Particle counter

Abstract

The utility model provides a particle counter which comprises a shell, a light channel used for light beam propagation and a cavity used for scattering are arranged in the shell, the light channel is communicated with the cavity, and a light source assembly used for emitting light beams, a light guiding assembly, a scattered light collecting assembly and a light collecting structure are sequentially arranged from the light channel to the cavity. A light beam enters the cavity after being guided by the light guiding assembly, the scattered light collecting assembly and the light collecting structure are combined with the shell at the position of the cavity, the light source assembly and the light guiding assembly are sequentially arranged on a light channel path along a light beam propagation path, and the light guiding assembly comprises an optical fiber and a lens set. The lens group comprises a first cylindrical lens, a second cylindrical lens and a second focusing lens. According to the utility model, the particle counter can obtain more homogenized flat-topped light beams, so that the light intensity of light spots in a photosensitive area is more uniform, and stray light in the process that the light beams are emitted from a laser to be removed by a light trap can be reduced at the same time.

Description

Technical Field

[0001] The utility model relates to the technical field related to optical detection devices, and more precisely to a particle counter. Background Art

[0002] A clean room refers to a well-sealed space where parameters such as air cleanliness, temperature, humidity, pressure, and noise are controlled as required. A particle counter monitors the distribution of particles in a clean room to determine whether the cleanliness of the clean room is up to standard.

[0003] However, different levels of cleanliness have different requirements for the concentration distribution of particles that can exist in the clean room space. The higher the cleanliness level requirement of the clean room, the smaller the particle size required to be identified. Particle counters usually identify and count particles by irradiating particles with a light beam to obtain the scattered light of the particles. However, the smaller the particle size to be identified, the higher the requirement for the particle counter. The accuracy of the particle counter's particle counting for each particle size standard is affected by various noise signals, such as the uniformity of the intensity of the light of the light source beam irradiating the fluid part, the stray light formed by the light source beam, circuit noise, the dark current of the photodetector, etc. Since an overlapping area is formed when the light beam irradiates the fluid, in order to ensure the accuracy of particle size identification, it is required that the light intensity of the light spot in the overlapping area of ​​the particles in the fluid is as uniform as possible when passing through the light beam. Therefore, spherical mirrors, cylindrical mirrors and other shaping mirror groups are often used to compress and collimate the light beam to homogenize the Gaussian beam emitted by the laser light source to form a flat-top light. The mirror group embedded in the beam propagation path makes the shell structure design of the particle counter relatively complex, and it is necessary to consider the removal of stray light on the beam propagation path.

[0004] In summary, the field needs to improve the existing particle counter so that the particle counter can obtain a more uniform flat-top beam, make the light spot intensity in the photosensitive area more uniform, and reduce stray light from the time the beam is emitted from the laser to the time it is removed by the light trap. Utility Model Content

[0005] In view of this, an object of the present invention is to provide a particle counter.

[0006] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0007] A particle counter comprises a shell, wherein the shell has an optical channel for light beam propagation and a cavity for scattering, the optical channel is connected with the cavity, and a light source component for emitting the light beam, a light guide component, a scattered light collection component and a light collection structure are sequentially arranged from the optical channel to the cavity; the light beam enters the cavity after being guided by the light guide component; the scattered light collection component and the light collection structure are combined with the shell at the cavity; the light source component and the light guide component are sequentially arranged on the path of the optical channel along the light beam propagation path;

[0008] The light guiding assembly includes an optical fiber and a lens group, the lens group includes a first cylindrical lens, a second cylindrical lens and a second focusing lens, the busbar of the first cylindrical lens and the busbar of the second cylindrical lens are perpendicular to each other, the light beam is compressed and collimated by the first cylindrical lens and the second cylindrical lens and then incident on the optical fiber, and the second focusing lens is located at the light output end of the optical fiber.

[0009] Preferably, the lens assembly includes a first focusing lens disposed between the second cylindrical lens and the optical fiber, the light incident end face of the optical fiber is located at the focus of the first focusing lens, and is used to converge the light beam emitted by the second cylindrical lens and make it incident on the optical fiber.

[0010] Preferably, the convex surface of the first cylindrical lens faces the convex surface of the second cylindrical lens; the first cylindrical lens collimates the fast axis of the light beam, and the second cylindrical lens collimates the slow axis of the light beam.

[0011] Preferably, it also includes an air intake duct and an exhaust duct combined with the shell at the cavity, and the airflow to be measured enters the cavity through the air intake duct and is discharged from the exhaust duct, and the airflow to be measured overlaps with the light beam in the cavity to form a photosensitive area, and the photosensitive area is located at the focus of the second focusing lens.

[0012] Preferably, the air outlet of the air inlet duct and the air inlet of the exhaust duct are coaxial; the air outlet of the air inlet duct is smaller than the air inlet of the exhaust duct; and the photosensitive area is located between the air outlet of the air inlet duct and the air inlet of the exhaust duct.

[0013] Preferably, the light source component is a laser, and the laser is a semiconductor laser or a fiber laser.

[0014] Preferably, the scattered light collecting assembly comprises a reflector and a photodetector, and the reflector and the photodetector are respectively arranged on two opposite sides of the photosensitive area.

[0015] Preferably, the light collecting structure comprises a light trap arranged in combination with the shell, and the light beam is absorbed and removed by the light trap after passing through the photosensitive area.

[0016] Compared with the prior art, the advantages of the present invention are as follows: by arranging the first cylindrical lens and the second cylindrical lens to compress and collimate the light beam in the directions of the fast axis and the slow axis of the light beam respectively, and then guiding the collimated light beam into the optical fiber through the first focusing lens and then converging it through the second focusing lens, the particle counter can obtain a more homogenized flat-top light beam in the photosensitive area, making the light spot intensity in the photosensitive area more uniform, and at the same time, it can also reduce stray light in the process from the light beam being emitted from the laser to being removed by the light trap. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] like Figure 1 Shown is a schematic diagram of a particle counter of the utility model.

[0019] like Figure 2 Shown is a structural schematic diagram of an air path module of a particle counter of the utility model. DETAILED DESCRIPTION

[0020] The technical solution of the utility model will be clearly and completely described below through specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of them. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] See attached Figure 1 and attached Figure 2As shown, a particle counter of the present application includes a housing 1, and the housing 1 has an optical channel 11 for propagation of a light beam 21 and a cavity 12 for scattering. The optical channel 11 and the cavity 12 are connected, and a light source component, a light guide component, a scattered light collection component and a light collection structure for emitting the light beam 21 are sequentially arranged from the optical channel 11 to the cavity 12. The light beam 21 enters the cavity 12 after being guided by the light guide component, and the scattered light collection component and the light collection structure are arranged in combination with the housing 1 at the cavity 12. The light source component and the light guide component are arranged on the path of the optical channel 11 along the propagation path of the light beam 21, wherein the light source component is a laser 2. The light guiding assembly includes an optical fiber 3 and a lens group, which includes a first cylindrical lens 91, a second cylindrical lens 92, a first focusing lens 93 and a second focusing lens 10. The busbar of the first cylindrical lens 91 and the busbar of the second cylindrical lens 92 are perpendicular to each other. The light beam 21 is compressed and collimated by the first cylindrical lens 91 and the second cylindrical lens 92 and then incident on the optical fiber 3. The second focusing lens 92 is located at the light output end of the optical fiber 3.

[0022] In order to allow the light beam 21 emitted by the laser 2 to enter the optical fiber 3 and to avoid the spot area of ​​the light beam 21 at the end face of the optical fiber 3 being larger than the end face area of ​​the core of the optical fiber 3, which would result in the light beam 21 not being able to fully enter the optical fiber 3 and forming stray light, a first cylindrical lens 91 and a second cylindrical lens 92 are arranged between the laser 2 and the optical fiber 3 to guide the light beam 21 into the optical fiber 3 and to converge the light beam output by the optical fiber 3 through the second focusing lens 10.

[0023] The convex surface of the first cylindrical lens 91 is arranged opposite to the convex surface of the second cylindrical lens 92 , the first focusing lens 93 is arranged opposite to the plane of the second cylindrical lens 92 , the first cylindrical lens 91 collimates the fast axis of the light beam 21 , and the second cylindrical lens 92 collimates the slow axis of the light beam 21 .

[0024] The lens assembly includes a first focusing lens 93 disposed between the second cylindrical lens 10 and the optical fiber 3 . The light incident end face of the optical fiber 3 is located at the focus of the first focusing lens 93 , which is used to converge the light beam 21 emitted from the second cylindrical lens 10 and make it incident on the optical fiber 3 .

[0025] The second focusing lens 10 is located at the light output end face of the optical fiber 3, and the second focusing lens 10 converges the light beam 21 outputted from the optical fiber 3. As an practicable method, Figure 1 As shown, during the propagation process, the light beam 21 passes through the plane of the first cylindrical lens 91, the convex surface of the first cylindrical lens 91, the convex surface of the second cylindrical lens 92, the plane of the second cylindrical lens 92, the first focusing lens 93, and the optical fiber 3. Finally, the light beam 21 output through the optical fiber 3 is converged by the second focusing lens 10, and the converged light beam 21 enters the cavity 12 for scattering.

[0026] As an implementable manner, the generatrix of the first cylindrical lens 91 is taken as the first direction, and the generatrix of the second cylindrical lens 92 is taken as the second direction, and the first direction and the second direction are both perpendicular to the axial direction of the light beam 21, and the first direction and the second direction are perpendicular to each other. The first cylindrical lens 91 compresses and collimates the light in the fast axis direction of the light beam 21. The second cylindrical lens 92 compresses and collimates the light in the slow axis direction of the light beam 21.

[0027] Among them, the light beam 21 emitted by the laser 2 is incident from the plane of the first cylindrical lens 91, and is emitted from the convex surface of the first cylindrical lens 91. The fast axis of the light beam 21 is compressed and collimated. Then, it is incident from the convex surface of the second cylindrical lens 92, and is emitted from the plane of the second cylindrical lens 92. The slow axis of the light beam 21 is compressed and collimated. By shaping the light beam 21, that is, compressing and collimating the light beam 21 in the direction of the fast axis and the slow axis of the light beam, and guiding the light beam 21 into the optical fiber 3. The particle counter can obtain a more uniform flat-top beam, making the light spot intensity in the photosensitive area more uniform, and at the same time, it can also reduce stray light in the process from the light beam being emitted by the laser to being removed by the light trap. The light guiding component of the particle counter in this embodiment uses cylindrical lenses with convex surfaces arranged opposite to each other to achieve beam shaping.

[0028] Preferably, in this embodiment, the airflow to be measured and the light beam 21 overlap in the cavity to form a photosensitive area 8 , and the photosensitive area 8 is located at the focus of the second focusing lens 10 .

[0029] Preferably, see the attached Figure 2 As shown, in this embodiment, an air intake duct 71 and an exhaust duct 72 are provided on the shell 1. The air flow to be measured enters the cavity 12 through the air intake duct 71 and is discharged from the exhaust duct 72. The air outlet of the air intake duct 71 and the air inlet of the exhaust duct 72 are coaxial, the air outlet of the air intake duct 71 is smaller than the air inlet of the exhaust duct 72, and the photosensitive area 8 is located between the air outlet of the air intake duct 71 and the air inlet of the exhaust duct 72.

[0030] Preferably, see the attached Figure 1 and attached Figure 2As shown, the scattered light collection assembly in this embodiment includes a reflector 6 and a photodetector 5, and the reflector 6 and the photodetector 5 are respectively arranged on both sides of the photosensitive area 8. The reflector 6 and the photodetector 5 are arranged in combination with the shell wall of the shell 1 at the cavity 12. The reflector 6 collects the scattered light of the particles to be measured and reflects it to the photodetector 5. The photodetector 5 converts the received scattered light of the particles to be measured into an electrical signal. The photodetector 5 and the reflector 6 are arranged to meet the geometric optical relationship. A part of the scattered light of the particles to be measured can be directly received by the photodetector 5, and a part can be collected by the reflector 6 and then transmitted to the photodetector 5. The photodetector 5, such as a photodiode or a photomultiplier tube, converts the received light signal into an electrical signal. Among them, the flow direction of the gas flow to be measured in the cavity 12, the optical axis of the light beam 21 in the cavity 12, and the central axis of the reflector 6 are perpendicular to each other. Therefore, the reflector 6 and the photodetector 5 are arranged in a direction perpendicular to the optical axis of the light beam 21 in the cavity 12.

[0031] Preferably, see the attached Figure 1 and attached Figure 2 As shown, the light collecting structure in this embodiment includes a light trap 4 combined with the shell 1 at the cavity 12. The light beam 21 is excited by particles in the airflow to be measured in the photosensitive area 8 to emit scattered light. The light beam 21 is absorbed by the light trap 8 after passing through the photosensitive area 8.

[0032] Preferably, the laser used as the light source may be a semiconductor laser or a fiber laser.

[0033] The above description of the disclosed embodiments enables professionals in the field to implement or use the utility model. Various modifications to these embodiments will be apparent to professionals in the field, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the utility model. Therefore, the utility model will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features disclosed herein.

Claims

1. A particle counter, characterized in that: The invention comprises a shell, wherein the shell has an optical channel for light beam propagation and a cavity for scattering, the optical channel is connected with the cavity, and a light source component for emitting the light beam, a light guide component, a scattered light collection component and a light collection structure are sequentially arranged from the optical channel to the cavity; the light beam enters the cavity after being guided by the light guide component; the scattered light collection component and the light collection structure are combined with the shell at the cavity; the light source component and the light guide component are sequentially arranged on the path of the optical channel along the light beam propagation path; The light guiding assembly includes an optical fiber and a lens group, the lens group includes a first cylindrical lens, a second cylindrical lens and a second focusing lens, the busbar of the first cylindrical lens and the busbar of the second cylindrical lens are perpendicular to each other, the light beam is compressed and collimated by the first cylindrical lens and the second cylindrical lens and then incident on the optical fiber, and the second focusing lens is located at the light output end of the optical fiber.

2. A particle counter according to claim 1, characterized in that: The lens assembly includes a first focusing lens disposed between the second cylindrical lens and the optical fiber. The light incident end face of the optical fiber is located at the focus of the first focusing lens, and is used to converge the light beam emitted by the second cylindrical lens and make it incident on the optical fiber.

3. A particle counter according to claim 1, characterized in that: The convex surface of the first cylindrical lens faces the convex surface of the second cylindrical lens; the first cylindrical lens collimates the fast axis of the light beam, and the second cylindrical lens collimates the slow axis of the light beam.

4. A particle counter according to claim 1, characterized in that: It also includes an air intake duct and an exhaust duct combined with the shell at the cavity. The airflow to be measured enters the cavity through the air intake duct and is discharged from the exhaust duct. The airflow to be measured overlaps with the light beam in the cavity to form a photosensitive area, and the photosensitive area is located at the focus of the second focusing lens.

5. A particle counter according to claim 4, characterized in that: The air outlet of the air inlet duct and the air inlet of the exhaust duct are coaxial; the air outlet of the air inlet duct is smaller than the air inlet of the exhaust duct; and the photosensitive area is located between the air outlet of the air inlet duct and the air inlet of the exhaust duct.

6. A particle counter according to claim 1, characterized in that: The light source component is a laser, and the laser is a semiconductor laser or a fiber laser.

7. A particle counter according to claim 4, characterized in that: The scattered light collecting component comprises a reflector and a photodetector, and the reflector and the photodetector are respectively arranged on two sides of the photosensitive area.

8. A particle counter according to claim 4, characterized in that: The light collecting structure comprises a light trap combined with the shell, and the light beam is absorbed and removed by the light trap after passing through the photosensitive area.

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