CN209311319U - Quartz tuning fork photoacoustic spectrum sensor - Google Patents
Quartz tuning fork photoacoustic spectrum sensor Download PDFInfo
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- CN209311319U CN209311319U CN201822113875.9U CN201822113875U CN209311319U CN 209311319 U CN209311319 U CN 209311319U CN 201822113875 U CN201822113875 U CN 201822113875U CN 209311319 U CN209311319 U CN 209311319U
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- reflecting mirror
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Abstract
The utility model discloses quartz tuning fork photoacoustic spectrum sensors, are related to gas detection technology field, comprising: light source and the light in the optical path of light source collimate part；First reflecting mirror, the first reflecting mirror are inclined on pedestal to by dipped beam collimation part side, and the first reflecting mirror is located at from the optical path that light collimation part projects；Second reflecting mirror, the second reflecting mirror and the first reflecting mirror are oppositely arranged on pedestal；Quartz tuning-fork, quartz tuning-fork is set on the base and between the first reflecting mirror and the second reflecting mirror, the light that light collimation part projects to form reflected light through being mutually reflected between the first reflecting mirror and the second reflecting mirror, and the plane where reflected light is located between the both arms gap of quartz tuning-fork.The utility model quartz tuning fork photoacoustic spectrum sensor improves sensitivity and the signal-to-noise ratio of detection gas, can be used for the detection of super low concentration gas.
Description
Technical field
The utility model relates to gas detection technology fields, in particular to quartz tuning fork photoacoustic spectrum sensor.
Background technique
The development of Trace gas detection technology is for ambient air monitoring, the mankind or animals and plants physiological status and explosive
Long-range detection etc. all have a very important significance.
Generally, Trace gas detection technology can be divided into non-spectral detection technique and spectrum detection technique two major classes.
Non-spectral Trace gas detection technology specifically includes that ultrasonic gas detection technique, thermocatalytic gas detection method, gas-chromatography
Method (analytic hierarchy process (AHP)) etc..In the spectrum detection technique of trace gas, by the difference of spectrum mechanism of production, and it can be divided into
Two class of emission spectrum and absorption spectrum.Gas molecule is also just different to the absorbing state of electromagnetic wave due to its structure difference.
Absorption spectrum gas detection technology is to the attenuation degree by electromagenetic wave radiation therein according to gas molecule come detection gas
Concentration.Absorption spectrum gas detection technology have measurement range it is big, can measurement of multi-components, can continuous monitoring and other advantages, gradually
As ideal trace gas concentration detection instrument.
With the fast development of semiconductor laser technology, start largely to swash using semiconductor in gas photo acoustic spectrometry system
Light device is as driving source.So that near-infrared semiconductor laser is widely applied, market is on sale for the development of the communication technology
GaAs and indium phosphide laser wavelength range are between 0.5 μm -2 μm, the overtone area in gas infrared absorption, with such
The continuous improvement of the accessories performance such as the temperature controller of laser and electric current driving source, the diode laser of single mode narrow linewidth
Device is increasingly applied to gas detection.In order to match with the compact size of the semiconductor laser occurred recently, and
And it is immune to environmental background signal, kosterev et al. is by quartz tuning-fork (Quartz Tuning Fork, QTF) as sensitive
In acoustic resonance detector application optoacoustic spectroscopy, quartz enhanced photoacoustic spectroscopy technology (Quartz Enhanced is formed
Photoacoustic Spectroscopy, QEPAS) QTF is compact-sized, diameter about 3mm；Quality factor is high, up to 10000-
100000, (environmental gas that occurrence depends on surrounding)；It is cheap.Magazine " REVIEW OF SCIENTIFIC
INSTRUMENTS ", article " the Applications of of Anatoliy A.Kostereva and Frank K.Tittel
Quartz tuning forks in spectroscopic gas sensing ", periodical number and the page number are 76,043105
(2005) in, the typical case in the detection using quartz tuning-fork in spectroscopic gas is taught, which issues laser
Laser gas chamber in quartz tuning-fork both arms between gap pass through, be added wavelength modulation laser cause the gas in gas chamber to produce
The raw resonance with frequency, and then the vibration of tuning fork two-arm is made to generate low current signal.The system laser light beam is only capable of across tuning fork
Once, it is then dispersed into space, the signal strength of capacity usage ratio and quartz tuning-fork vibration generation is all very low.And in reality
In, quartz tuning fork photoacoustic the spectral technique circuit itself especially during electric signal transmission and week in the entire system
Enclosing noise brought by electromagnetic field cannot ignore.And in light concentration gas detection, the piezoelectric signal ten of quartz tuning-fork generation
It is point faint, and the intensity for needing to extract harmonic signal also wants low, is easy to be covered by system noise, this becomes quartz tuning-fork light
A bottleneck of the acousto-optic spectral technology in terms of super low concentration gas detection.
Utility model content
For disadvantages described above, the purpose of the utility model is to provide a kind of quartz tuning fork photoacoustic spectrum sensors, improve
The sensitivity of detection gas and signal-to-noise ratio can be used for the detection of super low concentration gas.
To achieve the above object, the technical solution of the utility model is:
Quartz tuning fork photoacoustic spectrum sensor, comprising: light source and the light in the optical path of the light source collimate part；First
Reflecting mirror, first reflecting mirror is inclined on pedestal to close to light collimation part side, and first reflecting mirror
Positioned at from the optical path that light collimation part projects；Second reflecting mirror, second reflecting mirror are opposite with first reflecting mirror
Setting is on the base；Quartz tuning-fork, quartz tuning-fork setting on the base and be located at first reflecting mirror and
Between second reflecting mirror, the light that the light collimation part projects is through phase between first reflecting mirror and second reflecting mirror
Reflected light mutually is reflected to form, the plane where the reflected light is located between the both arms gap of the quartz tuning-fork.
Preferably, second reflecting mirror is parallel with first reflecting mirror.
Preferably, first reflecting mirror is arranged on the base by return reflection mirror, first reflecting mirror
Lower end be mutually connected with the upper end of the return reflection mirror, the lower end of the return reflection mirror is fixed on the pedestal
On, the light that the light collimation part projects is perpendicular to plane where the return reflection mirror.
Preferably, the light that projects of light collimation part is perpendicular to the plane where the return reflection mirror, described first
Reflecting mirror is higher than the bottom end in the both arms gap of the quartz tuning-fork with the position that the return reflection mirror is mutually connected.
Preferably, the light source is laser.
Preferably, the light collimation part is collimator, the collimator is connect by optical fiber with the laser.
Preferably, the center line in the both arms gap of the quartz tuning-fork coincides with the plane where the reflected light.
Preferably, the pedestal is horizontal base, the plane and the horizontal base where the reflected light are mutually hung down
Directly.
Preferably, the plane where the reflected light is mutually perpendicular to plane where the both arms of the quartz tuning-fork.
After above-mentioned technical proposal, the beneficial effects of the utility model are:
When work, after the reflection of the first reflecting mirror, it is anti-to be reflected into second after light collimation part collimation for the light that light source issues
It penetrates on mirror, the second reflecting mirror reflects light back into the first reflecting mirror again, is mutually reflected between the first reflecting mirror and the second reflecting mirror
Reflected light is formed, the plane where reflected light is located between the both arms gap of quartz tuning-fork, i.e., the light issued from light collimation part is more
The secondary both arms gap through quartz tuning-fork is equivalent to the light intensity of the light of enhancing, and because light intensity is directly proportional to the intensity of piezoelectric signal, because
This can substantially enhance the photoacoustic signal generated in the photo acoustic spectrometry system, improve the sensitivity and noise of detection gas
Than can be used for the detection of super low concentration gas.
In the utility model, by the way that return reflection mirror is arranged, when light is mutual between the first reflecting mirror and the second reflecting mirror
Reflection, when reaching return reflection mirror, the transmitting road Guang Huibeiyuan is reflected back, therefore reflected light can pass through quartz tuning-fork second
Both arms gap further enhances the piezoelectric signal of quartz tuning-fork generation, improves sensitivity and the signal-to-noise ratio of detection gas.
To sum up, the utility model quartz tuning fork photoacoustic spectrum sensor solves quartz tuning fork photoacoustic spectrum in the prior art
For sensor when light concentration gas detects, the piezoelectric signal that quartz tuning-fork generates is very faint, covers vulnerable to system noise, can not
The problem of detecting light concentration gas.The utility model quartz tuning fork photoacoustic spectrum sensor, improves the sensitivity of detection gas
With signal-to-noise ratio, it can be used for the detection of super low concentration gas.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of quartz tuning fork photoacoustic spectrum sensor in the prior art；
In figure: 1- light source, 2- light collimate part, the first reflecting mirror of 3-, 4- pedestal, the second reflecting mirror of 5-, 6- quartz tuning-fork, 7-
Reflected light, 8- return reflection mirror.
Specific embodiment
With reference to the accompanying drawings and examples, the utility model is further described.
As shown in Figure 1, a kind of quartz tuning fork photoacoustic spectrum sensor, comprising: light source 1 and in the optical path of light source 1
Light collimates part 2；First reflecting mirror 3, the first reflecting mirror 3 are inclined on pedestal 4 to by dipped beam collimation 2 side of part, and first
Reflecting mirror 3 is located at from the optical path that light collimation part 2 projects；Second reflecting mirror 5, the second reflecting mirror 5 are set relatively with the first reflecting mirror 3
It sets on pedestal 4；Quartz tuning-fork 6, quartz tuning-fork 6 be arranged on pedestal 4 and be located at the first reflecting mirror 3 and the second reflecting mirror 5 it
Between, the light that light collimation part 2 projects to form reflected light 7 through being mutually reflected between the first reflecting mirror 3 and the second reflecting mirror 5, reflected light 7
The plane at place is located between the both arms gap of quartz tuning-fork 6.When work, light source 1 issue light through light collimation part 2 collimate after,
After the reflection of the first reflecting mirror 3, it is reflected on the second reflecting mirror 5, the second reflecting mirror 5 reflects light back into the first reflecting mirror 3 again,
The formation reflected light being mutually reflected between first reflecting mirror 3 and the second reflecting mirror 5, the plane where reflected light are located at quartz tuning-fork
Between 6 both arms gap, i.e., the light issued from light collimation part 2 is equivalent to the light of enhancing repeatedly through the both arms gap of quartz tuning-fork 6
Light intensity, and because light intensity is directly proportional to the intensity of piezoelectric signal, therefore can substantially enhance and be generated in the photo acoustic spectrometry system
Photoacoustic signal, improve sensitivity and the signal-to-noise ratio of detection gas, can be used for the detection of super low concentration gas.
As shown in Figure 1, the second reflecting mirror 5 is parallel with the first reflecting mirror 3.First reflecting mirror 3 is set by return reflection mirror 8
It sets on pedestal 4, the lower end of the first reflecting mirror 3 is mutually connected with the upper end of return reflection mirror 8, the lower end of return reflection mirror 8
Portion is fixed on pedestal 4, and return reflection mirror 8 can be by the former road of the reflected light 7 being reflected on return reflection mirror 8 from the second reflecting mirror 5
It reflects back.Light collimates the light of the injection of part 2 perpendicular to the plane where return reflection mirror 8, the first reflecting mirror 3 and return reflection mirror
The position of 8 phases linking is higher than the bottom end in the both arms gap of quartz tuning-fork 6.By the way that return reflection mirror 8 is arranged, when light is in the first reflection
It is mutually reflected between mirror 3 and the second reflecting mirror 5, when reflected light 7 reaches return reflection mirror 8, reflected light 7 can be reflected back by former road
It goes, therefore reflected light 7 can pass through the both arms gap of quartz tuning-fork 6 for second, further enhances the piezoelectricity letter of the generation of quartz tuning-fork 6
Number, improve sensitivity and the signal-to-noise ratio of detection gas.
As shown in Figure 1, light source 1 is laser.It is collimator that light, which collimates part 2, and collimator is connect by optical fiber with laser,
Laser of the collimator for laser to issue is collimated.
As shown in Figure 1, the center line in the both arms gap of quartz tuning-fork 6 coincides with the plane where reflected light 7.Pedestal 4
For horizontal base, the plane where reflected light 7 is mutually perpendicular to horizontal base.Plane and quartz tuning-fork 6 where reflected light 7
Plane where both arms is mutually perpendicular to.
The realization working principle of the utility model quartz tuning fork photoacoustic spectrum sensor is as follows:
Injection Current by changing laser carries out wavelength modulation, makes laser with frequency with low frequency trapezoidal wave electric current
vcWhile inswept whole Absorption Line, it is with frequencyThe high frequency sinusoidal of (resonant frequency of the quartz tuning-fork in gas)
Modulated signal is modulated wavelength.At this moment the instantaneous frequency for exporting laser can be expressed as
V (t)=vc+δcosωt (1)
Wherein δ is frequency modulation(PFM) amplitude, and the π f of ω=2 is modulating frequency.
If incident laser intensity is I0(v), transmitted light intensity I (v) is in unsaturated weak absorbing, suction of the gas to light
Receipts can be described with Beer-Lambert law:
I (v)=I0(v)exp[-S(T)g(v,v0)PLρ] (2)
Wherein, S (T) indicates the intensity of spectral line of gas absorption spectrum line in temperature T, unit cm-1/(mol·cm-2)；
g(v,v0) indicating the linear function of gas absorption spectrum line, unit cm, it is used to indicate the profile of tested absorption line, with quilt
The content for surveying the temperature of gas, stagnation pressure and each section gas is related；P indicates working gas pressure, unit atm；L indicates laser
Across the length of gas, unit cm；ρ indicates Gas Molecular Density, and unit is molecule/ (cm3·atm)。
In the case where absorption coefficient very little, i.e. S (T) g (v, v0) PL ρ be much smaller than 1, ignore the variation of light intensity, according to formula
(2), transmission laser intensity can be with approximate representation are as follows:
I(v)≈I0(v)[1-S(T)g(v,v0)PLρ] (3)
Define two nondimensional amounts:Indicate laser scanning frequency departure centre frequency
Degree.M is known as the index of modulation, is the ratio of modulation depth and high half width values of spectral line half.
Wherein v0For absorption spectrum centre frequency, v is the instantaneous frequency for exporting laser, Δ vLFor the halfwidth of absorption line
Degree
Know that instantaneous frequency v is the function of time t by formula (1), then under the conditions of Lorentzian lineshape, the instantaneous transmission of laser
Intensity can indicate are as follows:
So absorbing light intensity can indicate are as follows:
From (5) as can be seen that when near scanning to gas absorption spectrum line,The factor
Influence increased dramatically, i.e. a part of detected gas of laser energy absorbs, and the laser that gas absorbs specific wavelength causes laser rays
The recess of type finally causes the recess of signal line style.The piezoelectric signal demodulation that quartz tuning-fork vibration generates is obtained with each
Rd harmonic signal corresponds to the concentration of gas by the second harmonic signal intensity demodulated.
Due to light between the first reflecting mirror 6 and the second reflecting mirror 5 multiple reflections, the substantially enhancing of light intensity, second harmonic
Signal also will substantially enhance, therefore the sensitivity of gas concentration detection will also increase with signal-to-noise ratio.
The utility model is not limited to above-mentioned specific embodiment, and those skilled in the art visualize from above-mentioned
Hair, without creative labor, the various transformation made are all fallen within the protection scope of the utility model.
Claims (9)
1. a kind of quartz tuning fork photoacoustic spectrum sensor, comprising: light source and the light in the optical path of the light source collimate part；Its
It is characterized in that,
First reflecting mirror, first reflecting mirror are inclined on pedestal to close to light collimation part side, and described the
One reflecting mirror is located at from the optical path that light collimation part projects；
Second reflecting mirror, second reflecting mirror and first reflecting mirror are oppositely arranged on the base；
Quartz tuning-fork, the quartz tuning-fork setting is on the base and positioned at first reflecting mirror and second reflecting mirror
Between, the light that the light collimation part projects between first reflecting mirror and second reflecting mirror through being mutually reflected to form reflection
Light, the plane where the reflected light are located between the both arms gap of the quartz tuning-fork.
2. quartz tuning fork photoacoustic spectrum sensor according to claim 1, which is characterized in that second reflecting mirror and institute
It is parallel to state the first reflecting mirror.
3. quartz tuning fork photoacoustic spectrum sensor according to claim 2, which is characterized in that first reflecting mirror passes through
Return reflection mirror is arranged on the base, and the lower end of first reflecting mirror and the upper end of the return reflection mirror are mutually held in the mouth
It connects, the lower end of the return reflection mirror is fixed on the base, and the light that the light collimation part projects is perpendicular to the retroeflection
Plane where reflecting mirror.
4. quartz tuning fork photoacoustic spectrum sensor according to claim 3, which is characterized in that the light collimation part projected
For light perpendicular to the plane where the return reflection mirror, first reflecting mirror and the position that the return reflection mirror is mutually connected are high
In the bottom end in the both arms gap of the quartz tuning-fork.
5. quartz tuning fork photoacoustic spectrum sensor according to claim 1, which is characterized in that the light source is laser.
6. quartz tuning fork photoacoustic spectrum sensor according to claim 5, which is characterized in that the light collimation part is collimation
Device, the collimator are connect by optical fiber with the laser.
7. quartz tuning fork photoacoustic spectrum sensor according to claim 1, which is characterized in that the both arms of the quartz tuning-fork
The center line in gap coincides with the plane where the reflected light.
8. quartz tuning fork photoacoustic spectrum sensor according to claim 7, which is characterized in that the pedestal is horizontal base
Seat, the plane where the reflected light are mutually perpendicular to the horizontal base.
9. quartz tuning fork photoacoustic spectrum sensor according to claim 8, which is characterized in that flat where the reflected light
Face is mutually perpendicular to plane where the both arms of the quartz tuning-fork.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201822113875.9U CN209311319U (en) | 2018-12-17 | 2018-12-17 | Quartz tuning fork photoacoustic spectrum sensor |
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| CN201822113875.9U CN209311319U (en) | 2018-12-17 | 2018-12-17 | Quartz tuning fork photoacoustic spectrum sensor |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110646348A (en) * | 2019-10-15 | 2020-01-03 | 哈尔滨工业大学 | Quartz photoacoustic spectrum sensing system based on parallel incidence |
| CN113189013A (en) * | 2021-04-07 | 2021-07-30 | 山西大学 | Photoacoustic sensing device and method |
-
2018
- 2018-12-17 CN CN201822113875.9U patent/CN209311319U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110646348A (en) * | 2019-10-15 | 2020-01-03 | 哈尔滨工业大学 | Quartz photoacoustic spectrum sensing system based on parallel incidence |
| CN110646348B (en) * | 2019-10-15 | 2021-11-16 | 哈尔滨工业大学 | Quartz photoacoustic spectrum sensing system based on parallel incidence |
| CN113189013A (en) * | 2021-04-07 | 2021-07-30 | 山西大学 | Photoacoustic sensing device and method |
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