CN1484014A - Method for simutaneously measuring two kinds of gases by using one diode-laser device - Google Patents
Method for simutaneously measuring two kinds of gases by using one diode-laser device Download PDFInfo
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- CN1484014A CN1484014A CNA031325416A CN03132541A CN1484014A CN 1484014 A CN1484014 A CN 1484014A CN A031325416 A CNA031325416 A CN A031325416A CN 03132541 A CN03132541 A CN 03132541A CN 1484014 A CN1484014 A CN 1484014A
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Abstract
The invention is a method to use a diode laser to synchronously measure two gases, referring to a frequency multiplying technique and a spectral analysis. The method: the diode laser is used as emitting source; its output light is converted into horizontal light by lens, then separated into two lights by film plating lens; the reflex passes through the standard pool with one measured gas, then focused on the detector and input into the computer to obtain a spectrum of the standard gas; the transmission light converges on the frequency multiplier, then converted into horizontal light, which passes through the measured gas, then separated by dichromatic spectroscope; the relevant reflex converges on the detector, input into the computer to obtain a spectrum of the measured gas; the transmission light through the spectroscope converges by lens, then received by a detector to obtain a spectrum of the other measured gas; then it makes the comparison to measure temperature, pressure and concentration of the measured gas.
Description
Technical field: the present invention relates to a kind of frequency doubling technology and spectral analysis technique, be specifically related to utilize a laser instrument to measure two kinds of gas concentrations simultaneously, and determine the medial temperature of gas in the light path and the method for pressure simultaneously
Background technology: at present, can realize that the technology of online gas-monitoring mainly contains difference absorption spectrum (DOAS) technology, laser radar (LIDAR) technology and diode laser spectrum technology.Wherein, generally all the applied optics parametric oscillator is as emissive source for the DOAS technology, and the costing an arm and a leg of optical parametric oscillator, and this technology is very high to the requirement of spectroscopic instruments, sensitive detection parts is so cause the cost of equipment set very high.The LIDAR technology is subjected to the influence of external environment easily, can descend along with the increase of wind speed as the precision of its measurement, and the maintenance cost of equipment is very high, so it seldom is used for the real-time monitoring to dusty gas, mainly as the generaI investigation of dusty gas.At present, in the world, the existing relevant report that utilizes diode laser spectrum technology on-line monitoring dusty gas concentration, but mostly be to utilize a diode laser to measure a kind of gas concentration, also have and monitor multiple gases concentration simultaneously, but all will increase the quantity of corresponding diode laser.This will make the cost of gas concentration on-line monitoring equipment increase, and very difficult miniaturization.
Summary of the invention: utilize a diode laser can only measure a kind of problem of gas at present for solving, the invention provides the method that diode laser of a kind of usefulness is measured two kinds of gas densities simultaneously.Concrete grammar of the present invention is: with a diode laser as emissive source; The output light of diode laser at first becomes directional light with lens, then above-mentioned light is divided into two-beam through mirror coating; Be filled with the standard pool of one of tested gas through the reflected light process of mirror coating, with lens the light by standard pool is converged on the detector again, detector is transformed into electric signal and amplification signal with light signal, the electric signal that amplifies is input in the computing machine through the mode detuner, obtains calibrating gas spectrum; Transmitted light through mirror coating converges on the frequency multiplier with lens, and then make the light through frequency multiplier become directional light with lens, this moment, light was become the light of two wavelength by a kind of light of wavelength, made this directional light through gas to be measured, made it by the dichroic beam splitter beam split; Its reflected light converges on the detector through lens, and detector is transformed into electric signal and amplification signal with light signal, and the electric signal of amplification is input in the computing machine through the mode detuner, obtains a tested gaseous spectrum; Received by a detector after converging through lens by spectroscopical transmitted light, detector is transformed into electric signal and amplification signal with light signal again, and the electric signal of amplification is input in the computing machine through the mode detuner, obtains another tested gaseous spectrum; By the above-mentioned spectrum that records being compared temperature, pressure and the concentration that to measure tested gas.The temperature of described diode laser is controlled by temperature controller, and its temperature-control range is 8～60 ℃, and temperature-controlled precision is 0.1 ℃; The input current of diode laser is controlled by current controller, and its range of control is 0～200mA, and control accuracy is 0.1mA.Be wavelength-modulated that realizes diode laser and the signal to noise ratio (S/N ratio) that improves measurement, the present invention utilizes a bench saw tooth wave producer and a sine-wave generator, their output signal is passed to frequency mixer, and the output signal of frequency mixer is passed to the current controller of diode laser.In spectral measurement, every through a sawtooth period, can obtain three spectrum simultaneously, i.e. calibrating gas spectrum a, a tested gaseous spectrum b and another tested gaseous spectrum c.In order to obtain high signal to noise ratio (S/N ratio), obtain spectrum a1, spectrum b1 and spectrum c1 by multispectral adding up (wanting ten spectrum at least).These three spectrum are carried out spectral analysis: at first, can obtain the broadening and the displacement information of diatomics absorbing light spectral line, can determine the medial temperature T and the average pressure P of gas to be measured by broadening amount and displacement by spectrum a1 and spectrum b1 are analyzed; According to T and P value, change the diatomics absorbing light spectral line among the spectrum b1 under the standard conditions diatomics absorbing light spectral line, and obtain the concentration of diatomics gas in the gas to be measured by peak value measurement; Then spectrum c1 is analyzed.By the T that obtains previously, P value, change the absorbing light spectral line of other gas molecule among the spectrum c1 under the standard conditions gas molecule absorbing light spectral line by software, again by spectrum simulation with analyze the concentration that obtains another kind or two kinds of gases to be measured.Can measure the concentration of two or more gas like this by a diode laser simultaneously, and measure the medial temperature and the pressure of gas in the light path simultaneously, thereby improve the gas concentration monitoring accuracy, and the cost that reduces the gas concentration on-line monitoring instrument of exploitation.Utilize the gas concentration monitoring instrument device of this method exploitation can be used for the gas of atmospheric pollution gas and various industrial processes discharging in the gas that combustion product gases comprised of coal fired power plant discharging and dust, the city is implemented online, real-time monitoring.Its advantage is can the lowering apparatus cost, and makes device miniaturization.
Description of drawings: Fig. 1 is an index path of the present invention, and Fig. 2 is the index path of embodiment two.
Embodiment one: consult Fig. 1, present embodiment utilizes a diode laser 1 as emissive source (its centre wavelength is in 400～4000nm scope), the temperature of diode laser is by temperature controller 2 controls (the temperature control scope of temperature controller is 8 ℃～60 ℃, and temperature-controlled precision is 0.1 ℃); The input current of diode laser is by current controller 3 controls (range of control is 0-200mA, and control accuracy is 0.1mA).For the wavelength-modulated of realization diode laser with for improving the signal to noise ratio (S/N ratio) of measuring, (the sawtooth wave frequency can be set in 1Hz～100Hz scope one bench saw tooth wave producer 5, crest voltage can be set in the scope of 100-1000mV) and among sine-wave generator 6 (the sinusoidal wave frequency of output can be set in the 1kHz-100kHz scope, and crest voltage will be set to about the 1/2-1/3 of crest voltage of sawtooth wave) is used to test.The sawtooth wave of its output and sine wave signal are input in the frequency mixer 4, and the output terminal of frequency mixer 4 links to each other with current controller, is superimposed among the Control current.The output light of diode laser at first becomes directional light with lens 7, become two bundle directional lights through plated film lens 8 (its reflectivity is in the 5%-20% scope), its reflecting bundle directional light (makes it to be under the standard conditions through a standard pool 9 that is filled with a certain amount of a kind of diatomics gas (also must be one of tested gas), be that pressure is 1atm, temperature is 25 ℃), with lens 10 light by standard pool 9 is converged on the detector 11, detector 11 changes light signal into electric signal and amplification signal, behind detuner 12, be input to microcomputer 13, obtain spectrum a; Another Shu Guangyong lens 14 converge to frequency doubling device 15 (for example BBO, KDP crystal etc.), it is in order to improve shg efficiency that lens 14 focus on purpose, behind frequency doubling device, light beam becomes the laser (wavelength is respectively λ and λ/2) of two wavelength by the laser of a wavelength, utilizes lens 16 to make the light of two wavelength become directional light again again.This bundle directional light is through gas 17 to be measured (gas air inclusion X to be measured and another or several gas), and through dichroic beam splitter 18 beam split, reflection wavelength is λ, and transmission peak wavelength is λ/2; Reflected light converges to detector 20 through lens 19, and detector 20 changes light signal into electric signal and amplification signal, by being input to microcomputer 13 after detuner 21 demodulation, obtains spectrum b; Transmitted light receives with detector 23 through convergent lens 22, and detector 23 changes light signal into electric signal and amplification signal, through detuner 24 demodulation, again the signal after the demodulation is input to microcomputer 13, obtains spectrum c.
To some measurement situation, then need double-colored directional light is coupled to an end of silica fibre, the light that penetrates from the optical fiber other end becomes directional light by another lens, make it by gas to be measured, converged to an end of another optical fiber again by lens, the light of its other end output becomes directional light through lens again and passes through dichroic beam splitter.
Embodiment two: what present embodiment and embodiment one were different is, light by frequency doubling device is after lens become directional light, again through the end of Lens Coupling to silica fibre, the light that penetrates from the optical fiber other end becomes directional light by lens again and makes it by gas to be measured, converged to an end of another optical fiber again by lens, the light of another optical fiber output becomes directional light through another lens again and shines to dichroic beam splitter.Consulting Fig. 2 below specifies: to some measurement situation, then need to utilize lens A1 to be coupled to the end of silica fibre A2 double-colored directional light, the light that penetrates from the optical fiber other end becomes directional light by another lens A3, make it by gas 17 to be measured, converged to the end of another optical fiber A6 again by lens A5, the light of its other end output becomes directional light by dichroic beam splitter 18 through lens A7 again.When the diode laser actuator temperature raise, its centre wavelength increased, thus the control temperature of diode laser determine to depend on the position of diatomics characteristic absorption spectrum line in spectrum a1.The purpose that charges into diatomics is that when measuring, the wavelength tuning range of diode laser can cover the characteristic absorption spectrum line of whole diatomics because its characteristic light spectral line is narrow.
Claims (3)
1, measure the method for two kinds of gases with a diode laser simultaneously, it is characterized in that its method is: with a diode laser as emissive source; The output light of diode laser at first becomes directional light with lens, then above-mentioned light is divided into two-beam through mirror coating; Be filled with the standard pool of one of tested gas through the reflected light process of mirror coating, with lens the light by standard pool is converged on the detector again, detector is transformed into electric signal and amplification signal with light signal, the electric signal that amplifies is input in the computing machine through the mode detuner, obtains calibrating gas spectrum; Transmitted light through mirror coating converges on the frequency multiplier with lens, and then make the light through frequency multiplier become directional light with lens, this moment, light was become the light of two wavelength by a kind of light of wavelength, made this directional light through gas to be measured, made it by the dichroic beam splitter beam split; Its reflected light converges on the detector through lens, and detector is transformed into electric signal and amplification signal with light signal, and the electric signal of amplification is input in the computing machine through the mode detuner, obtains a tested gaseous spectrum; Received by a detector after converging through lens by spectroscopical transmitted light, detector is transformed into electric signal and amplification signal with light signal again, and the electric signal of amplification is input in the computing machine through the mode detuner, obtains another tested gaseous spectrum; By the above-mentioned spectrum that records being compared temperature, pressure and the concentration that to measure tested gas.
2, diode laser of usefulness according to claim 1 is measured the method for two kinds of gases simultaneously, it is characterized in that utilizing a bench saw tooth wave producer and a sine-wave generator, their output signals of two are all passed to frequency mixer, and the output signal of frequency mixer is passed to the current controller of diode laser.
3, diode laser of usefulness according to claim 1 is measured the method for two kinds of gases simultaneously, it is characterized in that light by frequency multiplier is after lens become directional light, again through the end of Lens Coupling to silica fibre, the light that penetrates from the optical fiber other end becomes directional light by lens again and makes it by gas to be measured, converged to an end of another optical fiber again by lens, the light of another optical fiber output becomes directional light through another lens again and shines to dichroic beam splitter.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB031325416A CN1195215C (en) | 2003-07-30 | 2003-07-30 | Method for simutaneously measuring two kinds of gases by using one diode-laser device |
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| CNB031325416A CN1195215C (en) | 2003-07-30 | 2003-07-30 | Method for simutaneously measuring two kinds of gases by using one diode-laser device |
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| CN1195215C CN1195215C (en) | 2005-03-30 |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101523175B (en) * | 2006-12-18 | 2011-01-19 | 丰田自动车株式会社 | Exhaust gas temperature analysis apparatus, method |
| CN101504367B (en) * | 2009-03-10 | 2011-07-20 | 哈尔滨工业大学 | Apparatus for simultaneously monitoring concentration of carbon monoxide and carbon dioxide |
| CN103528970A (en) * | 2013-10-22 | 2014-01-22 | 长春长光思博光谱技术有限公司 | Light path system in portable near-infrared analyzer |
| CN103728270A (en) * | 2013-12-29 | 2014-04-16 | 西藏民族学院 | Method and device for detecting multi-component gas through semiconductor laser modulated spectrum |
| CN106323910A (en) * | 2016-10-08 | 2017-01-11 | 安徽中科智泰光电测控科技有限公司 | Urban comprehensive pipe gallery open type multi-component gas on-line monitoring early warning device |
| CN108287150A (en) * | 2017-12-06 | 2018-07-17 | 北京无线电计量测试研究所 | The detection method and equipment of buffer gas in a kind of atomic bubble |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112461778A (en) * | 2020-11-09 | 2021-03-09 | 蚌埠依爱消防电子有限责任公司 | High-precision multi-channel combustible gas detector |
-
2003
- 2003-07-30 CN CNB031325416A patent/CN1195215C/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101523175B (en) * | 2006-12-18 | 2011-01-19 | 丰田自动车株式会社 | Exhaust gas temperature analysis apparatus, method |
| CN101504367B (en) * | 2009-03-10 | 2011-07-20 | 哈尔滨工业大学 | Apparatus for simultaneously monitoring concentration of carbon monoxide and carbon dioxide |
| CN103528970A (en) * | 2013-10-22 | 2014-01-22 | 长春长光思博光谱技术有限公司 | Light path system in portable near-infrared analyzer |
| CN103728270A (en) * | 2013-12-29 | 2014-04-16 | 西藏民族学院 | Method and device for detecting multi-component gas through semiconductor laser modulated spectrum |
| CN103728270B (en) * | 2013-12-29 | 2017-10-03 | 西藏民族学院 | A kind of semiconductor laser modulated spectrum multicomponent gas detection method and device |
| CN106323910A (en) * | 2016-10-08 | 2017-01-11 | 安徽中科智泰光电测控科技有限公司 | Urban comprehensive pipe gallery open type multi-component gas on-line monitoring early warning device |
| CN108287150A (en) * | 2017-12-06 | 2018-07-17 | 北京无线电计量测试研究所 | The detection method and equipment of buffer gas in a kind of atomic bubble |
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