CN201811917U - Photoacoustic spectrum gas detection system based on Mach-Zehnder interferometer - Google Patents
Photoacoustic spectrum gas detection system based on Mach-Zehnder interferometer Download PDFInfo
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- CN201811917U CN201811917U CN2010202735828U CN201020273582U CN201811917U CN 201811917 U CN201811917 U CN 201811917U CN 2010202735828 U CN2010202735828 U CN 2010202735828U CN 201020273582 U CN201020273582 U CN 201020273582U CN 201811917 U CN201811917 U CN 201811917U
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Abstract
A photoacoustic spectrum gas detection system based on a Mach-Zehnder interferometer belongs to gas detection technique and comprises a coherent source I, a coherent source II, a phase demodulating system and the like, wherein the coherent source I is connected to a modulator, the modulator is connected to a photoacoustic cell through a common optical fiber, and monochromatic light with periodically changing strength acts on gas to be tested, thereby generating small sound. The coherent source II is connected to a coupler 2*2 through a common optical fiber to form a detection light path. The photoacoustic spectrum gas detection system is characterized in that one arm of the Mach-Zehnder interferometer is used as a sensor for detecting sound, the sensor is fixed into the photoacoustic cell to serve as a test arm, another arm of the Mach-Zehnder interferometer is used as a reference arm connected to the coupler 2*2, the test arm and the reference arm are respectively connected to two ends of another coupler 2*2 in the same direction, and the couplers 2*2 are connected to the phase demodulating system through common optical fibers. The photoacoustic spectrum gas detection system can be normally used in highly electromagnetic and radioactive environment, can be used for detecting special gas environments, and convenient for multiplexing to form a network, thereby realizing multi-point monitoring.
Description
Technical field
The utility model relates to a kind of optoacoustic spectroscopy gas detecting system of the full optics based on Mach-Zehnder interferometer, specifically is a kind of system that utilizes arm of Mach-Zehnder interferometer moral to carry out the optoacoustic spectroscopy gas detection as the optics microphone.
Background technology
Optoacoustic effect is based on the effect that inspires sound wave after the material absorbing light modulated by radiationless hot relaxation heat release, has just found optoacoustic effect as far back as Bell in 1880 etc.Carry out in the absorption spectrum law that gas concentration detects many, optoacoustic spectroscopy has the following advantages: test specification is wide.Photoacoustic technique is the light energy signal that detection material directly absorbs by radiationless transition, rather than the light energy signal of sample is crossed in the measurement transmission, sample is to reflection of incident light like this, scattering can not have influence on measurement result, the sample of fully opaque and high scattering is energy measurement also, measurement range almost spreads all over all states of sample, such as: gas, liquid, Gu, gel, powder, film, colloid etc., but early stage because optoacoustic effect too a little less than, unanimity does not obtain paying attention to, up to the 20 actual seventies, development along with laser technology and feeble signal Detection Techniques, particularly Kreuzer in 1971 utilizes tunable laser to do light source, record the gas absorption spectrum that concentration is low to moderate 10-7 μ g/L, and analyzed the use LASER Light Source theoretically and high sensitivity feeble signal detector can reach 10-13 to the gas optoacoustic spectroscopy detection limit order of magnitude, after this, photoacoustic spectroscopy is developed rapidly.Another advantage is exactly: photoacoustic signal intensity is directly proportional with incident intensity under the situation that absorption of sample luminous energy does not reach capacity, and along with the development of laser technology, the energy that improves incident light becomes relatively easy to increase detection sensitivity.
Because outstanding advantages such as the high sensitivity that the photoacoustic spectroscopy instrument has, great dynamic range, detection in real time, make people very big interest be arranged to the optoacoustic spectroscopy detection technique, continually develop new light sources, research sound sensing technology and Detection of Weak Signals technology, improve the optoacoustic spectroscopy theory, making analyser various aspects of performance based on optoacoustic spectroscopy have significantly improves, in recent years, on industrial and agricultural production, environmental monitoring, military battlefield, many gas-detecting devices based on optoacoustic spectroscopy had been developed in minimum gas monitoring field in succession.The optoacoustic spectroscopy gas analyzer mainly is made up of six parts: monochromatic source, modulator, photoacoustic cell, sonic transducer, signal amplify and detect data recording and transmission.The photo-acoustic spectrometer of commercial typing seldom generally need design voluntarily according to research object and breadboard condition in actual applications and build.The photoacoustic signal that optoacoustic effect excites is surveyed by highly sensitive sonic transducer, uses electret formula capacitor microphone usually.Its monochromatic source of photo-acoustic spectrometer of general design, the amplification and the detection system of signal are positioned at the scene, but at some special occasions, as 1) strong magnetoelectricity and radioactive environment, because physical characteristics is restricting the operation of common microphone, the influence of outside strong-electromagnetic field can cause the forfeiture of these functions of the equipments even destroy them.Traditional microphone comprises capacitor, electret and dynamic microphone, uses to rely on the electronic circuit that contains capacitor or coil.These electronic packages in microphone are highstrung to interference electronics or electromagnetism; 2) gas environment is such as in the colliery excavation site.Electric spark is forbidden occurring in the scene, this means exciting of coherent source to be placed on long-rangely, with the long-range placement of light source, imports in the photoacoustic cell by optical fiber, and there is the hidden danger of safety in the microphone that also just means electronics; 3) detect in the application in environmental contaminants monitoring and battlefield surroundings toxicity, because gas detection equipment dispersed placement, the scene often can not provide power supply, this just need provide on-the-spot passive, structure is small and exquisite, integrated level and the high photoacoustic cell of high sensitivity, and is convenient with what realize detecting.
＜Proceedings of the CSEE〉2008,28 (34): p40～46. authors are Yun Yuxin, Chen Weigen, Sun Caixin, Pan's Chong, name is called in " the optoacoustic spectroscopy detection method of methane gas in the transformer oil " article and has proposed a kind of novel micro gas detection technology based on optoacoustic effect, have highly sensitive, selectivity is good, advantages such as dynamic detection range is big, but this detection technique is subject to measurement environment, when having outside electromagnetic field, badly influence measuring accuracy, even the function of checkout equipment can be lost.
Summary of the invention
In order to overcome defective and the deficiency that prior art exists, the utility model proposes a kind of method and system of optoacoustic spectroscopy gas detection of the full light based on Mach-Zehnder interferometer.
The technical solution of the utility model realizes in the following manner:
A kind of optoacoustic spectroscopy gas detecting system based on Mach-Zehnder interferometer, comprise coherent source I, II, modulator, photoacoustic cell, two 2*2 coupling mechanisms, Mach-Zehnder interferometer and phase demodulating systems, coherent source I is connected to modulator, modulator is connected to photoacoustic cell by ordinary optic fibre and excites gas to be measured, produce small sound, constitute the sound excitation light path; Coherent source II is connected to form on the 2*2 coupling mechanism by ordinary optic fibre and detects light path, an arm that it is characterized in that Mach-Zehnder interferometer is fixed on as the sensor of surveying sound becomes test arm in the photoacoustic cell, another arm is connected on the 2*2 coupling mechanism as the reference arm; Test arm and reference arm are connected to another 2*2 coupling mechanism in the same way on two input ends separately, and the 2*2 coupling mechanism is connected in the phase demodulating system through ordinary optic fibre.
Described phase demodulating system is general phase demodulating instrument, and the model of producing as Canadian Avensys company is the phase demodulating instrument of DPSK.
The utility model gas detecting system in use, the photoacoustic cell in the utility model system placed the gaseous environment that need to detect or with gas extraction to photoacoustic cell.After coherent source I produced monochromatic light, by modulator, light intensity produced periodic the variation, by be connected to the photoacoustic cell of far-end than long ordinary optic fibre, injected photoacoustic cell, with gas effect to be measured, produced sound.Coherent source II injects the 2*2 coupling mechanism with the coherent light that produces by long ordinary optic fibre, promptly enter Mach-Zehnder interferometer, be fixed in the photoacoustic cell after the test arm of interferometer is packaged, and reference arm is stayed outside the photoacoustic cell, two arms interfere by another 2*2 coupling mechanism again, and the signal after the interference is passed the phase demodulating system back by long ordinary optic fibre.Utilize an arm of Mach-Zehnder interferometer to survey sound as sensor, monochromatic light enters photoacoustic cell, behind the gas absorption light to be measured, produce small sound, acoustic pressure causes that brachium of an arm of interferometer etc. changes, and another arm does not change as a reference, two arms produce optical path difference, after the interference, produce the variation of light and shade striped, the variation that promptly produces phase place, by follow-up phase demodulating system, detect the variation of phase place, thereby determine acoustic pressure, and then release the concentration of gas.
The used optoacoustic spectroscopy gas detection principle of prior art as shown in Figure 1, coherent source gives off can be by the monochromatic light of gas absorption to be measured, become the monochromatic light of light intensity periodically-varied through the modulation of modulator, enter photoacoustic cell, behind the gas absorption monochromatic light, cause its radiationless relaxation of periodicity, show as the cyclical variation of pressure on the macroscopic view, promptly form sound wave; Sonic transducer changes it into electric signal after detecting pressure wave, and this electric signal is detected by lock-in amplifier or Boxcar integrator, and notes, and also can give remote computer analyzing and processing or deposit.
Concrete action principle of the present utility model is as follows: the monochromatic light of the be detected gas absorption that coherent source produces, after ovennodulation, form the laser of light intensity periodically-varied, after entering photoacoustic cell, by gas absorption, produce sound wave, be subjected to the influence of acoustic pressure, the length of the pickup arm of packaged Mach-Zehnder interferometer, refractive indexes etc. change, the optical path difference that causes interferometer two arms changes, phase place after the interference changes, by the phase demodulating system, we can come out the variation demodulation of phase place again, like this reacting condition of phase place the intensity of acoustic pressure, and the concentration of the intensity of acoustic pressure and gas has direct relation, can express the concentration of gas by suitable algorithm.
The utlity model has following advantage: have the highly sensitive while of optoacoustic spectroscopy method, no electronic package is connected on the fibre-optical probe, and any electro permanent magnetic or electrostatic interference are inoperative to microphone, can normally use in forceful electric power magnetic, radioactive environment; The sound-detection system of full optical fiber does not have an effect with flammable explosive gas such as gas, can be used for the detection of special gas environment; Based on the system of optical fiber, be convenient to a plurality of multiplexingly, form network, realize the remote monitor of multiple spot.
Description of drawings
Fig. 1 is the structural representation of the used optoacoustic spectroscopy gas detection of prior art.
Wherein: 1, coherent source, 2, modulator, 3, photoacoustic cell, 4, microphone, 5, signal amplify and the test section, and 6, data recording and hop.
Fig. 2 is the structural representation of the utility model gas detecting system.
Wherein: 7, coherent source I, 8, modulator, 9, ordinary optic fibre, 10, photoacoustic cell, 11, coherent source II, 12, ordinary optic fibre, 13,2*2 coupling mechanism, 14, test arm, 15, reference arm, 16,2*2 coupling mechanism, 17, ordinary optic fibre, 18, the phase demodulating system.
Embodiment
Below in conjunction with drawings and Examples the utility model is described further, but is not limited thereto.
Embodiment:
The utility model embodiment as shown in Figure 2, comprise coherent source I 7, II11, modulator 8, photoacoustic cell 10, two 2*2 coupling mechanisms 13,16, Mach-Zehnder interferometer and phase demodulating systems 18, coherent source I 7 is connected to modulator 8, modulator 8 is connected to photoacoustic cell by ordinary optic fibre 9 and excites gas to be measured for 10 li, produce small sound, constitute the sound excitation light path; Coherent source II 11 is connected to form on the 2*2 coupling mechanism 13 by ordinary optic fibre 12 and detects light path, an arm that it is characterized in that Mach-Zehnder interferometer is fixed on photoacoustic cell as the sensor of surveying sound becomes test arm 14 for 10 li, and another arm is connected on the 2*2 coupling mechanism 13 as reference arm 15; Test arm 14 and reference arm 15 are connected to another 2*2 coupling mechanism 16 in the same way on two input ends separately, and 2*2 coupling mechanism 16 is connected in the phase demodulating system 18 through ordinary optic fibre 17.
Claims (1)
1. optoacoustic spectroscopy gas detecting system based on Mach-Zehnder interferometer, comprise coherent source I, II, modulator, photoacoustic cell, two 2*2 coupling mechanisms, Mach-Zehnder interferometer and phase demodulating systems, coherent source I is connected to modulator, modulator is connected to photoacoustic cell by ordinary optic fibre and excites gas to be measured, produce small sound, constitute the sound excitation light path; Coherent source II is connected to form on the 2*2 coupling mechanism by ordinary optic fibre and detects light path, an arm that it is characterized in that Mach-Zehnder interferometer is fixed on as the sensor of surveying sound becomes test arm in the photoacoustic cell, another arm is connected on the 2*2 coupling mechanism as the reference arm; Test arm and reference arm are connected to another 2*2 coupling mechanism in the same way on two input ends separately, and the 2*2 coupling mechanism is connected in the phase demodulating system through ordinary optic fibre.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101936879A (en) * | 2010-07-28 | 2011-01-05 | 山东大学 | Photoacoustic spectroscopy gas detecting system based on Mach-Zehnder interferometer |
| CN107063552A (en) * | 2016-11-30 | 2017-08-18 | 深圳市中葛科技有限公司 | A kind of fiber-optic fiber gas pressure sensor |
| CN110470630A (en) * | 2018-05-11 | 2019-11-19 | 西安电子科技大学 | A kind of distribution type fiber-optic gas sensor based on difference modes |
| CN110988122A (en) * | 2019-12-03 | 2020-04-10 | 山东大学 | Sectional type coupling device and method suitable for upward inclined borehole sound wave test |
-
2010
- 2010-07-28 CN CN2010202735828U patent/CN201811917U/en not_active Expired - Lifetime
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101936879A (en) * | 2010-07-28 | 2011-01-05 | 山东大学 | Photoacoustic spectroscopy gas detecting system based on Mach-Zehnder interferometer |
| CN107063552A (en) * | 2016-11-30 | 2017-08-18 | 深圳市中葛科技有限公司 | A kind of fiber-optic fiber gas pressure sensor |
| CN110470630A (en) * | 2018-05-11 | 2019-11-19 | 西安电子科技大学 | A kind of distribution type fiber-optic gas sensor based on difference modes |
| CN110988122A (en) * | 2019-12-03 | 2020-04-10 | 山东大学 | Sectional type coupling device and method suitable for upward inclined borehole sound wave test |
| CN110988122B (en) * | 2019-12-03 | 2021-09-03 | 山东大学 | Sectional type coupling device and method suitable for upward inclined borehole sound wave test |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20110427 Effective date of abandoning: 20111130 |
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| AV01 | Patent right actively abandoned |
Granted publication date: 20110427 Effective date of abandoning: 20111130 |