CN205607853U - Gaseous sensing system that absorbs of self -mixing based on tunable semiconductor laser - Google Patents
Gaseous sensing system that absorbs of self -mixing based on tunable semiconductor laser Download PDFInfo
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- CN205607853U CN205607853U CN201620287017.4U CN201620287017U CN205607853U CN 205607853 U CN205607853 U CN 205607853U CN 201620287017 U CN201620287017 U CN 201620287017U CN 205607853 U CN205607853 U CN 205607853U
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Abstract
The utility model relates to a gaseous sensing system that absorbs of self -mixing based on tunable semiconductor laser, including semiconductor laser (1) even extremely light collection and coupling unit (2) and gas chamber (5) of cooperation in proper order, gas chamber 's rear end face is equipped with the speculum, other is equipped with the drive circuit of signal processing unit (3), signal display terminal (4) and modulated laser, the drive circuit of laser instrument produce drive semiconductor laser's (1) voltage signal, the semiconductor laser that can make collects through light and launches laser with the coupling unit to get into gas chamber, by gas chamber gaseous absorb and by gas chamber 's back end surface reflection readjustment semiconductor laser intracavity of awaiting measuring, signal processing unit connects the photocurrent that PD produced among the semiconductor laser and converts voltage signal into and handles through signal processing unit, exports the signal display terminal.
Description
Technical field
This utility model relates to a kind of optical interference sensing technology, particularly to a kind of Self-mixing GAS ABSORPTION sensing technology.
Background technology
Gas spectroscopy is measured and can be realized the noncontact quantitative measurement of gas concentration, it is adaptable to complex environment and poisonous, have
Do harm to, be corrosive gas detecting.The principle of the measurement gas concentration of absorption spectrometry is when light beam is through gassiness
After absorption cell, its output intensity understands i.e. Beer-Lambert law of decaying because of gas molecules sorb, by measuring
Penetrate light intensity magnitude, and gas concentration size can be obtained according to incident intensity and gas absorption cross-section information.Meanwhile, structure
Simply, compact, stable self-mixed interference system can amplify gas absorption signal, it is possible to obtains high sensitivity gas and inhales
The collection of letters number.Self-mixed interference is in the laser that laser instrument exports is reflected by external object or scatters entrance laser cavity and to occur dry
The phenomenon related to.Owing to feedback light carries the phase information of extraneous light path, therefore laser self-mixing interference signal frequency, strong
Degree can reflect the information of gas concentration in time.Can be simultaneously in laser self-mixing interference system, particularly laser light source
Carrying out sensing measurement as sensing element, simple in construction, compact reduction are measured system cost, and can be strengthened interference signal
Signal to noise ratio is to obtain high sensitivity detection.
Carrying out gas spectroscopy measurement technology at present mainly uses direct absorption process to measure gas concentration, and signal is more weak, therefore
In remote, high-sensitivity measurement limited.Meanwhile, the method cannot provide the length of gas to be measured.
Utility model content
This utility model purpose is, for avoiding the weak point of above-mentioned technology, it is provided that one can a kind of high s/n ratio, Gao Ling
Sensitivity, easily collimation can be used for remote GAS ABSORPTION sensing, have business-like potential ability and are easily achieved batch metaplasia
The Self-mixing GAS ABSORPTION sensing technology produced, has higher sensitivity and measurement scope.
This utility model adopts the following technical scheme that in order to achieve the above object, a kind of based on tunable semiconductor laser
From mixed gas absorb sensor-based system, including semiconductor laser (1) and successively coordinate be connected to light collect and coupling unit
And gas chamber (5) (2)；The rear end face of gas chamber (5) is provided with reflecting mirror；It is additionally provided with signal processing unit (3),
Signal display terminal (4) and the drive circuit (6) of modulation laser instrument；The drive circuit (6) of described laser instrument produces
Drive the voltage signal of semiconductor laser (1)；The semiconductor laser (1) that can modulate is collected by light and couples single
Unit (2) launches laser, and enters gas chamber (5), by gas chamber's GAS ABSORPTION to be measured and by gas chamber (5)
Rear end face reflection readjustment semiconductor laser (1) intracavity；Described signal processing unit (3) connects semiconductor laser
(1) in PD produce photoelectric current and be converted to voltage signal through signal processing unit (3) process, output to signal show
Show terminal.
Described semiconductor laser (1) includes the semiconductor laser meeting gas absorption spectrum line centre wavelength, as
1653nmDFB semiconductor laser can be as the light source etc. of methane gas detection.
Described gas chamber (5) is the cavity body structure loading gas, and described cavity body structure includes the chamber of closing such as
Resonant cavity, calculus chamber etc., described cavity body structure includes that the chamber of open chamber is as done, any reflecting surface, the sky fed back
Gas chamber.
This utility model absorbs the application of sensor-based system, driving of laser instrument based on semiconductor laser (1) from mixed gas
Galvanic electricity road (6) produces the voltage signal driving semiconductor laser (1), to obtain swashing of semiconductor laser (1)
Light frequency and intensity modulation output, with that reach to cover GAS ABSORPTION live width to be measured and be obtained in that self-mixed interference distance is surveyed
The purpose of amount signal；The semiconductor laser (1) that can modulate is collected by light and is launched laser with coupling unit (2),
Enter gas chamber (5), adjust back semiconductor laser by GAS ABSORPTION to be measured and by the end face reflection of gas chamber (5)
(1) intracavity；The now concentration information carrying gas to be measured from mixed signal of semiconductor laser (1) intracavity；Institute
State the photoelectric current accepting PD generation in semiconductor laser (1) in signal processing unit (3) and be converted to voltage letter
Number processing, final output is also shown by reception signal terminal.
According to the ultimate principle of spectroscopy, every kind of material has oneself distinctive absorption spectrum, swashs in conjunction with internal modulation quasiconductor
The output intensity relational expression from mixing sensing technology of light device is the most above-mentioned.
This utility model beneficial effect: compared with the prior art, 1) this utility model employing self-mixed interference technology, its
It is capable of higher measurement sensitivity, it is possible to ensure remote, highly sensitive relative to direct absorption process gas measurement technique
The sensing measurement of degree.2) this utility model uses internal modulation technology, and it is relative to direct measuring, it is possible to obtains and swashs
Distance between light device and gas to be measured, using the teaching of the invention it is possible to provide more information, it is simple to gas to be measured is carried out data analysis.
In a word, this utility model uses the concentration information of self-mixed interference commercial measurement gas, and it is relative to direct absorption process
Gas measurement technique is capable of higher measurement sensitivity, is obtained in that the distance between laser instrument and gas to be measured simultaneously,
More information can be provided, it is simple to gas to be measured is carried out data analysis.
Accompanying drawing explanation
Fig. 1 be tunable semiconductor laser from mixed gas absorb sensor-based system schematic diagram；
Fig. 2 is Self-mixing GAS ABSORPTION Fundamentals of Sensors.
Label in figure: 1 semiconductor laser；2 light are collected and coupling unit；3 signal processing units；4 signals (connect
Receive) display terminal；5 gas chamber；The drive circuit of 6 laser instrument.
Detailed description of the invention
This utility model provides the detection of gas sensor-based system of a kind of self-mixed interference based on the direct absorption techniques of gas, will
Gas concentration signal to be measured is converted into the method for the Parameters variation such as the amplitude of light wave, phase place, frequency.This utility model is to adopt
Directly absorb with gas and the sensor of self-mixed interference principle, by scattered light, gas signal to be measured is fed back to laser instrument
And be transformed in the frequency of self-mixing interference, amplitude of variation, the anti-interference of measured signal and strong security can be realized
Transmission.
This utility model is based on tunable semiconductor laser absorbs sensor-based system from mixed gas as it is shown in figure 1, use half
Conductor laser 1 is also equipped with light collection and coupling unit 2；One signal processing unit 3；One signal display terminal 4；
One gas chamber 5；The drive circuit 6 of one modulation laser instrument constitutes absorbing from mixed gas of tunable semiconductor laser
Sensor-based system.
Semiconductor laser 1 is also equipped with light collection and coupling unit 2；One signal processing unit 3；One signal shows
Terminal 4；One gas chamber 5；The drive circuit 6 of one modulation laser instrument constitutes oneself of tunable semiconductor laser spectrum
Hybrid gas sensing system；The drive circuit 6 of described laser instrument produces the voltage signal driving semiconductor laser 1,
To obtain laser frequency and the intensity modulation output of semiconductor laser 1, to reach to cover GAS ABSORPTION live width to be measured also
It is obtained in that the purpose of self-mixed interference distance measurement signals.The semiconductor laser of modulation is collected by light and coupling unit
I.e. optical fiber collimator or collimation lens set can shaped laser light beam launch laser, enter gas chamber, by gas to be measured
Body absorbs and is adjusted back in semiconductor laser cavity by the end face reflection of gas chamber.Now certainly mixing in semiconductor laser cavity
Close signal and carry the concentration information of gas to be measured.Described signal processing unit accepts PD (light in semiconductor laser
Electric diode) photoelectric current that produces be converted to voltage signal and process, final output is also shown by reception signal terminal.
Described semiconductor laser includes the semiconductor laser meeting gas absorption spectrum line centre wavelength, as
1653nmDFB semiconductor laser can be as the light source etc. of methane gas detection.
Described gas chamber 5 is the cavity body structure loading gas, and described cavity body structure includes the chamber such as resonance closed
Chamber, calculus chamber etc., described cavity body structure includes that open chamber is as done, any reflecting surface, the air chamber fed back
Room.
Described signal processing unit 3 includes photoelectric current amplification circuit and phase-locked amplifying circuit, or simple amplifying circuit
Combine to obtain corresponding signal etc. with LabVIEW program.
Described signal display terminal 4 is arbitrary display terminal, including computer monitor, mobile telephone display etc..
Survey concentration of methane gas example:
This example uses tunable semiconductor to measure the concentration of methane gas as senser element, selected technology maturation
The DFB semiconductor laser of 1653nm, as sensing light source, sends energy under the driving of the drive circuit of modulation laser instrument
Being absorbed by methane gas, the feedback light being simultaneously reflected back in laser instrument makes laser instrument produce interference signal, and it exports expression formula
It is shown below
I=I0(v,t)[1+nsin(wt)][1+mexp{-2α(v)LeN}cos(2πvτL)] (4)
The first harmonic item of self-mixing interference is from mixed ranging signal, can obtain length Le of gas chamber to be measured,
Interference signal second harmonic term its length relevant to gas concentration N to be measured and air chamber length Le typically the magnitude of 10 meters,
By phase-locked amplify obtain second harmonic signal and combine first harmonic obtain gas chamber's length Le can obtain to be measured
Gas concentration.
Self-mixing GAS ABSORPTION Fundamentals of Sensors as shown in Figure 2, inhaled by gas by Self-mixing GAS ABSORPTION sensor-based system
Receive the semiconductor laser of spectral line and laser is made up of the GAS ABSORPTION chamber reflected.The laser that laser instrument sends is by gas
Absorption chamber is reflected in laser chamber, produces and interferes.The light under feedback-less is without modulation case of semiconductor laser
Strong and frequency is I respectively0And v0, internal modulation electric current is n and v to light intensity and the frequency modulation(PFM) amplitude of laser instrumentf, Le is
The length of air chamber, the optic spectrum line of gas to be measured is α (v), α0Light absorption line intensity, vcAbsworption peak mid frequency,
Δ v Absorption Line half-breadth.The absorption law of self-mixed interference theory and combining Beer-Lambert according to internal modulation obtains laser
Device output intensity I is:
I=I0(v,t)[1+nsin(wt)][1+mexp{-2α(v)LeN}cos(2πvτL)] (1)
V=v0+vfsin(wt) (2)
In formula (1), the intensity modulated Coefficient m of mixing certainly is that ratio is in the constant of feedback intensity, w in working condition one timing
Angular frequency for the electric current of internal modulation.
One standard atmosphere pressure, the collision broadening of infrared spectrum particle plays a major role, and absorption line shape α (v) of gas can
Describe by normalized Lorentz line style,
Formula (1) understands, and the first harmonic item of self-mixing interference is from mixed ranging signal, can obtain gas to be measured
Length Le of fluid chamber, interference signal second harmonic term is relevant to gas concentration N to be measured and air chamber length Le, by lock
Amplify mutually and obtain second harmonic signal and combine gas chamber's length Le that first harmonic obtains that can to obtain gas to be measured dense
Degree.
Length Le of gas chamber to be measured and gas concentration N to be measured is obtained by above formula.Based on tunable semiconductor laser
Compared with the testing the speed with traditional self-mixed interference technology from hybrid gas sensing system of spectrum is tested the speed with traditional interference technique
Having higher sensitivity, structure is compacter.Use self-mixed interference technology to measure technology as detection of gas to be currently
It is suggested first.
Claims (5)
1. based on tunable semiconductor laser from a mixed gas absorption sensor-based system, including semiconductor laser (1)
And cooperation is connected to light collection and coupling unit (2) and gas chamber (5) successively；The rear end face of gas chamber (5) is provided with
Reflecting mirror；It is additionally provided with signal processing unit (3), signal display terminal (4) and the drive circuit (6) of modulation laser instrument；
The drive circuit (6) of described laser instrument produces the voltage signal driving semiconductor laser (1)；That can modulate partly leads
Body laser (1) is collected by light and is launched laser with coupling unit (2), and enters gas chamber (5), by gas
Chamber GAS ABSORPTION to be measured is also reflected readjustment semiconductor laser (1) intracavity by the rear end face of gas chamber (5)；Described
Signal processing unit (3) connects the photoelectric current of PD generation in semiconductor laser (1) and is converted to voltage signal through letter
Number processing unit (3) processes, output to signal display terminal.
The most according to claim 1 based on tunable semiconductor laser from mixed gas its spy of absorption sensor-based system
Levying and be, described semiconductor laser (1) includes the semiconductor laser meeting gas absorption spectrum line centre wavelength.
The most according to claim 1 based on tunable semiconductor laser from mixed gas absorption sensor-based system, its
Feature is, semiconductor laser be 1653nm be DFB semiconductor laser.
The most according to claim 1 based on tunable semiconductor laser from mixed gas absorption its feature of sensor-based system
Being that described gas chamber (5) is the cavity body structure loading gas, described cavity body structure includes resonant cavity or micro-long-pending
Sub-chamber, described cavity body structure includes the chamber of open chamber.
The most according to claim 1 based on tunable semiconductor laser from mixed gas absorption its feature of sensor-based system
It is that described signal processing unit (3) includes that photoelectric current amplification circuit and phase-locked amplifying circuit obtain corresponding signal.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201620287017.4U CN205607853U (en) | 2016-04-07 | 2016-04-07 | Gaseous sensing system that absorbs of self -mixing based on tunable semiconductor laser |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105823755A (en) * | 2016-04-07 | 2016-08-03 | 南京大学 | Self-mixing gas absorption sensing system based on tunable semiconductor laser |
| CN111398215A (en) * | 2020-04-23 | 2020-07-10 | 山东大学 | Portable intermediate infrared high-sensitivity multi-component gas measurement and analysis system and working method thereof |
-
2016
- 2016-04-07 CN CN201620287017.4U patent/CN205607853U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105823755A (en) * | 2016-04-07 | 2016-08-03 | 南京大学 | Self-mixing gas absorption sensing system based on tunable semiconductor laser |
| CN105823755B (en) * | 2016-04-07 | 2019-02-15 | 南京先进激光技术研究院 | It is a kind of that sensor-based system is absorbed from mixed gas based on tunable semiconductor laser |
| CN111398215A (en) * | 2020-04-23 | 2020-07-10 | 山东大学 | Portable intermediate infrared high-sensitivity multi-component gas measurement and analysis system and working method thereof |
| CN111398215B (en) * | 2020-04-23 | 2021-04-16 | 山东大学 | Portable intermediate infrared high-sensitivity multi-component gas measurement and analysis system |
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| C14 | Grant of patent or utility model | ||
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| TR01 | Transfer of patent right |
Effective date of registration: 20180607 Address after: 210038 A building, Longgang science and Technology Park, Heng Yuan Road, Xingang Development Zone, Nanjing, Jiangsu. Patentee after: NANJING INSTITUTE OF ADVANCED LASER TECHNOLOGY Address before: 210093 Hankou Road, Drum Tower District, Nanjing, Jiangsu Province, No. 22 Patentee before: Nanjing University |