CN106290165A - General frequency strengthens optoacoustic spectroscopy acousimeter and uses the gas detection apparatus of this acousimeter - Google Patents
General frequency strengthens optoacoustic spectroscopy acousimeter and uses the gas detection apparatus of this acousimeter Download PDFInfo
- Publication number
- CN106290165A CN106290165A CN201610810363.0A CN201610810363A CN106290165A CN 106290165 A CN106290165 A CN 106290165A CN 201610810363 A CN201610810363 A CN 201610810363A CN 106290165 A CN106290165 A CN 106290165A
- Authority
- CN
- China
- Prior art keywords
- tuning
- crystal oscillator
- quartz crystal
- fork type
- arm
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- 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
- G01N21/1702—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
Abstract
The present invention devises the single tube coaxial quartz enhanced photoacoustic spectroscopy acousimeter of a kind of general frequency enhancement mode, by Parameters Optimal Design of raising one's arm tuning-fork type quartz crystal oscillator, makes tuning-fork type quartz crystal oscillator have relatively low resonant frequency simultaneouslyfHigher Q-value, and make the first general frequency vibration amplitude of this tuning fork be higher than its fundamental vibration amplitude, so that the general frequency of tuning fork can be applicable to quartz enhanced photoacoustic spectroscopy technology.The general frequency of tuning fork first is far above its fundamental frequency, and when spectrophone operation is under general band mode, the chamber length of resonator cavity is considerably reduced, and beneficially optical alignment reduces spectrophone size.The single tube acoustic resonant cavity that one complete is inserted into the gap of raising one's arm of tuning-fork type quartz crystal oscillator, forms general frequency enhancement mode single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter.The both sides of single tube acoustic resonant cavity have slit, make sound wave by slit promote tuning-fork type quartz crystal oscillator raise one's arm vibration and produce the signal of telecommunication.Improve sound wave coupling efficiency and survey signal to noise ratio.
Description
Technical field
The present invention relates to gas sensing techniques, a kind of general frequency strengthens optoacoustic spectroscopy acousimeter and uses this acousimeter
Gas detection apparatus.
Background technology
Optoacoustic spectroscopy detects spirit as a kind of novel spectrographic detection technology with its zero absorption background, high selectivity, height
The advantages such as sensitivity are widely used in industry-by-industries such as environmental conservation, industrial stokehold, precision agriculture production, medical diagnosiss.
When a branch of laser modulated is through testing sample, if the wavelength of laser matches with the Absorption Line of sample, laser energy
Will be absorbed by the sample, and absorb the sample molecule of light energy by ground state transition to excited state.Instability due to excited state
Property, sample molecule can release energy and by all means to ground state transition.If the outside radiated photons of sample molecule transition
To ground state, it it is now radiation transistion.If sample molecule is sent out by collision de excitation, now for radiationless transition.Optoacoustic spectroscopy is just
Being the one of radiationless transition, the sample molecule being in excited state causes the gas local temperature of surrounding periodically by collision
Change, and then produce the transmission of pressure wave direction surrounding, this pressure wave is sound wave.Detect acoustic pressure by acoustic wave transducer and incite somebody to action
It is converted into the concentration of the signal of telecommunication just energy inverting testing sample, here it is optoacoustic spectroscopy is for the principle of gas detecting.
In traditional optoacoustic spectroscopy, acoustic wave transducer is highly sensitive mike, its shortcoming be the responsive bandwidth of mike very
Wide so that the environment noise in addition to forgiving gas concentration information is easily brought in detection system.U.S.'s Lay in 2002
The laser science group of this university has developed a kind of novel optoacoustic spectroscopy and has been called quartz enhanced photoacoustic spectroscopy technology, and this technology is adopted
By commercial natural frequency it is～the tuning-fork type quartz crystal oscillator (abbreviation tuning fork) of 32kHz replaces broadband microphone, serve as
Acoustic wave transducer.In quartz enhanced photoacoustic spectroscopy device, laser is focused the gap of raising one's arm by tuning-fork type quartz crystal oscillator, when treating
After test sample product absorb laser energy and produce sound wave, raising one's arm by after acoustic wave excitation of tuning-fork type quartz crystal oscillator, raising one's arm can be reciprocal
Vibration.When two of this tuning-fork type quartz crystal oscillator raise one's arm and promoted by sound wave, tuning-fork type quartz crystal oscillator is by piezoelectric effect,
Vibration is converted into output electric current, then with preamplifier by current draw out, then is finally inversed by institute by signal post-processing
The gas concentration information needed.Tuning-fork type quartz crystal oscillator has three advantages: first, and it only has near fixing frequency～32kHz
Response, the response to the sound of other frequency range is faint, and this creates sensor based on tuning-fork type quartz crystal oscillator the highest ring
Border noise immunity ability；Second, it has high Q-value, and high q-factor means higher signal peak in optoacoustic spectroscopy
Value, is beneficial to improve signal to noise ratio；3rd, tuning-fork type quartz crystal oscillator only (is raised one's arm on the contrary for two of tuning fork at symmetric oscillation mode
Direction move reciprocatingly) under could produce electric current, and two are raised one's arm and are not produced electric current when doing motion in the same direction, and therefore this more enters one
Step reduces from the noise jamming outside tuning fork.
Traditional quartz enhanced photoacoustic spectroscopy acousimeter uses commercial natural frequency to be 32kHz, and gap of raising one's arm is about 300
The tuning fork quartz crystal oscillator of μm.In order to improve tuning-fork type quartz crystal oscillator detectivity, acoustic resonant cavity (AmR) is configured to tuning fork
Limit sound wave on formula quartz crystal oscillator and form resonant check effect.The entirety being made up of tuning fork and acoustic resonant cavity is referred to as spectrum
Acousimeter.Typical spectrophone configuration uses two stainless steel capillaries to be vertically mounted on tuning-fork type quartz as resonator cavity
The both sides of crystal oscillator limit sound wave.Scientific research result shows, the performance of spectrophone is had important by the length of acoustic resonant cavity
Impact, optimal acoustic resonance cavity length is between λ and λ/2, and wherein λ is wave length of sound.For commercial 32kHz sound
Fork, frequency of sound wave is 32kHz, and corresponding optimum resonance chamber length is about 9mm.Quartz enhanced photoacoustic spectroscopy device must be examined
Consider a bit, the chamber length of resonator cavity can bring beam collimation problem, light beam to contact with tuning fork and any of resonator cavity surface
The strongest background noise can be produced, thus affect detection signal to noise ratio.
Quartz enhanced photoacoustic spectroscopy acousimeter based on commercial 32kHz is good near infrared region performance, and wherein distribution is anti-
The preferable light sources of beam quality such as feedback formula DFB semiconductor laser and external cavity tunable laser diode are often used as exciting
Light source.But, when the angle of divergence of excitation source is compared with big or beam quality is poor, for example with LED or mid-infrared quantum stage
When during connection laser instrument, the light source such as (QCL) is as the driving source of photoacoustic signal, exciting light is difficult to collimate 300 μ by 32kHz tuning fork
M raises one's arm gap, because the strongest background noise can be produced.Meanwhile, 32kHz commercialization tuning fork is not applied for Terahertz (THz) light
Source, because the wavelength of Terahertz is the highest than 2 orders of magnitude of near-infrared wavelength, its minimum beam diameter is usually 400-500 μm.
Limiting to release the gap of raising one's arm of 32kHz commercialization tuning fork, scientific research personnel devises the customization that gap is 700-1000 μm of raising one's arm
Big tuning fork.Italy photon and nanotechnology research professor Borri to take the lead in devising resonant frequency be 4.2kHz, between raising one's arm
Gap is the customization tuning fork of 1mm, and this tuning fork combines thz laser device to detect methanol.But frequency is the sound wave of 4.2kHz
Corresponding wavelength is up to 81mm, and the longest wave length of sound result in excitation beam and cannot collimate by acoustic resonant cavity, thus
Limit detectivity.It is 7.2kHz that professor Dong Lei of University Of Shanxi's laser spectrum institute devises a kind of resonant frequency,
Gap of raising one's arm is about the customization tuning fork of 800 μm.In spectrophone based on this 7.2kHz customization tuning fork, two internal diameters are
The stainless steel capillary of 1.3mm is configured to customize the both sides of tuning fork to improve sound wave coupling efficiency respectively.Compared to not joining
The tuning fork of standby acoustic resonator, it is thus achieved that the snr gain factor of 40 times.Even so, frequency is the sound wave correspondence of 7.2kHz
Wavelength be still up to 46mm, this assembles for exciting light beam collimation and spectrophone is all the biggest challenge.Recently
Research in, the single tube coaxial configuration quartz enhanced photoacoustic spectroscopy of a kind of novelty is suggested, by improve resonator cavity sound wave couple
Efficiency strengthens detectivity and shortens the chamber length of resonator cavity to solve beam collimation problem.Due to 7.2kHz customization tuning fork
Gap of raising one's arm has reached 800 μm, and an external diameter is inserted into tuning fork less than the stainless steel capillary of 800 μm and raises one's arm by this conditions permit
Gap is as acoustic resonant cavity, thus avoids the configuration mode placing two stainless steel capillaries in the both sides of tuning fork respectively.
Sound wave accumulates in this single tube configures, and defines quasi stationary wave, thus optimization chamber length is foreshortened to 38mm and by resonance
The snr gain factor in chamber brings up to 100.But the optimum chamber length of 38mm is still than resonator cavity based on 32kHz commercialization tuning fork
Long about 4 times.
Therefore when using quartz enhanced photoacoustic spectroscopy acousimeter based on the big tuning fork of customization, at single tube coaxial configuration quartz
Shorten the length of acoustic resonant cavity on the basis of strengthening optoacoustic spectroscopy the most further, make it easy to optical alignment, and improve humorous
The sound wave coupling efficiency between chamber and tuning fork that shakes has become and have to solve the technical problem that.
Tuning-fork type quartz crystal oscillator includes that be fixed together by bottom, be spaced necessarily and be vertically arranged is raised one's arm a pair, two
Relative one side of raising one's arm is referred to as medial surface, and the one side relative with medial surface is referred to as lateral surface；The normal direction of inside and outside side with shake
Dynamic direction is parallel；Upper two vertical planes vertical with direction of vibration of raising one's arm are referred to as the face of raising one's arm.
Summary of the invention
The present invention solves that in current single tube coaxial quartz enhanced photoacoustic spectroscopy acousimeter, acoustic resonance cavity length is long, difficult
To carry out the technical problem of optical alignment, it is provided that a kind of general frequency strengthens optoacoustic spectroscopy acousimeter and uses the gas of this acousimeter to visit
Survey device.
General frequency of the present invention strengthens optoacoustic spectroscopy acousimeter and adopts the following technical scheme that realization: a kind of general frequency increases
Strong optoacoustic spectroscopy acousimeter, including fundamental frequency be 2.8kHz, the first general frequent rate be 17.7kHz tuning-fork type quartz crystal oscillator with
And use the resonator cavity of single tube coaxial manner configuration with tuning-fork type quartz crystal oscillator；First pin ground connection of tuning-fork type quartz crystal oscillator,
Second pin output photoacoustic signal；The gap g that raises one's arm of described tuning-fork type quartz crystal oscillator is 700 μm, and the long L that raises one's arm is 17mm, thickness T
It is 0.25mm for 1mm, interdigital width w；Described resonator cavity use stainless steel capillary make, the internal diameter of this stainless steel capillary and
External diameter is respectively 0.62mm and 0.98mm；The middle part external diameter of described resonator cavity is polished to 650 μm, and resonator cavity is inserted into tuning fork
The position being polished between two of formula quartz crystal oscillator raise one's arm and in the middle part of resonator cavity is positioned at the gap of raising one's arm of tuning-fork type quartz crystal oscillator
Place；The axis of resonator cavity is vertical with the face of raising one's arm of tuning-fork type quartz crystal oscillator, and in the middle part of resonator cavity, the both sides place of being polished respectively has opened one
Width is 90 μm, the slit of a length of 200 μm；A length of 9.5mm～19mm of described resonator cavity, the axle center of resonator cavity and tuning fork
Formula quartz crystal oscillator raise one's arm bottom vertical interval h be 7mm.
The fundamental frequency of the commercial tuning-fork type quartz crystal oscillator of the most conventional 32kHz is 32768Hz, its first general frequency band >
200kHz, and Oscillation Amplitude is the most weak, so being rarely employed in quartz enhanced photoacoustic spectroscopy based on 32kHz commercialization tuning fork
The general frequency band of tuning fork.When using the tuning-fork type quartz crystal oscillator of customization, by reducing the base of design customization tuning-fork type quartz crystal oscillator
Again and again rate thus reduce its general frequent rate, effectively the general frequency vibration of customization tuning-fork type quartz crystal oscillator can be used for quartz enhancing
In optoacoustic spectroscopy.The more important thing is, by optimizing the parameter of raising one's arm of design customization tuning fork, customization tuning-fork type quartz crystal oscillator can be made
General frequency band Oscillation Amplitude more than fundamental vibration amplitude, thus beneficially enhancing signal.
General frequency of the present invention strengthens optoacoustic spectroscopy acousimeter (general frequency enhancement mode single tube coaxial configuration quartz enhanced photoacoustic
Spectrophone) have employed a fundamental frequency be 2.8kHz, the first general frequent rate be the tuning-fork type quartz crystal oscillator of 17.7kHz
(customization tuning fork) and the coaxial configuration of single tube.The schematic diagram of tuning-fork type quartz crystal oscillator as shown in Figure 1, 2, shaking of tuning-fork type quartz crystal oscillator
Arm gap g is about 700 μm, and the long L that raises one's arm is 17mm, and thickness T is 1mm, and interdigital width w is 0.25mm.According to formulaWherein E is the Young's modulus of quartz, and ρ is quartz density.As n=1.194, obtain is tuning fork
Fundamental frequency f0；Obtain as n=2.988 is the first general frequent rate f1.The resonant frequency f of tuning-fork type quartz crystal oscillator and Q-value
Can be recorded by following experimental technique: functional generator produces the sine wave that amplitude is fixed, frequency changes, by defeated for this sine wave
Enter on a pin of tuning-fork type quartz crystal oscillator, and be linked into lock-in amplifier from the signal of another pin of tuning fork output
Input.Change the frequency that functional generator is sinusoidal wave, be allowed to the resonant frequency of scanned tuning fork, lock-in amplifier record sound
The output voltage of fork corresponding frequencies, obtains the frequency response curve of tuning fork.By permissible to the matching of fork frequency response curve
The fundamental vibration parameter obtaining tuning fork is f0=2.868kHz, Q0=5800, R0=721k Ω, the first general frequency band vibration parameters is
f1=17.741kHz, Q1=12553, R1=162k Ω.
Two main loss mechanisms external losses and internal loss, determine tuning fork Q-value size.External losses is
Owing to tuning fork is raised one's arm the interaction with surrounding medium.Internal loss includes supporting loss, surface loss, volume loss and thermoelastic
Loss.The fundamental vibration of tuning fork can be counted as a single-point oscillator at tuning fork top, supports that loss can be left in the basket, so
The Q-value of tuning fork can represent～wT/L with the geometric parameter of tuning fork；And in the first general frequency vibration of tuning fork, tuning fork Q-value base
This, by supporting that loss determines, is proportional to (1/n2)(L/T)3.Being raised one's arm Parameters Optimal Design by tuning fork, increasing L/T value can reduce
The support loss of tuning fork root, so that general frequency band obtains than Base Band the Q-value of big 2 times.Tuning-fork type described herein quartz
The resonator cavity that crystal oscillator is equipped with is made up of a complete stainless steel capillary, and internal diameter and the external diameter of this capillary tube are respectively 0.62mm
And 0.98mm.This single tube resonator cavity is inserted between tuning fork two is raised one's arm and forms single tube coaxial configuration quartz enhanced photoacoustic spectroscopy
Acousimeter, schematic diagram is as shown in Figure 3.The middle part (waist thickness) of resonator cavity is polished to 650 μm, makes resonator cavity
External diameter is less than the gap of raising one's arm of tuning fork, as shown in Figure 4,5.In the middle part of resonator cavity, a width has respectively been opened in both sides is 90 μm, a length of
The slit of 200 μm, sound wave is delivered to, by this slit, the inner side that tuning fork is raised one's arm, thus promotes tuning fork vibration to export the signal of telecommunication.
Gas detection apparatus of the present invention adopts the following technical scheme that realization: a kind of gas detection apparatus, bag
Including a functional generator, the modulated signal outfan of functional generator connects has Laser Drive plate, Laser Drive plate to drive
A dynamic Distributed Feedback Laser；The emitting light path of described Distributed Feedback Laser is provided with battery of lens；Also include that is positioned at going out of battery of lens
Penetrate the spectrum in light path and survey acoustic device；Described spectrum is surveyed acoustic device and is included a miniature gas cell and be located within miniature gas cell
General frequency strengthens optoacoustic spectroscopy acousimeter；First pin of described tuning-fork type quartz crystal oscillator is connected to ground wire；Tuning-fork type quartz crystal oscillator
The second pin by preamplifier connect have a lock-in amplifier；Also include computer；The signal of lock-in amplifier is defeated
Go out end to be connected with a signal input part of computer；The synchronous signal output end of described functional generator and lock-in amplifier
Synchronous signal input end be connected.
Gas detection apparatus based on general frequency enhancing optoacoustic spectroscopy acousimeter of the present invention is as shown in Figure 6.Middle cardiac wave
The single mode CW distributed feedback type semiconductor laser (DFB) of a length of 1.37 μm is used as excitation source to produce optoacoustic letter
Number.Functional generator produces low frequency sawtooth and is input to the wavelength of scan laser in Laser Drive.On this sawtooth waveforms
One frequency of superposition is the sinusoidal signal of f/2, and wherein f is fundamental frequency or the first general frequent rate of the used tuning fork of acousimeter.Swash
The output light of light device is collimated by fiber coupler and is passed through spectrophone.The piezoelectric signal of spectrophone output is first
Being processed by a homemade transimpedance preamplifier, the feedback resistance in amplifier is about 10M Ω.Preamplifier output
Signal is imported in lock-in amplifier and is modulated demodulation, and the time constant of lock-in amplifier is set to 1s, and filtering bandwidth is
12dB/octave, corresponding lock-in amplifier detective bandwidth is Δ f=0.25Hz.One computer quilt equipped with data collecting card
It is used for gathering and recording data.Vapor in the atmosphere is selected as testing sample to assess the performance of this acousimeter.According to
HITRAN data base, water 7303.23cm-1Absorption Line be selected as target absorption line, its line is by force 8.05 × 10-22cm/mol.Empty
Water content in gas is measured in real time by direct absorption spectrum and is determined.
Customization tuning fork the most described herein is used, respectively, to detection under fundamental vibration pattern and general frequency vibration pattern
Water vapour content in air.Laser fiber collimator is installed in the work scanning exciting light on an XYZ D translation platform
Use position.As shown in Figure 4,5, laser action position is scanned to top open part, the position of laser action along Z axis from tuning fork root
The distance of tuning fork root (bottom of namely raising one's arm) relatively is designated as h, sees that Fig. 1, corresponding tuning fork detectable signal are recorded.Through water
After vapour concentration normalization, the output signal of tuning fork is shown in the figure 7 as the function of h.When tuning fork is operated in fundamental vibration
Time under pattern, the position of its detectable signal maximum is h=15mm rather than the tuning fork top of moment maximum.This is due to column
Sound wave is easily revealed from tuning fork top, to causing the sound wave cannot the 100% effective and result of tuning fork effect.Starting stage signal
Slight rising is owing to laser beam distance tuning fork root is relatively near, creates photo-thermal effect.When tuning fork operates at general frequency vibration dynamic model
Time under formula, detectable signal creates two nodes respectively at h=7.5mm and h=16mm, and the spy obtained at h=7.5mm
Survey signal amplitude big 2 times than at h=16mm.Compared to fundamental vibration pattern, this customization tuning fork operates at the first general frequency vibration dynamic model
Big 8 times of the signal amplitude obtained under formula.This experiment test is operated in fundamental vibration and general frequency vibration, laser corresponding to tuning fork
The optimal modulation degree of depth be respectively 0.35cm-1And 0.44cm-1。
When being equipped with acoustic resonant cavity to tuning fork, in general frequency enhancing optoacoustic spectroscopy acousimeter, acoustic resonant cavity installation is vertical
The position amplitude important to detectable signal.The installation that applicant utilizes 3D printer to print one group of differing heights is propped up
Frame, can be installed acoustic resonant cavity at various height on h by support, and h is as shown in Figure 1.For customizing the fundamental frequency of tuning fork
Frequency of vibration and the first general frequency vibration frequency are respectively 2.8kHz and 17.7kHz, and corresponding wave length of sound is 120mm and 19mm.
120mm is difficult to collimate for micro acoustic resonator cavity, and the most traditional fundamental frequency operation pattern is not suitable for based on fixed
The coaxial configuration of tuning fork single tube processed.In the present invention, applicant will be in conjunction with general frequency vibration pattern and the coaxial quartz enhanced photoacoustic spectroscopy of single tube
Acousimeter be referred to as general frequency enhancement mode single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter.Studying general frequency enhancement mode single tube
In coaxial configuration quartz enhanced photoacoustic spectroscopy spectrophone during the problem of h and acousimeter signal amplitude, the length quilt of resonator cavity
It is set to sound wave half-wavelength, i.e. 9.5mm.Vertical installation position h of resonator cavity is to the amplitude of spectrophone detectable signal and Q-value
Impact be drawn in Fig. 8.Being similar to be not added with the tuning fork of resonator cavity, operation single tube under general frequency pattern coaxial configuration quartz increases
There is maximum respectively at h=7mm and 16.5mm in the detectable signal amplitude that strong optoacoustic spectroscopy acousimeter obtains, the most corresponding position
Put single tube coaxial configuration quartz enhanced photoacoustic spectroscopy spectrophone Q-value and minimum occurs, indicate at h=7mm and 16.5mm
The coupling efficiency of acoustic resonant cavity and tuning fork is the highest.Result shows when Resonant Intake System is 9.5mm, when right angle setting height is 7mm,
Compared to the customization tuning fork in resonance free chamber, the amplitude of detectable signal is carried by single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter
High about 10 times.
The length of resonator cavity important in spectrophone, it is considered to opening in the middle part of resonator cavity and standing wave
Formation condition, experimentally optimum Resonant Intake System is between λ and λ/2.At research Resonant Intake System to general frequency enhancement mode single tube altogether
When axle configures the performance impact of quartz enhanced photoacoustic spectroscopy spectrophone, the right angle setting height of resonator cavity is fixed on h=
7mm, the length of resonator cavity changes to 9.5mm (λ) from 19mm (λ).Fig. 9 illustrates cavity length and general frequency enhancement mode single tube is total to
The relation of axle configuration quartz enhanced photoacoustic spectroscopy detectable signal amplitude, wherein data point is by Lorentz fit.Work as cavity length
During for 14.5mm, the signal amplitude of general frequency enhancement mode single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter obtains maximum
4.6mV.This amplitude single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter signal amplitude compared to a length of 9.5mm in chamber improves
5 times, improve about 50 times compared to the customization tuning fork without acoustic resonant cavity.
(h=7mm, chamber is long for the general frequency enhancement mode single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter of parameter optimum
14.5mm) it is drawn in Figure 10 with the resonance free chamber operation second harmonic signal customizing tuning fork acquisition under fundamental frequency model.General
Frequently the signal amplitude that enhancement mode single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter obtains is 4.6mV, about resonance free
380 times of chamber tuning fork signal amplitude.By the wavelength of tuned laser, make the target absorption of the wavelength departure steam of exciting light
Line, can obtain 1 σ noise of spectrophone.For general frequency enhancement mode single tube coaxial configuration quartz enhanced photoacoustic spectroscopy survey sound
The customization tuning fork σ noise in device and resonance free chamber is respectively 2 μ V and 1.6 μ V.Using this general frequency enhancement mode single tube coaxial configuration stone
When water vapor in air is measured by English enhancing optoacoustic spectroscopy acousimeter, the Output optical power of laser instrument used is 23mW,
Detection signal to noise ratio is 2300, and the normalization equivalent noise absorptance obtained is
When trace gas is detected, the first selected target acquisition line close with the centre wavelength of light source.Swashed by DFB
The temperature control circuit locked laser temperature of light device, by controlling driving electric current, makes the wavelength inswept target absorption line of laser instrument.Tool
Body is to use second harmonic detection technology, the f that the electric current of laser instrument is occurred by functional generator1/ 2 signal frequency modulation, its
Middle f1The first general frequency for tuning fork used.Gas to be measured is by after laser excitation, and de excitation sends out the acoustic signals of generation by the first general frequency
For f1Tuning-fork type quartz crystal oscillator collection and be translated into the corresponding signal of telecommunication.The signal of telecommunication sequentially passes through preamplifier, lock
Put, then enter computer system by data collecting card.Data are after computed in software, and gas concentration information is with people the most at last
Machine interactive interface shows on screen.Described corresponding software is the known technology of those skilled in the art, is easy to write
's.When measuring certain gas, should be calibrated by the Standard Gases of concentration known in advance, calibrated device just can be right
This kind of gas measures.The technology that described scaling method is known to those skilled in the art, preamplifier used,
Lock-in amplifier is the common instrument of this area, has Multiple Type available, and described Distributed Feedback Laser is according to gas to be measured
Wavelength can conveniently purchase.
The invention has the beneficial effects as follows: one, devise the coaxial quartz enhanced photoacoustic spectroscopy of single tube of a kind of general frequency enhancement mode
Acousimeter, by Parameters Optimal Design of raising one's arm tuning-fork type quartz crystal oscillator, makes tuning-fork type quartz crystal oscillator have relatively low simultaneously
Resonant frequency f and higher Q-value, and make the first general frequency vibration amplitude of this tuning fork be higher than its fundamental vibration amplitude, so that sound
Pitch general frequency and can be applicable to quartz enhanced photoacoustic spectroscopy technology.Two, the general frequency of tuning fork first is far above its fundamental frequency, when spectrum is surveyed
When the operation of sound device is under general band mode, the chamber length of resonator cavity is considerably reduced, and beneficially optical alignment reduces spectrophone
Size.Three, the single tube acoustic resonant cavity that complete is inserted into the gap of raising one's arm of tuning-fork type quartz crystal oscillator, forms general frequency and strengthen
Type single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter.The both sides of single tube acoustic resonant cavity have slit, make sound wave pass through
Slit promotes raising one's arm of tuning-fork type quartz crystal oscillator to vibrate and produce the signal of telecommunication.The coaxial configuration of this single tube is greatly improved sound wave coupling
Close efficiency, improve detection signal to noise ratio.
Accompanying drawing explanation
Fig. 1 is tuning-fork type quartz crystal oscillator main TV structure schematic diagram.
Fig. 2 is tuning-fork type quartz crystal oscillator side-looking structural representation.
Fig. 3 is general frequency enhancement mode single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter perspective view.
Fig. 4 is the side-looking structural representation of the coaxial resonator cavity of single tube.
Fig. 5 is the plan structure schematic diagram of the coaxial resonator cavity of single tube.
Fig. 6 is Experimental equipment based on general frequency enhancement mode single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter:
1-functional generator, 2-Laser Drive plate, 3-DFB laser instrument, 4-battery of lens, 5-spectrum survey acoustic device, 51-enters
Penetrate window, 52-exit window, 53-air inlet, 54-gas outlet, the general frequency of 55-strengthens optoacoustic spectroscopy acousimeter, 56-miniature gas cell,
6-energy meter, 7-mechanical pump, 8-gas flow control valve, 9-piezometer, 10-filter element, 11-ground wire, 12-the first pin, 13-
Two pins, 14-preamplifier, 15-lock-in amplifier, 16-computer.
Fig. 7 is operated under fundamental vibration pattern (a) and general frequency vibration pattern (b) for customization tuning fork, laser action position with
The relation of tuning fork signal amplitude.
Fig. 8 is the different vertical installation of resonator cavity in general frequency enhancement mode single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter
Highly h is on acousimeter signal amplitude and the impact of Q-value；A () is the impact on signal amplitude, (b) is the shadow to acousimeter Q-value
Ring.
Fig. 9 be general frequency enhancement mode single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter signal amplitude along with acoustics humorous
The schematic diagram of chamber (AmR) length of shaking change.
Figure 10 is the second harmonic signal that general frequency enhancement mode single tube coaxial configuration quartz enhanced photoacoustic spectroscopy acousimeter obtains
Second harmonic signal contrast is obtained with the tuning fork in resonance free chamber.
Detailed description of the invention
A kind of general frequency strengthens optoacoustic spectroscopy acousimeter, including fundamental frequency be 2.8kHz, the first general frequent rate be 17.7kHz
Tuning-fork type quartz crystal oscillator and with tuning-fork type quartz crystal oscillator use single tube coaxial manner configuration resonator cavity；Tuning-fork type quartz-crystal
The first pin 12 ground connection shaken, the second pin 13 exports photoacoustic signal；The gap g that raises one's arm of described tuning-fork type quartz crystal oscillator is 700 μ
M, the long L that raises one's arm are 17mm, and thickness T is 1mm, and interdigital width w is 0.25mm；Described resonator cavity uses stainless steel capillary to make,
Internal diameter and the external diameter of this stainless steel capillary are respectively 0.62mm and 0.98mm；The middle part external diameter of described resonator cavity is polished to
650 μm, resonator cavity be inserted into two of tuning-fork type quartz crystal oscillator raise one's arm between and resonator cavity in the middle part of the position that is polished be positioned at
The gap location of raising one's arm of tuning-fork type quartz crystal oscillator；The axis of resonator cavity is vertical, in resonator cavity with the face of raising one's arm of tuning-fork type quartz crystal oscillator
It is 90 μm that both sides, the portion place of being polished respectively has opened a width, the slit of a length of 200 μm；The a length of 9.5mm of described resonator cavity
～19mm, raise one's arm vertical interval h of bottom of the axle center of resonator cavity and tuning-fork type quartz crystal oscillator is 7mm.
The a length of 14.5mm of described resonator cavity.
A kind of gas detection apparatus, including a functional generator 1, the modulated signal outfan of functional generator 1 connects
Laser Drive plate 2, Laser Drive plate 2 is had to drive a Distributed Feedback Laser 3；Set on the emitting light path of described Distributed Feedback Laser 3
There is battery of lens 4；Also include that the spectrum on an emitting light path being positioned at battery of lens 4 surveys acoustic device 5；Described spectrum surveys acoustic device 5
Including a miniature gas cell 56 and be located at general frequency within miniature gas cell 56 and strengthen optoacoustic spectroscopy acousimeter 55；Described tuning-fork type
First pin 12 of quartz crystal oscillator is connected to ground wire 11；Second pin 13 of tuning-fork type quartz crystal oscillator is by preamplifier 14 even
It is connected to a lock-in amplifier 15；Also include computer 16；The signal output part of lock-in amplifier 15 and computer letter
Number input is connected；The synchronous signal output end of described functional generator 1 and the synchronous signal input end of lock-in amplifier 15
It is connected.
The emitting light path of described miniature gas cell 56 is provided with energy meter 6, the signal output part of energy meter 6 and computer 16
Another signal input part is connected.Energy meter 6 is placed at the exit window of spectrum survey acoustic device and detects emergent light
Power.
When certain gas is measured, by this kind of gas of concentration known, measurement apparatus is demarcated in advance,
This kind of gas just can be measured by calibrated device.
One modulating frequency of functional generator 1 is f1Sine wave deliver on Laser Drive plate 2, Laser Drive plate
2 can regulate injection current and the temperature controlling Distributed Feedback Laser 3.The corresponding gas to be measured of the emission center wavelength of Distributed Feedback Laser 3
Target absorption line.The light that Distributed Feedback Laser 3 sends enters spectrum after battery of lens 4 carries out optical shaping and surveys acoustic device 5.Its
Detailed process is, collimated beam initially passes through by CaF2The incidence window 51 made, subsequently into QEPAS sensory package.Used
QEPAS sensory package is that general frequency strengthens optoacoustic spectroscopy acousimeter 55 (quartz enhancing light based on the enhancing coaxial configuration of single tube of general frequency
Sound spectrophone), as shown in Figure 3.Gone out by the exit window 52 of miniature gas cell 56 by the light beam of QEPAS sensory package outgoing
Penetrating, wherein incidence window 51 and the exit window 52 of miniature gas cell 56 tilts to install to avoid interference with phenomenon with the angle of about 5 °
Occur.By the light ingoing power meter 6 of exit window 52 outgoing, it is carried out power detection.Miniature gas cell 56 has an air inlet
53 and gas outlet 54 can ensure that gas to be measured can smooth and easy entrance miniature gas cell 56, during measurement, gas is at miniature gas cell 56
Interior uniformly mixing.Gas outlet 54 is connected with the mechanical pump 7 of gas flow control valve 8 with one, and air inlet 53 is sequentially and pressure
Meter 9 is connected with filter element 10.When mechanical pump 7 works, ambient atmos is inhaled into miniature gas cell 56 after going the removal of impurity by filter element 10,
The pressure of whole gas circuit is measured by piezometer 9, and gas flow rate is controlled by gas flow control valve 8.Sent by Distributed Feedback Laser 3
Excitation gas to be measured produces sound wave, and sound wave promotes tuning fork vibration and then produces the signal of telecommunication and exported by the second pin 13.
The signal of telecommunication first step carries out signal amplification and process through preamplifier 14, is then fed into lock-in amplifier 15 and carries out secondary
Harmonic wave demodulates.The reference signal of lock-in amplifier demodulation is from the synchronous port of functional generator 1.The signal of demodulation is put through lock
Sending into computer 16, computer 16 gathers and records data.
Two raise one's arm between space be referred to as gap of raising one's arm；The spacing in face of front and back raising one's arm is that raising one's arm of raising one's arm is long to be referred to raise one's arm
Bottom is to the spacing at top, and thickness of raising one's arm refers to each spacing raised one's arm on vibration-direction；Raise one's arm width (the most interdigital width
Degree) refer to each former and later two spacing raising one's arm between face of raising one's arm.
When specifically applying, apparatus of the present invention can with real-time online by the gas concentration to be measured surveyed and show at computer
On, have that high accuracy, portability be strong, the function of on-line monitoring.
Claims (4)
1. a general frequency strengthens optoacoustic spectroscopy acousimeter, it is characterised in that include fundamental frequency be 2.8 kHz, first general again and again
Rate is the tuning-fork type quartz crystal oscillator of 17.7 kHz and uses the resonator cavity of single tube coaxial manner configuration with tuning-fork type quartz crystal oscillator；
First pin (12) ground connection of tuning-fork type quartz crystal oscillator, the second pin (13) output photoacoustic signal；Described tuning-fork type quartz crystal oscillator
Gap of raising one's armgIt is 700 m, length of raising one's armLFor 17mm, thicknessTIt is 1 mm, interdigital widthwIt is 0.25 mm；Described resonator cavity is adopted
Making with stainless steel capillary, the internal diameter of this stainless steel capillary and external diameter are respectively 0.62 mm and 0.98 mm；Described resonance
The middle part external diameter in chamber is polished to 650 m, resonator cavity be inserted into two of tuning-fork type quartz crystal oscillator raise one's arm between and resonator cavity
The position that middle part is polished is positioned at the gap location of raising one's arm of tuning-fork type quartz crystal oscillator；The axis of resonator cavity and tuning-fork type quartz crystal oscillator
Face of raising one's arm is vertical, and in the middle part of resonator cavity, the both sides place of being polished respectively has opened a width is 90 m, the slit of a length of 200 m；Institute
Stating a length of 9.5 mm ~ 19mm of resonator cavity, the axle center of resonator cavity and tuning-fork type quartz crystal oscillator are raised one's arm the vertical interval of bottomh
For 7mm.
General frequency the most as claimed in claim 1 strengthens optoacoustic spectroscopy acousimeter, it is characterised in that described resonator cavity a length of
14.5mm。
3. a gas detection apparatus, including a functional generator (1), the modulated signal outfan of functional generator (1) is even
Being connected to Laser Drive plate (2), Laser Drive plate (2) drives a Distributed Feedback Laser (3)；Going out of described Distributed Feedback Laser (3)
Penetrate light path and be provided with battery of lens (4)；It is characterized in that, also include that the spectrum on an emitting light path being positioned at battery of lens (4) is surveyed
Acoustic device (5)；Described spectrum survey acoustic device (5) include a miniature gas cell (56) and be located at miniature gas cell (56) internal as
General frequency described in claim 1 or 2 strengthens optoacoustic spectroscopy acousimeter (55)；First pin (12) of described tuning-fork type quartz crystal oscillator
It is connected to ground wire (11)；Second pin (13) of tuning-fork type quartz crystal oscillator is connected by preamplifier (14) has one phase-locked to put
Big device (15)；Also include computer (16)；The signal output part of lock-in amplifier (15) is defeated with a signal of computer (16)
Enter end to be connected；The synchronous signal output end of described functional generator (1) and the synchronous signal input end of lock-in amplifier (15)
It is connected.
4. gas detection apparatus as claimed in claim 3, it is characterised in that set on the emitting light path of described miniature gas cell (56)
Energy meter (6), the signal output part of energy meter (6) is had to be connected with another signal input part of computer (16).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610810363.0A CN106290165A (en) | 2016-09-08 | 2016-09-08 | General frequency strengthens optoacoustic spectroscopy acousimeter and uses the gas detection apparatus of this acousimeter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610810363.0A CN106290165A (en) | 2016-09-08 | 2016-09-08 | General frequency strengthens optoacoustic spectroscopy acousimeter and uses the gas detection apparatus of this acousimeter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN106290165A true CN106290165A (en) | 2017-01-04 |
Family
ID=57710989
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201610810363.0A Pending CN106290165A (en) | 2016-09-08 | 2016-09-08 | General frequency strengthens optoacoustic spectroscopy acousimeter and uses the gas detection apparatus of this acousimeter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN106290165A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2018188429A1 (en) * | 2017-04-11 | 2018-10-18 | 山西大学 | Beat effect-based quartz-enhanced photoacoustic spectroscopy gas detection apparatus and method |
| CN111272663A (en) * | 2020-02-10 | 2020-06-12 | 山西大学 | Gas detection device and method |
| CN113295620A (en) * | 2021-05-24 | 2021-08-24 | 暨南大学 | Optical fiber coupled all-solid-state enhanced photoacoustic spectroscopy gas photoacoustic detection module and method |
| WO2022267555A1 (en) * | 2021-06-23 | 2022-12-29 | 暨南大学 | Radial cavity quartz-enhanced photoacoustic spectrophone and gas detection device comprising same |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003104767A2 (en) * | 2002-06-10 | 2003-12-18 | William Marsh Rice University | Quartz-enhanced photoacoustic spectroscopy |
| CN104280340A (en) * | 2014-10-28 | 2015-01-14 | 山西大学 | Device and method for detecting gas based on LED light source and by adopting electrical modulation phase elimination way |
| CN105651374A (en) * | 2016-01-27 | 2016-06-08 | 山西大学 | Single-tube and coaxial photo-acoustic spectrum sound detector and gas detection device adopting sound detector |
-
2016
- 2016-09-08 CN CN201610810363.0A patent/CN106290165A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003104767A2 (en) * | 2002-06-10 | 2003-12-18 | William Marsh Rice University | Quartz-enhanced photoacoustic spectroscopy |
| CN104280340A (en) * | 2014-10-28 | 2015-01-14 | 山西大学 | Device and method for detecting gas based on LED light source and by adopting electrical modulation phase elimination way |
| CN105651374A (en) * | 2016-01-27 | 2016-06-08 | 山西大学 | Single-tube and coaxial photo-acoustic spectrum sound detector and gas detection device adopting sound detector |
Non-Patent Citations (4)
| Title |
|---|
| A.SAMPAOLO 等: "Quartz-enhanced photoacoustic spectroscopy exploiting tuning fork overtone modes", 《APPLIED PHYSICS LETTERS》 * |
| FRANK K. TITTEL 等: "Analysis of overtone flexural modes operation in quartz-enhanced photoacoustic spectroscopy", 《OPTICS EXPRESS》 * |
| HONGPENG WU 等: "Position effects of acoustic micro-resonator in quartz enhanced photoacoustic spectroscopy", 《SENSORS AND ACTUATORS B》 * |
| HUADAN ZHENG 等: "Single-tube on-beam quartz-enhanced photoacoustic spectroscopy", 《OPTICS LETTERS》 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2018188429A1 (en) * | 2017-04-11 | 2018-10-18 | 山西大学 | Beat effect-based quartz-enhanced photoacoustic spectroscopy gas detection apparatus and method |
| CN111272663A (en) * | 2020-02-10 | 2020-06-12 | 山西大学 | Gas detection device and method |
| CN111272663B (en) * | 2020-02-10 | 2021-02-02 | 山西大学 | Gas detection device and method |
| CN113295620A (en) * | 2021-05-24 | 2021-08-24 | 暨南大学 | Optical fiber coupled all-solid-state enhanced photoacoustic spectroscopy gas photoacoustic detection module and method |
| CN113295620B (en) * | 2021-05-24 | 2023-02-17 | 暨南大学 | Optical fiber coupled all-solid-state enhanced photoacoustic spectroscopy gas photoacoustic detection module and method |
| WO2022267555A1 (en) * | 2021-06-23 | 2022-12-29 | 暨南大学 | Radial cavity quartz-enhanced photoacoustic spectrophone and gas detection device comprising same |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105651374B (en) | The coaxial optoacoustic spectroscopy acousimeter of single tube and the gas detection apparatus for using the acousimeter | |
| CN104237135B (en) | CO gas detecting systems and method based on quartz tuning fork strengthened optoacoustic spectroscopy | |
| CN107064012B (en) | Quartz enhanced photoacoustic spectroscopy gas-detecting device and method based on beat effect | |
| CN101506645B (en) | Cavity-enhanced photo acoustic trace gas detector with improved feedback loop | |
| CN106290165A (en) | General frequency strengthens optoacoustic spectroscopy acousimeter and uses the gas detection apparatus of this acousimeter | |
| US20090249861A1 (en) | Stable photo acoustic trace gas detector with optical power enhancement cavity | |
| CN107271368A (en) | A kind of interior cavity-enhanced photo acoustic spectrum-type trace-gas sensors device | |
| US10444199B2 (en) | Evanescent-wave quartz-enhanced photoacoustic sensor with resonator elements | |
| Li et al. | Calibration-free mid-infrared exhaled breath sensor based on BF-QEPAS for real-time ammonia measurements at ppb level | |
| CN103175790B (en) | Double-quartz-crystal-oscillator spectral phonometer and gas detection device employing same | |
| CN104849214A (en) | Enhanced multi-group photoacoustic spectrum gas sensing device based on quartz tuning fork | |
| CN107677610A (en) | A kind of cantilever beam and photoacoustic cell double resonance enhanced photo acoustic spectral detection system and method | |
| CN102713565A (en) | Gas sensor based on photoacoustic detection | |
| CN104280340B (en) | The gas detection apparatus based on LED light source and using electricity modulation phase resolving therapy and method | |
| CN103105365A (en) | Photoacoustic spectroscopy telemetering method and device based on micro quartz tuning fork optoacoustic effect | |
| CN113433072B (en) | Gas concentration sensor and gas concentration detection device | |
| CN103175791A (en) | Multi-quartz-crystal-oscillator spectral phonometer and gas detection device employing same | |
| CN211602897U (en) | Photoacoustic cell structure in photoacoustic spectrum oil gas detection device | |
| CN103063574A (en) | Membrane-type minitype photoacoustic cell and application thereof | |
| WO2022267555A1 (en) | Radial cavity quartz-enhanced photoacoustic spectrophone and gas detection device comprising same | |
| CN106124411A (en) | A kind of wide spectral type optoacoustic spectroscopy trace materials long-range detection device and method | |
| Li et al. | Design of a high-sensitivity differential Helmholtz photoacoustic cell and its application in methane detection | |
| CN113295620B (en) | Optical fiber coupled all-solid-state enhanced photoacoustic spectroscopy gas photoacoustic detection module and method | |
| CN107884344A (en) | A kind of optoacoustic spectroscopy gas sensing system of the active air chamber based on semiconductor laser | |
| CN103149681A (en) | Tuning fork type photo-chopper and trace gas measuring device using tuning fork type photo-chopper |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20170104 |