CN116183510A - Photo-induced thermal bomb spectrum signal detection device, gas detection device and method - Google Patents
Photo-induced thermal bomb spectrum signal detection device, gas detection device and method Download PDFInfo
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Abstract
The invention provides a photoelastic spectrum signal detection device, a gas detection device and a method, comprising the following steps: electrode-improved quartz tuning fork; the electrode-modified quartz tuning fork includes: two rectangular tuning fork arms, a tuning fork base and two tuning fork pins; the outer side surface of the first rectangular tuning fork vibroseis is not covered by an electrode, and the inner side surface and the front side surface and the rear side surface are covered by the electrode; four sides of the second rectangular tuning fork vibroseis are covered by the electrodes; when the detection device works, laser is incident into the quartz tuning fork from the outer side surface of the first rectangular tuning fork vibro-arm, and an electric signal is generated under the action of a photo-induced thermal spring effect and is output from a tuning fork pin; the electrical signal corresponds to a photoelastic spectrum signal of the incident laser. The invention improves the tuning fork excitation efficiency, improves the photo-thermal bomb spectrum efficiency, enhances the photo-thermal bomb effect and enhances the detection capability of the photo-thermal bomb spectrum.
Description
Technical Field
The invention belongs to the field of gas sensing, and particularly relates to a photo-thermal bomb spectrum signal detection device, a gas detection device and a method.
Background
Trace gas detection techniques have been widely used in many fields including industrial process control, medical diagnostics, environmental monitoring, and the like. Conventional detection techniques, such as gas chromatography/mass spectrometry and electrochemical non-optical techniques, have the technical defects of high cost, complex structure, slow reaction speed and the like. The optical sensing technology has the characteristics of high sensitivity, strong selectivity, high response speed and the like, and is widely studied in recent years. In a plurality of optical sensing technologies, photoacoustic and photoelastic spectra have the advantages of high sensitivity, compact structure, wide dynamics and the like, and thus, the photoacoustic and photoelastic spectra have great potential in trace gas detection. The advantage of photoacoustic spectroscopy and photothermal spectroscopy over other spectroscopic methods is that high sensitivity detection can be achieved with a small gas volume.
As a new variant of photoacoustic and photothermal spectroscopy techniques, photo-induced thermoelastic spectroscopy (LITES) techniques based on quartz tuning forks have been rapidly developed in recent years. When the modulated incident laser passes through the gas absorption cell and irradiates the surface of the quartz tuning fork, the energy after the interaction of the laser and molecules is detected by the quartz tuning fork. Due to the thermoelastic effect of the quartz, the thermal energy absorbed by the quartz is converted into mechanical energy of vibration of the quartz tuning fork, and is resonantly amplified by the quartz tuning fork. The mechanical energy generated by vibration is converted into electric energy by the piezoelectric effect of the quartz tuning fork. Commercial quartz tuning forks have a resonance frequency of 32.7kHz and 10 at standard atmospheric pressure 4 High Q factor of (3), its wholeThe body shape is U-shaped.
The following 3 disadvantages exist in the current quartz enhanced photoelastic spectroscopy technology: first, the excitation beam is difficult to collimate and excite accurately. After passing through the gas absorption cell, the laser irradiates the surface of the tuning fork from the front. The light beam is generally in the form of normal incidence, and the incidence point of the light beam is generally selected at the top point of the U-shape at the bottom of the oscillating arm of the tuning fork. Because the surface of the tuning fork is covered with silver plating electrodes in most areas, the tuning fork has larger reflection influence on incident light, so that excitation light is difficult to focus on quartz materials, and light beams are difficult to collimate. Second, the current laser excitation location is on the tuning fork surface and is not the optimal response location of the tuning fork to light. One of the key steps in the photo-thermal-elastic effect is to generate an electrical signal through the piezoelectric effect when the tuning fork resonates, so that a larger piezoelectric effect must be excited to generate a stronger photo-thermal-elastic effect. The current position of the excitation of the light beam is located on the normal incidence surface of the tuning fork and is not the position of the greatest stress when the tuning fork vibrates, so that the maximum piezoelectric effect, namely the maximum photo-thermal elastic effect, cannot be excited. Third, in the prior art, the interaction between the quartz material and the excitation beam is insufficient, so that the photo-induced thermoelastic effect is not strong, and the photo-induced thermoelastic spectral sensitivity is not enough. The incident light is vertically incident and passes through the U-shaped vertex of the tuning fork, and the thickness of the quartz tuning fork is 0.3mm, so that in the existing photo-thermal elastic spectrum technology, the absorption path for generating the photo-thermal elastic effect is only 0.3mm. The incident light is not fully absorbed and utilized, so that the generated photo-thermal elasticity effect is small, and the generated signal amplitude is small, thereby influencing the detection sensitivity.
In summary, the above 3 disadvantages result in the existing photoelastic spectrum with low excitation efficiency and insufficient sensitivity of the quartz tuning fork, which affects the gas detection sensitivity.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a photo-induced thermal bomb spectrum signal detection device, a gas detection device and a method, and aims to solve the problems that the existing quartz tuning fork has low excitation efficiency and insufficient photo-induced thermal bomb spectrum sensitivity and influences the gas detection sensitivity.
In order to achieve the above object, the present invention provides a photo-thermal elastic spectrum signal detection device, comprising: electrode-improved quartz tuning fork;
the electrode-modified quartz tuning fork includes: two rectangular tuning fork arms, a tuning fork base and two tuning fork pins; the outer side surface of the first rectangular tuning fork vibroseis is not covered by an electrode, and the inner side surface and the front side surface and the rear side surface are covered by the electrode; four sides of the second rectangular tuning fork vibroseis are covered by the electrodes;
when the detection device works, laser is incident into the quartz tuning fork from the outer side surface of the first rectangular tuning fork vibro-arm, and an electric signal is generated under the action of a photo-induced thermal spring effect and is output from a tuning fork pin; the electrical signal corresponds to a photoelastic spectrum signal of the incident laser.
In an alternative example, the first rectangular tuning fork vibratable arm is either one of two rectangular tuning fork vibratable arms.
In an alternative example, the signal amplitude of the photo-thermal elastic spectrum signal is highest when the laser light is incident from a preset position of the first rectangular tuning fork vibro-arm; the height of the preset position is the same as the height of the connecting point of the U-shaped cambered surface of the tuning fork base and the rectangular tuning fork oscillating arm.
In a second aspect, the present invention provides a gas detection device including the photo-thermal elastic spectrum signal detection device given in the first aspect, which is further characterized by comprising: a semiconductor laser, a focusing device and a signal demodulation device;
the semiconductor laser is used for projecting laser to the gas to be detected;
the focusing device is used for focusing the laser passing through the gas to be detected to the photo-thermal elastic spectrum signal detection device;
the photo-thermal bomb spectrum signal detection device is used for outputting corresponding electric signals under the action of the laser;
the signal demodulation device is used for demodulating the electric signal to obtain concentration information of the gas to be detected.
In an alternative example, the signal demodulating apparatus includes: a pre-amplifier and a phase-locked amplifier;
the preamplifier is used for carrying out trans-impedance amplification on the electric signal output by the photo-thermal bomb spectrum signal detection device to obtain a corresponding photo-thermal bomb spectrum signal;
the lock-in amplifier is used for demodulating the photo-thermal elastic spectrum signal and solving to obtain the concentration information of the gas to be detected.
In an alternative example, the apparatus further comprises: a transparent container;
the transparent container is used for bearing the gas to be detected.
In an alternative example, the semiconductor laser is used for projecting laser light with different wavelengths to the gas to be detected so as to detect different kinds of gas to be detected.
In a third aspect, the present invention provides a method for detecting a photoelastic spectrum signal, including the steps of:
removing an electrode covered on the outer side surface of a rectangular tuning fork arm of the quartz tuning fork;
controlling laser to enter the quartz tuning fork from the outer side surface after the electrode is removed, and generating an electric signal under the action of a photo-thermal elastic effect to be output from a pin of the quartz tuning fork; the electrical signal corresponds to a photoelastic spectrum signal of the incident laser.
In an alternative example, when the laser light is incident from the preset position of the outer side surface, the signal amplitude of the photoelastic spectrum signal is the highest; the height of the preset position is the same as the height of the connecting point of the U-shaped cambered surface of the tuning fork base and the rectangular tuning fork oscillating arm.
In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:
the invention provides a photoelastic spectrum signal detection device, a gas detection device and a method, and provides a novel internal and external synchronous excitation mode. The outside electrode of the vibrating arm of the electrode improved tuning fork crystal oscillator is manually removed to form an incident window of laser. Allowing the laser to be excited from the side of the oscillating arm from the outside into the inside of the quartz tuning fork oscillating arm. In the excitation mode, the inner side surface and the outer side surface with larger stress are simultaneously excited by the light beam, so that the tuning fork excitation efficiency is improved.
The invention provides a photoelastic spectrum signal detection device, a gas detection device and a method, which greatly improve the interaction length of a quartz tuning fork and laser. The laser beam is incident from the outside of the oscillating arm, the silver electrode layer plated on the inner side of the oscillating arm is used as a reflecting mirror, after exciting the inner surface of the oscillating arm of the tuning fork, light is reflected by the silver electrode layer when exiting the surface of the tuning fork, enters the oscillating arm of the tuning fork again and then exits from the outside of the oscillating arm of the tuning fork, and in the process, the exciting beam passes back and forth for 2 times through the width of the oscillating arm of the tuning fork.
The invention provides a photoelastic spectrum signal detection device, a gas detection device and a method, which establish an optimal action position of tuning fork lateral excitation. By analyzing the surface stress of the tuning fork, the optimal action positions of the outer surface and the inner convenient surface of the side surface of the oscillating arm of the tuning fork are respectively located at a position away from the opening of the tuning fork. The special position is the position with the largest stress on the inner surface and the outer surface when the tuning fork arm vibrates, and can obtain larger photo-thermal elastic effect.
The invention provides a photoelastic spectrum signal detection device, a gas detection device and a method, wherein the photoelastic spectrum detection device based on electrode-improved crystal oscillator improves tuning fork excitation efficiency, photoelastic spectrum efficiency and photoelastic effect, has the characteristics of high thermoelastic effect, high response speed and the like, and further improves detection signal-to-noise ratio and sensitivity by 15 times through lateral excitation enhanced photoelastic spectrum. By changing the wavelength of the laser, other various gas detection can be realized, and the detection capability of the photo-thermal elastic spectrum can be effectively improved.
Drawings
Fig. 1 is a three-dimensional perspective view of an electrode-modified quartz tuning fork according to an embodiment of the present invention.
Fig. 2 is a top view of an electrode-modified quartz tuning fork provided by an embodiment of the invention.
FIG. 3 is a graph showing the frequency response of an electrode-modified quartz tuning fork according to an embodiment of the invention.
Fig. 4 is a schematic diagram of stress distribution of a vibrating arm of the quartz tuning fork provided by the embodiment of the invention when excited to vibrate.
FIG. 5 is a graph showing the relative pressures experienced by the outer and inner surfaces of the quartz tuning fork at different locations of the vibrating arm when excited to vibrate, according to an embodiment of the present invention.
Fig. 6 is a schematic diagram of different feature points of different light spot focusing positions in a lateral excitation enhanced photo-thermal bomb spectrum according to an embodiment of the present invention.
Fig. 7 is a signal amplitude diagram obtained at different focal positions of light spots in a lateral excitation enhanced photo-thermal bomb spectrum according to an embodiment of the present invention.
Fig. 8 is a photo-thermal bullet signal amplitude diagram corresponding to different laser modulation depths in a lateral excitation enhanced photo-thermal bullet spectrum according to an embodiment of the present invention.
Fig. 9 is a comparison chart of second harmonic signals of a lateral excitation enhanced photo-thermal bomb spectrum and a traditional photo-thermal bomb spectrum provided by an embodiment of the present invention.
FIG. 10 is a schematic diagram of an electrode-modified quartz tuning fork electrode according to an embodiment of the present invention.
FIG. 11 is a schematic diagram of a system for detecting a photo-thermal bomb spectrum gas with enhanced lateral excitation according to an embodiment of the present invention.
The same reference numbers are used throughout the drawings to reference like elements or structures, wherein: 1 is computer equipment; 2 is a function signal generator; 3 is an adder; 4 is laser drive; 5 is a semiconductor laser; 6 is a gas absorption tank; 7 is a light focusing device; 8 is an electrode improved quartz tuning fork; 9 is a pre-amplifier; 10 is a lock-in amplifier.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The invention provides a lateral double-optical-path double-excitation enhanced photo-thermal bomb spectrum technology and a gas detection device thereof, and aims to solve the 3 technical problems in the prior art. The invention relates to a novel photoelastic spectrum technology based on an electrode improved quartz tuning fork. Whereas a commercially available quartz tuning fork has 8 sides plated with electrodes, the electrode-modified quartz tuning fork of the present invention employed removes 1 side plated electrode therein, forming a window allowing excitation light to enter the interior of the quartz tuning fork. Therefore, one electrode is removed from the surface of the first quartz tuning fork, a large number of window areas are formed for light to enter, and the collimation difficulty is reduced. Secondly, light enters the quartz material, and directly excites the point with the largest pressure stress when the tuning fork vibrates, so that larger deformation and larger piezoelectric effect are obtained. Second, light is not incident from the front side perpendicular to the tuning fork plane, but enters from the side of the tuning fork vibrissa, so that the interaction strength of light and quartz materials is greatly improved.
The invention is realized by the following specific technical scheme. The standard commercial quartz crystal oscillator comprises two oscillating arms, and 4 faces of each oscillating arm are plated with electrodes. The technical scheme and the gas detection device are based on an electrode-improved quartz tuning fork, and one side electrode of one vibrating arm is removed, so that a light incident window is formed. Hydrofluoric acid with the volume fraction of more than 65% is matched with a mask plate to corrode electrodes of a quartz tuning fork. The mask plate covers the electrode on the side face of the quartz tuning fork arm, the etching time is about 5 minutes, the electrode on the side face of the quartz tuning fork can be removed by the method, and the electrode-improved quartz tuning fork is formed, and the three-dimensional perspective view is shown in fig. 1, and the upper view is shown in fig. 2.
We measured the frequency response curve of the electrode modified quartz tuning fork as shown in fig. 3. The abscissa is the response frequency and the ordinate is the normalized vibration amplitude corresponding to the different vibration frequencies. The output signal of the tuning fork is fitted through Lorentz (Lorentz) function, so that the frequency response curve of the electrode modified quartz tuning fork is Lorentz linear, the center frequency is about 32775Hz, and the corresponding Q value is about 12000. This parameter demonstrates that the electrode modification does not affect the frequency response curve of the quartz tuning fork, which has a resonance curve comparable to that of a standard commercial quartz tuning fork.
Next we analyzed the stress distribution of the quartz tuning fork during vibration by COMOL Multiphysics multiphysics field coupling software. The stress analysis is based on the principle of finite element analysis. By creating a coupled resonator model and meshing of the tuning fork, we can obtain the received stress distribution of the inner and outer surfaces of the tuning fork vibroseis during vibration. Fig. 4 shows a schematic diagram of stress distribution to which a vibrating arm of a quartz tuning fork is subjected when excited to vibration. As can be seen from fig. 4, the stress distribution of the tuning fork is mainly located on the side of the oscillating arm of the tuning fork when the tuning fork oscillates. The stress received by the side of the tuning fork is much greater than the stress received by the front side. Thus, it is demonstrated that in the photo-induced thermoelastic effect, the beam excites the side of the tuning fork to obtain a greater output than the front. Fig. 5 shows the stresses to which the outer and inner surfaces of the oscillating arms of the tuning fork are subjected at different heights from the starting point, starting from the U-shaped opening of the tuning fork. As can be seen from fig. 5, as the height Δh increases, the pressure on both the inner and outer surfaces of the tuning fork vibrating arm increases. At the height corresponding to the connection point of the U-shaped cambered surface of the rectangular tuning fork vibrissal and the tuning fork base, delta H is 3.8mm, the pressure of the outer surface of the tuning fork vibrissal is maximized, and the pressure of the inner surface of the tuning fork is increased exponentially. Thus, if the inner surface of the vibrating arm of the tuning fork can be excited, the effect of the photo-thermal elastography will be greatly improved.
It should be noted that, the dimensions of different quartz tuning fork structures are different, and the embodiment of the invention is only exemplified by a tuning fork of a model with a connection point height Δh of 3.8mm, and the specific dimensions of the tuning fork do not constitute any limitation on the embodiment of the invention, and those skilled in the art can select the tuning fork dimensions according to actual needs.
The gas detection device provided by the invention comprises the following parts: a function generator; an adder connected with the modulation signal output end of the function generator; a laser driver connected with the signal output end of the adder; a laser driven by the laser driver, the laser being configured to emit at least excitation light; the optical fiber component is arranged on the emergent light path of the laser; the outgoing laser acts on the electrode-modified quartz tuning fork crystal oscillator after passing through the gas tank; a preamplifier connected with the pins of the crystal oscillator; and the phase-locked amplifier is connected with the output end of the preamplifier, and the phase-locked amplifier is connected with the synchronous signal output end of the function generator. Further, the computer equipment with a data acquisition card is respectively connected with the output end of the lock-in amplifier and the input end of the function generator.
The invention opens up preliminary experimental research based on the electrode-modified quartz tuning fork, and explores the optimal response position of the electrode-modified quartz tuning fork vibro-arm. After passing through the gas cell, the excitation beam is focused on the side of the vibrating arm of the electrode-modified quartz tuning fork. Let Δh=0mm at the tuning fork U-shaped opening, the spot focus position scan down the outside of the quartz tuning fork vibroseis as shown in fig. 6. The signal amplitude of the electrode-modified tuning fork was recorded at different heights Δh, and the relationship of the obtained photo-thermal elastic signal amplitude to the height Δh is shown in fig. 7. Three feature Point positions are shown in fig. 7, point a being the start Point of the recorded signal of fig. 7, point B being at Δh=3.8mm, and Point C being the quartz tuning fork U-shaped apex position. As can be seen from fig. 7, the electrode-modified tuning fork can obtain the maximum photoelastic signal at Δh=3.8 mm.
In further experiments, we optimized the modulation depth of the laser in the photoelastic spectrum. By changing the amplitude of the modulation signal superimposed on the semiconductor laser, the wavelength modulation depth of the outgoing light of the laser is changed. The photo-thermal thermoelastic signal amplitude output by the electrode modified quartz tuning fork at different wavelength modulation depths is recorded, and then normalized to obtain the graph 8. As can be seen from fig. 8, the photo-thermal elastic signal amplitude of the electrode-modified quartz tuning fork increases monotonically with increasing laser wavelength modulation depth. The modulation depth of the laser wavelength reaches 2.3cm -1 At this point, the photoelastic signal reaches a maximum and no longer increases with wavelength modulation depth. Thus 2.3cm -1 Is the optimal laser wavelength modulation depth in this experiment.
After the optimal excitation position and the optimal laser wavelength modulation depth are obtained, the air is detectedWater molecules in (a) are examples. The signal of the lateral excitation enhanced photo-thermal bomb spectrum is measured, and compared with the signal of the traditional quartz enhanced photo-thermal bomb spectrum at present. Fig. 9 shows a comparison of second harmonic signals obtained from two lateral excitation enhanced photo-thermoelastic spectroscopy (SE-LITES) and conventional photo-thermoelastic spectroscopy (conventional LITES). In the traditional LITES technology, excitation light is directly focused at the U-shaped vertex position of the front surface of the tuning fork; in SE-LITES I, the laser is focused at tuning fork feature Point B (see fig. 6, Δh=3.8 mm); in SE-LITES II, the laser is focused at tuning fork feature Point C (see FIG. 6, tuning fork U-shaped apex). The injection current of the laser is controlled at 42mA to 54mA, and the corresponding laser wavelength range is 7194.4cm -1 To 7195.1cm -1 Can cover water molecules at 7194.8cm -1 An absorption line at. Calculated from fig. 9, when the laser was focused at Δh=3.8 mm, the obtained second harmonic signal was 10.45mV, the noise was 2.95 μv, and the signal-to-noise ratio was 3540. Compared with the traditional photo-thermal elastography, the signal is 0.48mV, the noise is 1.96 mu V, and the signal-to-noise ratio is 246. The lateral excitation enhanced photo-induced thermal bomb spectrum improves the detection signal-to-noise ratio and sensitivity by 15 times. Therefore, the lateral excitation enhanced photo-thermal elastography can effectively improve the detection sensitivity.
The electrode-modified quartz tuning fork 8 is shown in fig. 10. The electrode-modified quartz tuning fork 8 is composed of a tuning fork base 8.1, a rectangular tuning fork oscillating arm 8.2 and a tuning fork pin 8.3. Only three surfaces of the four surfaces of the rectangular tuning fork vibrating arm are covered with electrodes, one of the outer side surfaces 8.4 is not covered with the electrodes, and the quartz material is directly exposed for light to enter.
An embodiment of the gas detection device according to the present invention is shown in fig. 11. The computer device 1 controls the function generator 2 through serial communication, the function generator 2 generates a modulation signal and a scanning signal required by the semiconductor laser 5, the modulation signal and the scanning signal are added by the adder 3, and a driving signal obtained by the addition is input to the laser driver 4. The laser driver 4 realizes temperature and current control of the laser chip. The semiconductor laser 5 driven by the driver 4 emits laser light for interaction with gas molecules. The laser emitted by the semiconductor laser 5 firstly passes through a transparent gas pool 6 filled with the gas to be tested, and then is focused by a focusing device 7 and irradiates on the side face 8.4 of the quartz tuning fork oscillating arm of the electrode improvement. The electrode-modified quartz tuning fork 8 interacts with the laser, and an electrical signal is generated due to the photo-thermal spring effect and is output by the tuning fork pin 8.3. The electrical signal is fed via tuning fork pin 8.3 to a pre-amplifier 9 for trans-impedance amplification and then to a lock-in amplifier 10 for demodulation. The synchronizing signal of the function signal generator 2 is connected to the reference channel of the lock-in amplifier 10 for signal demodulation. The lock-in amplifier is connected with the computer equipment 1 through a serial port, and the gas concentration data is transmitted to the computer equipment 1 for display and storage.
The invention relates to a lateral excitation enhanced photo-thermal bomb spectrum technology and a gas detection device adopting the technology. The electrode improved crystal oscillator has a completely new electrode distribution structure, has a low-frequency resonance frequency of 32.7kHz through geometric parameter design, is convenient for laser beam incidence excitation by forming a rectangular electrodeless cover band on the outer side surface of the oscillating arm, and is more suitable for photo-thermal elastic spectrum detection by using a silver layer electrode on the inner surface of the oscillating arm as a reflecting mirror so as to form double excitation and double-channel light absorption enhancement between the inner side and the outer side of the oscillating arm. The photoelastic spectrum detection device based on the electrode-improved quartz tuning fork has the characteristics of high thermoelastic effect, high response speed and the like, can realize detection of other various gases by changing the wavelength of the laser, and can effectively improve the detection capability of the photoelastic spectrum.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (9)
1. A photothermal elastance spectrum signal detection device, comprising: electrode-improved quartz tuning fork;
the electrode-modified quartz tuning fork includes: two rectangular tuning fork arms, a tuning fork base and two tuning fork pins; the outer side surface of the first rectangular tuning fork vibroseis is not covered by an electrode, and the inner side surface and the front side surface and the rear side surface are covered by the electrode; four sides of the second rectangular tuning fork vibroseis are covered by the electrodes;
when the detection device works, laser is incident into the quartz tuning fork from the outer side surface of the first rectangular tuning fork vibro-arm, and an electric signal is generated under the action of a photo-induced thermal spring effect and is output from a tuning fork pin; the electrical signal corresponds to a photoelastic spectrum signal of the incident laser.
2. The apparatus of claim 1, wherein the first rectangular tuning fork vibratable arm is either one of two rectangular tuning fork vibratable arms.
3. The apparatus according to claim 1 or 2, wherein the signal amplitude of the photoelastic spectrum signal is highest when the laser light is incident from a preset position of the first rectangular tuning fork vibro-arm; the height of the preset position is the same as the height of the connecting point of the U-shaped cambered surface of the tuning fork base and the rectangular tuning fork oscillating arm.
4. A gas detection device comprising the photoelastic spectrum signal detection device according to any one of claims 1 to 3, characterized by further comprising: a semiconductor laser, a focusing device and a signal demodulation device;
the semiconductor laser is used for projecting laser to the gas to be detected;
the focusing device is used for focusing the laser passing through the gas to be detected to the photo-thermal elastic spectrum signal detection device;
the photo-thermal bomb spectrum signal detection device is used for outputting corresponding electric signals under the action of the laser;
the signal demodulation device is used for demodulating the electric signal to obtain concentration information of the gas to be detected.
5. The apparatus of claim 4, wherein the signal demodulating means comprises: a pre-amplifier and a phase-locked amplifier;
the preamplifier is used for carrying out trans-impedance amplification on the electric signal output by the photo-thermal bomb spectrum signal detection device to obtain a corresponding photo-thermal bomb spectrum signal;
the lock-in amplifier is used for demodulating the photo-thermal elastic spectrum signal and solving to obtain the concentration information of the gas to be detected.
6. The apparatus as recited in claim 4, further comprising: a transparent container;
the transparent container is used for bearing the gas to be detected.
7. The apparatus according to any one of claims 4 to 6, wherein the semiconductor laser is configured to project laser light of different wavelengths toward the gas to be detected to detect different kinds of the gas to be detected.
8. The photoelastic spectrum signal detection method is characterized by comprising the following steps of:
removing an electrode covered on the outer side surface of a rectangular tuning fork arm of the quartz tuning fork;
controlling laser to enter the quartz tuning fork from the outer side surface after the electrode is removed, and generating an electric signal under the action of a photo-thermal elastic effect to be output from a pin of the quartz tuning fork; the electrical signal corresponds to a photoelastic spectrum signal of the incident laser.
9. The method of claim 8, wherein the signal amplitude of the photoelastic spectral signal is highest when the laser light is incident from the outside face preset position; the height of the preset position is the same as the height of the connecting point of the U-shaped cambered surface of the tuning fork base and the rectangular tuning fork oscillating arm.
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