CN102252982A - Wavelength drift compensation method for laser gas analyzer - Google Patents
Wavelength drift compensation method for laser gas analyzer Download PDFInfo
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- CN102252982A CN102252982A CN 201110109540 CN201110109540A CN102252982A CN 102252982 A CN102252982 A CN 102252982A CN 201110109540 CN201110109540 CN 201110109540 CN 201110109540 A CN201110109540 A CN 201110109540A CN 102252982 A CN102252982 A CN 102252982A
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Abstract
The invention discloses a wavelength drift compensation method for a laser gas analyzer. The wavelength drift compensation method for the laser gas analyzer is mainly used for compensating the central wavelength drift of a distributed feedback laser (DFB). In the method, the absorption peak position of a signal to be tested is detected and the absorption peak offset is fed back to a laser temperature control module, so that the central wavelength drift of the laser can be compensated. A multi-characteristic-point measurement method is adopted, so that the deviation of noises such as optical interference fringes and the like from the monitoring of the laser central wavelength offset can be reduced, the offset of the laser central wavelength can be measured precisely, and the whole system is credible.
Description
Background technology
The present invention relates to the laser gas analyzer field, be specially a kind of wave length shift compensation method that is used for laser gas analyzer.
Background technology
Semiconductor (DFB) laser gas analyzer is the gas controlling device of a kind of " in real time ", " online ", is usually used in fields such as petrochemical industry, iron and steel, cement, environmental protection, industrial on-line monitoring.Laser gas analyzer is a kind of highly sensitive gas analysis means, and its principle is after the laser of specific wavelength passes through gas, because of being subjected to the absorption at gas specific absorption peak, to produce the decay of light intensity.The available Beer-Lambert law of the decay of light intensity accurate description:
Wherein
Be respectively after laser passes through gas, by the light intensity before the gas, v is the frequency of laser, and P, X and L are respectively pressure, concentration and the light paths of gas.The strong S(T of line) be the function of temperature T, linear function
The shape of expression absorption line.By the Beer-Lambert law as can be known, the decay of light intensity and the concentration of tested gas are directly proportional, thereby can obtain the concentration of tested gas by the decay of Laser Measurement after by gas.Simultaneously,, be not subjected to the interference of other gases, have very high measurement sensitivity because the emission peak very narrow (less than 15MHz) of Distributed Feedback Laser can select single gas absorption spectrum line to measure during work.
The semiconductor laser gas analyser is usually used in industry spot " online " monitoring, calibrate cumbersomely, and dismantle and once calibrate general half a year.But long-time " online " continual work can make semiconductor laser ageing, and laser instrument centre wavelength and output power intensity can change in time.For the semiconductor laser gas analyser, the variation of laser intensity is little to the influence of the measurement result of semiconductor laser gas analyzer, if light intensity reach 5% just can be correct measure the gas that will monitor.But the variation of laser instrument centre wavelength can make the absorption peak position that measures change, thereby causes the error of follow-up data processing procedure.If laser instrument center wavelength shift amount is excessive, the absorption peak position can make measurement result mistake occur away from default absorption peak monitoring location especially.
Laser has very strong coherence, and each surperficial reflected light can form interference in the light path, and interference fringe is superimposed upon on the measuring-signal can change the shape of absorption peak, thereby influences the judgement of absorption peak position.In industry spot, the vibration of instrument can cause that the little relatively of each parts of instrument moves the position of interference fringe instability in addition.At this moment, determine that laser instrument centre wavelength will be not accurate enough, deviation may take place because of the interference of interference fringe if just measure the peak of absorption peak.
Summary of the invention
The purpose of this invention is to provide a kind of wave length shift compensation method that is used for laser gas analyzer, can compensate Distributed Feedback Laser center wavelength shift in the laser gas analyzer, to solve the work long hours problem of the Distributed Feedback Laser center wavelength shift that exists of laser gas analyzer in the prior art.
In order to achieve the above object, the technical solution adopted in the present invention is:
A kind of wave length shift compensation method that is used for laser gas analyzer, described laser gas analyzer adopts Distributed Feedback Laser, it is characterized in that: the flashlight that utilizes photodetector to receive Distributed Feedback Laser in the described laser gas analyzer obtains measuring-signal, utilize the data acquisition system (DAS) in the laser gas analyzer to gather measuring-signal, utilize the data handling system in the laser gas analyzer that the measuring-signal that described data acquisition system (DAS) collects is handled again; Described data handling system is chosen the peak point that absorbs main peak in the measuring-signal, absorb the peak point at other peak, main peak both sides, absorb main peak and other peak-to-peak zero point totally five points as unique point, and ask for the mean value of five unique point side-play amounts, described mean value is the side-play amount of Distributed Feedback Laser centre wavelength, obtain the temperature Control current value of corresponding D FB laser instrument after described data handling system is handled once more to the side-play amount of the Distributed Feedback Laser centre wavelength that calculates, and the temperature Control current value of described Distributed Feedback Laser is delivered to Distributed Feedback Laser temperature control modules in the laser gas analyzer; Described Distributed Feedback Laser temperature control modules is exported the electric current of corresponding size according to the temperature Control current value of described Distributed Feedback Laser, and then the Distributed Feedback Laser temperature that changes, with the skew of compensation Distributed Feedback Laser centre wavelength.
The pressure of gas to be measured, the change of temperature can change the width of absorption peak.The change of the absorption peak width that causes for the change that compensates because of gaseous tension to be measured, temperature, the present invention calculates according to measuring-signal and absorbs main peak and other peak, and its variable quantity compensated to five unique points, the influence that measurement brings to system laser centre wavelength of compensation absorption peak wide variety.
The present invention adopts the measurement multi-characteristic points to monitor simultaneously, asks average mode to measure the side-play amount of Distributed Feedback Laser centre wavelength to the deviation that each unique point occurs.
Among the present invention, the monitoring of five unique points can obtain the side-play amount of laser instrument centre wavelength, and side-play amount obtains the temperature Control current of Distributed Feedback Laser after by data processing, by changing the temperature of Distributed Feedback Laser, realizes the compensation of laser instrument centre wavelength drift.
Description of drawings
Fig. 1 is the one-piece construction of laser gas analyzer.
Fig. 2 is the second harmonic signal of absorption peak and the acquisition curve map of five unique point datum lines.
Departure curve synoptic diagram when Fig. 3 drift occurs for Distributed Feedback Laser centre wavelength.
Fig. 4 is the drift-compensated process flow diagram of Distributed Feedback Laser centre wavelength.
Embodiment
As shown in Figure 1.Laser gas analyzer mainly comprises laser emitting module, signal acquisition module and central authorities' control and digital signal processing module composition.The transmitter module of semiconductor laser gas analyser and receiver module all by the fixing mode of flange, are fixed in the industry monitoring scene, so dismounting, orientation ratio difficulty.Just can dismantle, calibrate once about general half a year.But the centre wavelength of Distributed Feedback Laser can be drifted about along with the increase of stream time, if do not adopt Distributed Feedback Laser centre wavelength drift compensation technology, the position of absorption peak can change in time, and the later stage signal Processing is brought difficulty, when serious, output is the result can make mistakes.
As shown in Figure 2.As can see from Figure 2, the second harmonic signal that laser gas analyzer collects by lock-in amplifier has following feature: primary minimum absorption peak both sides respectively have one to absorb other peak greatly, and main peak and other peak-to-peak measuring-signal can pass through zero point.The present invention is according to the characteristics of acquired signal, selected the unique point at these five very big, minimum, the zero points that are easier to accurately to measure, as the datum line of monitoring laser instrument centre wavelength drift value, obtain the drift value of Distributed Feedback Laser centre wavelength by the difference of monitor signal waveform and datum line.Article five, the position of datum line in signal data is respectively
As shown in Figure 3.As can see from Figure 3, between five of acquired signal unique points and the datum line deviation appears.Side-play amount
As shown in FIG., total side-play amount is the mean value of five datum line side-play amounts
Monitoring can reduce the measurement because of certain unique points of noise effect such as interference fringes, and bring than mistake to final measurement in the time of by a plurality of datum line.
As shown in Figure 4.The second harmonic signal that collects obtains the drift value of Distributed Feedback Laser centre wavelength after data processing module is handled
,, can obtain and the center wavelength shift amount through the calculating of Distributed Feedback Laser temperature control modules
The Distributed Feedback Laser temperature Control current i that value is relevant changes the working temperature of Distributed Feedback Laser, thereby realizes the compensation of Distributed Feedback Laser centre wavelength.
In order to compensate the change of gas absorption peak width to be measured with pressure, temperature.Laser gas analyzer is measured parameters such as gas temperature to be measured, pressure simultaneously when work (temperature and pressure of gas to be measured relates to final gas concentration result's compensation, be two parameters that the semiconductor laser gas analyser must be monitored), bring the calculated value that theoretical calculation formula can obtain gas absorption peak width to be measured into, the position of every datum line is revised according to the variation of gas absorption peak width to be measured, just can compensate because the influence that the variation of gas absorption peak width brings this method.
Claims (1)
1. wave length shift compensation method that is used for laser gas analyzer, described laser gas analyzer adopts Distributed Feedback Laser, it is characterized in that: the flashlight that utilizes photodetector to receive Distributed Feedback Laser in the described laser gas analyzer obtains measuring-signal, utilize the data acquisition system (DAS) in the laser gas analyzer to gather measuring-signal, utilize the data handling system in the laser gas analyzer that the measuring-signal that described data acquisition system (DAS) collects is handled again; Described data handling system is chosen the peak point that absorbs main peak in the measuring-signal, absorb the peak point at other peak, main peak both sides, absorb main peak and other peak-to-peak zero point totally five points as unique point, and ask for the mean value of five unique point side-play amounts, described mean value is the side-play amount of Distributed Feedback Laser centre wavelength, obtain the temperature Control current value of corresponding D FB laser instrument after described data handling system is handled once more to the side-play amount of the Distributed Feedback Laser centre wavelength that calculates, and the temperature Control current value of described Distributed Feedback Laser is delivered to Distributed Feedback Laser temperature control modules in the laser gas analyzer; Described Distributed Feedback Laser temperature control modules is exported the electric current of corresponding size according to the temperature Control current value of described Distributed Feedback Laser, and then the Distributed Feedback Laser temperature that changes, with the skew of compensation Distributed Feedback Laser centre wavelength.
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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102654447A (en) * | 2012-04-12 | 2012-09-05 | 安徽皖仪科技股份有限公司 | Device and method for reducing optical interference of laser gas analyzer |
| CN104198416A (en) * | 2014-09-15 | 2014-12-10 | 南京国电环保科技有限公司 | Real-time compensation method of measurement errors caused by spectrograph wavelength drift |
| CN106253994A (en) * | 2016-08-26 | 2016-12-21 | 武汉电信器件有限公司 | The compensation method of a kind of wave length shift and compensation device |
| CN108181268A (en) * | 2017-12-19 | 2018-06-19 | 重庆川仪自动化股份有限公司 | The bearing calibration of laser analyzer spectral line and system |
| CN108918441A (en) * | 2015-11-25 | 2018-11-30 | 上海禾赛光电科技有限公司 | A kind of gas remote measurement method and device |
| CN109541100A (en) * | 2018-12-13 | 2019-03-29 | 安徽皖仪科技股份有限公司 | Signal drift processing method, device and the multichannel detector of multi-channel wavelength |
| CN109596564A (en) * | 2018-10-12 | 2019-04-09 | 上海禾赛光电科技有限公司 | A kind of laser control device, array and control method |
| CN109870872A (en) * | 2017-12-05 | 2019-06-11 | 深圳光峰科技股份有限公司 | The Automatic adjustment method and projection device of light-source system and light-source system |
| CN112782119A (en) * | 2020-12-30 | 2021-05-11 | 汉威科技集团股份有限公司 | Laser gas detection method and system capable of monitoring wavelength |
| CN113466174A (en) * | 2020-03-31 | 2021-10-01 | 比亚迪半导体股份有限公司 | Methane gas concentration detection method and device and microcontroller |
| WO2024031765A1 (en) * | 2022-08-12 | 2024-02-15 | 武汉光迅科技股份有限公司 | Wave compensation method and apparatus, and device and readable storage medium |
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Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102654447A (en) * | 2012-04-12 | 2012-09-05 | 安徽皖仪科技股份有限公司 | Device and method for reducing optical interference of laser gas analyzer |
| CN104198416A (en) * | 2014-09-15 | 2014-12-10 | 南京国电环保科技有限公司 | Real-time compensation method of measurement errors caused by spectrograph wavelength drift |
| CN108918441A (en) * | 2015-11-25 | 2018-11-30 | 上海禾赛光电科技有限公司 | A kind of gas remote measurement method and device |
| CN108918441B (en) * | 2015-11-25 | 2020-11-03 | 上海禾赛科技股份有限公司 | Gas remote measuring method and device |
| US10700788B2 (en) * | 2016-08-26 | 2020-06-30 | Wuhan Telecommunication Devices Co., Ltd. | Method and apparatus for compensating for wavelength drift |
| CN106253994A (en) * | 2016-08-26 | 2016-12-21 | 武汉电信器件有限公司 | The compensation method of a kind of wave length shift and compensation device |
| WO2018036031A1 (en) * | 2016-08-26 | 2018-03-01 | 武汉电信器件有限公司 | Method and device for compensating wavelength drift |
| CN106253994B (en) * | 2016-08-26 | 2018-12-14 | 武汉电信器件有限公司 | A kind of compensation method and compensation device of wave length shift |
| CN109870872B (en) * | 2017-12-05 | 2021-02-26 | 深圳光峰科技股份有限公司 | Light source system, automatic adjusting method of light source system and projection equipment |
| CN109870872A (en) * | 2017-12-05 | 2019-06-11 | 深圳光峰科技股份有限公司 | The Automatic adjustment method and projection device of light-source system and light-source system |
| CN108181268A (en) * | 2017-12-19 | 2018-06-19 | 重庆川仪自动化股份有限公司 | The bearing calibration of laser analyzer spectral line and system |
| CN109596564A (en) * | 2018-10-12 | 2019-04-09 | 上海禾赛光电科技有限公司 | A kind of laser control device, array and control method |
| CN109541100A (en) * | 2018-12-13 | 2019-03-29 | 安徽皖仪科技股份有限公司 | Signal drift processing method, device and the multichannel detector of multi-channel wavelength |
| CN113466174A (en) * | 2020-03-31 | 2021-10-01 | 比亚迪半导体股份有限公司 | Methane gas concentration detection method and device and microcontroller |
| CN112782119A (en) * | 2020-12-30 | 2021-05-11 | 汉威科技集团股份有限公司 | Laser gas detection method and system capable of monitoring wavelength |
| WO2024031765A1 (en) * | 2022-08-12 | 2024-02-15 | 武汉光迅科技股份有限公司 | Wave compensation method and apparatus, and device and readable storage medium |
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Application publication date: 20111123 |