CN103575687B - Portable CO 2highly sensitive detection system - Google Patents
Portable CO 2highly sensitive detection system Download PDFInfo
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- CN103575687B CN103575687B CN201310454511.6A CN201310454511A CN103575687B CN 103575687 B CN103575687 B CN 103575687B CN 201310454511 A CN201310454511 A CN 201310454511A CN 103575687 B CN103575687 B CN 103575687B
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Abstract
The invention discloses 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 current controller, main control chip connects SD card by SPI interface, main control chip is connected with host computer by universal asynchronous receiving-transmitting forwarder, described laser temperature controller is all connected with Distributed Feedback Laser with current controller, enter in Herroitt multiple reflectance cell after the laser that described Distributed Feedback Laser is launched is collimated by optical fiber collimator, photodetector detects the spectral signal in Herroitt multiple reflectance cell, photodetector is connected with signal conditioning circuit, signal conditioning circuit is connected with described main control chip.Present system integrated level is high, and volume is little, lightweight, low in energy consumption, be convenient to outfield experiments and some flight experiments, adopt embedded system, directly can obtain concentration value, and can store, do not need the subsequent treatment of host computer, adopt multiple reflectance cell, considerably increase detection sensitivity.
Description
Technical field
The present invention relates to tunable diode absorption spectroscopy techniques field, particularly relate 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, cause serious meteorological disaster, China is country the most serious because of Loss Caused by Meteorological Disasters in the world, 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 carrying out greenhouse gases detection system is very important.
At present to greenhouse gases, the methane that especially content is lower, domestic or adopt gas chromatography and sampling
Method measure, this method not only system maintenance expense is large, can not monitor continuously, and due to
Need certain preprocessing process after its sampling and make the resultant error of measurement 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
By the interference of other gas.This characteristic has obvious advantage compared with other method.
(2) it be a kind of to all at all effective current techique of the infrared activist having an absorption, same
Instrument can measure the instrument of other component easily instead, only needs 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 the highly sensitive advantage of Su Du Kuai ﹑.When not malfunctioning sensitivity, its time divides
The rate of distinguishing can in ms magnitude.The major domain 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, air
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
2relative concentration is lower in atmosphere, and thus the noise ratio that detects of detector is larger.
3. system needs to carry data storage function, facilitates the Data Analysis Services in later stage.
Summary of the invention
The object of the invention is exactly the defect in order to make up prior art, provides a kind of portable CO
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 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, enter in Herroitt multiple reflectance cell after the laser that described Distributed Feedback Laser is launched is collimated by optical fiber collimator, photodetector detects 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, laser scans waveform is generated by main control chip, produce the sawtooch sweep laser wavelength of 500Hz, configuration-system peripherals again, detect SD card whether to insert and init state, when after the success of detection 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 detects the spectral signal in Herroitt multiple reflectance cell, spectral signal is converted to electric signal by photodetector, the analog to digital converter collection of main control chip nursed one's health by signal conditioning circuit after electric signal, control chip is according to langbobier law, original spectral data is through background deduction, absorbance curve is obtained after baseline fitting, according to the relative wavelength of the laser instrument demarcated wavelength coverage after stabilization, on frequency domain, integration is carried out to absorbance, known absorbing light path, CO
2strong and the temperature of Absorption Line, calculate concentration by integral area, every 150ms calculates a concentration results stored in SD card, preserves once original absorption spectra data every 10 seconds simultaneously, revises in order to during data processing to concentration.
Described Herroitt multiple reflectance cell is at 25 × 10 × 10cm
3volume in, achieve 80 number of pass times, total optical path is 20m, and Herroitt multiple reflectance cell both sides eyeglass is coated with the anti-film of increasing of 2004nm wave band.
Described main control chip selects the STM32F103 processor of ARMCotex-M3 kernel, 72MHz clock frequency, 64KBSRAM, and use ADC on sheet to carry out data acquisition, resolution is 12bit, sampling rate 1Msps.
Electronic system achieves miniaturization laser instrument and drives on single circuit board, signal condition, the functions such as data acquisition and processing (DAP) circuit.The laser instrument driver module of miniaturization is used to instead of traditional commercial controllers, ensure the prerequisite of control accuracy and speed in electric current and temperature control under, effectively reduce power consumption and the volume of system, key effect is served in miniaturization realizes, the current module control accuracy selected at present is 0.1%, temperature control precision is 0.01 DEG C, meets the accuracy requirement needed for retrieving concentration, plate is integrated with the signal conditioning circuit of low noise, the light current realizing detector flows to the function such as conversion and signal filtering conditioning of voltage, main control chip selects the STM32F103 processor of ARMCotex-M3 kernel, 72MHz clock frequency, 64KBSRAM, ADC on sheet is used 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, amplitude and the offset adjusted that modulate circuit realizes waveform is exported by rear class, to obtain suitable laser scans wavelength coverage, data between processor and ADC and DAC are transmitted as DMA pattern, effectively alleviate processor calculating pressure, concentration result of calculation can be sent or be stored in plate and carry on SD card by serial ports, the FatFs file system of applicable damascene structures has been transplanted in system, SD card is read and write by SPI mode.System the fastest Data Update cycle 150ms, the flux that can be used for vortex correlation detects, power consumption <1.2W, volume 25 × 10 × 10cm
3, weight <3Kg, uses 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 detects 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: present system integrated level is high, and volume is little, lightweight, low in energy consumption, be convenient to outfield experiments and some flight experiments, adopt embedded system, directly can obtain concentration value, and can store, do not need the subsequent treatment of host computer, adopt multiple reflectance cell, considerably increase detection sensitivity, multiple reflectance cell is lower to temperature susceplibility, avoids 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 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 communication, described laser temperature controller 2 is all connected with Distributed Feedback Laser 6 with current controller 3, enter in Herroitt multiple reflectance cell 8 after the laser that described Distributed Feedback Laser 6 is launched is collimated by optical fiber collimator 7, spectral signal in photodetector 9 pairs of Herroitt multiple reflectance cells 8 detects, 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, laser scans waveform is generated by main control chip 1, produce the sawtooch sweep laser wavelength of 500Hz, configuration-system peripherals again, detect SD card 4 whether to insert and init state, when after the success of detection SD card 4 carry, 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 collimates, spectral signal in photodetector 9 pairs of Herroitt multiple reflectance cells 8 detects, spectral signal is converted to electric signal by photodetector 9, the analog to digital converter collection of main control chip 1 is by the electric signal after signal conditioning circuit 10 conditioning, control chip 1 is according to langbobier law, original spectral data is through background deduction, absorbance curve is obtained after baseline fitting, according to the relative wavelength of the laser instrument demarcated wavelength coverage after stabilization, on frequency domain, integration is carried out to absorbance, known absorbing light path, CO
2strong and the temperature of Absorption Line, calculate concentration by integral area, every 150ms calculates a concentration results stored in SD card 4, and the absorption spectra data that every preservation in 10 seconds is once original simultaneously, revises concentration in order to during data processing.
Described Herroitt multiple reflectance cell 8 is at 25 × 10 × 10cm
3volume in, achieve 80 number of pass times, total optical path is 20m, and Herroitt multiple reflectance cell 8 both sides eyeglass is coated with the anti-film of increasing of 2004nm wave band.
Described main control chip 1 selects the STM32F103 processor of ARMCotex-M3 kernel, 72MHz clock frequency, 64KBSRAM, and use ADC on sheet to carry out data acquisition, 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 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, enter in Herroitt multiple reflectance cell after the laser that described Distributed Feedback Laser is launched is collimated by optical fiber collimator, photodetector detects 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, laser scans waveform is generated by main control chip, produce the sawtooch sweep laser wavelength of 500Hz, configuration-system peripherals again, detect SD card whether to insert and init state, when after the success of detection 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 detects the spectral signal in Herroitt multiple reflectance cell, spectral signal is converted to electric signal by photodetector, the analog to digital converter collection of main control chip nursed one's health by signal conditioning circuit after electric signal, control chip is according to langbobier law, original spectral data is through background deduction, absorbance curve is obtained after baseline fitting, according to the relative wavelength of the laser instrument demarcated wavelength coverage after stabilization, on frequency domain, integration is carried out to absorbance, known absorbing light path, CO
2strong and the temperature of Absorption Line, calculate concentration by integral area, every 150ms calculates a concentration results stored in SD card, preserves once original absorption spectra data every 10 seconds simultaneously, revises in order to during data processing to concentration.
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, achieve 80 number of pass times, total optical path is 20m, and Herroitt multiple reflectance cell both sides eyeglass is coated with the anti-film of increasing of 2004nm wave band.
3. portable CO according to claim 1
2highly sensitive detection system, is characterized in that: described main control chip selects the STM32F103 processor of ARMCotex-M3 kernel, 72MHz clock frequency, 64KBSRAM, and use ADC on sheet to carry out data acquisition, resolution is 12bit, sampling rate 1Msps.
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| CN103575687B true CN103575687B (en) | 2016-02-10 |
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| CN105954229B (en) * | 2016-04-21 | 2019-09-24 | 中国科学院半导体研究所 | Alkanes gas detecting system and method based on step-scan integrated absorption method |
| 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 |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102230882A (en) * | 2011-04-12 | 2011-11-02 | 朱坚磊 | Air testing platform adopting Herroitt multiple-reflection specimen chamber |
| 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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| JP5555923B2 (en) * | 2012-06-25 | 2014-07-23 | ゼネラルパッカー株式会社 | Gas concentration measurement method for packaging machines |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102230882A (en) * | 2011-04-12 | 2011-11-02 | 朱坚磊 | Air testing platform adopting Herroitt multiple-reflection specimen chamber |
| 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 |
Non-Patent Citations (2)
| Title |
|---|
| 基于可调谐半导体激光吸收光谱对CO2浓度的测量;袁松等;《大气与环境光学学报》;20121130;第7卷(第6期);第433页最后一段至435页，第436页第一段、倒数第二段及附图1-4 * |
| 基于可调谐半导体激光吸收光谱的氧气测量方法研究;张帅等;《光谱学与光谱分析》;20091031;第29卷(第10期);2593-2596 * |
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