fiber is in series connection with the gas room; the output ends of the two common optical fibers are connected with the phase demodulating system; the optical phase difference of two beams output by two-path common optical fibers is detected by the phase demodulating system to indirectly calculate the gas refractive index, and further calculate the gas concentration. The gas detection system of the invention has the advantages of radiation resistance, corrosion resistance and electromagnetic interference resistance, and capability of safely operate in harmful environment, and being not influenced by the environment.
Description
Technical field
The present invention relates to a kind of gas detecting system, specifically is a kind of new gas detection system based on fibre optic interferometer.
Background technology
Environmental pollution is the focal issue of whole world extensive concern in recent years, and in various environmental pollutions, atmospheric pollution is the most outstanding.Along with the fast development of modernization industry society, Atmospheric Carbon Dioxide, harmful gases such as sulphuric dioxide are increasing, and it is extremely urgent how these gas componants to be made accurate quantitative analysis.
At present, gas detection technology development both at home and abroad rapidly, detection method is the difference to some extent with the difference of measurand also.The atmosphere pollution of being familiar with at present has kind more than 100 approximately, and these pollutants are present in the atmosphere with molecule and two kinds of forms of particle.Method with optics detected gas concentration mainly contains following several now:
1, difference absorption spectrum technology difference absorption spectrum technology (DOAS) is to come its kind of inverting and concentration according to trace gas composition in the atmosphere in the characteristic absorption character of ultraviolet and visible spectrum wave band.Utilize differential technique can eliminate the influence of atmospheric turbulence to signal, interference between the different pollutants and humidity, aerocolloidal interference can be satisfied the requirement of continuous monitoring.The technical matters of DOAS technology existence at present is how to obtain high-quality measure spectrum.Because this technology is a kind of low light level spectrum detection technique, requires total system that various random noises are had shield effectiveness preferably, so it is many to influence the factor of measure spectrum.
When 2, infrared absorption principle light passed gas, characteristic frequency spectral line luminous energy will be by gas absorption, thereby the energy of the light of this frequency is weakened.Degree that light ray energy weakens and gas concentration and the light distance of process in gas is proportional, and this relation is obeyed from the lam-bert-beer law.And then calculate gas concentration.It has overcome in the past detection method poisons easily and wears out, is subject to the shortcoming of such environmental effects, simultaneously it also have highly sensitive, response speed fast, good selective.
3, tunable laser diodes laser absorption spectrum technology tunable laser diodes laser absorption spectrum technology is a kind of highly sensitive, the high-resolution atmospheric trace gas absorption spectrum detection technique that latest developments are got up.Scan gas absorption to be measured peak by the size control optical maser wavelength of regulating electric current, measuring the outer signal of tested gas absorption peak and absorption peak compares, with nonlinear least square method measured spectral line is carried out match, thereby draw the composition and the concentration of tested gas.Its major advantage is highly sensitive,, obtained using widely at aspects such as atmospheric trace gas detection, industrial process control, pollution source discharging detections.To most of trace gas molecules, its detectability generally all can reach the 99B magnitude, even the 99I magnitude.
4, Laser Photoacoustic technology optoacoustic spectroscopy (PAs) technology is based on optoacoustic effect, and acoustic wave produces from the absorption of gas to optical radiation.In air chamber, produce photoacoustic waves by laser diode emission pulse laser bundle, detect the amplitude of sound wave, utilize the corresponding relation of magnitudes of acoustic waves and gas concentration to obtain the concentration of gas through highly sensitive sound detector.Optoacoustic spectroscopy is a kind of desirable no ambient noise signal technology, has the detection sensitivity height, dynamic range is big, and the responsiveness of optoacoustic spectroscopy detector advantages such as almost co-wavelength is irrelevant.In recent years, along with the development of laser technology, the Laser Photoacoustic spectral technique is also grown up gradually.The practicability of semiconductor laser and highly sensitive sound wave detector makes optoacoustic spectroscopy obtain paying attention to.Different with traditional spectrum monitoring method, photoacoustic technique is that monitoring object absorbs that part of energy that shows with the acoustic pressure form in the heat energy that produces behind the luminous energy, even under the weak situation about absorbing of height reflection, very little absorption can also can be detected by sound wave detector.Though photocaustic spectroscopy detection technique development in recent years is rapid, still have some key issues to need to be resolved hurrily.Adopt open optoacoustic chamber to help realizing on-the-spot continuous sampling and detection, but must adopt the acoustic resonance mode of operation, keep this mode of operation and must solve the relevant technologies problem.Because site environment changes, the optoacoustic spectroscopy system is subjected to the influence of other interference gas especially easily when measuring, and how getting rid of the overlap of spectral lines of heterogeneity gas and disturbing is a key issue that improves this precision of method.
Western part of China science and technology in January, 2009 " the middle ten days " the 08th volume total the 163rd phase author of the 02nd phase provides a kind of method with the concentration of dusty gas in the principle of interference measurement air in theory for honest super, Han Dongxin, Bai Huaiyan name are called " based on the detection discussion of the Air Pollutant Emission concentration of the Young interference experiment of light. ".But this detection technique is subjected to the influence of environment easily, badly influences the degree of accuracy of measurement.
Summary of the invention
The present invention has proposed a kind of a kind of new gas detection system based on fibre optic interferometer of full optics in order to overcome the influence of external environment.
Technical scheme of the present invention realizes in the following manner:
A kind of new gas detection system based on fibre optic interferometer, form by semiconductor laser, isolator, 1*2 coupling mechanism, air chamber, ordinary optic fibre and phase demodulating system, the tail optical fiber that it is characterized in that semiconductor laser inserts isolator, the output terminal of isolator links to each other with ordinary optic fibre, the other end of ordinary optic fibre is connected with the input end of 1*2 coupling mechanism, two of the 1*2 coupling mechanism in the same way output terminal link to each other serial connection air chamber in the middle of ordinary optic fibre wherein respectively with two ordinary optic fibres; The output terminal of two ordinary optic fibres is connected with the phase demodulating system, and the light phase of measuring the two-beam of exporting through the two-way ordinary optic fibre by the phase demodulating system is poor, obtains the refractive index of gas indirectly, and then obtains the concentration of gas.
Gas detecting system of the present invention in use, measured gas is charged into air chamber, the refractive index that charges into meeting change light of gas, the light that semiconductor laser sends is through isolator, enter coupling mechanism, be divided into two-way through light behind the coupling mechanism, the refractive index that has changed light that charges into owing to gas, the refractive index that does not add air chamber with another road is different, can make two-way light produce optical path difference like this, finally this two-way light all enters the phase demodulating system, measures phase differential, obtain the refractive index of gas indirectly, and then obtain the concentration of gas.
Concrete action principle of the present invention is as shown in Figure 1: semiconductor laser (1) sends laser, enter isolator (2) by its tail optical fiber, the output terminal of isolator (2) links to each other with ordinary optic fibre (6), the other end of ordinary optic fibre (6) links to each other with an end of 1*2 coupling mechanism (3), light just enters 1*2 coupling mechanism (3) through isolator (2), be divided into two bundles through 1*2 coupling mechanism (3) back light, two of 1*2 coupling mechanism (3) in the same way output terminal respectively with ordinary optic fibre (7), (8) link to each other, this two-beam just enters ordinary optic fibre (7), (8), ordinary optic fibre (8) links to each other with an air chamber (4), the other end of air chamber (4) links to each other with ordinary optic fibre (9), the output terminal of ordinary optic fibre (9) and ordinary optic fibre (7) links to each other with phase demodulating system (5), that two-way light has just entered the phase demodulating system, system measures phase differential by phase demodulating, measure the refractive index of gas indirectly, and then obtain the concentration of gas.Come out from coupling mechanism (3), light is divided into two-way, and the ordinary optic fibre (7) of leading up to directly connects phase demodulating system (5), and establishing this road is l from the fiber lengths that coupling mechanism (3) comes out to the phase demodulating system
1, be n in the refractive index of ordinary optic fibre (7) transmission
1, then this Lu Guangcong coupling mechanism (3) comes out to the light path that enters phase demodulating system (5) and is [1]
1=n
1l
1Another Lu Guangcong coupling mechanism (3) comes out, and enters air chamber (4) through ordinary optic fibre (8), passes through ordinary optic fibre (9) again and enters phase demodulating system (5), and the length of establishing ordinary optic fibre (8), air chamber (4), ordinary optic fibre (9) is respectively l
2, l
3l
4, the refractive index that light transmits in them is respectively n
1, n
2, n
1, then this Lu Guangcong coupling mechanism (3) comes out to the light path that enters phase demodulating system (5) and is [1]
2=n
1l
2+ n
2l
3+ n
1l
4, this two-way light has optical path difference Δ l, can interfere.n
1Be the refractive index in the ordinary optic fibre, n
2Be the refractive index in the air chamber, meeting changes along with the variation of the concentration of gas.Detect the variation of phase place by phase demodulating system (5), because n
1, l
1, l
2, l
3, l
4Being quantitatively, is constant, has only n
2Be variable, so let us can obtain n
2, again because refractive index is relevant with the concentration of gas, we so that can obtain the concentration of gas.
The present invention has following advantage: utilize interference of light principle, and by fiber optic conduction, the variation of phase demodulating system demodulation phase, and then the concentration of definite gas.The light that semiconductor laser comes out is divided into two bundles, and the coherence is good, interferes obviously, and phase demodulating system demodulation phase degree of accuracy height makes the final height of degree of accuracy as a result, and error is little; Make light no longer be subjected to the influence of environment with fiber optic conduction, can resist strong magnetic force, anti-intense radiation makes final application stronger; This contrive equipment is also fairly simple, easily operation.
Description of drawings
Fig. 1 is the structural representation of gas detecting system of the present invention.
Wherein: 1, semiconductor laser 2, isolator 3,1*2 coupling mechanism 4, air chamber 5, phase demodulating system
6, ordinary optic fibre 7, ordinary optic fibre 8, ordinary optic fibre 9, ordinary optic fibre
Embodiment
The present invention will be further described below in conjunction with drawings and Examples, but be not limited thereto.
Embodiment:
The embodiment of the invention as shown in Figure 1, form by semiconductor laser (1), isolator (2), 1*2 coupling mechanism (3), air chamber, ordinary optic fibre and phase demodulating system, the tail optical fiber that it is characterized in that semiconductor laser (1) inserts isolator (2), the output terminal of isolator (2) links to each other with ordinary optic fibre (6), the other end of ordinary optic fibre (6) is connected with the input end of 1*2 coupling mechanism (3), two of 1*2 coupling mechanism (3) in the same way output terminal link to each other serial connection air chamber (4) in the middle of the ordinary optic fibre (8) wherein respectively with two ordinary optic fibres (7), (8); The output terminal of two ordinary optic fibres (7), (9) is connected with phase demodulating system (5), the light phase of measuring the two-beam of exporting through two-way ordinary optic fibre (7), (9) by phase demodulating system (5) is poor, obtain the refractive index of gas indirectly, and then obtain the concentration of gas.
Claims (1)
1. new gas detection system based on fibre optic interferometer, form by semiconductor laser, isolator, 1*2 coupling mechanism, air chamber, ordinary optic fibre and phase demodulating system, the tail optical fiber that it is characterized in that semiconductor laser inserts isolator, the output terminal of isolator links to each other with ordinary optic fibre, the other end of ordinary optic fibre is connected with the input end of 1*2 coupling mechanism, two of the 1*2 coupling mechanism in the same way output terminal link to each other serial connection air chamber in the middle of ordinary optic fibre wherein respectively with two ordinary optic fibres; The output terminal of two ordinary optic fibres is connected with the phase demodulating system, and the light phase of measuring the two-beam of exporting through the two-way ordinary optic fibre by the phase demodulating system is poor, obtains the refractive index of gas indirectly, and then obtains the concentration of gas.
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| CN2010102818666A CN101968441B (en) | 2010-09-15 | 2010-09-15 | New-type gas detection system based on fiber interferometer |
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| CN2010102818666A CN101968441B (en) | 2010-09-15 | 2010-09-15 | New-type gas detection system based on fiber interferometer |
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| CN101968441B CN101968441B (en) | 2012-05-30 |
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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102226759A (en) * | 2011-03-21 | 2011-10-26 | 山东大学 | Minim moisture detection system based on scanning method |
| CN103076304A (en) * | 2013-01-05 | 2013-05-01 | 浙江理工大学 | Modulation type laser interference method and device for measuring air refractive index |
| CN103344608A (en) * | 2013-06-24 | 2013-10-09 | 哈尔滨工业大学 | Refractive index sensor for non-symmetric high-sensitivity dual-optical fiber ring coupled M-Z (Mach-Zehnder) interferometer |
| CN104570219A (en) * | 2015-01-05 | 2015-04-29 | 浙江大学宁波理工学院 | Integrated optical sensor based on period waveguide microcavity resonance interference effect |
| CN108713134A (en) * | 2016-03-29 | 2018-10-26 | 松下知识产权经营株式会社 | Particle detection sensor |
| CN109211800A (en) * | 2018-11-14 | 2019-01-15 | 国网黑龙江省电力有限公司电力科学研究院 | Utilize the method for gas concentration lwevel in 632.8nm wave band of laser measurement sulfur hexafluoride gas |
| CN109211799A (en) * | 2018-11-14 | 2019-01-15 | 国网黑龙江省电力有限公司电力科学研究院 | The method that 980nm wave band of laser measures concentration of SO 2 gas in sulfur hexafluoride gas |
| CN109238990A (en) * | 2018-11-06 | 2019-01-18 | 广州市怡文环境科技股份有限公司 | A kind of gas concentration detection system and method |
| CN110749549A (en) * | 2019-11-22 | 2020-02-04 | 山东大学 | Device and method for monitoring components and concentration of malodorous gas |
| CN112147098A (en) * | 2020-11-03 | 2020-12-29 | 安徽大学 | Gas type and concentration detection system based on anomalous dispersion effect |
| CN112485225A (en) * | 2019-09-12 | 2021-03-12 | 大连市艾科微波光电子工程研究有限公司 | Optical fiber probe based on laser interference |
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| CN201803949U (en) * | 2010-09-15 | 2011-04-20 | 山东大学 | Novel gas detection device based on optical fiber interferometer |
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2010
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| CN101576488A (en) * | 2009-06-05 | 2009-11-11 | 西南石油大学 | Optoelectronic hybrid integration sensor device of sulfureted hydrogen gas concentration and test method thereof |
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Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102226759A (en) * | 2011-03-21 | 2011-10-26 | 山东大学 | Minim moisture detection system based on scanning method |
| CN103076304A (en) * | 2013-01-05 | 2013-05-01 | 浙江理工大学 | Modulation type laser interference method and device for measuring air refractive index |
| CN103076304B (en) * | 2013-01-05 | 2015-01-14 | 浙江理工大学 | Modulation type laser interference method and device for measuring air refractive index |
| CN103344608A (en) * | 2013-06-24 | 2013-10-09 | 哈尔滨工业大学 | Refractive index sensor for non-symmetric high-sensitivity dual-optical fiber ring coupled M-Z (Mach-Zehnder) interferometer |
| CN103344608B (en) * | 2013-06-24 | 2015-06-24 | 哈尔滨工业大学 | Refractive index sensor for non-symmetric high-sensitivity dual-optical fiber ring coupled M-Z (Mach-Zehnder) interferometer |
| CN104570219A (en) * | 2015-01-05 | 2015-04-29 | 浙江大学宁波理工学院 | Integrated optical sensor based on period waveguide microcavity resonance interference effect |
| CN108713134A (en) * | 2016-03-29 | 2018-10-26 | 松下知识产权经营株式会社 | Particle detection sensor |
| CN109238990A (en) * | 2018-11-06 | 2019-01-18 | 广州市怡文环境科技股份有限公司 | A kind of gas concentration detection system and method |
| CN109211800A (en) * | 2018-11-14 | 2019-01-15 | 国网黑龙江省电力有限公司电力科学研究院 | Utilize the method for gas concentration lwevel in 632.8nm wave band of laser measurement sulfur hexafluoride gas |
| CN109211799A (en) * | 2018-11-14 | 2019-01-15 | 国网黑龙江省电力有限公司电力科学研究院 | The method that 980nm wave band of laser measures concentration of SO 2 gas in sulfur hexafluoride gas |
| CN112485225A (en) * | 2019-09-12 | 2021-03-12 | 大连市艾科微波光电子工程研究有限公司 | Optical fiber probe based on laser interference |
| CN110749549A (en) * | 2019-11-22 | 2020-02-04 | 山东大学 | Device and method for monitoring components and concentration of malodorous gas |
| CN112147098A (en) * | 2020-11-03 | 2020-12-29 | 安徽大学 | Gas type and concentration detection system based on anomalous dispersion effect |
| CN112147098B (en) * | 2020-11-03 | 2024-01-16 | 安徽大学 | Gas type and concentration detection system based on anomalous dispersion effect |
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| CN101968441B (en) | 2012-05-30 |
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