CN110231307A - Open light path gas concentration detection apparatus and method based on TDLAS technology - Google Patents
Open light path gas concentration detection apparatus and method based on TDLAS technology Download PDFInfo
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- CN110231307A CN110231307A CN201811602180.5A CN201811602180A CN110231307A CN 110231307 A CN110231307 A CN 110231307A CN 201811602180 A CN201811602180 A CN 201811602180A CN 110231307 A CN110231307 A CN 110231307A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N2021/0106—General arrangement of respective parts
- G01N2021/0112—Apparatus in one mechanical, optical or electronic block
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
- G01N2021/396—Type of laser source
- G01N2021/399—Diode laser
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Abstract
The present invention relates to gas-detecting device technical fields, more particularly to a kind of open light path gas concentration detection apparatus based on TDLAS technology, including Laser Control System, laser, collimator, reflecting system, photodetector, data processing system and display system；The Laser Control System includes current control circuit, temperature-control circuit；The tail optical fiber of laser connects the collimator, and by the atmosphere of radiating laser beams to open light path, reflecting system again passes through the atmosphere of open light path, converge on photodetector for reflecting the laser beam that laser emits；Photodetector is for acquiring the laser signal being reflected back through reflecting system and converting electric signal for it；Data processing system finally handles digital signal；Display system is used to show the concentration of gas.The present invention is measured using open light path, avoids the error and complex operations in gas sampling process, more convenient, efficient, applied widely.
Description
Technical field
The present invention relates to gas-detecting device technical field more particularly to a kind of open light paths based on TDLAS technology
Gas concentration detection apparatus and method.
Background technique
TDLAS technology (abbreviation of Tunable Diode Laser Absorption Spectroscopy) is called adjustable
Humorous diode laser absorption spectral technique.The technology is mainly the narrow linewidth for utilizing semiconductor laser with tunable and wavelength with note
The characteristic for entering electric current change obtains the single absorption line of gas molecule, to calculate the concentration of tested gas.
Currently on the market, have related technical personnel by TDLAS Technology application in terms of gas detection, but use equal
It is that laser analyzes gas by fixed optical path pool, this mode cannot be detected in real time, in certain specific reality
Under operating condition, sampling work is extremely difficult, and detection is made to become complicated.
Summary of the invention
The main object of the present invention provides a kind of open light path gas based on TDLAS technology aiming at the above problem
Bulk concentration detection device and method.
The present invention to achieve the above object, using following technical scheme: a kind of open light path gas based on TDLAS technology
Bulk concentration detection device, it is characterised in that: including Laser Control System, laser, collimator, reflecting system, photodetection
Device, data processing system and display system；
The Laser Control System includes current control circuit, temperature-control circuit；
Wherein, current control circuit is used to control the Injection Current of laser, and temperature-control circuit is for controlling laser
Driving temperature；
The tail optical fiber of the laser connects the collimator, by the atmosphere of radiating laser beams to open light path,
Reflecting system again passes through the atmosphere of open light path, converges for reflecting the laser beam that laser emits
Gather on photodetector；
Photodetector is for acquiring the laser signal being reflected back through reflecting system and converting electric signal for it；
Data processing system includes pre-amplification circuit, locking phase amplifying circuit, A/D conversion circuit and computer；
Wherein, pre-amplification circuit for amplifying the electric signal that photodetector exports, use by locking phase amplifying circuit
In the second harmonic component for demodulating amplified electric signal, A/D conversion circuit is used to convert computer for analog electrical signal
The digital electric signal being capable of handling, computer will finally be handled digital signal；
Display system is used to show the concentration of gas.
Preferably, the reflecting system is using face battle array corner reflector, using gold-plated protective film, so that it is in 650nm to far
Reflectivity in infra-red range is up to 98%.
Preferably, the Laser Control System selects the LDC-3724C of ILX Lightwave company.
Preferably, the laser uses Distributed Feedback Laser.
Preferably, the photodetector is that extended pattern amplifies InGaAs detector.
A kind of open light path gas concentration detection method based on TDLAS technology, comprising the following steps:
1) clear under test gas determines the central wavelength of measurement laser；
It 2) is the incident laser for measuring wavelength using laser control circuit driving laser generation wavelength；
3) incident laser is collimated using collimator, by the shoot laser after collimation, directive reflection is after gas absorbs
System；
4) reflection angle of reflecting system is adjusted, until the laser beam after reflection, which again passes by after gas absorbs, is radiated at light
On electric explorer；
5) photodetector converts electric signal for collected reflected laser signal and is sent to electric signal
Data processing circuit obtains the concentration of under test gas after relevant calculation；
6) display system shows the gas concentration measured.
The beneficial effects of the present invention are: 1) present invention is measured using open light path, gas sampling process is avoided
In error and complex operations, it is more convenient, efficient, it is applied widely；
2) present invention is measured using open light path, can be with telemetry quick and precisely to the gas in regional atmospheric
Body measures, significant to the inherent law for understanding regional cyclically-varying and climate change.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of the present apparatus；
Fig. 2 is the flow chart of the present apparatus.
Specific embodiment
With reference to the accompanying drawing and the preferred embodiment specific embodiment that the present invention will be described in detail.As shown in Figure 1, a kind of base
It is opened in the open light path gas concentration detection apparatus of TDLAS technology, the present invention mainly for CO and CO2 gas
The detection of formula light path.
Referring to Fig. 1, including Laser Control System, laser, collimator, reflecting system, photodetector, data processing
System and display system.By taking the concentration for detecting CO2 as an example:
Laser controller selects the LDC-3724C of ILX Lightwave company, sets initial operating temperature as 31.4
Degree, initialization electric current are 90mA, are demarcated using wavelength of the wavemeter to laser, central wavelength 2002.863nm.
The sawtooth signal that frequency is 50Hz is output to controller, the amplitude of sawtooth wave is adjusted, realizes the tunable of optical maser wavelength, and
Scan specific absorption line；
Laser selects semiconductor laser, and preferred embodiment is using Distributed Feedback Laser, and Distributed Feedback Laser can produce
(but laser of the present invention includes but is not limited to DFB laser to the laser of any wavelength between 750nm -3000nm
Device, this will not be repeated here)；
Reflecting system is using face battle array corner reflector, using gold-plated protective film, so that it is within the scope of 650nm to far infrared
Reflectivity is up to 98%；
Receiving end uses cage construction, installs aperture, lens, optical filter and detector, successively convenient for the steady of system
It is fixed and integrated；
Photodetector is that extended pattern amplifies InGaAs detector, can amplify to signal is received, increase signal-to-noise ratio,
Improve measurement accuracy.
The electric signal that detector generates is sent into the AD capture card that sample rate is 100kS/s, data acquisition；
Pre-amplification circuit, locking phase amplifying circuit and A/D conversion circuit of the electric signal of acquisition Jing Guo data processing system
Afterwards, it is converted into the manageable digital electric signal of computer and is output to display system after terminal is handled, by liquid
Crystal display screen is shown.
Referring to fig. 2, by taking the concentration for detecting CO2 as an example, method includes the following steps:
1) according to the prior art it is found that central wavelength be 2004nm when laser it is the sensitiveest for the detection of CO2 concentration, because
This, the present invention is using the characteristic absorption line near 2004nm, Absorption Line two number higher than Absorption Line near common 1572nm by force
Magnitude, it is easier to realize high-sensitivity measurement (using the characteristic absorption line near 1568nm when measurement CO gas concentration)；
2) experimental system generates sawtooth signal by signal generator using semiconductor laser as laser source, defeated
Out to realizing the tunable of laser wavelength on the controller of laser；
3) laser tail optical fiber connects optical fiber collimator, by radiating laser beams into open light path atmosphere, by CO2 gas
Directive corner reflector after body absorbs；
4) reflection angle of face battle array corner reflector is adjusted, until the laser beam after reflection is radiated on photodetector, is swashed
It is again passed through in open light path atmosphere after light reflection, after the absorption of CO2 gas, signal gathering is on photodetector；Increase
Add a reflecting system, increasing laser in a limited space enhances absorption of the gas to laser by the light path of under test gas
Effect increases the accuracy and reliability of measurement result；A series of equipment, including signal processing can be connected after photodetector
Laser emitter and photodetector are placed in the same side by system and display system, facilitate execute-in-place, increase practicability；?
In terms of fine adjustment, the difficulty for adjusting reflecting system is more convenient well below adjusting photodetector.
5) optical signal received is converted electric signal by photodetector, and electric signal is sent to data processing electricity
Road.Since electric signal is very faint, so the pre-amplification circuit in data processing circuit first amplifies electric signal, i.e., will
In the power amplification of electric signal to the receptible input power range of locking phase amplifying circuit institute, then again by amplified electric signal
It is transferred to locking phase amplifying circuit, locking phase amplifying circuit demodulates the second harmonic component of amplified electric signal, and will be secondary humorous
Wave component is sent to A/D conversion circuit, and A/D conversion circuit converts microprocessor for the second harmonic component of simulation and is capable of handling
Digital signal and digital signal be sent to computer handled (using pre-amplification circuit, locking phase amplifying circuit and A/D
Conversion circuit carries out processing to electric signal and belongs to existing mature technology, and which is not described herein again)；
6) concentration that CO2 can be obtained after the data processing of computer, then shows in the display system.
Through the above steps, the present invention selects somewhere detect on the spot within 48 hours, and AZ7752 is selected to hold CO2 measurement
Instrument compares measurement.The sampling time interval of the two is set as 1 minute.
Comparing result is drawn scatter plot and its equation of linear regression to examine and the correlation of the two by the present invention, is calculated
The related coefficient arrived is 0.837, shows that two kinds of apparatus measures results relevances are preferable.
The above results can be seen that this method detection CO2 concentration with the CO2 concentration that conventional instrument detects be it is similar,
And more rapid and convenient, this demonstrate the feasibilities of this method.
In addition, open light path Gas Thickness Detecting Technology of the present invention has very greatly in terms of atmospheric environment protection
Potentiality, be a kind of efficient, accurate gas concentration detection method.
It will be appreciated by those skilled in the art that attached drawing is the schematic diagram of a preferred embodiment, the embodiments of the present invention
Serial number is for illustration only, does not represent the advantages or disadvantages of the embodiments.
The above is only a preferred embodiment of the present invention, it is noted that for the ordinary skill people of the art
For member, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications are also answered
It is considered as protection scope of the present invention.
Claims (6)
1. a kind of open light path gas concentration detection apparatus based on TDLAS technology, it is characterised in that: including laser control
System, laser, collimator, reflecting system, photodetector, data processing system and display system；
The Laser Control System includes current control circuit, temperature-control circuit；
Wherein, current control circuit is used to control the Injection Current of laser, and temperature-control circuit is used to control the drive of laser
Dynamic temperature；
The tail optical fiber of the laser connects the collimator, by the atmosphere of radiating laser beams to open light path,
Reflecting system again passes through the atmosphere of open light path, converges to for reflecting the laser beam that laser emits
On photodetector；
Photodetector is for acquiring the laser signal being reflected back through reflecting system and converting electric signal for it；
Data processing system includes pre-amplification circuit, locking phase amplifying circuit, A/D conversion circuit and computer；
Wherein, pre-amplification circuit is for amplifying the electric signal that photodetector exports, and locking phase amplifying circuit is for solving
The second harmonic component of amplified electric signal is recalled, A/D conversion circuit can for converting computer for analog electrical signal
The digital electric signal of processing, computer will finally be handled digital signal；
Display system is used to show the concentration of gas.
2. the open light path gas concentration detection apparatus according to claim 1 based on TDLAS technology, feature exist
In: the reflecting system is using face battle array corner reflector, using gold-plated protective film, so that it is within the scope of 650nm to far infrared
Reflectivity is up to 98%.
3. the open light path gas concentration detection apparatus according to claim 1 based on TDLAS technology, feature exist
In: the Laser Control System selects the LDC-3724C of I LX Li ghtwave company.
4. the open light path gas concentration detection apparatus according to claim 1 based on TDLAS technology, feature exist
In: the laser uses Distributed Feedback Laser.
5. the open light path gas concentration detection apparatus according to claim 1 based on TDLAS technology, feature exist
In: the photodetector is that extended pattern amplifies I nGaAs detector.
6. a kind of open light path gas concentration detection side based on TDLAS technology as described in claim 1-5 any one
Method, comprising the following steps:
1) clear under test gas determines the central wavelength of measurement laser；
It 2) is the incident laser for measuring wavelength using laser control circuit driving laser generation wavelength；
3) incident laser is collimated using collimator, by the shoot laser after collimation after gas absorbs directive reflecting system；
4) reflection angle of reflecting system is adjusted, until the laser beam after reflection, which again passes by, is radiated at photoelectricity spy after gas absorbs
It surveys on device；
5) photodetector converts electric signal for collected reflected laser signal and electric signal is sent to data
Processing circuit obtains the concentration of under test gas after relevant calculation；
6) display system shows the gas concentration measured.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811602180.5A CN110231307A (en) | 2018-12-26 | 2018-12-26 | Open light path gas concentration detection apparatus and method based on TDLAS technology |
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| CN201811602180.5A CN110231307A (en) | 2018-12-26 | 2018-12-26 | Open light path gas concentration detection apparatus and method based on TDLAS technology |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110567911A (en) * | 2019-09-30 | 2019-12-13 | 大连艾科科技开发有限公司 | Device for detecting oxygen concentration in inflammable gas and application thereof |
| CN111007025A (en) * | 2019-12-27 | 2020-04-14 | 深圳华领医学技术有限公司 | Detection device capable of detecting and displaying three concentrations of methane gas |
| CN111948173A (en) * | 2020-08-12 | 2020-11-17 | 电子科技大学 | TDLAS signal processing system based on acousto-optic correlation technique |
-
2018
- 2018-12-26 CN CN201811602180.5A patent/CN110231307A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110567911A (en) * | 2019-09-30 | 2019-12-13 | 大连艾科科技开发有限公司 | Device for detecting oxygen concentration in inflammable gas and application thereof |
| CN111007025A (en) * | 2019-12-27 | 2020-04-14 | 深圳华领医学技术有限公司 | Detection device capable of detecting and displaying three concentrations of methane gas |
| CN111948173A (en) * | 2020-08-12 | 2020-11-17 | 电子科技大学 | TDLAS signal processing system based on acousto-optic correlation technique |
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Application publication date: 20190913 |