A tracer fluorescent aerosol detection module based on dual-band light source

Abstract

The present invention relates to the field of atmospheric environmental pollution prevention and control services, and specifically discloses a tracer type fluorescent aerosol detection module based on a dual-band light source, wherein the measuring cavity is a straight hexagonal prism structure, and the six sides are respectively connected to the first light source structure, the second light source structure, the first dissipation channel, the second dissipation channel, the forward channel structure and the backward channel structure, and the top is provided with an aerosol inlet, and the bottom is provided with an aerosol outlet; the first light source structure and the first dissipation channel are coaxially arranged, and the central axis passes through the center of the measuring cavity, the second light source structure and the second dissipation channel are coaxially arranged, and the central axis passes through the center of the measuring cavity, and the forward channel structure and the backward channel structure are coaxially arranged, and the central axis passes through the center of the measuring cavity. The present invention realizes efficient detection of multi-dimensional fingerprint data of bioaerosols through the reasonable arrangement of optical channels in the measuring cavity and the design of the measuring cavity, and effectively improves the online detection capability for bioaerosols.

Description

Technical Field

[0001] The present invention relates to the field of atmospheric environmental pollution prevention and control services, and in particular to a tracer-type fluorescent aerosol detection module based on a dual-band light source. Background Art

[0002] Bioaerosols are deeply involved in biogeochemical cycles and have important potential impacts on climate change and human health. The online analysis technology based on the autofluorescence characteristics of bioaerosols is also called laser-induced fluorescence (LIF). The principle of this method is that the natural fluorescent substances in bioaerosol particles are excited by ultraviolet light to produce a scattered fluorescence spectrum that is different from the incident band. Bioaerosols are detected and identified through specific fluorescence spectra. The LIF method has technical advantages such as non-invasiveness and instantaneous detection, which greatly improves the detection sensitivity and efficiency of bioaerosols.

[0003] At present, there are certain uncertainties in the measurement of fluorescent bioaerosols based on the LIF method. For example, non-biological particles such as secondary organic aerosols and combustion source particles will be mistakenly identified as biological particles. The identification between weak fluorescent bioaerosols and interfering non-biological particles is still challenging, and the background noise caused by the optical measurement system is difficult to ignore. To address this problem, on the one hand, starting from the analysis results, the differentiation of bioaerosols can be improved by improving data analysis methods and establishing a fluorescence spectrum library; on the other hand, the accuracy and dimension of instrument measurement can be improved, and more comprehensive particle information can be used for measurement. Therefore, at the technical level, a multi-dimensional, low-noise bioaerosol detection technology is urgently needed to improve the rapid identification capability and quantitative analysis level of bioaerosols. Summary of the invention

[0004] In view of the uncertainty in the measurement of bioaerosol based on the LIF method, the present invention provides a tracer type fluorescent aerosol detection module based on a dual-band light source.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A tracer fluorescent aerosol detection module based on a dual-band light source comprises a measuring cavity body, a first light source structure, a second light source structure, a first dissipative channel, a second dissipative channel, a forward channel structure and a backward channel structure; the measuring cavity body is a straight hexagonal prism structure, six sides of which are respectively connected to the first light source structure, the second light source structure, the first dissipative channel, the second dissipative channel, the forward channel structure and the backward channel structure, an aerosol inlet is arranged on the top, and an aerosol outlet is arranged on the bottom; the first light source structure and the first dissipative channel are coaxially arranged and the central axis passes through the center of the measuring cavity body, the second light source structure and the second dissipative channel are coaxially arranged and the central axis passes through the center of the measuring cavity body, the forward channel structure and the backward channel structure are coaxially arranged and the central axis passes through the center of the measuring cavity body.

[0007] Preferably, the first light source structure includes an ultraviolet excitation light source and a first collimating lens; the ultraviolet light beam emitted by the ultraviolet excitation light source is collimated by the first collimating lens and then enters the measuring cavity, a part of the collimated light beam directly penetrates the aerosol in the measuring cavity and then enters the first dissipation channel, and another part of the collimated light beam is scattered by the aerosol particles in the measuring cavity, and the scattered part of the light beam enters the forward channel structure for detection.

[0008] Preferably, the second light source structure includes a visible light source, a linear polarizer, a second collimating lens and a cylindrical beam compression lens. The visible light source emits a divergent visible light beam, which is converted into a linearly polarized light beam after passing through the linear polarizer. The linearly polarized light beam is converted into a collimated circular light beam after passing through the second collimating lens. The collimated circular light beam is converted into linear horizontal polarized light after passing through the cylindrical beam compression lens. The linear horizontal polarized light enters the measuring cavity for detection.

[0009] Preferably, the backward channel structure includes a backward focusing lens, a cubic beam splitter, a backward S channel and a backward P channel; after the linear horizontal polarized light is scattered by the aerosol particles, a part of the scattered light beam passes through the backward focusing lens, and the backward focusing lens focuses the scattered light beam axially onto the cubic beam splitter, and the cubic beam splitter splits the focused light beam into s-polarized light and p-polarized light, the s-polarized light enters the backward S channel, and the p-polarized light enters the backward P channel.

[0010] Preferably, the backward S channel includes a backward first focusing lens and a backward first light detection module, and the backward P channel includes a backward second focusing lens and a backward second light detection module; the s-polarized light passes through the backward first focusing lens and is focused on the backward first light detection module for detection, and the p-polarized light passes through the backward second focusing lens and is focused on the backward second light detection module for detection.

[0011] Preferably, the forward channel structure includes a forward focusing lens, a forward first dichroic filter, a forward second dichroic filter, a forward particle size channel, a first fluorescence channel and a second fluorescence channel; after the linear horizontal polarized light is scattered by the aerosol particles, another part of the scattered light beam passes through the forward focusing lens, and the forward focusing lens focuses the scattered light beam axially onto the forward first dichroic filter, and the focused light beam is reflected by the forward first dichroic filter to the forward particle size channel for detection; the ultraviolet light beam induces the aerosol to produce fluorescence, and the stray fluorescence passes through the forward focusing lens, and the forward focusing lens focuses the stray fluorescence axially onto the forward first dichroic filter, and the focused fluorescence beam penetrates the first dichroic filter to the forward second dichroic filter, and the second dichroic filter reflects a part of the fluorescence beam to the first fluorescence channel for detection, and another part of the fluorescence beam is transmitted to the second fluorescence channel for detection.

[0012] Preferably, the forward particle size channel includes a forward first focusing lens and a forward first light detection module, the first fluorescence channel includes a forward second focusing lens and a forward second light detection module, and the second fluorescence channel includes a forward third focusing lens and a forward third light detection module.

[0013] Preferably, the ultraviolet excitation light source uses ultraviolet light with a wavelength of 280nm; and the visible light source uses visible light with a wavelength of 637nm.

[0014] Preferably, the light apertures of the first light source structure and the first dissipation channel and the second light source structure and the second dissipation channel are 1 inch; and the light apertures of the forward channel structure and the backward channel structure are 2 inches.

[0015] Preferably, optical flat windows are provided at the connection places between the first light source structure, the second light source structure, the first dissipation channel, the second dissipation channel, the forward channel structure and the backward channel structure and the side surface of the measuring chamber body.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The detection module of the present invention uses a dual-band system of visible light source and ultraviolet excitation light source as a spatial light source through reasonable configuration of light sources and measurement channels, and realizes synchronous in-situ measurement of particle size, depolarization ratio, and fluorescence signals in two wavelength ranges through five signal channels in a relatively small volume space, which helps to realize efficient detection and identification of bioaerosols through multi-dimensional fingerprint data.

[0018] The detection module of the present invention comprises a measuring cavity and a matching detection device. The measuring cavity realizes synchronous measurement of forward particle size signals, depolarization ratio signals and excitation fluorescence signals of bioaerosols with autofluorescence characteristics such as fungal spores and pollen through reasonable allocation and combination of dual-waveguide integrated light sources, multiple measurement channels and dichroic filters. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a structural diagram of an embodiment of the present invention;

[0020] Figure 2 For the present invention Figure 1 Schematic diagram of the optical path of an embodiment.

[0021] In the figure, 1-measuring cavity; 2-first light source structure; 3-second light source structure; 4-first dissipation channel; 5-second dissipation channel; 6-forward channel structure; 7-backward channel structure; 8-optical flat window; 11-aerosol inlet; 21-ultraviolet excitation light source; 22-first collimating lens; 31-visible light source; 32-linear polarizer; 33-second collimating lens; 34-cylindrical beam-pressing lens; 61-forward focusing lens; 62-forward first dichroic filter; 63-forward second dichroic filter; 64-forward particle size channel; 65 -first fluorescent channel; 66-second fluorescent channel; 71-backward focusing lens; 72-cube beam splitter; 73-backward S channel; 74-backward P channel; 641-forward first focusing lens; 642-forward first light detection module; 651-forward second focusing lens; 652-forward second light detection module; 661-forward third focusing lens; 662-forward third light detection module; 731-backward first focusing lens; 732-backward first light detection module; 741-backward second focusing lens; 742-backward second light detection module;

[0022] Symbol a represents the propagation path of the ultraviolet light beam generated by the ultraviolet excitation light source and the fluorescent light beam induced by the ultraviolet light beam; symbol b represents the propagation path of the visible light beam generated by the visible light source; symbol c represents the aerosol particle flow. DETAILED DESCRIPTION

[0023] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Please refer to the following Figure 1 and Figure 2A tracer fluorescent aerosol detection module based on a dual-band light source comprises a measuring cavity body 1, a first light source structure 2, a second light source structure 3, a first dissipative channel 4, a second dissipative channel 5, a forward channel structure 6 and a backward channel structure 7; the measuring cavity body 1 is a straight hexagonal prism structure, and the six sides are respectively connected to the first light source structure 2, the second light source structure 3, the first dissipative channel 4, the second dissipative channel 5, the forward channel structure 6 and the backward channel structure 7, an aerosol inlet 11 is arranged on the top, and an aerosol outlet is arranged on the bottom; the first light source structure 2 and the first dissipative channel 4 are coaxially arranged and the central axis passes through the center of the measuring cavity body 1, the second light source structure 3 and the second dissipative channel 5 are coaxially arranged and the central axis passes through the center of the measuring cavity body 1, and the forward channel structure and the backward channel structure 7 are coaxially arranged and the central axis passes through the center of the measuring cavity body 1.

[0025] In this embodiment, the measuring cavity 1 is used to hold aerosol particles to be measured; the first light source structure 2 generates an electromagnetic wave of a first wavelength, and the second light source structure 3 generates an electromagnetic wave of a second wavelength. The first wavelength and the second wavelength can be any band or any wavelength in visible light and ultraviolet light, and the first wavelength and the second wavelength are in different bands or wavelengths; the first dissipative channel 4 corresponds to the first light source structure 2, and the second dissipative channel 5 corresponds to the second light source structure 3. The first dissipative channel 4 is used to dissipate the electromagnetic wave generated by the first light source structure 2 after particle detection, and the second dissipative channel 5 is used to dissipate the electromagnetic wave generated by the second light source structure 3 after particle detection. The first dissipative channel 4 and the second dissipative channel 5 can avoid the increase of background noise in the detection module cavity caused by stray light; the aerosol inlet 11 is used to input aerosol particle flow for detection, and the aerosol outlet is used to discharge the aerosol particle flow that has completed detection; the backward channel structure 7 is used to receive electromagnetic waves scattered in the measuring cavity 1 for detection, and the forward channel structure 6 is used to receive electromagnetic waves scattered in the measuring cavity 1 for detection.

[0026] In one embodiment of the present invention, the aerosol inlet 11 is located at the top of the measuring chamber body 1, and the inlet cover is matched with the measuring chamber body 1 by means of a threaded joint locking sealing ring; the aerosol outlet is located at the bottom of the measuring chamber body 1, and the outlet cover is matched with the measuring chamber body 1 by means of a threaded joint locking sealing ring; this detection module can realize the detection of single particle flow through the sheath gas turbulence device.

[0027] In one embodiment of the present invention, the first light source structure 2 includes an ultraviolet excitation light source 21 and a first collimating lens 22; the ultraviolet light beam emitted by the ultraviolet excitation light source 21 is collimated by the first collimating lens 22 and then enters the measuring cavity 1, a part of the collimated light beam directly penetrates the aerosol in the measuring cavity 1 and then enters the first dissipation channel 4, and another part of the collimated light beam is scattered by the aerosol particles in the measuring cavity 1, and the scattered part of the light beam enters the forward channel structure 6 for detection.

[0028] In this embodiment, the bioaerosol particles in the measuring chamber 1 are irradiated with ultraviolet light, and the natural fluorescent substances in the bioaerosol particles will produce a scattered fluorescence spectrum different from the incident band, and the specific fluorescence spectrum also enters the forward channel structure 6 for detection.

[0029] In one embodiment of the present invention, the second light source structure 3 includes a visible light source 31, a linear polarizer 32, a second collimating lens 33 and a cylindrical beam compression lens 34. The visible light source 31 emits a divergent visible light beam, which is converted into a linear polarized light beam after passing through the linear polarizer 32. The linear polarized light beam is converted into a collimated circular light beam after passing through the second collimating lens 33. The collimated circular light beam is converted into linear horizontal polarized light after passing through the cylindrical beam compression lens 34. The linear horizontal polarized light enters the measuring cavity 1 for detection.

[0030] In this embodiment, the visible light source 31 is a laser diode, and the original divergent light beam emitted by the laser diode can be converted into a linear polarized light beam through a linear polarizer 32.

[0031] In one embodiment of the present invention, the backward channel structure 7 includes a backward focusing lens 71, a cubic beam splitter 72, a backward S channel 73 and a backward P channel 74; after the linear horizontal polarized light is scattered by the aerosol particles, a part of the scattered light beam passes through the backward focusing lens 71, and the backward focusing lens 71 focuses the scattered light beam axially onto the cubic beam splitter 72, and the cubic beam splitter 72 divides the focused light beam into s-polarized light and p-polarized light, the s-polarized light enters the backward S channel 73, and the p-polarized light enters the backward P channel 74.

[0032] In this embodiment, the s-polarized light is detected through the backward S channel 73, and the p-polarized light is detected through the backward P channel 74. The depolarization ratio of the aerosol can be calculated based on the values ​​of the s-polarized light and the p-polarized light obtained by the detection.

[0033] In one embodiment of the present invention, the backward S channel 73 includes a backward first focusing lens 731 and a backward first light detection module 732, and the backward P channel 74 includes a backward second focusing lens 741 and a backward second light detection module 742; the s-polarized light passes through the backward first focusing lens 731 and is focused on the backward first light detection module 732 for detection, and the p-polarized light passes through the backward second focusing lens 741 and is focused on the backward second light detection module 742 for detection.

[0034] In this embodiment, the backward first light detection module 732 and the backward second light detection module 742 also need to cooperate with the signal acquisition module and the computer for measurement. The backward first light detection module 732 and the backward second light detection module 742 convert the optical signal into an electrical signal, which is collected by the signal acquisition module and finally counted, organized and displayed by the computer.

[0035] In one embodiment of the present invention, the ultraviolet excitation light source 21 emits ultraviolet light with a wavelength of 280 nm, and the visible light source 31 emits visible light with a wavelength of 637 nm, which is only used as an explanation of the present invention and is not limited thereto.

[0036] In one embodiment of the present invention, the forward channel structure 6 includes a forward focusing lens 61, a forward first dichroic filter 62, a forward second dichroic filter 63, a forward particle size channel 64, a first fluorescent channel 65 and a second fluorescent channel 66; after the linear horizontal polarized light is scattered by the aerosol particles, another part of the scattered light beam passes through the forward focusing lens 61, and the forward focusing lens 61 focuses the scattered light beam axially onto the forward first dichroic filter 62, and the focused light beam is passed through the forward first dichroic filter 62. It is reflected to the forward particle size channel 64 for detection; the ultraviolet light beam induces the aerosol to produce fluorescence, and the stray fluorescence passes through the forward focusing lens 61. The forward focusing lens 61 focuses the stray fluorescence axially onto the forward first dichroic filter 62. The focused fluorescence beam penetrates the first dichroic filter to the forward second dichroic filter 63. The second dichroic filter reflects part of the fluorescence beam to the first fluorescence channel 65 for detection, and the other part of the fluorescence beam is transmitted to the second fluorescence channel 66 for detection.

[0037] In this embodiment, the transmission wavelength range of the forward first dichroic filter 62 is 390-550nm, and the scattered light with a wavelength above 550nm will enter the forward particle size channel 64 for detection; the wavelength of the scattered light in the 390-550nm band is smaller than the visible light but larger than the ultraviolet light, so the scattered signals in this part are all fluorescence signals induced by bioaerosols; the transmission wavelength range of the forward second dichroic filter 63 is 390-475nm, and the collected fluorescence signals are further divided into two channels, which are used to further identify the type of fluorescent bioaerosol by distinguishing substances with autofluorescent characteristics.

[0038] In one embodiment of the present invention, the forward particle size channel 64 includes a forward first focusing lens 641 and a forward first light detection module 642, the first fluorescence channel 65 includes a forward second focusing lens 651 and a forward second light detection module 652, and the second fluorescence channel 66 includes a forward third focusing lens 661 and a forward third light detection module 662.

[0039] In this embodiment, scattered light with a wavelength above 550nm is focused onto the forward first light detection module 642 through the forward first focusing lens 641, scattered light with a wavelength of 475-550nm is focused onto the forward second light detection module 652 through the forward second focusing lens 651, and scattered light with a wavelength of 390-475nm is focused onto the forward third light detection module 662 through the forward third focusing lens 661. The forward first light detection module 642, the forward second light detection module 652 and the forward third light detection module 662 convert the optical signal into an electrical signal, thereby further performing signal collection.

[0040] In one embodiment of the present invention, the light apertures of the first light source structure 2 and the first dissipative channel 4 and the second light source structure 3 and the second dissipative channel 5 are 1 inch; the light apertures of the forward channel structure 6 and the backward channel structure 7 are 2 inches.

[0041] In this embodiment, the detection module expands the collection range of the signal acquisition channel through an irregular design. The window diameter of the light source and the dissipation channel in the cavity is 1 inch, and the window diameter of the signal acquisition channel reaches 2 inches, which can effectively improve the detection sensitivity of weaker aerosol depolarization signals and fluorescence signals.

[0042] In one embodiment of the present invention, optical flat windows 8 are provided at the connection points between the first light source structure 2 , the second light source structure 3 , the first dissipative channel 4 , the second dissipative channel 5 , the forward channel structure 6 and the backward channel structure 7 and the side of the measuring chamber body 1 .

[0043] In this embodiment, an optical flat window 8 is provided on each side of the optical channel of the measuring chamber body 1, which is used to form a seal at the connection between the first light source structure 2, the second light source structure 3, the first dissipation channel 4, the second dissipation channel 5, the forward channel structure 6 and the backward channel structure 7 and the side of the measuring chamber body 1 respectively.

[0044] The present invention also provides a tracer-type fluorescent aerosol detection system based on a dual-band light source, comprising the above-mentioned tracer-type fluorescent aerosol detection module based on a dual-band light source, and specifically also including a power module, an air path module, and a signal acquisition module; the power module provides power for the detection module, the air path module and the signal acquisition module, the air path module provides aerosol for the detection module and recovers the aerosol, and the signal acquisition module is used to collect the electrical signal converted from the optical signal on the light detection module.

[0045] In this embodiment, the detection module cooperates with the power module, the gas path module and the signal acquisition module to perform measurements. In addition to the targeted measurement of bioaerosols, the depolarization ratio and particle size distribution of other types of aerosols can also be measured.

[0046] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A tracer fluorescent aerosol detection module based on a dual-band light source, characterized in that: It includes a measuring cavity body, a first light source structure, a second light source structure, a first dissipative channel, a second dissipative channel, a forward channel structure and a backward channel structure; the measuring cavity body is a straight hexagonal prism structure, and the six sides are respectively connected to the first light source structure, the second light source structure, the first dissipative channel, the second dissipative channel, the forward channel structure and the backward channel structure, an aerosol inlet is arranged on the top, and an aerosol outlet is arranged on the bottom; the first light source structure and the first dissipative channel are coaxially arranged and the central axis passes through the center of the measuring cavity body, the second light source structure and the second dissipative channel are coaxially arranged and the central axis passes through the center of the measuring cavity body, the forward channel structure and the backward channel structure are coaxially arranged and the central axis passes through the center of the measuring cavity body; The first light source structure includes an ultraviolet excitation light source and a first collimating lens; the ultraviolet light beam emitted by the ultraviolet excitation light source enters the measuring cavity after being collimated by the first collimating lens, a part of the collimated light beam directly penetrates the aerosol in the measuring cavity and enters the first dissipation channel, another part of the collimated light beam is scattered by the aerosol particles in the measuring cavity, and a part of the scattered light beam enters the forward channel structure for detection; The second light source structure comprises a visible light source, a linear polarizer, a second collimating lens and a cylindrical beam-suppression lens, wherein the visible light source emits a divergent visible light beam, which is converted into a linearly polarized light beam after passing through the linear polarizer, and the linearly polarized light beam is converted into a collimated circular light beam after passing through the second collimating lens, and the collimated circular light beam is converted into a linear horizontally polarized light after passing through the cylindrical beam-suppression lens, and the linear horizontally polarized light enters the measuring cavity for detection; The backward channel structure includes a backward focusing lens, a cubic beam splitter, a backward S channel and a backward P channel; after the linear horizontal polarized light is scattered by the aerosol particles, a part of the scattered light beam passes through the backward focusing lens, the backward focusing lens focuses the scattered light beam axially onto the cubic beam splitter, the cubic beam splitter splits the focused light beam into s-polarized light and p-polarized light, the s-polarized light enters the backward S channel, and the p-polarized light enters the backward P channel; The backward S channel includes a backward first focusing lens and a backward first light detection module, and the backward P channel includes a backward second focusing lens and a backward second light detection module; The s-polarized light passes through the first backward focusing lens and is focused to the first backward light detection module for detection, and the p-polarized light passes through the second backward focusing lens and is focused to the second backward light detection module for detection; The forward channel structure includes a forward focusing lens, a forward first dichroic filter, a forward second dichroic filter, a forward particle size channel, a first fluorescent channel, and a second fluorescent channel; After the linear horizontal polarized light is scattered by the aerosol particles, another part of the scattered light beam passes through the forward focusing lens, and the forward focusing lens focuses the scattered light beam axially onto the forward first dichroic filter, and the focused light beam is reflected by the forward first dichroic filter to the forward particle size channel for detection; the ultraviolet light beam induces the aerosol to produce fluorescence, and the stray fluorescence passes through the forward focusing lens, and the forward focusing lens focuses the stray fluorescence axially onto the forward first dichroic filter, and the focused fluorescence light beam penetrates the first dichroic filter to the forward second dichroic filter, and the second dichroic filter reflects a part of the fluorescence light beam to the first fluorescence channel for detection, and another part of the fluorescence light beam is transmitted to the second fluorescence channel for detection; The forward particle size channel includes a forward first focusing lens and a forward first light detection module, the first fluorescence channel includes a forward second focusing lens and a forward second light detection module, and the second fluorescence channel includes a forward third focusing lens and a forward third light detection module; The first light source structure emits ultraviolet light with a wavelength of 280nm, and the second light source structure emits visible light with a wavelength of 637nm; This detection module adopts an irregular design, and the light apertures of the first light source structure and the first dissipative channel and the second light source structure and the second dissipative channel are set to 1 inch, and the light apertures of the forward channel structure and the backward channel structure are set to 2 inches.

2. According to claim 1, a tracer type fluorescent aerosol detection module based on a dual-band light source is characterized in that: Optical flat windows are provided at the connection places between the first light source structure, the second light source structure, the first dissipation channel, the second dissipation channel, the forward channel structure and the backward channel structure and the side surface of the measurement cavity body.

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