A dual-component gas detection system and method based on photo-thermal elastic spectroscopy

Abstract

The application discloses a two-component gas detection system and method based on photo-induced thermoelastic spectrum. The detection system comprises a laser generating device, the laser generating device is connected with a gas chamber, the gas chamber is connected with a sensing device, the sensing device is connected with an output device, the laser generating device comprises two sets of DFB driving controllers and DFB lasers, the two sets of DFB driving controllers and the DFB lasers are jointly connected with a coupler, and the coupler is connected with the gas chamber; the sensing device comprises a first tuning fork and a second tuning fork which are oppositely arranged, adjacent fork arms of the first tuning fork and the second tuning fork are close to each other but not in contact with each other, a laser beam output from the gas chamber passes between the adjacent fork arms of the first tuning fork and the second tuning fork and hits the first tuning fork and the second tuning fork at the same time. A collimator is arranged between the gas chamber and the sensing device. The output device comprises a preamplifier, the preamplifier is connected with a phase-locked amplifier, the phase-locked amplifier is connected with a data collector, and the data collector is connected with a computer. The application has simple and reasonable structure and can simultaneously complete detection of two-component gas.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gas detection, and particularly relates to a dual-component gas detection system and method based on photo-thermal elastic spectroscopy. BACKGROUND

[0002] The gas detection technology is widely used in modern society: the determination of harmful gas content in the air, the concentration detection of special gas in the chemical and medical fields, the emission concentration detection of coal pollution gas, etc. all cannot do without this technology. However, the current gas detection technology also has the problem of single gas sensing component, and the realization of multi-component gas sensing still mostly needs to adopt the mode of "multi-component detection multi-sensor", and in some occasions, the gas is corrosive, and the contact type detection may damage the tuning fork, which greatly limits the use scene.

[0003] The photo-thermal elastic spectroscopy technology is a relatively mature technology at present, which refers to that after a material is irradiated by light, the photon energy interacts with the crystal lattice, the vibration is intensified, the temperature is raised, and the electrical properties of the material are changed due to the change of the temperature. The photo-thermal elastic spectroscopy technology can improve the sensitivity and detection limit through the power and the absorption optical path, has the advantages of convenient detection, low cost, etc., and can be well applied in high-precision occasions. SUMMARY

[0004] In order to overcome the above technical problems, the application provides a dual-component gas detection system and method based on photo-thermal elastic spectroscopy, two beams of laser with different wave bands are combined, then pass through the gas chamber, and then hit two tuning forks with different resonance frequencies at the same time, so as to realize non-contact detection and achieve the effect of simultaneously detecting two-component gas.

[0005] In order to achieve the above purpose, the application adopts the following technical scheme:

[0006] A dual-component gas detection system based on photo-thermal elastic spectrum, comprising a laser generating device, the laser generating device is connected with a gas chamber, the gas chamber is connected with a sensing device, the sensing device is connected with an output device, the laser generating device comprises a DFB driving controller one and a DFB driving controller two, the DFB driving controller one is connected with a DFB laser one, the DFB driving controller two is connected with a DFB laser two, the DFB laser one and the DFB laser two are collectively connected with a coupler, the DFB laser one and the DFB laser two are both narrow-line-width modulatable semiconductor continuous light lasers, the DFB laser one and the DFB laser two are different in output wavelength and can correspond to the absorption peaks of two kinds of measured gases respectively to realize targeted detection; the output end of the coupler is connected with the gas chamber; the sensing device comprises a tuning fork one and a tuning fork two, the resonance frequencies of the tuning fork one and the tuning fork two are different, the tuning fork one and the tuning fork two are placed side by side and the fork surfaces are located in the same plane, the tuning fork one is placed in a forward direction, the tuning fork two is inverted, the adjacent fork arms of the tuning fork one and the tuning fork two are close but not in contact; the laser beam output by the gas chamber passes between the adjacent fork arms of the tuning fork one and the tuning fork two and hits the tuning fork one and the tuning fork two at the same time, a 0.3mm large-spot collimator is arranged between the gas chamber and the sensing device to ensure that the laser can hit the tuning fork one and the tuning fork two at the same time.

[0007] The DFB driving controller one provides driving current and temperature control and provides driving signals for the DFB laser one; the DFB driving controller two provides driving current and temperature control and provides driving signals for the DFB laser two; the coupler enters the gas chamber after light combination; the laser emitted by the gas chamber enters the tuning fork one and the tuning fork two with different resonance frequencies through the collimator; the tuning fork one and the tuning fork two will generate photo-thermal elastic effect after absorbing laser energy and generate current signals respectively; the output device collects, analyzes and processes the electric signals to obtain the final detection result.

[0008] The gas chamber adopts a long optical path absorption gas chamber, which can improve the absorption optical path and improve the sensitivity and detection limit of gas detection.

[0009] The output device comprises a preamplifier connected with the output end of the sensing device, the preamplifier is connected with a lock-in amplifier, the lock-in amplifier is connected with a data collector, and the data collector is connected with a computer; after the electric signals generated by the tuning fork one and the tuning fork two enter the preamplifier, the preamplifier realizes the conversion of the current signals to voltage signals and amplifies them; the lock-in amplifier demodulates the voltage signals; the data collector collects the demodulated voltage signal data and then transmits the data to the computer for signal processing and gas concentration calculation.

[0010] A dual-component gas detection method based on photo-thermal elastic spectrum, comprising the following steps:

[0011] S1. According to the absorption peaks of two measured gases X and Y, the DFB driving controller one provides driving current and temperature control, and provides driving signal for the DFB laser one, so that the DFB laser one emits laser corresponding to the absorption peak wavelength of the gas X; the DFB driving controller two provides driving current and temperature control, and provides driving signal for the DFB laser two, so that the DFB laser two emits laser corresponding to the absorption peak wavelength of the gas Y; the coupler combines the two different wavelength lasers emitted by the DFB laser one and the DFB laser two and then emits into the gas chamber;

[0012] S2. The to-be-detected gas enters the gas chamber from the gas inlet, and the laser emitted from the gas chamber enters the arms of the tuning fork one and the tuning fork two through the collimator; the tuning fork one and the tuning fork two generate photo-thermal-elastic effect after absorbing the laser energy, and respectively generate current signals;

[0013] S3. After the electric signals generated by the tuning fork one and the tuning fork two enter the preamplifier, the preamplifier realizes conversion of the current signals into voltage signals and amplifies the voltage signals; the lock-in amplifier demodulates the voltage signals; the data collector collects the demodulated voltage signal data, and then transmits the data to the computer for signal processing and calculation of the gas concentration, so as to finally complete the detection of the dual-component gas.

[0014] Compared with the prior art, the beneficial effects of the present application are:

[0015] 1. In the present application, the sensing device is improved from the traditional single tuning fork into the upper and lower staggered double tuning fork placement mode; the laser hits the arms of the two tuning forks, and the two tuning forks generate photo-thermal-elastic effect after absorbing the laser energy, and respectively generate current signals; based on the photo-thermal-elastic spectrum technology and the frequency division multiplexing technology, the purpose of realizing the detection of the dual-component gas by using single light beam and double tuning forks is achieved.

[0016] 2. The present application sets the laser generating device connected to the gas chamber connected to the collimator connected to the sensing device; compared with the quartz enhanced photoacoustic spectrum technology, the non-contact detection can be realized, the tuning fork can be prevented from being damaged due to the corrosiveness of the gas in some cases, and the long optical path absorption gas chamber is used to further improve the detection precision and sensitivity by increasing the absorption optical path. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is the overall schematic diagram of the present application;

[0018] Figure 2 is the sensing device schematic diagram in the present application. DETAILED DESCRIPTION

[0019] Embodiments of the present application are described below in detail with reference to the drawings, examples of which are shown in the drawings, wherein the same or similar notations are used to denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are used only for explanation of the present application, and cannot be understood as a limitation of the present application.

[0020] A dual-component gas detection system based on photothermal elastic spectroscopy, comprising a laser generating device, the laser generating device is connected to a gas chamber, the gas chamber is connected to a sensing device, the sensing device is connected to an output device, the laser generating device comprises a DFB driving controller one and a DFB driving controller two, the DFB driving controller one is connected to a DFB laser one, the DFB driving controller two is connected to a DFB laser two, the DFB laser one and the DFB laser two are jointly connected to a coupler; the output end of the coupler is connected to the gas chamber; the sensing device comprises a tuning fork one and a tuning fork two, the resonance frequencies of the tuning fork one and the tuning fork two are different, the tuning fork one and the tuning fork two are placed side by side and the fork surfaces are located in the same plane, the tuning fork one is placed in a forward direction, the tuning fork two is placed in an inverted direction, the adjacent fork arms of the tuning fork one and the tuning fork two are close but not in contact; the laser beam output from the gas chamber passes between the adjacent fork arms of the tuning fork one and the tuning fork two and hits the tuning fork one and the tuning fork two at the same time. A collimator is arranged between the gas chamber and the sensing device. The gas chamber adopts a long optical path absorption gas chamber. The output device comprises a preamplifier connected to the output end of the sensing device, the preamplifier is connected to a lock-in amplifier, the lock-in amplifier is connected to a data acquisition device, and the data acquisition device is connected to a computer.

[0021] A dual-component gas detection method based on photothermal elastic spectroscopy, comprising the following steps:

[0022] S1. Adjusting the laser generating device according to the absorption peaks of two measured gases X and Y, the DFB driving controller one provides driving current and temperature control and provides driving signals for the DFB laser one, so that the DFB laser one emits laser corresponding to the absorption peak wavelength of the gas X; the DFB driving controller two provides driving current and temperature control and provides driving signals for the DFB laser two, so that the DFB laser two emits laser corresponding to the absorption peak wavelength of the gas Y; the coupler combines the two different wavelength lasers emitted by the DFB laser one and the DFB laser two and then shoots into the gas chamber;

[0023] S2. The gas to be detected enters the gas chamber from the gas inlet and exits the gas chamber from the gas outlet, the laser emitted from the gas chamber enters the fork arms of the tuning fork one and the tuning fork two through the collimator, and the tuning fork one and the tuning fork two generate photo-thermal elastic effect after absorbing laser energy and generate current signals respectively;

[0024] S3. The electrical signals generated by tuning fork one and tuning fork two enter the preamplifier, the preamplifier converts the current signal to a voltage signal and amplifies it, the lock-in amplifier demodulates the voltage signal, the data collector collects the demodulated voltage signal data, then transmits the data to the computer, performs signal processing and gas concentration calculation, and finally completes the detection of the two-component gas.

[0025] The gas chamber adopts a long optical path absorption gas chamber, which can improve the absorption optical path and improve the sensitivity and detection limit of gas detection.

[0026] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and deformations can be made to the above embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A dual component gas detection system based on photo-thermal spectrum, comprising a laser generating device, said laser generating device connected to a gas chamber, said gas chamber connected to a sensing device, said sensing device connected to an output device, characterized in that, The laser generating device comprises a DFB driving controller I and a DFB driving controller II, the DFB driving controller I is connected with a DFB laser I, the DFB driving controller II is connected with a DFB laser II, and the DFB laser I and the DFB laser II are jointly connected with a coupler; the output wavelengths of the DFB laser I and the DFB laser II are different; The output end of the coupler is connected with a gas chamber; The sensing device comprises a tuning fork I and a tuning fork II, the resonance frequencies of the tuning fork I and the tuning fork II are different, the tuning fork I and the tuning fork II are placed side by side and the fork surfaces are located in the same plane, the tuning fork I is placed in a normal direction, the tuning fork II is placed in an inverted direction, and the adjacent fork arms of the tuning fork I and the tuning fork II are close but not in contact; The laser beam output by the gas chamber passes between the adjacent fork arms of the tuning fork I and the tuning fork II and hits the tuning fork I and the tuning fork II at the same time; A collimator is arranged between the gas chamber and the sensing device; The collimator adopts a 0.3mm large spot collimator; The gas chamber adopts a long optical path absorption gas chamber; The output device comprises a preamplifier connected with the output end of the sensing device, the preamplifier is connected with a lock-in amplifier, the lock-in amplifier is connected with a data collector, and the data collector is connected with a computer.

2. A method for detecting a binary gas based on photo-thermal elastic spectroscopy, characterized in that, The two-component gas detection system based on the photo-thermal elastic spectrum comprises the following steps: S1. The laser generating device is adjusted according to the absorption peaks of two measured gases X and Y, the DFB driving controller I provides driving current and temperature control and provides a driving signal for the DFB laser I, so that the DFB laser I emits laser corresponding to the absorption peak wavelength of the gas X; the DFB driving controller II provides driving current and temperature control and provides a driving signal for the DFB laser II, so that the DFB laser II emits laser corresponding to the absorption peak wavelength of the gas Y; and the coupler combines the two different wavelength lasers emitted by the DFB laser I and the DFB laser II and then emits the combined laser into the gas chamber; S2. The to-be-detected gas enters the gas chamber from the gas inlet and exits the gas chamber from the gas outlet, the laser emitted by the gas chamber enters the fork arms of the tuning fork I and the tuning fork II through the collimator, and the tuning fork I and the tuning fork II generate current signals after absorbing the laser energy and generating the photo-thermal elastic effect; S3. After the current signals generated by the tuning fork I and the tuning fork II enter the preamplifier, the preamplifier converts the current signals into voltage signals and amplifies the voltage signals, the lock-in amplifier demodulates the voltage signals, the data collector collects the demodulated voltage signal data, and then transmits the data to the computer for signal processing and gas concentration calculation, and finally completes the detection of the two-component gas.

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