Multi-pass enhanced Helmholtz photoacoustic spectrometry gas detection device

Abstract

The utility model discloses a multi-pass enhanced Helmholtz photoacoustic spectrometry gas detection device in the technical field of gas detection, which comprises a circuit module, a photoacoustic detection component, an optical component and two groups of fixing mechanisms, the circuit module comprises a laser driving circuit, a modulation-demodulation circuit and a power panel, the photoacoustic detection assembly comprises a differential Helmholtz resonant cavity, a microphone and a cavity fixing frame, the optical assembly comprises a laser, a laser collimator and an EDFA, the two sets of fixing mechanisms correspond to the left side and the right side of the photoacoustic detection assembly respectively, and control mechanisms are arranged in front of the tops of the two sets of fixing mechanisms. Mounting frames are arranged at the tops of the two groups of fixing mechanisms, an incident end reflecting mirror is arranged on the mounting frame on the left side, and an emergent end reflecting mirror is arranged on the mounting frame on the right side, so that the problems that an existing detection device is relatively complicated in structure, relatively complicated in operation and relatively poor in applicability, and is not suitable for large-scale popularization due to a large number of parts are solved.

Description

Technical Field

[0001] The utility model relates to the technical field of gas detection, in particular to a multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device. Background Art

[0002] Photoacoustic spectroscopy has become one of the current popular trace gas detection technologies due to its advantages such as fast response speed, small gas sampling volume, long working life, high sensitivity, and good selectivity. When the target gas molecules in the cavity are excited by the laser source, the molecules in the ground state will jump to the excited state. However, the excited molecules are unstable, so they will release all or part of the absorbed light energy as heat energy through non-radiative relaxation, which causes the local temperature of the sample to increase, resulting in thermal expansion, and further increasing the gas pressure. By modulating the incident light periodically, the accumulated heat source causes a temperature change at the same frequency, thus presenting a periodic pressure wave. Demodulating the sound pressure change detected by the microphone can obtain the concentration information of the target gas. Since photoacoustic spectroscopy is an indirect absorption spectroscopy technology and there is no need to detect the optical signal during the detection process, laser interference and incident light intensity fluctuations will not affect it, and combining with wavelength modulation technology can effectively eliminate the background signal absorbed from the window and cell wall, which is also the reason why the detection sensitivity of photoacoustic spectroscopy technology is relatively high.

[0003] However, the existing detection devices have a relatively complex structure and many parts, are not suitable for large-scale promotion, and have cumbersome operations and poor applicability. Summary of the Utility Model

[0004] The purpose of this part is to outline some aspects of the embodiments of the utility model and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this part, as well as in the abstract and the name of the utility model of the specification, to avoid obscuring the purpose of this part, the abstract, and the name of the utility model. However, such simplifications or omissions shall not be used to limit the scope of the utility model.

[0005] Therefore, the purpose of the utility model is to provide a multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device, which can solve the problems that the existing detection devices have a relatively complex structure, many parts, are not suitable for large-scale promotion, have cumbersome operations, and poor applicability.

[0006] To solve the above technical problems, the present utility model provides a multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device, adopting the following technical solutions: It includes a circuit module, a photoacoustic detection component, an optical component, and two groups of fixing mechanisms. The circuit module includes a laser drive circuit, a modulation and demodulation circuit, and a power supply board. The photoacoustic detection component includes a differential Helmholtz resonator, a microphone, and a cavity fixing bracket. The optical component includes a laser, a laser collimator, and an EDFA. The two groups of fixing mechanisms are respectively located on the left and right sides of the photoacoustic detection component. Control mechanisms are provided in front of the tops of the two groups of fixing mechanisms. Mounting brackets are provided on the tops of the two groups of fixing mechanisms. An incident end mirror is provided on the left mounting bracket, and an exit end mirror is provided on the right mounting bracket.

[0007] Optionally, the laser drive circuit is connected to the modulation and demodulation circuit. Both the laser drive circuit and the modulation and demodulation circuit are electrically connected to the power supply board. The modulation and demodulation circuit is connected to the microphone.

[0008] By adopting the above technical solution, both the laser drive circuit and the modulation and demodulation circuit are electrically connected to the power supply board.

[0009] Optionally, the laser drive circuit includes a temperature control module and a current control module. The temperature control module uses a TEC temperature control chip. The current control module uses a feedback amplifier circuit. The modulation and demodulation circuit includes a signal generation module, a detector receiving module, and a demodulation module.

[0010] By adopting the above technical solution, the laser drive circuit is set.

[0011] Optionally, the microphone is vertically arranged inside the differential Helmholtz resonator cavity, and the cavity fixing bracket is sleeved outside the differential Helmholtz resonator.

[0012] By adopting the above technical solution, the microphone is installed and set.

[0013] Optionally, the laser is a tunable semiconductor laser. The laser is connected to the EDFA, and the EDFA is connected to the laser collimator.

[0014] By adopting the above technical solution, the laser is connected.

[0015] Optionally, the fixing mechanism includes a fixing box. A fixing rod is provided at the top of the fixing box. A lifting groove is formed at the top of the fixing rod. A lifting rod is arranged in the lifting groove. The top of the lifting rod is fixedly connected to the mounting bracket. A lifting screw rod is screwed inside the cavity of the lifting rod. The bottom of the lifting screw rod is rotatably connected in the lifting groove. A lifting gear is sleeved on the outer side of the lifting screw rod. A driving rod is rotatably connected to the right side of the fixing rod. A driving handle is provided on the right side of the driving rod. A driving gear is provided on the left side of the driving rod. Both the driving gear and the lifting gear are bevel gears. The driving gear and the lifting gear are meshed with each other. The control mechanism includes a control screw rod.

[0016] By adopting the above technical solution, the height of the mounting bracket is adjusted.

[0017] Optionally, a rotating rod is provided at the bottom of the fixing rod. The rotating rod is rotatably connected inside the fixing box. A control groove is formed inside the fixing box. The control screw rod is rotatably connected in the control groove. The right side of the control screw rod penetrates through the fixing box. A control handle is provided on the right side of the control screw rod. The control screw rod is a forward and reverse screw rod. Two control sliding plates adapted to the control groove are screwed on the control screw rod. Both of the two control sliding plates are slidably connected in the control groove. Control side plates are provided at the bottoms of the two control sliding plates. Control rods are provided on the sides of the two control side plates close to each other. Clamping plates are provided on the sides of the two control rods close to each other. The two clamping plates are respectively arranged on both sides of the rotating rod.

[0018] By adopting the above technical solution, the angle of the mounting bracket is adjusted.

[0019] In summary, the present utility model has at least the following beneficial effects: simple structure, few components, suitable for large-scale promotion. At the same time, an optoacoustic spectroscopy gas detection device combining a Herriott multi-pass cell, an EDFA, and a differential Helmholtz resonator is provided. While ensuring a small volume, high-sensitivity optoacoustic signal detection is realized. The operation is simple, the result is accurate and intuitive, the operation difficulty of the equipment is reduced, and the practicability of the equipment is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for describing the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a schematic structural diagram of the present utility model;

[0022] Figure 2Schematic structural diagram of the fixing mechanism of the present utility model;

[0023] Figure 3 Schematic sectional structural diagram of the fixing mechanism of the present utility model;

[0024] Figure 4 Schematic sectional structural diagram of the control mechanism of the present utility model.

[0025] Description of reference numerals: 1. Circuit module; 101. Laser drive circuit; 102. Modulation and demodulation circuit; 103. Power supply board; 2. Fixing mechanism; 201. Fixing box; 2011. Control groove; 202. Fixing rod; 2022. Rotating rod; 203. Lifting groove; 204. Lifting rod; 205. Lifting lead screw; 206. Lifting gear; 207. Driving rod; 208. Driving handle; 209. Driving gear; 3. Photoacoustic detection component; 301. Differential Helmholtz resonator; 302. Microphone; 303. Cavity fixing bracket; 4. Optical component; 401. Laser; 402. Laser collimator; 403. EDFA; 5. Control mechanism; 501. Control lead screw; 502. Control handle; 503. Control slide plate; 504. Control side plate; 505. Control rod; 506. Clamping plate; 6. Mounting bracket; 7. Incident end mirror; 8. Exit end mirror. Detailed implementation manners

[0026] The following is a further detailed description of the present utility model in conjunction with the attached Figures 1-4 drawings.

[0027] In the first embodiment, referring to Figure 1 , in order to solve the problems that the existing detection device has a relatively complex structure, many parts, is not suitable for large-scale popularization, and has cumbersome operation and poor applicability, the present utility model discloses a multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device, including a circuit module 1, a photoacoustic detection component 3, an optical component 4 and two groups of fixing mechanisms 2, characterized in that: the circuit module 1 includes a laser drive circuit 101, a modulation and demodulation circuit 102 and a power supply board 103, the photoacoustic detection component 3 includes a differential Helmholtz resonator 301, a microphone 302 and a cavity fixing bracket 303, the optical component 4 includes a laser 401, a laser collimator 402 and an EDFA 403, the two groups of fixing mechanisms 2 are respectively located on the left and right sides of the photoacoustic detection component 3, control mechanisms 5 are provided in front of the tops of the two groups of fixing mechanisms 2, mounting brackets 6 are provided on the tops of the two groups of fixing mechanisms 2, an incident end mirror 7 is provided on the left mounting bracket 6, and an exit end mirror 8 is provided on the right mounting bracket 6.

[0028] Based on the above characteristics, the working principle of this embodiment is as follows: First, the laser driver circuit 101 drives the laser 401. The laser emitted by the laser 401 is amplified in power by the EDFA 403 and then irradiated onto the laser collimator 402. Subsequently, it enters the fixing mechanism 2 through the laser collimator 402, and then reflects back and forth between the incident end mirror 7 and the exit end mirror 8. The optical path can be controlled by adjusting the fixing mechanism 2 and the control mechanism 5. The differential Helmholtz resonator 301 is fixed by the cavity fixing frame 303 and placed between the incident end mirror 7 and the exit end mirror 8, enabling the laser to pass through the resonator cavity multiple times. The excited acoustic signal is collected by the microphone 302. At the same time, the acoustic signal with the opposite phase generated in the reference cavity is collected by the microphone 302 on this cavity. The signals of the two microphones are connected to the modulation and demodulation circuit and demodulated into a second harmonic (2f) signal after differential amplification. Information such as the concentration of the gas in the cavity can be obtained by analyzing the 2f signal.

[0029] Embodiment 2, referring to Figures 1-4, in this embodiment, in order to solve the problems that the existing detection device has a relatively complex structure, many parts, is not suitable for large-scale promotion, and has cumbersome operation and poor applicability. Based on the same concept as in the above-mentioned Embodiment 1, this multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device further includes a laser driving circuit 101 connected to a modulation and demodulation circuit 102. Both the laser driving circuit 101 and the modulation and demodulation circuit 102 are electrically connected to a power supply board 103. The modulation and demodulation circuit 102 is connected to a microphone 302. The laser driving circuit 101 includes a temperature control module and a current control module. The temperature control module uses a TEC temperature control chip, and the current control module uses a feedback amplifier circuit. The modulation and demodulation circuit 102 includes a signal generation module, a detector receiving module, and a demodulation module. The microphone 302 is vertically arranged inside the cavity of the differential Helmholtz resonator 301. A cavity fixing frame 303 is sleeved outside the differential Helmholtz resonator 301. The laser 401 is a tunable semiconductor laser. The laser 401 is connected to an EDFA 403, and the EDFA 403 is connected to a laser collimator 402. The fixing mechanism 2 includes a fixing box 201. A fixing rod 202 is provided at the top of the fixing box 201. A lifting groove 203 is opened at the top of the fixing rod 202. A lifting rod 204 is arranged inside the lifting groove 203. The top of the lifting rod 204 is fixedly connected to a mounting frame 6. A lifting lead screw 205 is screwed inside the cavity of the lifting rod 204. The bottom of the lifting lead screw 205 is rotatably connected inside the lifting groove 203. A lifting gear 206 is sleeved outside the lifting lead screw 205. A driving rod 207 is rotatably connected to the right side of the fixing rod 202. A driving handle 208 is provided on the right side of the driving rod 207. A driving gear 209 is provided on the left side of the driving rod 207. Both the driving gear 209 and the lifting gear 206 are bevel gears, and the driving gear 209 and the lifting gear 206 are meshed with each other. The control mechanism 5 includes a control lead screw 501. A rotating rod 2022 is provided at the bottom of the fixing rod 202. The rotating rod 2022 is rotatably connected inside the cavity of the fixing box 201. A control groove 2011 is opened inside the fixing box 201. The control lead screw 501 is rotatably connected inside the control groove 2011. The right side of the control lead screw 501 penetrates through the fixing box 201. A control handle 502 is provided on the right side of the control lead screw 501. The control lead screw 501 is a forward and reverse lead screw. Two control sliding plates 503 adapted to the control groove 2011 are screwed on the control lead screw 501. Both groups of control sliding plates 503 are slidably connected inside the control groove 2011. Control side plates 504 are provided at the bottoms of both groups of control sliding plates 503. Control rods 505 are provided on the sides of both groups of control side plates 504 close to each other. Clamping plates 506 are provided on the sides of both groups of control rods 505 close to each other. The two clamping plates 506 are respectively arranged on both sides of the rotating rod 2022.

[0030] Based on the above features, the working principle of this embodiment is as follows: Rotating the driving handle 208 drives the driving rod 207 to rotate. The driving rod 207 drives the driving gear 209 to rotate. The driving gear 209 drives the engaged lifting gear 206 to rotate. The lifting gear 206 drives the lifting screw rod 205 to rotate. The lifting screw rod 205 drives the lifting rod 204 to rotate. Under the limitation of the lifting groove 203, the lifting rod 204 moves upward, driving the mounting bracket 6 to rotate, adjusting the heights of the incident end mirror 7 and the exit end mirror 8. Rotating the control handle 502 forward drives the control screw rod 501 to rotate forward. The control screw rod 501 drives the two control sliding plates 503 to rotate. Under the limitation of the control groove 2011, the two control sliding plates 503 move away from each other. The two control sliding plates 503 respectively drive the two control side plates 504 to move away from each other. The two control side plates 504 respectively drive the two control rods 505 to move away from each other. The two control rods 505 respectively drive the two clamping plates 506 to move away from each other, canceling the clamping and fixing of the rotating rod 2022. Rotating the fixing rod 202 drives the lifting rod 204 and the rotating rod 2022 to rotate. The lifting rod 204 drives the mounting bracket 6 to rotate. The mounting bracket 6 drives the incident end mirror 7 and the exit end mirror 8 to rotate. After the adjustment is completed, rotating the control handle 502 in the reverse direction drives the two control sliding plates 503 to move closer to each other. The two control sliding plates 503 respectively drive the two clamping plates 506 to move closer to each other, clamping and fixing the rotating rod 2022, and completing the angle adjustment.

[0031] The above are all the preferred embodiments of the present invention, and the protection scope of the present invention is not limited by this. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device, comprising a circuit module (1), a photoacoustic detection component (3), an optical component (4) and two sets of fixing mechanisms (2), characterized in that: The circuit module (1) comprises a laser driving circuit (101), a modulation and demodulation circuit (102) and a power board (103); the photoacoustic detection component (3) comprises a differential Helmholtz resonant cavity (301), a microphone (302) and a cavity fixing frame (303); the optical component (4) comprises a laser (401), a laser collimator (402) and an EDFA (403); two sets of fixing mechanisms (2) are respectively provided on the left and right sides of the photoacoustic detection component (3); a control mechanism (5) is provided in front of the top of the two sets of fixing mechanisms (2); a mounting frame (6) is provided on the top of the two sets of fixing mechanisms (2); an incident end reflector (7) is provided on the left mounting frame (6); and an exit end reflector (8) is provided on the right mounting frame (6).

2. The multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device according to claim 1, characterized in that: The laser driving circuit (101) is connected to the modulation and demodulation circuit (102), and the laser driving circuit (101) and the modulation and demodulation circuit (102) are both connected to the power board (103) by wires, and the modulation and demodulation circuit (102) is connected to the microphone (302).

3. The multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device according to claim 1, characterized in that: The laser driving circuit (101) comprises a temperature control module and a current control module, the temperature control module adopts a TEC temperature control chip, the current control module adopts a feedback amplification circuit, and the modulation and demodulation circuit (102) comprises a signal generating module, a detector receiving module and a demodulation module.

4. The multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device according to claim 1, characterized in that: The microphone (302) is vertically arranged in the inner cavity of the differential Helmholtz resonant cavity (301), and the cavity fixing frame (303) is sleeved on the outer side of the differential Helmholtz resonant cavity (301).

5. The multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device according to claim 1, characterized in that: The laser (401) is a tunable semiconductor laser, the laser (401) is connected to an EDFA (403), and the EDFA (403) is connected to a laser collimator (402).

6. The multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device according to claim 1, characterized in that: The fixing mechanism (2) comprises a fixing box (201), a fixing rod (202) is provided at the top of the fixing box (201), a lifting slot (203) is provided at the top of the fixing rod (202), a lifting rod (204) is provided in the lifting slot (203), the top of the lifting rod (204) is fixedly connected to the mounting frame (6), a lifting screw rod (205) is screwed into the inner cavity of the lifting rod (204), the bottom of the lifting screw rod (205) is rotatably connected in the lifting slot (203), and the lifting rod (204) is fixedly connected to the mounting frame (6). The outer side of the screw rod (205) is sleeved with a lifting gear (206); the right side of the fixed rod (202) is rotatably connected to a driving rod (207); the right side of the driving rod (207) is provided with a driving handle (208); the left side of the driving rod (207) is provided with a driving gear (209); the driving gear (209) and the lifting gear (206) are both bevel gears; the driving gear (209) and the lifting gear (206) are meshed with each other; and the control mechanism (5) comprises a control screw rod (501).

7. The multi-pass enhanced Helmholtz photoacoustic spectroscopy gas detection device according to claim 6, characterized in that: The bottom of the fixed rod (202) is provided with a rotating rod (2022), and the rotating rod (2022) is rotatably connected to the inner cavity of the fixed box (201). A control groove (2011) is opened in the fixed box (201), and the control screw rod (501) is rotatably connected in the control groove (2011). The right side of the control screw rod (501) passes through the fixed box (201), and the right side of the control screw rod (501) is provided with a control handle (502). The control screw rod (501) is a forward and reverse screw rod. The control screw rod (501) ) are screwed with two groups of control slide plates (503) adapted to the control groove (2011), the two groups of control slide plates (503) are slidably connected in the control groove (2011), the bottoms of the two groups of control slide plates (503) are provided with control side plates (504), the sides of the two groups of control side plates (504) close to each other are provided with control rods (505), the sides of the two groups of control rods (505) close to each other are provided with clamping plates (506), and the two groups of clamping plates (506) are respectively arranged on both sides of the rotating rod (2022).

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