CN103575687A - Portable high-sensitivity CO2 detection system - Google Patents
Portable high-sensitivity CO2 detection system Download PDFInfo
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- CN103575687A CN103575687A CN201310454511.6A CN201310454511A CN103575687A CN 103575687 A CN103575687 A CN 103575687A CN 201310454511 A CN201310454511 A CN 201310454511A CN 103575687 A CN103575687 A CN 103575687A
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Abstract
The invention discloses a portable high-sensitivity CO2 detection system. The portable high-sensitivity CO2 detection system comprises a main control chip, a laser temperature controller and a current controller, wherein the laser temperature controller and the current controller are connected with the main control chip; the main control chip is connected with an SD (Secure Digital) card by an SPI (Serial Peripheral Interface) and is connected with an upper computer by a universal asynchronous transceiving transmitter; the laser temperature controller and the current controller are respectively connected with a DFB (Distributed Feed Back) laser; laser emitted by the DFB laser enters a Herroitt multireflection absorption cell after being collimated by an optical-fiber collimator; a photoelectric detector detects spectral signals in the Herroitt multireflection absorption cell, and is connected with a signal conditioning circuit; the signal conditioning circuit is connected with the main control chip. The portable CO2 high-sensitivity detection system disclosed by the invention has the advantages that the integration level is high, the volume is small, the weight is light, the power consumption is low, and outfield experiment and certain flying experiment are convenient; due to the adoption of an embedded type system, a concentration value can be directly obtained and can be stored without subsequent processing of the upper computer; due to the adoption of the multireflection absorption cell, the detection sensitivity is greatly improved.
Description
Technical field
The present invention relates to tunable diode absorption spectroscopy techniques field, relate in particular to a kind of portable CO
2highly sensitive detection system.
Background technology
Whole world change has become the environmental problem that the mankind are concerned about most, and its core is climate change, and the greenhouse effect that wherein carbon containing greenhouse gas concentration aggravates are main causes of climate change.Greenhouse effect cause global warming, caused serious meteorological disaster, China is in the world because of the most serious country of Loss Caused by Meteorological Disasters, the discharge of greenhouse gases accounts for the very great share of world's total emission volumn, this situation is brought on the one hand China's Sheng Tai ﹑ environment and is had a strong impact on, and is also faced with the pressure that huge international convention is honoured an agreement simultaneously.Therefore the development of carrying out greenhouse gases detection system is very important.
At present to greenhouse gases, the lower methane of content especially, domestic or adopt gas chromatography and sampling
Method measure, not only system maintenance expense of this method is large, can not continuous monitoring, and due to
The resultant error that needs certain preprocessing process after its sampling and make to measure is larger.
Semiconductor laser with tunable has narrow linewidth and the quick tuning characteristic of wavelength, is the perfect light source of Trace gas detection.Gas detecting system based on tunable diode laser absorption spectroscopy has Gao Fen Bian and Shuais ﹑ high sensitivity and the feature such as the response time is fast, is the method for the highly sensitive fast monitored of trace gas.Its principal feature comprises:
(1) the high-resolution spectral technique of Gao Xuan Ze ﹑, due to " fingerprint " feature of molecular spectrum, it is not
Be subject to the interference of other gas.This characteristic has been compared obvious advantage with other method.
(2) it be a kind of to all at the infrared activist who has an absorption effective current techique all, same
Instrument can be measured the instrument of other component easily instead, only need to change laser instrument and Standard Gases.Due to
This feature is easy to just can be made into measure multi-component instrument simultaneously.
(3) it has advantages of that Su Du Kuai ﹑ is highly sensitive.The in the situation that of malfunctioning sensitivity not, its time divides
The rate of distinguishing can be in ms magnitude.The major domain of applying this technology has: molecular spectrum research, industrial process prison
Observing and controlling system, combustion process diagnostic analysis, engine efficiency and motor-vehicle tail-gas measurement, spark-test, atmosphere
Middle trace contamination gas-monitoring etc.
Portable CO
2mainly there is following difficult point in detection system:
1. detection system requires little volume and power consumption, needs high detection sensitivity simultaneously.
2.CO
2in air, relative concentration is lower, thereby the noise ratio that detector detects is larger.
3. system need to carry data storage function, facilitates the data analysis in later stage to process.
Summary of the invention
The object of the invention is exactly in order to make up the defect of prior art, and a kind of portable CO is provided
2highly sensitive detection system.
The present invention is achieved by the following technical solutions:
A kind of portable CO
2highly sensitive detection system, include main control chip, what be connected with main control chip has laser temperature controller and a current controller, main control chip connects SD card by SPI interface, main control chip is by universal asynchronous receiving-transmitting forwarder and upper machine communication, described laser temperature controller is all connected with Distributed Feedback Laser with current controller, after collimating by optical fiber collimator, the laser of described Distributed Feedback Laser transmitting enters in Herroitt multiple reflectance cell, photodetector is surveyed the spectral signal in Herroitt multiple reflectance cell, photodetector is connected with signal conditioning circuit, signal conditioning circuit is connected with the analog to digital converter of described main control chip, by main control chip, generate laser scans waveform, produce the sawtooch sweep laser wavelength of 500Hz, configuration-system peripherals again, whether detect SD card inserts and init state, after detecting the success of SD card carry, spanned file folder in SD card, to preserve concentration value and original spectrum signal, soft start Distributed Feedback Laser, described laser temperature controller and current controller drive Distributed Feedback Laser, after Distributed Feedback Laser is Wavelength stabilized, laser enters in Herroitt multiple reflectance cell after optical fiber collimator collimation, photodetector is surveyed the spectral signal in Herroitt multiple reflectance cell, photodetector is converted to electric signal by spectral signal, electric signal after the analog to digital converter collection of main control chip is nursed one's health by signal conditioning circuit, control chip is according to langbobier law, original spectrum data are through background deduction, after baseline fitting, obtain absorbance curve, the relative wavelength of the wavelength coverage according to the laser instrument of having demarcated after stablizing, absorbance is carried out on frequency domain to integration, known absorbing light path, CO
2strong and the temperature of Absorption Line, calculates concentration by integral area, and every 150ms calculates a concentration results and deposits SD card in, and preserve once original absorption spectra data simultaneously every 10 seconds, during in order to data processing, concentration revised.
Described Herroitt multiple reflectance cell is at 25 * 10 * 10cm
3volume in, realized number of pass times 80 times, total optical path is 20m, is coated with the anti-film of increasing of 2004nm wave band on the eyeglass of Herroitt multiple reflectance cell both sides.
Described main control chip is selected the STM32F103 processor of ARM Cotex-M3 kernel, 72MHz clock frequency, and 64KB SRAM, is used ADC on sheet to carry out data acquisition, and resolution is 12bit, sampling rate 1Msps.
Electronic system has been realized miniaturization laser instrument and has been driven on single circuit board, signal condition, the functions such as data acquisition and processing (DAP) circuit.Use the laser instrument driver module of miniaturization to substitute traditional commercial controller, aspect electric current and temperature control, guaranteeing under the prerequisite of control accuracy and speed, power consumption and the volume of system have been effectively reduced, in realizing, miniaturization played key effect, the current module control accuracy of selecting is at present 0.1%, temperature control precision is 0.01 ℃, meets the required accuracy requirement of retrieving concentration, integrated low noise signal conditioning circuit on plate, the light current of realizing detector flows to the functions such as the conversion of voltage and signal filtering conditioning, main control chip is selected the STM32F103 processor of ARM Cotex-M3 kernel, 72MHz clock frequency, 64KB SRAM, use ADC on sheet to carry out data acquisition, resolution is 12bit, sampling rate 1Msps, the sweep waveform signal of laser instrument is generated by the DAC of 12bit on sheet, by rear class output modulate circuit, realized amplitude and the offset adjusted of waveform, to obtain suitable laser scans wavelength coverage, data transmission between processor and ADC and DAC is DMA pattern, effectively alleviated processor calculating pressure, concentration result of calculation can send or be stored in plate by serial ports and carry on SD card, in system, transplanted the FatFs file system of applicable damascene structures, by SPI mode, read and write SD card.150ms of the fastest Data Update cycle of system, the flux that can be used for vortex correlation detects, power consumption <1.2W, volume 25 * 10 * 10cm
3, weight <3Kg, is used the powered battery can continuous working 8 hours.
Optical system adopts 2004nm distributed feed-back (DFB) laser instrument, and light beam enters multiple reflectance cell after collimating device collimation, and detector is surveyed spectral signal simultaneously.Multiple reflectance cell compact appearance, Stability Analysis of Structures is reliable, and both sides eyeglass is coated with the anti-film of the increasing of 2004nm wave band, can effectively reduce light loss, and resistance to variation of ambient temperature ability is strong simultaneously, and temperature variation is smaller on beam path impact.
Advantage of the present invention is: level of integrated system of the present invention is high, and volume is little, lightweight, low in energy consumption, be convenient to outfield experiments and some flight experiments, adopt embedded system, can directly obtain concentration value, and can store, the subsequent treatment that does not need host computer, adopts multiple reflectance cell, has greatly increased detection sensitivity, multiple reflectance cell is lower to temperature susceplibility, has avoided the impact of temperature variation on light path.
Accompanying drawing explanation
Fig. 1 is principle assumption diagram of the present invention.
Fig. 2 is process flow diagram of the present invention.
Embodiment
As shown in Figure 1, 2, a kind of portable CO
2highly sensitive detection system, it is characterized in that: include main control chip 1, what be connected with main control chip 1 has laser temperature controller 2 and a current controller 3, main control chip 1 connects SD card 4 by SPI interface, main control chip 1 is by universal asynchronous receiving-transmitting forwarder and host computer 5 communications, described laser temperature controller 2 is all connected with Distributed Feedback Laser 6 with current controller 3, the laser of described Distributed Feedback Laser 6 transmittings enters in Herroitt multiple reflectance cell 8 after collimating by optical fiber collimator 7, spectral signal in 9 pairs of Herroitt multiple reflectance cells 8 of photodetector is surveyed, photodetector 9 is connected with signal conditioning circuit 10, signal conditioning circuit 10 is connected with the analog to digital converter of described main control chip 1, by main control chip 1, generate laser scans waveform, produce the sawtooch sweep laser wavelength of 500Hz, configuration-system peripherals again, whether detect SD card 4 inserts and init state, after detecting the 4 carry successes of SD card, spanned file folder in SD card 4, to preserve concentration value and original spectrum signal, soft start Distributed Feedback Laser 6, described laser temperature controller 2 and current controller 4 drive Distributed Feedback Laser 6, after Distributed Feedback Laser 6 is Wavelength stabilized, laser enters in Herroitt multiple reflectance cell 8 after optical fiber collimator 7 collimations, spectral signal in 9 pairs of Herroitt multiple reflectance cells 8 of photodetector is surveyed, photodetector 9 is converted to electric signal by spectral signal, electric signal after the analog to digital converter collection of main control chip 1 is nursed one's health by signal conditioning circuit 10, control chip 1 is according to langbobier law, original spectrum data are through background deduction, after baseline fitting, obtain absorbance curve, the relative wavelength of the wavelength coverage according to the laser instrument of having demarcated after stablizing, absorbance is carried out on frequency domain to integration, known absorbing light path, CO
2strong and the temperature of Absorption Line, calculates concentration by integral area, and every 150ms calculates a concentration results and deposits SD card 4 in, and preserve once original absorption spectra data simultaneously every 10 seconds, during in order to data processing, concentration revised.
Described Herroitt multiple reflectance cell 8 is at 25 * 10 * 10cm
3volume in, realized number of pass times 80 times, total optical path is 20m, is coated with the anti-film of increasing of 2004nm wave band on Herroitt multiple reflectance cell 8 both sides eyeglasses.
Described main control chip 1 is selected the STM32F103 processor of ARM Cotex-M3 kernel, 72MHz clock frequency, and 64KB SRAM, is used ADC on sheet to carry out data acquisition, and resolution is 12bit, sampling rate 1Msps.
Claims (3)
1. a portable CO
2highly sensitive detection system, it is characterized in that: include main control chip, what be connected with main control chip has laser temperature controller and a current controller, main control chip connects SD card by SPI interface, main control chip is by universal asynchronous receiving-transmitting forwarder and upper machine communication, described laser temperature controller is all connected with Distributed Feedback Laser with current controller, after collimating by optical fiber collimator, the laser of described Distributed Feedback Laser transmitting enters in Herroitt multiple reflectance cell, photodetector is surveyed the spectral signal in Herroitt multiple reflectance cell, photodetector is connected with signal conditioning circuit, signal conditioning circuit is connected with the analog to digital converter of described main control chip, by main control chip, generate laser scans waveform, produce the sawtooch sweep laser wavelength of 500Hz, configuration-system peripherals again, whether detect SD card inserts and init state, after detecting the success of SD card carry, spanned file folder in SD card, to preserve concentration value and original spectrum signal, soft start Distributed Feedback Laser, described laser temperature controller and current controller drive Distributed Feedback Laser, after Distributed Feedback Laser is Wavelength stabilized, laser enters in Herroitt multiple reflectance cell after optical fiber collimator collimation, photodetector is surveyed the spectral signal in Herroitt multiple reflectance cell, photodetector is converted to electric signal by spectral signal, electric signal after the analog to digital converter collection of main control chip is nursed one's health by signal conditioning circuit, control chip is according to langbobier law, original spectrum data are through background deduction, after baseline fitting, obtain absorbance curve, the relative wavelength of the wavelength coverage according to the laser instrument of having demarcated after stablizing, absorbance is carried out on frequency domain to integration, known absorbing light path, CO
2strong and the temperature of Absorption Line, calculates concentration by integral area, and every 150ms calculates a concentration results and deposits SD card in, and preserve once original absorption spectra data simultaneously every 10 seconds, during in order to data processing, concentration revised.
2. portable CO according to claim 1
2highly sensitive detection system, is characterized in that: described Herroitt multiple reflectance cell is at 25 * 10 * 10cm
3volume in, realized number of pass times 80 times, total optical path is 20m, is coated with the anti-film of increasing of 2004nm wave band on the eyeglass of Herroitt multiple reflectance cell both sides.
3. portable CO according to claim 1
2highly sensitive detection system, is characterized in that: described main control chip is selected the STM32F103 processor of ARM Cotex-M3 kernel, 72MHz clock frequency, and 64KB SRAM, is used ADC on sheet to carry out data acquisition, and resolution is 12bit, sampling rate 1Msps.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105954229A (en) * | 2016-04-21 | 2016-09-21 | 中国科学院半导体研究所 | Detection system and method for alkane gas based on step-and-scan integrated absorption process |
| CN109085083A (en) * | 2018-07-18 | 2018-12-25 | 中国地质大学（北京） | Acquisition methods, system and the terminal device of ratio are inhaled in methane trip |
| CN111044485A (en) * | 2019-12-04 | 2020-04-21 | 清华大学合肥公共安全研究院 | Tunable laser absorption harmonic demodulation circuit and method based on FPGA (field programmable Gate array) synchronous signals |
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| JP2012208126A (en) * | 2012-06-25 | 2012-10-25 | General Packer Co Ltd | Gas concentration measuring method in packaging machine |
| CN103105366A (en) * | 2013-01-22 | 2013-05-15 | 中国科学院安徽光学精密机械研究所 | Method and device for detecting CO2 carbon isotope by infrared spectrum |
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| CN102230882A (en) * | 2011-04-12 | 2011-11-02 | 朱坚磊 | Air testing platform adopting Herroitt multiple-reflection specimen chamber |
| JP2012208126A (en) * | 2012-06-25 | 2012-10-25 | General Packer Co Ltd | Gas concentration measuring method in packaging machine |
| CN103105366A (en) * | 2013-01-22 | 2013-05-15 | 中国科学院安徽光学精密机械研究所 | Method and device for detecting CO2 carbon isotope by infrared spectrum |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105954229A (en) * | 2016-04-21 | 2016-09-21 | 中国科学院半导体研究所 | Detection system and method for alkane gas based on step-and-scan integrated absorption process |
| CN109085083A (en) * | 2018-07-18 | 2018-12-25 | 中国地质大学（北京） | Acquisition methods, system and the terminal device of ratio are inhaled in methane trip |
| CN109085083B (en) * | 2018-07-18 | 2020-07-14 | 中国地质大学（北京） | Method and system for acquiring methane absorption ratio and terminal equipment |
| CN111044485A (en) * | 2019-12-04 | 2020-04-21 | 清华大学合肥公共安全研究院 | Tunable laser absorption harmonic demodulation circuit and method based on FPGA (field programmable Gate array) synchronous signals |
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