CN112924388B - Orthogonal double-channel acoustic resonance device - Google Patents

Abstract

The utility model provides an orthogonal binary channels acoustic resonance device, resonance device includes the square, and first side and second side are the adjacent side of square, be provided with the first chamber unit that passes first side and its opposite face on the square, pass the second chamber unit of second side and its opposite face, first chamber unit includes first resonant cavity and symmetrical coaxial first buffer chamber and the second buffer chamber that set up at first resonant cavity both ends, the second chamber unit includes second resonant cavity and symmetrical coaxial third buffer chamber and the fourth buffer chamber that set up at resonant cavity both ends, the intersection zone that first resonant cavity and second resonant cavity center formed is provided with the acoustic pipe of perpendicular to two resonant cavity constitution planes, be provided with acoustic sensor on the other end of acoustic pipe. The invention realizes the double-channel synchronous measurement, simultaneously provides multiplied detection sensitivity, and increases the sampling flow of the measurement system, thereby greatly expanding the applicable range.

Description

Orthogonal dual-channel acoustic resonance device

technical field

The invention relates to the technical field of atmospheric environmental pollutant monitoring, in particular to an orthogonal dual-channel acoustic resonance device.

Background technique

Photoacoustic spectroscopy is a spectroscopic technique based on the photoacoustic effect. The basic principle is that the sample particles absorb periodic light energy to generate weak pressure waves, namely sound waves. In photoacoustic spectroscopy, the weak acoustic signal of the acoustic resonator is usually used to amplify, so a good structure design of the acoustic resonator can effectively improve the detection sensitivity and detection limit. For example, the Chinese invention patent CN104697933B announced on June 12, 2017 a three-channel acoustic resonator photoacoustic spectrum sensing device. The invention patent uses three mutually parallel acoustic resonant cavities as the absorption channels of three different light-absorbing components. The three light sources generate acoustic signals through the acoustic resonant cavities, and the acoustic signals are transmitted to the Microphone detection. Although the use of three resonant cavities can realize multi-wavelength and multi-component trace gas absorption detection, the detection sensitivity of single component and single wavelength has not been improved. With the development of the field of atmospheric detection, especially the detection of weak absorbing components.

Contents of the invention

In order to further improve detection sensitivity and detection limit, the present invention proposes an orthogonal dual-channel acoustic resonance device. The specific scheme is as follows:

Orthogonal dual-channel acoustic resonance device, comprising a block, the first side and the second side are adjacent sides of the block, the block is provided with a first cavity unit passing through the first side and its opposite face, passing through the second side And the second cavity unit on the opposite side, the first cavity unit includes the first resonant cavity and the first buffer chamber and the second buffer chamber symmetrically and coaxially arranged at both ends of the first resonant cavity, the second cavity unit includes the first The second resonant cavity and the third buffer chamber and the fourth buffer chamber are arranged symmetrically and coaxially at both ends of the resonant cavity, and the intersection area formed by the center of the first resonant cavity and the second resonant cavity is provided with an acoustic wall perpendicular to the plane formed by the two resonant cavities. A conduit, the other end of which is provided with an acoustic sensor.

Optimally, the acoustic sensor is a microphone or a tuning fork.

Optimally, four holes corresponding to the buffer chambers are opened on the upper surface of the block, the holes on the first buffer chamber and the third buffer chamber are used as sampling holes, the second buffer chamber and the fourth buffer chamber are The holes on the chamber are sample outlets, the outer ends of the first buffer chamber and the third buffer chamber are used as incident windows, and the outer ends of the second buffer chamber and the fourth buffer chamber are used as outlet windows.

Optimally, the injection hole can input gas or aerosol particles.

Optimally, windows are provided on both the incident window and the exit window.

Optimally, the diameter range of the first resonant cavity and the second resonant cavity is 2-4 times the diameter of the laser beam.

Optimally, the length L1 of the first resonant cavity is equal to the length L2 of the second resonant cavity, the first resonant cavity, the second resonant cavity, wherein L1=L2=L, Lmin<L<Lmax, L=C /2f, C is the speed of sound, fmin=1000Hz, fmax=20000Hz; the length of the four buffer chambers is H=L/2, and the diameter of the buffer chamber is 2-4 times the diameter of the resonant cavity.

Optimized, also includes,

a laser assembly for generating a beam of light sent to the entrance window;

The beam splitting component divides the beam emitted by the laser component into two beams and sends them to two incident windows respectively;

The lock-in amplifier is connected with the output end of the acoustic sensor and the output end of the control signal source, and is used for receiving the reference signal provided by the control signal source and demodulating the photoacoustic spectrum signal in the corresponding resonant cavity sensed by the acoustic sensor.

Optimally, the laser component includes a control signal source, a laser controller, and a laser arranged sequentially along the optical path.

Optimally, the light splitting assembly includes a half-mirror, a first plane mirror, and a second plane mirror, and the beam of the laser is divided into a first beam and a second beam through the center of the half-mirror, and the The first light beam coincides with the central axis of the first cavity unit, and the second light beam enters the second cavity unit after being reflected by the first plane reflector and the second plane reflector in sequence and coincides with the central axis of the second cavity unit .

The beneficial effect of the present invention is that: the present invention adds a second-channel acoustic resonance device on the basis of a single-channel acoustic resonance device, and each acoustic resonance device independently realizes the resonance amplification of the acoustic signal, and reaches the maximum sound pressure at the center of the cavity . The two acoustic modules are placed orthogonally. Since the time for light to pass through the acoustic resonance of the two channels is much shorter than the thermal relaxation time of gas molecules or aerosol particles, the acoustic signals generated by the two acoustic resonance devices can be approximately considered to be the same It is generated at all times, and then the superposition of the two resonantly amplified acoustic signals can be realized at the intersection point, which provides a doubled detection sensitivity and increases the sampling flow of the measurement system, thus greatly expanding its applicable range.

Description of drawings

Fig. 1 is a structural principle diagram of a spectrum sensing device including an orthogonal dual-channel acoustic resonance device in the present invention.

Fig. 2 is a cross-sectional view of the resonator device.

Fig. 3 is a perspective view of a first chamber unit and a second chamber unit.

Fig. 4 is a distribution diagram of the eigenfrequency of the dual cavities in the resonant device.

Fig. 5 is a pressure distribution diagram of the double cavity in the resonant device at a resonant frequency of 1742 Hz.

Fig. 6 is a frequency response diagram of a resonant device.

The description of each part in the accompanying drawings is as follows:

11. Function signal generator; 12. Laser controller; 13. Laser; 21. Half mirror; 22. First plane mirror; 23. Second plane mirror; 31. Square; 321. First resonance Cavity; 322, the first buffer chamber; 323, the second buffer chamber; 331, the second resonant cavity; 332, the third buffer chamber; 333, the fourth buffer chamber; 34, the sampling hole; 35, the sampling hole; 36 , window; 37, sound conduit; 4, acoustic sensor; 5, lock-in amplifier; 61, first detector; 62, second detector; 7, PC.

Detailed ways

Example 1

As shown in Figures 1-4, an orthogonal dual-channel acoustic resonance device includes a block 31, on which a first cavity unit on the first side of the block 31 and its opposite side is arranged, passing through the second side and its opposite side. For the second chamber unit on the opposite side, the first side and the second side are adjacent sides of the block 31 . The first cavity unit includes a first resonant cavity 321 and a first buffer chamber 322 and a second buffer chamber 323 symmetrically and coaxially arranged at both ends of the first resonant cavity 321, and the second cavity unit includes a second resonant cavity 331 and a second buffer chamber 323. The third buffer chamber 332 and the fourth buffer chamber 333 are arranged symmetrically and coaxially at both ends of the second resonant cavity 331, and the intersection area formed at the center of the first resonant cavity 321 and the second resonant cavity 331 is provided with a vertical and two resonant cavity components. A planar sound conduit 37, the other end of which is provided with an acoustic sensor 4. The acoustic sensor 4 is a microphone or a tuning fork.

The upper surface of the block 31 is provided with four holes corresponding to the buffer chambers, the holes on the first buffer chamber 322 and the third buffer chamber 332 are used as the injection holes 34, the second buffer chamber 323 and the second buffer chamber The holes on the four buffer chambers 333 are sampling holes 35, the outer ends of the first buffer chamber 322 and the third buffer chamber 332 are used as incident windows, and the outer ends of the second buffer chamber 323 and the fourth buffer chamber 333 are used as exit window.

Optimally, the injection hole 34 can input gas molecules or aerosol particles. In this embodiment, the injection hole 34 and or the sample outlet hole 35 are provided with concentration sensors for detecting the injection hole 34 and the Or the concentration of the material entering and leaving the sample outlet 35. In this solution, both the sampling hole 34 and the sampling hole 35 are provided with concentration sensors.

Both the incident window and the exit window are provided with windows 36 to form a closed environment and reduce the interference of external environmental noise to the measurement.

The length L1 of the first resonant cavity 321 is equal to the length L2 of the second resonant cavity 331 . The relationship between the first resonant cavity 321, the second resonant cavity 331 and the buffer chamber is as follows: L1=L2=L, Lmin<L<Lmax, L=C/2f, C is the speed of sound, fmin=1000Hz, fmax=20000Hz; The length of the four buffer chambers is H=L/2, and the diameter of the buffer chamber is 2-4 times the diameter of the resonant cavity. In this embodiment, the length of the first resonant cavity 321 and the second resonant cavity 331 are both L=C/2000Hz, and the diameter is twice the diameter of the laser spot.

The diameters of the first resonant cavity 321 and the second resonant cavity 331 are both 2-4 times the diameter of the laser spot. In this embodiment, the diameters of the first resonant cavity 321 and the second resonant cavity 331 are both 2 times the diameter of the laser spot.

Example 2

The difference from Embodiment 1 is that in this solution, the length of the first resonant cavity 321 and the second resonant cavity 331 are both L=C/4000Hz, and the diameter is 4 times the diameter of the laser spot. The diameter of the buffer chamber is 4 times the diameter of the resonant cavity.

Example 3

The difference from Embodiment 1 is that in this solution, the length of the first resonant cavity 321 and the second resonant cavity 331 are both L=C/3000Hz, the diameter is 3 times of the diameter of the laser spot, and the diameter of the buffer chamber is 3 times of the diameter of the resonant cavity. times.

Example 4

As shown in Figure 4, a spectral sensing device including the orthogonal dual-channel acoustic resonance device in any one of Embodiment 1, Embodiment 2, and Embodiment 3, also includes

A laser assembly, used to send light beams to the incident window; the laser assembly includes a control signal source, a laser controller 12, and a laser 13 arranged in sequence according to the optical path. In this embodiment, the control signal source is a function signal generator 11 . The light output by the laser 13 is pulsed light or modulated (mechanical chopping or electrical signal modulation) continuous light.

The light beam splitting component is divided into two beams emitted by the laser component and sent to two incident windows respectively; the light splitting component includes a half mirror 21, a first plane mirror 22, a second plane mirror 23, and the laser 13 The light beam passes through the center of the half mirror 21 and is divided into a first light beam and a second light beam. The first light beam coincides with the central axis of the first cavity unit, and the second light beam passes through the first plane reflector 22 and the second light beam in turn. After being reflected by the two plane mirrors 23, it enters into the second cavity unit and coincides with the central axis of the second cavity unit.

The lock-in amplifier 5 is connected to the output end of the acoustic sensor 4 and the output end of the control signal source, and is used to receive the reference signal provided by the control signal source and demodulate the photoacoustic spectrum signal in the corresponding resonant cavity sensed by the acoustic sensor 4 .

The device further includes a first detector 61 and a second detector 62, and the first detector 61 and the second detector 62 respectively correspond to receiving the light beam corresponding to the exit window.

The output ends of the first detector 61, the second detector 62, and the lock-in amplifier 5 are connected to the PC7, and the data are uploaded to the PC7 for analysis.

The resonance frequencies of the two acoustic resonance devices are shown in Figure 4. It can be seen from Figure 4 that only at the resonance frequency of 1742Hz, the two acoustic resonance devices will have the same sound pressure distribution as shown in Figure 5. When two acoustic resonant cavities resonate at the frequency of 1742Hz at the same time, the same sound pressure distribution of the two channels makes the sound pressure superimposed at the intersection of the two resonant devices. By sweeping the frequency of the cavity, it can be seen that the optimal acoustic signal amplification is only achieved at 1742 Hz as shown in Fig. 6 .

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, any person familiar with the technical field within the technical scope disclosed in the present invention, according to the technical solution of the present invention Any equivalent replacement or change of the inventive concepts thereof shall fall within the protection scope of the present invention.

Claims (6)

1. The orthogonal double-channel acoustic resonance device is characterized by comprising a square block (31), wherein a first side surface and a second side surface are adjacent side surfaces of the square block (31), a first cavity unit penetrating through the first side surface and the opposite side surface of the square block (31) and a second cavity unit penetrating through the second side surface and the opposite side surface of the square block are arranged on the square block (31), the first cavity unit comprises a first resonant cavity (321) and a first buffer chamber (322) and a second buffer chamber (323) which are symmetrically and coaxially arranged at two ends of the first resonant cavity (321), the second cavity unit comprises a second resonant cavity (331) and a third buffer chamber (332) and a fourth buffer chamber (333) which are symmetrically and coaxially arranged at two ends of the resonant cavity, an intersection area formed by the centers of the first resonant cavity (321) and the second resonant cavity (331) is provided with an acoustic guide pipe (37) which is perpendicular to the two resonant cavities to form a plane, and the other end of the acoustic guide pipe (37) is provided with an acoustic sensor (4); the acoustic sensor (4) is a microphone;

the length L1 of the first resonant cavity (321) is equal to the length L2 of the second resonant cavity (331), the first resonant cavity (321) and the second resonant cavity (331) are equal, wherein L1=L2=L, lmin < L < Lmax, L=C/2 f, C is sound velocity, fmin=1000 Hz, fmax=20000 Hz, the length H=L/2 of four buffer chambers is 2-4 times the diameter of the resonant cavities;

further comprises: a laser assembly for generating a beam of light that is transmitted toward the entrance window;

the beam splitting component is used for splitting the light beam emitted by the laser component into two beams and respectively transmitting the two beams to the two incident windows;

and the phase-locked amplifier (5) is connected with the output end of the acoustic sensor (4) and the output end of the control signal source and is used for receiving the reference signal provided by the control signal source and demodulating the photoacoustic signal in the corresponding resonant cavity perceived by the acoustic sensor (4).

2. The orthogonal dual-channel acoustic resonance device according to claim 1, wherein four holes which are respectively communicated with the buffer chambers are formed in the upper surface of the square block (31), the holes in the first buffer chamber (322) and the third buffer chamber (332) are used as sample injection holes (34), the holes in the second buffer chamber (323) and the fourth buffer chamber (333) are used as sample outlet holes (35), the outer end parts of the first buffer chamber (322) and the third buffer chamber (332) are used as incident windows, and the outer end parts of the second buffer chamber (323) and the fourth buffer chamber (333) are used as emergent windows.

3. The orthogonal two-channel acoustic resonator device according to claim 2, characterized in that a louver (36) is provided on both the entrance window and the exit window.

4. The orthogonal dual channel acoustic resonator device of claim 1, wherein the first resonator (321) and the second resonator (331) have diameters that are 2-4 times the laser beam diameter.

5. The orthogonal dual channel acoustic resonator device of claim 1, wherein the laser assembly comprises a control signal source, a laser controller (12), and a laser (13) arranged in order in the optical path.

6. The orthogonal dual-channel acoustic resonance device according to claim 5, wherein the beam splitting assembly comprises a half mirror (21), a first plane mirror (22) and a second plane mirror (23), the beam of the laser (13) is split into a first beam and a second beam through the center of the half mirror (21), the first beam coincides with the central axis of the first cavity unit, and the second beam sequentially enters the second cavity unit after being reflected by the first plane mirror (22) and the second plane mirror (23) and coincides with the central axis of the second cavity unit.