CN114778423A - Light receiving structure - Google Patents

Abstract

The invention discloses a light receiving structure, which is applied to a particle counting sensor and used for receiving scattered light of particles, and comprises a light collector and a photoelectric detector; the light working area, the light collector and the photoelectric detector are sequentially arranged, a light reflecting surface is arranged in the light collector, a light reflecting cavity is formed by the light reflecting surface in a surrounding mode, a light inlet and a light outlet are formed in the light collector, the light reflecting cavity is communicated with the outside through the light inlet and the light outlet, the light inlet faces the light working area, the photoelectric detector is exposed to the light reflecting cavity through the light outlet and at least partially shields the light outlet, and a light receiving surface of the photoelectric detector faces the light reflecting cavity. The light receiving structure can increase the collection amount of scattered light by the photoelectric detector, and is favorable for improving the accuracy of the particle counting sensor.

Description

Light receiving structure

Technical Field

The invention relates to the technical field related to particle counting sensors, in particular to a light receiving structure.

Background

The particle counting sensor is an instrument for counting dust particles based on the Mie scattering principle, a light source of the particle counting sensor emits light beams, the light beams form a light working area after light shaping, a gas circuit component is arranged at the light working area and drives an air flow to be detected to pass through the light working area, scattered light of single particles in the air flow, which is scattered by the Mie scattering, is received by a photoelectric detector arranged on one side of a photosensitive area and then converted into light current, the light current is converted into voltage pulse signals through an amplification processing circuit, and the size of the particle size can be distinguished by comparing different voltage pulse signals. The more scattered light the photodetector receives from the particle, the higher the accuracy of the particle resolution. Since the scattered light of the particle scatters outward in a spherical surface, the photodetector can only receive the scattered light projected in the direction. In order to make the photodetector receive more scattered light, a hemispherical mirror is generally disposed on a side of the optical working area opposite to the photodetector in the prior art, and the scattered light is received by the hemispherical mirror and reflected to the photodetector. In the mode, part of scattered light cannot be collected, and even if the light beam is shaped due to the divergence angle of the laser, stray light influencing accurate counting and particle distinguishing of the particle counting sensor exists inevitably in the light beam propagation process, and the stray light influences particle size distinguishing and particle accurate counting after being received by the photoelectric detector.

In summary, there is a need in the art for an improved structure for receiving scattered light from particles by a photodetector, which reduces the effect of stray light while increasing the amount of scattered light collected.

Disclosure of Invention

In view of the above, an object of the present invention is to provide a light receiving structure, disposed between an optical working area and a photodetector, having a light inlet and a light outlet, and having a light reflecting cavity therein, wherein the light reflecting cavity has two opposite reflecting surfaces, the light inlet faces the optical working area, and the light outlet is in butt joint with the photodetector, so as to increase the collection amount of scattered light by the photodetector through reflection.

In order to achieve the above object, the present invention provides a light receiving structure applied in a particle counting sensor for receiving scattered light of particles, the particle counting sensor comprising an optical working area formed by emitting light beams from a light source of the particle counting sensor, including a light collector and a photodetector; the light workspace the light-concentrating body photoelectric detector arranges in proper order, the light-concentrating body is inside to have the light reflex surface, the light reflex surface encloses to establish and forms light reflection chamber, light-concentrating body is seted up and is advanced light mouth and light-emitting window, the light reflection chamber passes through advance the light mouth with light-emitting window and outside intercommunication, advance the light mouth orientation light workspace, photoelectric detector warp the light-emitting window exposes for light reflection chamber and at least part shelter from the light-emitting window, photoelectric detector's light receiving face orientation light reflection chamber.

Preferably, the light reflecting surface includes two opposite reflecting surfaces, the peripheries of the two reflecting surfaces are closely connected, and the two reflecting surfaces respectively surround the light inlet and the light outlet.

Preferably, the region of the outer surface of the light collector facing the light beam is a light absorbing surface.

Preferably, the maximum orthographic projection area of the light inlet is larger than the orthographic projection area of the light working area along the projection line direction of the maximum orthographic projection area of the light inlet, and the edge of the orthographic projection of the light working area does not exceed the edge of the orthographic projection of the light inlet.

Preferably, the optical axis of the light working area position and the projection line direction of the maximum orthographic projection area of the light inlet have an included angle theta, and theta is larger than 10 degrees and smaller than 170 degrees.

Preferably, the light inlet and the light working area are coaxial.

Preferably, the light inlet and the light outlet are coaxial.

Preferably, the optical working area, the light inlet and the light outlet are coaxial.

Preferably, the light collector includes a first light reflector and a second light reflector, the first light reflector has a first reflecting surface, the second light reflector has a second reflecting surface, the first light reflector and the second light reflector are tightly connected at the periphery to form the light reflecting cavity, the first reflecting surface and the second reflecting surface are located in the light reflecting cavity, and the first reflecting surface and the second reflecting surface are arranged oppositely; the light inlet is positioned on the first light reflector, and the light outlet is positioned on the second light reflector.

Preferably, the light working area is arranged at a distance from the light inlet, and the distance between the light working area and the light inlet is 1-10 mm.

Compared with the prior art, the light receiving structure disclosed by the invention has the advantages that: the collection amount of scattered light by the photoelectric detector can be increased through the light receiving structure, and the accuracy of the particle counting sensor is improved; the light receiving structure can filter and absorb partial stray light, noise is reduced beneficially, and accuracy of the particle counting sensor is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic diagram of a light receiving structure disposed in a particle counting sensor according to the present invention.

Fig. 2 is a schematic structural diagram of an air channel assembly of the particle counting sensor.

Fig. 3 is a schematic cross-sectional view of a light receiving structure according to the present invention.

Fig. 4 is a schematic cross-sectional view showing a variation of a light receiving structure of the present invention.

Fig. 5 is a schematic cross-sectional view showing a variation of a light receiving structure of the present invention.

Fig. 6 is a schematic diagram showing a structure in which a variation of a light receiving structure according to the present invention is provided in a particle counting sensor.

Fig. 7 is a schematic diagram of a structure in which a variation of a light receiving structure according to the present invention is disposed in a particle counting sensor.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

As shown in fig. 1 and 2, the light receiving structure of the present application is applied to a particle counting sensor for receiving scattered light of particles, the particle counting sensor includes a light source 1, a light shaping component 3, a gas path component, a light trap 4 and a light receiving structure, the gas path component includes a gas inlet 8 and a gas exhaust 9, a gas flow 10 containing particles to be measured flows through the gas inlet 8 and the gas exhaust 9 to form a gas path, the light source 1 emits a light beam 21, the light beam 21 passes through the light shaping component 3 and then intersects with the gas path in an overlapping region to form a light working region 5, and the light beam 21 reaches the light trap 4 after passing through the light working region 5 and is received by the light trap. I.e. the particle counting sensor comprises an optical working area 5, which optical working area 5 is formed by an emission beam 21 of the light source 1 of the particle counting sensor. The air inlet part 8 is provided with an air inlet 81 facing the optical working area 5, the air exhaust part 9 is provided with an air exhaust port 91 facing the optical working area 5 and surrounds a propagation path of the light beam 21, the air inlet 81 and the air exhaust port 91 are respectively positioned on two sides of the optical working area 5 and are oppositely arranged, the gas flow 10 to be measured flows to the air exhaust port 91 of the air exhaust part 9 through the air inlet 81 of the air inlet part 8, the light beam 21 intersects with the gas flow 10 to be measured, and particles in the gas flow 10 to be measured interact with light in the optical working area to emit scattered light.

The light beam 21 shaped by the light shaping component 3 reaches the light trap 4 and is received by the light trap after passing through the light working area 5 on the propagation path, and the existence of the light receiving structure does not affect the change of the propagation path of the light beam 21, namely the light receiving structure is not arranged on the propagation path of the light beam 21. The gas flow 10 to be measured flows to the exhaust port 91 of the exhaust member 9 through the inlet 81 of the inlet member 8, and the existence of the light receiving structure does not obstruct the flow of the gas flow 10 to be measured or change the flow direction thereof. The light shaping component 3 is used for realizing collimation, compression and focusing of the light beam 21, and the components of the light shaping component include one or more selected from a spherical mirror, an aspherical mirror and a cylindrical mirror, and may further include size limiting structures such as a diaphragm and a through hole for limiting the cross-sectional size of the light beam, which are not specifically limited here.

As can be seen from fig. 3, the light receiving structure includes a light collecting body 6 and a photodetector 7, the light working area 5, the light collecting body 6, and the photodetector 7 are sequentially arranged, a light reflecting surface is provided inside the light collecting body 6, the light reflecting surface surrounds the light collecting body to form a light reflecting cavity 60, the light collecting body 6 is provided with a light inlet 601 and a light outlet 602, the light reflecting cavity 60 is communicated with the outside through the light inlet 601 and the light outlet 602, the light inlet 601 faces the light working area 5, the photodetector 7 is exposed to the light reflecting cavity 60 through the light outlet 602 and at least partially shields the light outlet 602, the photodetector 7 receives light in the light reflecting cavity 60, and a light receiving surface of the photodetector 7 faces the light reflecting cavity 60. After the particles are scattered in the optical working area 5, the scattered light enters the light reflection cavity 60 through the light inlet 601, part of the scattered light 22 directly enters the light receiving surface of the photoelectric detector 7, and part of the scattered light 23 enters the light receiving surface of the photoelectric detector 7 after being reflected once or multiple times by the light reflection surface in the light reflection cavity 60. The amount of scattered light received by the photodetector 7 can be increased by the light collector 6. The light inlet 601 and the light outlet 602 may be regular-shaped openings, such as circular openings and regular polygonal openings, or irregular-shaped openings, and preferably, the light inlet 601 and the light outlet 602 are circular openings, which is convenient for processing and adapting.

Further, the light working area 5 is spaced from the light inlet 601, and the minimum distance between the light working area and the light inlet 601 is 1-10 mm, such as 1.2mm, 1.5mm, 1.8mm, 2mm, 2.5mm, 3mm, 3.5 mm, 4mm, 5mm, 7mm, and 9 mm. The minimum distance is preferably 1.5-5 mm.

For better illustration, in fig. 3, the light inlet 601 and the light outlet 602 are respectively located at two ends of the light reflecting cavity 60, but the positions of the light inlet 601 and the light outlet 602 on the light collecting body 6 are not particularly limited, and since the scattered light can be incident on the light receiving surface of the photoelectric detector 7 through one or more reflections after entering the light reflecting cavity 60 of the light collecting body 6 through the light inlet 601, the relative positions of the light inlet 601 and the light outlet 602 on the light collecting body 6 do not need to be specifically limited. Preferably, the light entrance 601 is not at the focal point of the light reflecting surface.

The photodetector 7 is typically selected from a photomultiplier, a photodiode, and the like having a device for converting light into electrical energy, and the light receiving surface refers to a photosensitive surface in the photodetector 7 device. For example, a photodiode or an array of photodiodes is used, where the choice of photodetector is not specifically limited. The photodetector 7 is exposed to the light reflecting cavity 60 through the light outlet 602 and at least partially blocks the light outlet 602, that is, the photodetector 7 blocks the light outlet 602 wholly or partially, alternatively, as shown in fig. 4, the photodetector 7 may be disposed outside the light collector 6, so that the photodetector 7 has a distance from the light outlet 602. Alternatively, as shown in fig. 5, the photodetector 7 may partially extend into the light collector 6 through the light outlet 602; the light outlet 602 is completely or partially shielded. When the light receiving surface of the photodetector 7 has a distance from the light exit port 602, in general, the maximum orthographic projection area of the photodetector 7 is larger than the orthographic projection area of the light exit port 602 in that direction, and the orthographic projection of the light exit port 602 is in the central area of the orthographic projection of the photodetector 7. By completely or partially blocking the light exit port 602 by the photodetector 7, scattered light is prevented from overflowing the light exit port 602 when it enters the light receiving surface of the photodetector 7. Preferably, when the photodetector 7 partially protrudes into the light collector 6 through the light outlet 602, the periphery of the photodetector is tightly coupled with the light collector through the light outlet 602.

The light reflection surface can be a complete surface or formed by splicing a plurality of surfaces in a sealing way, and a common light reflection surface can be obtained by coating a film on the inner surface of the light collector to form a surface with strong light reflection, and the specific limitation is not required here. Preferably, the light reflecting surface includes two opposing reflecting surfaces, the two reflecting surfaces are closely connected at the periphery, and the two reflecting surfaces surround the light inlet 601 and the light outlet 602 respectively. Part of the scattered light 23 is incident on one of the reflecting surfaces, and is incident on the light receiving surface of the photodetector 7 after being reflected once or more times on both the reflecting surfaces, increasing the amount of reception of the scattered light by the photodetector 7.

Further, the area of the outer surface of the light collector 6 facing the light beam 21 is a light absorbing surface 612. The light absorbing surface 612 may be formed by coating a light absorbing paint or blackening. Part of stray light in the propagation path of the light beam 21 can be absorbed by the light absorbing surface 612, reducing the incidence of stray light directly or indirectly on the photodetector 7.

Preferably, the light is directed towards the light reflection cavity, the maximum orthographic projection area of the light inlet 601 is larger than the orthographic projection area of the light working area 5 along the projection line direction of the maximum orthographic projection area of the light inlet 601, and the orthographic projection edge of the light working area 5 does not exceed the orthographic projection edge of the light inlet 601. Ensuring that scattered light from the optical working area 5 propagates into the light reflection cavity 60 as much as possible in the direction of the light entrance 601.

The maximum diameter of the maximum orthographic projection area of the light entrance 601 is preferably 1 to 2 times, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 times, preferably 1.1 to 1.5 times, of the maximum diameter of the orthographic projection area of the optical work area 5 in the projection line direction of the maximum orthographic projection area of the light entrance 601.

As shown in fig. 6, the maximum area of the orthographic projection area of the light inlet 601 has a projection line, an included angle θ is formed between the optical axis of the light working area 5 and the projection line, and θ is greater than or equal to 10 ° and less than or equal to 170 °. Preferably 20 DEG-theta-90 DEG, for example 25 DEG, 30 DEG, 35 DEG, 40 DEG, 50 DEG, 60 DEG, 70 DEG, 80 deg. Particle diameter range of particles is monitored in micron and submicron based on particle counter particles, when Mie scattering occurs to the particles, scattering is more in the forward direction than in the backward direction of light, the directivity is obvious, and the quantity of the collected scattered light sources is favorably improved.

For the light inlet 601 and the light outlet 602 having regular opening shapes, it is preferable that the light inlet 601 and the light outlet 602 are coaxial to maximize the amount of scattered light received directly into the photodetector 7. It is further preferable to arrange the optical working area 5, the light entrance 601 and the light exit 602 coaxially. For the light inlet 601 and the light outlet 602 without regular opening shapes, the areas of the maximum orthographic projection areas of the two have the maximized overlap.

Preferably the light inlet 601 is coaxial with said light work area 5.

Preferably, the light inlet 601 and the light outlet 602 are coaxial.

Preferably, the optical working area 5, the light inlet 601 and the light outlet 602 are coaxial.

Specifically, the light collector 6 includes a first light reflector 61 and a second light reflector 62, the first light reflector 61 has a first reflection surface 611, the second light reflector 62 has a second reflection surface 621, the first light reflector 61 and the second light reflector 62 are closely connected at their peripheries to form the reflection cavity 60, the first reflection surface 611 and the second reflection surface 621 are located inside the light collector 6, and the first reflection surface 611 and the second reflection surface 621 are disposed opposite to each other. The light inlet 601 is located on the first light reflector 61, and the light outlet 602 is located on the second light reflector 62. The surface of the first light reflecting mirror 61 facing the light beam 21 is a light absorbing surface 612. The scattered light enters the light reflection cavity 60 through the light inlet 601, part of the scattered light 22 directly enters the light receiving surface of the photoelectric detector 7, and part of the scattered light 23 enters the first reflection surface 611 and/or the second reflection surface 621, and enters the light receiving surface of the photoelectric detector 7 after being reflected to the first reflection surface 611 and/or the second reflection surface 621 or enters the light receiving surface of the photoelectric detector 7 after being reflected once or for multiple times by the two reflection surfaces.

As a specific example, the bottom end of the first light reflector 61 facing the light working area 5 has a circular light inlet 601, and the bottom end of the second light reflector 62 away from the light working area 5 has a circular light outlet 602. The minimum distance between the optical working area 5 and the light inlet 601 is 2mm, the maximum diameter of the maximum orthographic projection area of the light inlet 601 is 1.3 times of the maximum diameter of the orthographic projection area of the optical working area 5 along the projection line direction of the maximum orthographic projection area of the light inlet 601, the included angle theta is 90 degrees, and the optical working area 5, the light inlet 601 and the light outlet 602 are coaxial.

As an implementable aspect, the first light reflecting mirror 61 may be selected from a hemispherical mirror, an ellipsoidal mirror, and a conical mirror, and the second light reflecting mirror 62 may be selected from a hemispherical mirror, an ellipsoidal mirror, and a conical mirror, and the concave surface thereof reflects light. Preferably, the first light reflecting mirror 61 is a hemispherical mirror, and the photodetector 7 is disposed at the focal point of the first light reflecting mirror 61 to increase the amount of scattered light received by the photodetector 7. The second light reflecting mirror 62 may be a hemispherical mirror, a conical mirror as shown in fig. 7, an ellipsoidal mirror, or the like, and the light entrance 601 is preferably not located at the reflection focal point of the second light reflecting mirror 62.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A light receiving structure, applied in a particle counting sensor for receiving scattered light of particles, the particle counting sensor comprising an optical working area formed by emitting a light beam by a light source of the particle counting sensor, characterized by comprising a light collector and a photodetector; the light working area, the light collector and the photoelectric detector are sequentially arranged, a light reflecting surface is arranged in the light collector, a light reflecting cavity is formed by the light reflecting surface in a surrounding mode, a light inlet and a light outlet are formed in the light collector, the light reflecting cavity is communicated with the outside through the light inlet and the light outlet, the light inlet faces the light working area, the photoelectric detector is exposed to the light reflecting cavity through the light outlet and at least partially shields the light outlet, and a light receiving surface of the photoelectric detector faces the light reflecting cavity.

2. The light-receiving structure according to claim 1, wherein the light-reflecting surface comprises two opposing reflecting surfaces, the two reflecting surfaces being joined at their peripheries, and the two reflecting surfaces surrounding the light-inlet and the light-outlet, respectively.

3. The light receiving structure of claim 1, wherein a region of the outer surface of the light collector facing the light beam is a light absorbing surface.

4. The light receiving structure of claim 1, wherein the maximum forward projection area of the light entrance is larger than the forward projection area of the light active area along the projection line of the maximum forward projection area of the light entrance, and the edge of the forward projection of the light active area does not exceed the edge of the forward projection of the light entrance.

5. The light-receiving structure according to claim 4, wherein an optical axis of the light working area position has an angle θ with a projection line direction of a maximum forward projection area of the light entrance, and 10 ° < θ < 170 °.

6. The light-receiving structure of claim 1, wherein the light entrance and the light active area are coaxial.

7. The light-receiving structure of claim 1, wherein the light entrance and the light exit are coaxial.

8. The light receiving structure of claim 1, wherein the light active region, the light input port, and the light output port are coaxial.

9. The light receiving structure according to claim 3, wherein the light collector includes a first light reflector having a first reflecting surface and a second light reflector having a second reflecting surface, the first light reflector and the second light reflector are joined to form the light reflecting cavity, the first reflecting surface and the second reflecting surface are located inside the light reflecting cavity, and the first reflecting surface and the second reflecting surface are arranged to face each other; the light inlet is positioned on the first light reflector, and the light outlet is positioned on the second light reflector.

10. The light-receiving structure as claimed in claim 1, wherein the light working area is spaced from the light entrance, and the minimum distance between the light working area and the light entrance is 1-10 mm.

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