CN107271368A - A kind of interior cavity-enhanced photo acoustic spectrum-type trace-gas sensors device - Google Patents
A kind of interior cavity-enhanced photo acoustic spectrum-type trace-gas sensors device Download PDFInfo
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- CN107271368A CN107271368A CN201710369282.6A CN201710369282A CN107271368A CN 107271368 A CN107271368 A CN 107271368A CN 201710369282 A CN201710369282 A CN 201710369282A CN 107271368 A CN107271368 A CN 107271368A
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- G—PHYSICS
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- 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
- G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- 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
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N2021/0106—General arrangement of respective parts
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract
The present embodiments relate to technical field of laser detection, more particularly to a kind of inner chamber strengthens optoacoustic spectroscopy formula trace-gas sensors device, described device includes the semiconductor laser set gradually along direction of beam propagation, chopper, laser alignment focusing system, front cavity mirror, tunable optic filter, gain medium, quartz tuning-fork, Effect of Back-Cavity Mirror；The piezoelectric signal that the quartz tuning-fork is produced is transmitted after amplifying through impedance amplifier to control and data collecting system, resonant frequency of the control with data collecting system for detecting quartz tuning-fork, and the chopper is controlled in real time, and the frequency f for being allowed to modulation is always the resonant frequency f0 of quartz tuning-fork；Computer connects the control and data collecting system, is controlled in real time by upper computer software Labview.The present apparatus can quick detection go out in atmospheric environment to there are a variety of trace gas.
Description
Technical field
The present invention relates to laser detection field, and in particular to a kind of utilization laser is to the detection method of trace gas and sets
It is standby.
Background technology
There are a variety of trace gas, such as methane (CH in atmospheric environment4), ozone (O3), carbon monoxide (CO) etc., concentration
In ppt-ppm magnitudes, although their content is very low, but there is very big influence to environment.Accurately measure these traces
The component of gas, content and its at any time between, the changes in distribution in space, also have for basic science and application technical research non-
Often important meaning.
In Trace gas detection technical research, metering system can be divided into non-spectral method and spectroscopic methodology.Compared to non-spectral method
Measurement means for, spectroscopic methodology has the advantages that high sensitivity, high-resolution, while with the rapid hair of laser spectrum tech
Exhibition and the research progress of laser device so that realize that the detection of trace gas becomes new research and led using laser spectrum tech
Domain.In numerous laser spectral measuring methods, optoacoustic spectroscopy is due to cost is low, detection performance is good and turns into current research
Focus.
The method of the investigative range and detectivity that improve Laser Photoacoustic Spectroscopy Detection Techniques generally includes photoacoustic cell
Two aspects of optimization design and the design of high sensitivity novel sensor.For example, Harren et al. passes through theory analysis and reality
Test research and longitudinal resonance optoacoustic pool structure is optimized design, and complete the detection of C2H2 gases, the spirit of its limit detection
Sensitivity is up to 6ppt.V.Koskinen etc. is completed to CO2 using sonic transducer of the micro-cantilever as optoacoustic spectroscopy detection system
Detection of gas object.What particularly Anatoliy A.Kosterev in the U.S. etc. were used with very high quality factor in 2002
Quartz tuning-fork proposes quartzy enhanced photo acoustic spectrum investigating system, substantially increases system pair first as sonic transducer
The antijamming capability of ambient noise, therefore the very big concern of research worker is received, deep exploratory development has been carried out to this,
And be widely used in various trace materials detections.The above method strengthens device using photoacoustic cell as acoustical signal, is only capable of to quilt
Survey material and carry out contact proximity detection, therefore significantly limit the detection to explosive, poisonous and harmful substance.
Therefore, the device or method researched and developed a kind of high sensitivity and can detected in any environment just become very
It is urgent.
The content of the invention
It is existing to solve the embodiments of the invention provide a kind of interior cavity-enhanced photo acoustic spectrum-type trace-gas sensors device
There is the limited technical problem of transducer sensitivity.
Enhancing optoacoustic spectroscopy formula trace-gas sensors device in a kind of inner chamber provided in an embodiment of the present invention, including along light beam
Semiconductor laser 1 that the direction of propagation is set gradually, chopper 2, laser alignment focusing system 3, front cavity mirror 4, tunable filtering
Device 5, gain medium 6, quartz tuning-fork 7, Effect of Back-Cavity Mirror 8；The semiconductor laser 1 is used for the kind that output wavelength is 940nm
Sub-light；The chopper 2 is to realize the intensity modulated to exporting laser；Two are included in the laser alignment focusing system 3
Non-spherical lens, its focal length is respectively 20-40mm, 30-60mm；The front cavity mirror 4 is high thoroughly, 2.0~2.5 μm high for plating 940nm
The plano-concave mirror of inverse medium film, the curvature of the plano-concave mirror is 100~500mm；The tunable optic filter 5 filters for narrow linewidth
Device, for choosing specific wavelength laser；The gain medium 6 is mixes Bladder stone crystal, and its doping concentration is 1%；It is described
Quartz tuning-fork 7 is placed in the place with a tight waist of laser resonator intracavitary oscillating laser；The laser of the Effect of Back-Cavity Mirror 8 output transmitance is not more than
5%；The a length of 100mm of chamber for the laser resonant cavity that the front cavity mirror 4 is constituted with Effect of Back-Cavity Mirror 8, the light beam of intracavitary oscillating laser is straight
Footpath is less than 300 μm；The piezoelectric signal that the quartz tuning-fork 7 is produced is transmitted after amplifying through impedance amplifier 9 to control to be adopted with data
Collecting system 10, resonant frequency of the control with data collecting system 10 for detecting quartz tuning-fork, and control in real time described
Chopper 2, the frequency f for being allowed to modulation is always the resonant frequency f0 of quartz tuning-fork；Computer 11 connects the control and data
Acquisition system 10, is controlled in real time by upper computer software Labview.
Further, the resonant frequency f0=32.768kHz.
Further, the tunable optic filter is narrow linewidth filter.
Further, the line width of the tunable optic filter is 0.1nm.
Further, the impedance amplifier includes preamplifier and lock-in amplifier, quartz tuning-fork (7) signal
Output end connects the preamplifier, and the lock-in amplifier control is connected with the data collecting system.
Further, the chopper is electrooptic modulator, acousto-optic modulator or magneto-optic modulator.
A kind of method that Trace gas detection is carried out using any of the above-described device provided in an embodiment of the present invention, including it is as follows
Step：Computer settings relevant parameter is inputted to control and data collecting system, and the control is controlled simultaneously with data collecting system
Chopper, tunable optic filter, impedance amplifier；Wherein, the computer controls the impedance amplifier to quartz tuning-fork
Resonant frequency is scanned, and the modulating frequency of the chopper is set according to the result of scanning, controls the chopper
Modulating frequency and the resonant frequency of the quartz tuning-fork be consistent；
Semiconductor laser exports 940nm seed lights, through chopper modulation output to laser alignment focusing system；Its
In, the laser of modulation turns into the laser light of a branch of collimation after first non-spherical lens by the laser alignment focusing system
Beam, then focused on after second non-spherical lens in gain medium；
Gain medium, which absorbs, to be given off the photon of 2.0-2.5 mum wavelengths after seed light and is formed in laser resonance intracavitary
Oscillating laser；By controlling tunable optic filter so that only existing a kind of oscillating laser of wavelength in resonator；
Target acquisition gas is absorbed after the oscillating laser in resonator, and gas locally produces the change of temperature and pressure,
And then form a kind of sound wave；
The quartz tuning-fork is placed in resonator at the beam waist position of oscillating laser, detects the sound wave between prong gap
Signal produces piezoelectric current signal, and the signal is transmitted after impedance amplifier amplification to the control and data acquisition system
System；
The computer obtains related data from the data collecting system, calculates the concentration of target acquisition gas.
Further, the trace gas is CO.
The present invention provides a kind of optoacoustic spectroscopy formula Trace gas detection technology, and gas to be detected is excited using tunable laser
After body, gas Absorption modulation laser energy, the change of temperature and air pressure is locally being produced, and then is forming sound wave, is passing through sound wave
Detecting element detects that the intensity stool and urine of the acoustic signals can be finally inversed by the concentration of trace gas, because tuning fork is placed in resonator beam
At waist, the sensitivity of detection is improved.
Brief description of the drawings
Technical scheme in order to illustrate the embodiments of the present invention more clearly, makes required in being described below to embodiment
Accompanying drawing is briefly introduced, it should be apparent that, drawings in the following description are only some embodiments of the present invention, for this
For the those of ordinary skill in field, without having to pay creative labor, it can also be obtained according to these accompanying drawings
His accompanying drawing.
Fig. 1 is the structural representation of sensor device described in one embodiment of the invention；
Fig. 2 is the flow chart of detection method described in one embodiment of the invention；
Embodiment
In order that the object, technical solutions and advantages of the present invention are clearer, below in conjunction with accompanying drawing the present invention is made into
One step it is described in detail, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole implementation
Example.Based on the embodiment in the present invention, what those of ordinary skill in the art were obtained under the premise of creative work is not made
All other embodiment, belongs to the scope of protection of the invention.
The preferred embodiment that the invention will now be described in detail with reference to the accompanying drawings.
Embodiment 1
In optoacoustic spectroscopy, because the detection limit of sensor is directly proportional to laser power, therefore, tunable laser
The size of device power output is most important for the detection performance of sensor.But at present for tunable laser, its laser
The laser power level exported outside device resonator be mW magnitudes (<50mW), and acoustic detection element is placed in outside resonator, i.e., it is sharp
With the laser energy outside chamber.The laser of this lower power levels causes the detection performance of photoacoustic spectrum sensor to be difficult to further
Lifting, it is impossible to meet the application demand in many fields.
And the power level of laser resonator intracavitary is then much larger than outside resonator, because laser output coupling mirror has
There is certain transmitance, by taking transmitance 5% as an example, then laser power density is 19 times outside chamber in resonator.It is basic based on more than
The fact, the present invention devises a kind of inner chamber enhancing optoacoustic spectroscopy formula trace-gas sensors device, utilizes near-infrared Solid State Laser
Acoustic detection element quartz tuning-fork is placed in the resonator of laser by device as the laser excitation source of whole sensor, i.e., sharp
With the superelevation laser energy of intracavitary.Further, since the laser generation that laser resonator intracavitary is produced repeatedly comes and goes and passes through sound wave
The prong gap of detecting element quartz tuning-fork, i.e., carried out repeatedly exciting to gas molecule, carried out equivalent to acoustic signals many
Secondary superposition, thus acoustic signals intensity is will further improve, significantly improve the trace gas detection limit of sensor.The present invention
Based on solid state laser technology, optoacoustic spectroscopy formula gas sensing techniques are combined with solid state laser technology, proposed a kind of new
The inner chamber enhancing optoacoustic spectroscopy trace-gas sensors technology of type, from truly promotion optoacoustic spectroscopy formula trace gas sensing
The practicalization of device technology.
Specifically, as shown in figure 1, a kind of inner chamber enhancing optoacoustic spectroscopy formula trace gas sensing provided in an embodiment of the present invention
Device device, including the semiconductor laser 1, chopper 2, laser alignment focusing system 3, preceding set gradually along direction of beam propagation
Hysteroscope 4, tunable optic filter 5, gain medium 6, quartz tuning-fork 7, Effect of Back-Cavity Mirror 8；The semiconductor laser 1 is used to export
Wavelength is 808nm, 880nm or 940nm seed light；The chopper 2 is to realize the intensity modulated to exporting laser；It is described
Comprising two non-spherical lenses in laser alignment focusing system 3, its focal length is respectively 20-40mm, 30-60mm；The front cavity mirror 4
For the plano-concave mirror of high saturating, 2.0~2.5 μm high inverse medium film of plating 808nm, 880nm or 940nm, the curvature of the plano-concave mirror is 100
~500mm；The tunable optic filter 5 is narrow linewidth filter, for choosing specific wavelength laser；The gain medium
6 is mix Bladder stone crystal, and its doping concentration is 1%；The quartz tuning-fork 7 is placed in the with a tight waist of laser resonator intracavitary oscillating laser
Place；The laser of the Effect of Back-Cavity Mirror 8 output transmitance is not more than 5%；The laser resonant cavity that the front cavity mirror 4 is constituted with Effect of Back-Cavity Mirror 8
The a length of 100mm of chamber, the beam diameter of intracavitary oscillating laser is less than 300 μm；The piezoelectric signal that the quartz tuning-fork 7 is produced is through resistance
Anti- amplifier 9 is transmitted after amplifying to control and data collecting system 10, and the control is used to detect stone with data collecting system 10
The resonant frequency of English tuning fork, and the chopper 2 is controlled in real time, the frequency f for being allowed to modulation is always the resonance of quartz tuning-fork
Frequency f0；Computer 11 connects the control and data collecting system 10, is controlled in real time by upper computer software Labview
System.
The output wavelength of semiconductor laser 1 that near-infrared solid laser device pumping source in described device is used is 700
~2000nm, particularly, according to laser crystal and doping concentration, can select output wavelength 808nm, 880nm, 940nm, the ripple
Length can effective excitation laser crystal, so as to improve pumping efficiency；Comprising two non-spherical lenses in collimation focusing system 3,
Its focal length is respectively 20-40mm, 30-60mm, preferably 30mm, 50mm；Front cavity mirror 4 for plating 808nm, 880nm or 940nm it is high thoroughly,
The plano-concave mirror of 2.0~2.5 μm high inverse medium film；Gain medium 6 to mix Bladder stone crystal, its doping concentration is 0.6~
1.5%, preferably 1%, 1% doping can be effectively matched with 808nm, 880nm or 940nm, lift pumping efficiency；Effect of Back-Cavity Mirror
8 laser output coupling mirrors, the output of Effect of Back-Cavity Mirror 8 transmitance can not be more than 5%, because transmitance is lower, intracavity power density
Higher, the power of driving source is stronger in optoacoustic spectroscopy, and for example transmitance is 5%, and intracavity power density is 19 times outside chamber；
Transmitance is 2%, and intracavity power density is 49 times outside chamber；Transmitance is 1%, and intracavity power density is 99 times outside chamber.Such as
Fruit selection transmitance is more than 5% Effect of Back-Cavity Mirror, and intracavity power density will be caused seriously to reduce, Effect on Detecting is influenceed.
The Effect of Back-Cavity Mirror 8 of laserresonator front cavity mirror 4 and resonator is plano-concave mirror, and its curvature is 100~500mm, laser
The chamber a length of 80~120mm, preferably 90mm, 100,110mm for the laser resonant cavity that device front cavity mirror 4 is constituted with Effect of Back-Cavity Mirror 8.Especially
It is 100mm, with that can concentrate the optimum length of optical energy, resonator is using the purpose of plano-concave mirror so that intracavitary vibrates
The beam diameter of laser is less than the prong gap width of quartz tuning-fork, and usually 300 μm, therefore, intracavitary oscillating laser is not by chamber
The influence of the quartz tuning-fork of interior insertion.
Chopper 2 is placed in intensity modulated of the output end of semiconductor laser 1 to realize LASER Light Source in sensing system,
Its modulating frequency is f=f0 (f0=32.768kHz is quartz tuning-fork resonant frequency).The modulating frequency of modulator is whole for f0/2's
Several times, the modulation frequency signal of modulator is input into impedance amplifier 9 as reference signal, and the signal of quartz tuning-fork is first
It is input into preamplifier, is then input to again in impedance amplifier 9 in foundation reference signal detection, impedance amplifier 9
Signal be input in computer and carry out data acquisition.Chopper is electrooptic modulator, acousto-optic modulator or magneto-optic modulator.
Tunable optic filter 5 is narrow linewidth filter (line width~0.1nm), and its working range is 2.0-2.5 μm, in system
In be used to choose specific wavelength laser, the absorbing wavelength of correspondence institute probe gas.
It is preferred that, quartz tuning-fork 7 is placed in the focal point of concave mirror, that is, laser resonator intracavitary oscillating laser is with a tight waist
At place, i.e. beam diameter minimum, such intracavitary oscillating laser can repeatedly come and go the prong by quartz tuning-fork without loss in the least
Gap.
The piezoelectric signal that impedance amplifier 9 is used to produce quartz tuning-fork amplifies and extracted, and is subsequently transmitted to control
With data collecting system 10, control can detect the resonant frequency of quartz tuning-fork with data collecting system 10, and control in real time
The frequency that chopper is allowed to modulation is always the resonant frequency of quartz tuning-fork.The impedance amplifier includes preamplifier and lock
Phase amplifier, the signal output part of quartz tuning-fork 7 connects the preamplifier, the lock-in amplifier control and the number
Connected according to acquisition system.
Computer connection control and data collecting system, are controlled in real time by upper computer software such as Labview.
Embodiment 2
In the present invention, target acquisition gas is by taking carbon monoxide (CO) as an example, and the absorbing wavelength of selection is 2.33 μm, will be swashed
Light device resonator is placed in concentration 1000ppm CO-N2 mixed gas, and the semiconductor laser modulated by chopper is poly- by collimation
Burnt system is incided in laser resonant cavity, is controlled tunable optic filter to choose the oscillating laser that wavelength is 2.33 μm, is excited
CO gases produce sound wave, extract the acoustic signals that quartz tuning-fork is detected using impedance amplifier amplification, are arrived according to inverting
The performance of such a inner chamber optoacoustic spectroscopy gas sensor of acoustic signals intensity evaluation, technique effect is excellent.
Realized especially by following steps, as shown in Figure 2：
Computer settings relevant parameter is inputted to control and data collecting system, the control and the same time control of data collecting system
Chopper processed, tunable optic filter, impedance amplifier；Wherein, the computer controls the impedance amplifier to quartz tuning-fork
Resonant frequency be scanned, the modulating frequency of the chopper is set according to the result of scanning, the copped wave is controlled
The modulating frequency of device and the resonant frequency of the quartz tuning-fork are consistent；
Semiconductor laser exports 940nm seed lights, through chopper modulation output to laser alignment focusing system；Its
In, the laser of modulation turns into the laser light of a branch of collimation after first non-spherical lens by the laser alignment focusing system
Beam, then focused on after second non-spherical lens in gain medium；
Gain medium, which absorbs, to be given off the photon of 2.0-2.5 mum wavelengths after seed light and is formed in laser resonance intracavitary
Oscillating laser；By controlling tunable optic filter so that only existing a kind of oscillating laser of wavelength in resonator；
Target acquisition gas is absorbed after the oscillating laser in resonator, and gas locally produces the change of temperature and pressure,
And then form a kind of sound wave；
The quartz tuning-fork is placed in resonator at the beam waist position of oscillating laser, detects the sound wave between prong gap
Signal produces piezoelectric current signal, and the signal is transmitted after impedance amplifier amplification to the control and data acquisition system
System；
The computer obtains related data from the data collecting system, calculates the concentration of target acquisition gas.
The trace gas is CO.
The output wavelength of semiconductor laser 1 that near-infrared solid laser device pumping source in methods described is used is 700
~2000nm, particularly, according to laser crystal and doping concentration, can select output wavelength 808nm, 880nm, 940nm, the ripple
Length can effective excitation laser crystal, so as to improve pumping efficiency；Comprising two non-spherical lenses in collimation focusing system 3,
Its focal length is respectively 20-40mm, 30-60mm, preferably 30mm, 50mm；Front cavity mirror 4 for plating 808nm, 880nm or 940nm it is high thoroughly,
The plano-concave mirror of 2.0~2.5 μm high inverse medium film；Gain medium 6 to mix Bladder stone crystal, its doping concentration is 0.6~
1.5%, preferably 1%, 1% doping can be effectively matched with 808nm, 880nm or 940nm, lift pumping efficiency；Effect of Back-Cavity Mirror
8 laser output coupling mirrors, the output of Effect of Back-Cavity Mirror 8 transmitance can not be more than 5%, because transmitance is lower, intracavity power density
Higher, the driving source in optoacoustic spectroscopy is stronger, and for example transmitance is 5%, and intracavity power density is 19 times outside chamber；Through
Rate is 2%, and intracavity power density is 49 times outside chamber；Transmitance is 1%, and intracavity power density is 99 times outside chamber.If choosing
The Effect of Back-Cavity Mirror that transmitance is more than 5% is selected, intracavity power density will be caused seriously to reduce, Effect on Detecting is influenceed.
The Effect of Back-Cavity Mirror 8 of laserresonator front cavity mirror 4 and resonator is plano-concave mirror, and its curvature is 100~500mm, laser
The chamber a length of 80~120mm, preferably 90mm, 100,110mm for the laser resonant cavity that device front cavity mirror 4 is constituted with Effect of Back-Cavity Mirror 8.Especially
It is 100mm, with that can concentrate the optimum length of optical energy, resonator is using the purpose of plano-concave mirror so that intracavitary vibrates
The beam diameter of laser is less than the prong gap width of quartz tuning-fork, and usually 300 μm, therefore, intracavitary oscillating laser is not by chamber
The influence of the quartz tuning-fork of interior insertion.
Chopper 2 is placed in intensity modulated of the output end of semiconductor laser 1 to realize LASER Light Source in sensing system,
Its modulating frequency is f=f0 (f0=32.768kHz is quartz tuning-fork resonant frequency).The modulating frequency of modulator is whole for f0/2's
Several times, the modulation frequency signal of modulator is input into impedance amplifier 9 as reference signal, and the signal of quartz tuning-fork is first
It is input into preamplifier, is then input to again in impedance amplifier 9 in foundation reference signal detection, impedance amplifier 9
Signal be input in computer and carry out data acquisition.Chopper is electrooptic modulator, acousto-optic modulator or magneto-optic modulator.
Tunable optic filter 5 is narrow linewidth filter (line width~0.1nm), and its working range is 2.0-2.5 μm, in system
In be used to choose specific wavelength laser, the absorbing wavelength of correspondence institute probe gas.
It is preferred that, quartz tuning-fork 7 is placed in the focal point of concave mirror, that is, laser resonator intracavitary oscillating laser is with a tight waist
At place, i.e. beam diameter minimum, such intracavitary oscillating laser can repeatedly come and go the prong by quartz tuning-fork without loss in the least
Gap.
The piezoelectric signal that impedance amplifier 9 is used to produce quartz tuning-fork amplifies and extracted, and is subsequently transmitted to control
With data collecting system 10, control can detect the resonant frequency of quartz tuning-fork with data collecting system 10, and control in real time
The frequency that chopper is allowed to modulation is always the resonant frequency of quartz tuning-fork.The impedance amplifier includes preamplifier and lock
Phase amplifier, the signal output part of quartz tuning-fork 7 connects the preamplifier, the lock-in amplifier control and the number
Connected according to acquisition system.
Computer connection control and data collecting system, are controlled in real time by upper computer software such as Labview.
Device embodiment described above is only schematical, wherein the unit illustrated as separating component can
To be or may not be physically separate.Some or all of module therein can be selected according to the actual needs
Realize the purpose of this embodiment scheme.
Through the above description of the embodiments, those skilled in the art can be understood that each embodiment can
Realized by the mode of software plus required general hardware platform, naturally it is also possible to pass through hardware.Understood based on such, on
The part that technical scheme substantially in other words contributes to prior art is stated to embody in the form of software product, should
Computer software product can be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disc, CD, including some fingers
Order is to cause a computer equipment (can be personal computer, server, or network equipment etc.) to perform each implementation
Method described in some parts of example or embodiment.
Finally it should be noted that：The above embodiments are merely illustrative of the technical solutions of the present invention, rather than its limitations；Although
The present invention is described in detail with reference to the foregoing embodiments, it will be understood by those within the art that：It still may be used
To be modified to the technical scheme described in foregoing embodiments, or equivalent substitution is carried out to which part technical characteristic；
And these modification or replace, do not make appropriate technical solution essence depart from various embodiments of the present invention technical scheme spirit and
Scope.
Claims (8)
1. a kind of inner chamber strengthens optoacoustic spectroscopy formula trace-gas sensors device, it is characterised in that described device is included along light beam
Semiconductor laser (1) that the direction of propagation is set gradually, chopper (2), laser alignment focusing system (3), front cavity mirror (4), can
Tuning filtering device (5), gain medium (6), quartz tuning-fork (7), Effect of Back-Cavity Mirror (8)；
The semiconductor laser (1) is used for the seed light that output wavelength is 940nm；
The chopper (2) is to realize the intensity modulated to exporting laser；
Comprising two non-spherical lenses in the laser alignment focusing system (3), its focal length is respectively 20-40mm, 30-60mm；
The front cavity mirror (4) is plating 940nm high saturating, the plano-concave mirror of 2.0~2.5 μm high inverse medium film, the curvature of the plano-concave mirror
For 100~500mm；
The tunable optic filter (5) is narrow linewidth filter, for choosing specific wavelength laser；
The gain medium (6) is mixes Bladder stone crystal, and its doping concentration is 1%；
The quartz tuning-fork (7) is placed in the place with a tight waist of laser resonator intracavitary oscillating laser；
Effect of Back-Cavity Mirror (8) the laser output transmitance is not more than 5%；
The a length of 100mm of chamber for the laser resonant cavity that the front cavity mirror (4) is constituted with Effect of Back-Cavity Mirror (8), the light of intracavitary oscillating laser
Beam diameter is less than 300 μm；
The piezoelectric signal that the quartz tuning-fork (7) produces is transmitted after amplifying through impedance amplifier (9) to control and data acquisition system
Unite (10), resonant frequency of the control with data collecting system (10) for detecting quartz tuning-fork, and control in real time described
Chopper (2), the frequency f for being allowed to modulation is always the resonant frequency f0 of quartz tuning-fork；Computer (11) connection it is described control with
Data collecting system (10), is controlled in real time by upper computer software Labview.
2. inner chamber strengthens optoacoustic spectroscopy formula trace-gas sensors device according to claim 1, it is characterised in that：It is described common
Vibration frequency f0=32.768kHz.
3. inner chamber strengthens optoacoustic spectroscopy formula trace-gas sensors device according to claim 1, it is characterised in that：It is described can
Tuning filtering device (5) is narrow linewidth filter.
4. inner chamber strengthens optoacoustic spectroscopy formula trace-gas sensors device according to claim 3, it is characterised in that：It is described can
The line width of tuning filtering device (5) is 0.1nm.
5. inner chamber strengthens optoacoustic spectroscopy formula trace-gas sensors device according to claim 1, it is characterised in that：The resistance
Anti- amplifier (9) includes preamplifier and lock-in amplifier, is put before quartz tuning-fork (7) the signal output part connection is described
Big device, the lock-in amplifier control is connected with the data collecting system (10).
6. inner chamber strengthens optoacoustic spectroscopy formula trace-gas sensors device according to claim 1, it is characterised in that：It is described to cut
Ripple device (2) is electrooptic modulator, acousto-optic modulator or magneto-optic modulator.
7. a kind of method that Trace gas detection is carried out according to one of claim 1-6 device, it is characterised in that：
Computer (11) setting relevant parameter is inputted to control and data collecting system (10), the control and data collecting system
(10) while controlling chopper (2), tunable optic filter (5), impedance amplifier (9)；Wherein, computer (11) the control institute
State impedance amplifier (9) to be scanned the resonant frequency of quartz tuning-fork (7), according to the result of scanning to the chopper (2)
Modulating frequency set, control the modulating frequency of the chopper (2) to be kept with the resonant frequency of the quartz tuning-fork (7)
Unanimously；
Semiconductor laser (1) exports 940nm seed lights, through the chopper (2) modulation output to laser alignment focusing system
(3)；Wherein, a branch of collimation is turned into after first non-spherical lens of the laser of modulation by the laser alignment focusing system (3)
Laser beam, then focused on after second non-spherical lens in gain medium；
Gain medium (6), which absorbs, to be given off the photon of 2.0-2.5 mum wavelengths after seed light and is formed in laser resonance intracavitary
Oscillating laser；By controlling tunable optic filter so that only existing a kind of oscillating laser of wavelength in resonator；
Target acquisition gas is absorbed after the oscillating laser in resonator, and gas locally produces the change of temperature and pressure, and then
Form a kind of sound wave；
The quartz tuning-fork (7) is placed in resonator at the beam waist position of oscillating laser, detects the sound wave between prong gap
Signal produces piezoelectric current signal, and the signal is transmitted to the control and data acquisition after the impedance amplifier (9) amplification
System (10)；
The computer (11) obtains related data from the data collecting system (10), calculates the dense of target acquisition gas
Degree.
8. inner chamber strengthens optoacoustic spectroscopy formula trace-gas sensors device according to claim 7, it is characterised in that：The trace
Amount gas is CO.
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