Handheld photoacoustic spectrum measuring instrument

Abstract

The utility model relates to the technical field of gas detection, and provides a handheld photoacoustic spectrum measuring instrument which comprises a shell, a photoacoustic cell capable of being filled with gas to be detected and a laser device providing a light source for the photoacoustic cell, the photoacoustic cell and the laser device are both arranged in the shell, a heat insulation sleeve is arranged outside the photoacoustic cell, and the heat insulation sleeve is arranged in the shell. And a semiconductor refrigerator is also arranged on the photoacoustic cell. According to the handheld photoacoustic spectrum measuring instrument disclosed by the utility model, the heat insulation sleeve is arranged outside the photoacoustic cell, so that heat generated by power consumption devices such as a mainboard in the shell can be blocked, the influence on the photoacoustic cell is avoided, and meanwhile, the temperature of the photoacoustic cell can be autonomously regulated and controlled by adopting the semiconductor cooler, so that the detection precision is more controllable.

Description

Technical Field

[0001] This utility model relates to the field of gas detection technology, specifically a handheld photoacoustic spectrometer. Background Technology

[0002] Photoacoustic spectroscopy measurement equipment uses a laser in conjunction with a photoacoustic cell to detect gas concentration through the photoacoustic principle. The photoacoustic cell is the core component. When it is working, the gas to be measured absorbs the laser and generates a temperature change in the photoacoustic cell to complete the photoacoustic conversion. Therefore, the temperature change of the photoacoustic cell itself will affect the accuracy of gas concentration detection. In existing photoacoustic spectroscopy measurement equipment, the photoacoustic cell is directly placed in the housing, which will be affected by the heat generated by the main board inside the housing, resulting in low measurement accuracy. Utility Model Content

[0003] The purpose of this invention is to provide a handheld photoacoustic spectroscopy measuring instrument, which can at least solve some of the defects in the prior art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a handheld photoacoustic spectrometer, comprising a housing, a photoacoustic cell into which a gas to be measured can be filled, and a laser that provides a light source for the photoacoustic cell. The photoacoustic cell and the laser are both disposed within the housing. A heat insulation sleeve is provided outside the photoacoustic cell, and a semiconductor cooler is also provided on the photoacoustic cell.

[0005] Furthermore, the heat insulation sleeve includes a plate covering the outside of the photoacoustic pool.

[0006] Furthermore, it also includes an acoustic wave detector for detecting the acoustic signal output by the photoacoustic cell.

[0007] Furthermore, the acoustic wave detector is electrically connected to the motherboard via a connector board.

[0008] Furthermore, the acoustic wave detector includes a microphone and an acoustic wave circuit board for mounting the microphone, and the acoustic wave circuit board is electrically connected to the motherboard through the connector.

[0009] Furthermore, the housing is provided with an inlet for filling the photoacoustic cell with the gas to be tested and an outlet for discharging the gas from the photoacoustic cell outside the housing.

[0010] Furthermore, the housing is also equipped with an air pump for drawing the gas to be tested into the photoacoustic cell.

[0011] Furthermore, it also includes a solenoid valve for controlling the opening and closing of the external air passage of the photoacoustic cell.

[0012] Furthermore, there are two solenoid valves, which are respectively located on the air path at the air inlet and the air path at the air outlet of the photoacoustic cell.

[0013] Furthermore, the photoacoustic cell is a dual-channel photoacoustic cell.

[0014] Compared with the prior art, the beneficial effects of this utility model are: a handheld photoacoustic spectrometer, by setting a heat insulation sleeve outside the photoacoustic cell, can block the heat generated by power-consuming devices such as the motherboard inside the shell, thus avoiding the impact on the photoacoustic cell. At the same time, the use of a semiconductor cooler can autonomously regulate the temperature of the photoacoustic cell, making the detection accuracy more controllable. Attached Figure Description

[0015] Figure 1 A perspective view of a handheld photoacoustic spectrometer provided for an embodiment of this utility model;

[0016] Figure 2 A schematic diagram of the internal structure of a handheld photoacoustic spectrometer after removing the casing, provided for an embodiment of this utility model;

[0017] Figure 3 A schematic diagram of the photoacoustic cell of a handheld photoacoustic spectrometer provided in this embodiment of the present invention;

[0018] Figure 4 A schematic diagram of the heat insulation sleeve of the photoacoustic cell of a handheld photoacoustic spectrometer provided for an embodiment of this utility model;

[0019] Figure 5 A schematic diagram showing the acoustic wave detector of the photoacoustic cell of a handheld photoacoustic spectrometer installed on the motherboard, as provided in an embodiment of this utility model.

[0020] In the attached diagram, the following labels are used: 1-Housing; 2-Photoacoustic cell; 3-Laser; 4-Heat insulation jacket; 5-Semiconductor cooler; 6-Heat insulation plate; 7-Connector; 8-Microphone; 9-Acoustic circuit board; 10-Main board; 11-Air inlet; 13-First solenoid valve; 14-Second solenoid valve; 15-Air pump. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0022] Please see Figures 1 to 5This utility model provides a handheld photoacoustic spectrometer, including a housing 1, a photoacoustic cell 2 for filling with a gas to be measured, and a laser 3 for providing a light source for the photoacoustic cell 2. Both the photoacoustic cell 2 and the laser 3 are housed within the housing 1. A heat insulation sleeve 4 is provided outside the photoacoustic cell 2, and a semiconductor cooler 5 is also provided on the photoacoustic cell 2. In this embodiment, by providing a heat insulation sleeve 4 outside the photoacoustic cell 2, heat generated by power-consuming devices such as the motherboard 10 inside the housing 1 can be blocked, preventing it from affecting the photoacoustic cell 2. Simultaneously, the use of the semiconductor cooler 5 allows for autonomous temperature control of the photoacoustic cell 2, making the detection accuracy more controllable. Specifically, the working principle of this measuring instrument is consistent with that of existing photoacoustic spectroscopy measuring instruments. Both involve a laser beam entering the photoacoustic cell 2, where photoacoustic conversion is achieved through the photoacoustic effect. The resulting signal is then processed by the mainboard 10 to calculate the concentration of the gas to be measured. The circuitry on the mainboard 10 is existing, and its processing and control are based on existing technology. The specific working principle is as follows: Photoacoustic spectroscopy is based on the photoacoustic effect, converting the modulated light signal into an acoustic signal in the photoacoustic cell 2. A high-sensitivity acoustic detector is then used to measure this acoustic signal. The intensity of the photoacoustic signal is proportional to the gas concentration and the amount of absorbed light energy. This indirect measurement method theoretically achieves extremely high detection sensitivity. Later, the continuous development of laser technology provided an ideal light source for photoacoustic spectroscopy detection technology, and the research on high-performance microphones improved the detection limit, sensitivity, and signal-to-noise ratio of gas in photoacoustic spectroscopy. The detectable gases using photoacoustic spectroscopy are constantly increasing, and its application range is continuously expanding. Therefore, applying photoacoustic spectroscopy to gas monitoring in transformer oil has very high practical value. According to quantum mechanics, when molecules are irradiated by photons of a specific frequency, they absorb photon energy and transition to higher energy levels. However, molecules in higher energy levels are unstable and will return to their ground state through non-radiative transitions. A portion of the released energy is converted into the average kinetic energy of the molecules, which macroscopically manifests as an increase in gas temperature. Therefore, if a periodically modulated light source is used for irradiation, a periodic temperature increase will occur. According to Avogadro's law, in a completely sealed environment (i.e., with a constant number of molecules and volume), this periodic temperature increase will generate periodic pressure. This periodic pressure change is a sound wave. Therefore, by detecting this sound wave, information about the gas in a sealed space can be obtained. This is the basic principle of photoacoustic spectroscopy for gas detection. The absorption of light energy by a gas essentially involves energy level transitions caused by gas molecules absorbing photon energy. Gas molecules in different states of motion have different energies. According to quantum mechanics, the energy of molecules in different states of motion is not continuous but quantized. This means that molecules can only exist in specific energy levels and there are no intermediate states. Furthermore, since the energy transfer of photons is also quantized, the process of molecules jumping from a low energy level to a high energy level can only be accomplished by absorbing photons of specific energies.In existing measuring instruments, the motherboard 10 generates heat during operation, which can easily affect the temperature of the photoacoustic cell 2, thus affecting its internal temperature. This embodiment cleverly incorporates a heat insulation sleeve 4 around the photoacoustic cell 2 to block the heat dissipation from the motherboard 10. The heat insulation sleeve 4 can utilize existing heat insulation materials, thereby improving the thermal stability of the photoacoustic cell 2. Furthermore, a TEC (thermal cooler 5) can be installed on the upper end of the photoacoustic cell 2, enabling the measuring instrument to autonomously adjust its temperature. The thermoelectric cooler 5 is existing technology, and its temperature control measures are readily available and will not be detailed here. The laser 3 is also existing technology. The optical fiber is not shown in the figures of this embodiment. The laser emitted by the laser 3 is transmitted through an optical fiber to the collimator before entering the interior of the photoacoustic cell 2. The optical fiber can be coiled according to the spatial arrangement within the housing 1.

[0023] Please see Figures 1 to 5 The heat insulation sleeve 4 includes a plate covering the outside of the photoacoustic cell 2. The heat insulation sleeve 4 can be integrally formed into a frame structure from the plate, or it can be assembled from multiple plates. Preferably, a heat insulation plate 6 is also provided above the heat insulation sleeve 4, which can also serve as a heat insulation function.

[0024] Please see Figures 1 to 5 The measuring instrument also includes an acoustic wave detector for detecting the acoustic signal output by the photoacoustic cell 2. In this embodiment, an acoustic wave detector can be used to detect the acoustic signal output by the photoacoustic cell 2. Preferably, the acoustic wave detector can be composed of a microphone 8 and an acoustic wave circuit board 9, which is existing technology. The microphone 8 can receive the acoustic signal and then the acoustic wave circuit board 9 transmits it to the main board 10. Preferably, in the prior art, most designs use an adapter board to transmit the acoustic signal to the main board 10, which is costly and makes the structure more complex. In this embodiment, a connector 7 is used to directly connect the acoustic wave circuit board 9 to the main board 10, which not only saves costs and simplifies the structure, but also reduces the number of signal transmissions and reduces signal noise.

[0025] Please see Figures 1 to 5 The housing 1 is provided with an inlet 11 for filling the photoacoustic cell 2 with the gas to be tested, and an outlet for exhausting the gas from the photoacoustic cell 2 out of the housing 1. In this embodiment, the gas to be tested can be filled into the photoacoustic cell 2 through the inlet 11, and the gas can be exhausted through the outlet after the measurement is completed.

[0026] Please see Figures 1 to 5 The housing 1 is further equipped with an air pump 15 for drawing the gas to be tested into the photoacoustic cell 2. In this embodiment, the air pump 15 can be used to draw the gas to be tested into the photoacoustic cell 2, which can improve the inflation efficiency.

[0027] Please see Figures 1 to 5An air passage is also provided inside the housing 1, and the opening and closing of the air passage can be controlled by a solenoid valve. Preferably, there are two solenoid valves, which are respectively located on the air passage at the air inlet and air outlet of the photoacoustic cell 2. The placement of two solenoid valves at the air inlet and outlet ensures that the photoacoustic cell 2 remains sealed during detection. In conjunction with the aforementioned air pump 15, the air passage connection is as follows: the air inlet 11 is connected to the air inlet of the air pump 15; the air outlet of the air pump 15 is connected to the air inlet of the first solenoid valve 13; the air outlet of the first solenoid valve 13 is connected to the air inlet of the photoacoustic cell 2; and the air outlet of the photoacoustic cell 2 is then connected to the air inlet of the second solenoid valve 14. The air outlet of the second solenoid valve 14 is connected to the air outlet. The two solenoid valves ensure that the photoacoustic cell 2 remains sealed during gas measurement.

[0028] Please see Figures 1 to 5 The photoacoustic cell 2 is a dual-channel photoacoustic cell 2. In this embodiment, the photoacoustic cell 2 can be a dual-channel photoacoustic cell 2, and correspondingly, two lasers 3 can be provided. The purpose of the two lasers 3 is to measure two different gases. The laser with the corresponding wavelength of the gas is selected. Two acoustic wave detectors can also be designed and set up side by side.

[0029] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A hand-held photoacoustic spectrometer comprising a housing, a photoacoustic cell into which a gas to be measured can be filled, and a laser which provides a light source for the photoacoustic cell, the photoacoustic cell and the laser being arranged in the housing, characterized in that: The photoacoustic cell is externally provided with a heat insulation sleeve, and the photoacoustic cell is further provided with a semiconductor refrigerator.

2. A hand-held photoacoustic spectrometer according to claim 1, wherein: The heat insulation sleeve comprises a plate body covering the photoacoustic cell.

3. The hand-held photoacoustic spectrometer of claim 1, wherein: The photoacoustic cell further comprises an acoustic wave detector for detecting the acoustic signal output by the photoacoustic cell.

4. A hand-held photoacoustic spectrometer according to claim 3, wherein: The acoustic wave detector is electrically connected with the main board through a connector board.

5. A hand-held photoacoustic spectrometer according to claim 4, wherein: The acoustic wave detector comprises a microphone and an acoustic wave circuit board for the microphone, and the acoustic wave circuit board is electrically connected with the main board through a connector.

6. The hand-held photoacoustic spectrometer of claim 1, wherein: The shell is provided with a gas inlet end for filling the photoacoustic cell with a gas to be measured and a gas outlet end for guiding the gas in the photoacoustic cell out of the shell.

7. The hand-held photoacoustic spectrometer of claim 1, wherein: The shell is further provided with a gas pump for pumping the gas to be measured to the photoacoustic cell.

8. The hand-held photoacoustic spectrometer of claim 1, wherein: The shell is further provided with electromagnetic valves for controlling the opening and closing of the external gas path of the photoacoustic cell.

9. A hand-held photoacoustic spectrometer according to claim 8, wherein: The electromagnetic valves are two, and the two electromagnetic valves are respectively arranged on the gas path at the gas inlet of the photoacoustic cell and on the gas path at the gas outlet of the photoacoustic cell.

10. The hand-held photoacoustic spectrometer of claim 1, wherein: The photoacoustic cell is a double-channel photoacoustic cell.

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