Particle counter

Abstract

The utility model discloses a particle counter, which is characterized in that a laser source emits a laser beam into a detection light chamber, and the laser beam is provided with a long axis and a short axis; the aspherical lens and the light collecting part are arranged on the light emitting side of the laser source and are opposite to each other, the aspherical lens compresses the laser beam, and the light collecting part collects laser and stray light in the detection light chamber; the 1 / 2 wave plate is arranged between the aspherical lens and the light collecting part, and the 1 / 2 wave plate rotates the polarization direction of the laser beam by 90 degrees; the air inlet nozzle provides aerosol airflow into the detection light chamber, and the aerosol airflow passes through the laser beam; the photoelectric detection unit detects a scattered light signal of the aerosol particles. According to the utility model, the problem of low signal intensity during small particle size detection can be solved, and the detection performance of the particle counter is improved.

Description

Technical Field

[0001] This utility model relates to the field of gas detection technology, and in particular to a particle counter. Background Technology

[0002] Particle counters often use laser diodes as the laser source. The laser light emitted by the laser diode is linearly polarized light with a polarization ratio of 50:1 or 100:1. The polarization state of the light affects the particle size signal. When detecting small particle sizes, there is a problem that the signal and noise intensities are close and cannot be well distinguished, thus reducing the detection performance of the particle counter.

[0003] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this application, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0004] In response to the problems mentioned in the background art, this utility model proposes a particle counter to solve the problem of low signal intensity when detecting small particles and improve the detection performance of the particle counter.

[0005] To achieve the above-mentioned objectives, the present invention employs the following technical solution:

[0006] In some embodiments of this application, a particle counter is provided, comprising:

[0007] A laser source is configured to emit a laser beam into a detection optical chamber, the laser beam having a major axis and a minor axis;

[0008] An aspherical lens is disposed on the light-emitting side of the laser source, and the aspherical lens is configured to compress the laser beam;

[0009] A light collecting unit is disposed at the light emission point of the laser source, the light collecting unit is disposed opposite to the aspherical lens, and the light collecting unit is configured to collect laser light and stray light in the detection light chamber;

[0010] A half-wave plate is disposed between the aspherical lens and the light collecting part, and the half-wave plate is configured to rotate the polarization direction of the laser beam by 90°;

[0011] An air inlet is configured to provide an aerosol flow into the detection optical chamber, the aerosol flow passing through the laser beam;

[0012] The photoelectric detection unit is configured to detect the scattered light signal from aerosol particles.

[0013] In some embodiments of this application, the laser source emits a first wavelength laser, and the half-wave plate is coated with a first wavelength dielectric film.

[0014] In some embodiments of this application, the laser source emits 808nm laser light, and the half-wave plate is coated with an 808nm dielectric film.

[0015] In some embodiments of this application, the laser source is a laser diode.

[0016] In some embodiments of this application, the photodetector includes a concave reflector and a photodetector, with the concave surface of the concave reflector facing the photodetector.

[0017] In some embodiments of this application, the concave reflector collects the scattered light signal at an angle greater than 125°.

[0018] In some embodiments of this application, the width of the laser beam in the photosensitive area after being compressed by the aspherical lens along its long axis is less than 0.02 mm.

[0019] In some embodiments of this application, the width of the laser beam in the photosensitive area after being compressed by the aspherical lens along its short axis ranges from 0.08 to 1.02 mm.

[0020] Compared with the prior art, the advantages and positive effects of this utility model are:

[0021] This case involves adjusting the polarization direction of the laser source in a particle counter by introducing a half-wave plate. This rotates the laser polarization direction by 90°, adjusting the angle between the incident light vibration surface perpendicular to the Y-view and the scattering surface to 90 degrees. At this point, the concave reflector collects the strongest scattered light at the center of the angle, while the linear light spot in the photosensitive area remains unchanged. Therefore, using a half-wave plate to adjust the laser polarization state can effectively improve the intensity of the scattered light signal and enhance the detection capability of the instrument.

[0022] Using an aspherical lens to compress the long axis of the laser source output spot creates a strip-shaped spot with uniform energy in the photosensitive area. This helps improve the consistency of the measured particle signal for the same particle size and is easy to adjust.

[0023] Other features and advantages of this utility model will become clearer after reading the specific embodiments of this utility model in conjunction with the accompanying drawings. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic diagram of a particle counter according to some embodiments;

[0026] Figure 2 This is yet another schematic diagram of a particle counter according to some embodiments.

[0027] Figure label:

[0028] 10. Laser source; 11. Laser beam;

[0029] 20. Aspherical lens;

[0030] 30. Half-wave plate;

[0031] 40. Light collection unit;

[0032] 50. Photodetector; 51. Concave mirror; 52. Photodetector;

[0033] 60. Air intake nozzle;

[0034] 70. Photosensitive region. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0037] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0038] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0039] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] The following disclosure provides many different embodiments or examples for implementing various structures of this invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0041] In some embodiments of this application, a particle counter is provided. Figure 1 An X-view of a particle counter. Figure 2 This is a Y-view of a particle counter.

[0042] The particle counter includes a laser source 10. The laser source 10 is configured to emit a laser beam 11 into a detection optical chamber. The laser beam 11 has a major axis and a minor axis. For example, the major axis of the laser beam 11 is oriented in the direction of... Figure 2 The Y-view shown is placed parallel to the ground plane, with the minor axis of laser beam 11 aligned with the horizontal plane. Figure 1 The X-view shown is placed parallel to the view.

[0043] The particle counter also includes an aspherical lens 20. The aspherical lens 20 is disposed on the light-emitting side of the laser source 10 and is configured to compress the laser beam 11. The aspherical lens 20 has high transmittance to the laser beam 11, and the laser beam 11 enters the detection light chamber through the aspherical lens 20.

[0044] Using an aspherical lens 20 to compress the long axis of the output spot of the laser source 10 forms a strip-shaped spot with uniform energy in the photosensitive area 70, which is beneficial to improving the consistency of the measured particle signal of the same particle size, and is simple to adjust.

[0045] The particle counter also includes a light collecting unit 40. The light collecting unit 40 is disposed at the light-emitting side of the laser source 10, and is positioned opposite to the aspherical lens 20. In other words, along the irradiation direction of the laser beam 11, the aspherical lens 20 and the light collecting unit 40 are positioned opposite each other, with the aspherical lens 20 closer to the laser source 10 and the light collecting unit 40 further away from the laser source 10. The light collecting unit 40 is configured to collect laser light and stray light within the detection chamber, reducing the optical noise of the photodetector 52.

[0046] The particle counter also includes a half-wave plate 30. The half-wave plate 30 is disposed between the aspherical lens 20 and the light collecting part 40, and the half-wave plate 30 is configured to rotate the polarization direction of the laser beam 11 by 90°.

[0047] The polarization state of light affects the particle size signal. When detecting small particle sizes, the signal and noise intensities are so similar that they cannot be well distinguished, reducing the detection performance of the particle counter. This case addresses this issue based on Mie scattering theory by adding a 1 / 2 waveplate (30°) to adjust the laser polarization state. When the angle between the incident light vibration plane and the scattering plane is adjusted to 90°, the collected particle size signal is significantly increased, thus solving the problem of low signal intensity when detecting small particles.

[0048] The particle counter also includes an air inlet 60. The air inlet 60 is configured to provide an aerosol flow into the detection chamber, the aerosol flow passing through the laser beam 11. The air inlet 60 and... Figure 2 The Y-view shown is set in parallel. Aerosol particles enter the photosensitive area 70 through the air inlet 60 and generate scattered light signals.

[0049] The particle counter also includes a photodetector 50. The photodetector 50 is configured to detect the scattered light signal from aerosol particles. The photodetector 50 and... Figure 1 The X-view shown is placed vertically with the photosensitive surface facing the photosensitive area 70. The scattered light signal generated by the particles is processed, and combined with the back-end circuit analysis, the particle size and quantity information of the particles are obtained.

[0050] This study analyzes the influence of polarization direction on the intensity of scattered light at a certain angle based on Mie scattering theory. A half-wave plate 30 is used to rotate the polarization state of the laser source 10 by 90°, so that the intensity of the scattered signal light collected by the photodetector 50 is maximized while ensuring that the light spot does not change. This effectively improves the signal strength of the particle counter and enhances the detection capability of the instrument.

[0051] In other words, this case adjusts the polarization direction of the laser source of the particle counter by introducing a half-wave plate 30, rotating the polarization direction of the laser by 90°, and adjusting the angle between the incident light vibration surface perpendicular to the Y-view and the scattering surface to 90 degrees. At this time, the concave reflector 51 collects the strongest scattered light at the center of the angle, while the linear light spot of the photosensitive area 70 does not change. Therefore, using the half-wave plate 30 to adjust the laser polarization state can effectively improve the intensity of the scattered light signal.

[0052] In some embodiments of this application, the laser source 10 emits a first wavelength laser beam, and the half-wave plate 30 is coated with a first wavelength dielectric film. In other words, the half-wave plate 30 has high transmittance to the laser beam 11.

[0053] For example, the laser source 10 emits an 808nm laser, and the half-wave plate 30 is a zero-order wave plate coated with an 808nm dielectric film, which has low sensitivity to temperature and incident angle.

[0054] In some embodiments of this application, to facilitate debugging, the particle counter is provided with a rotating device for rotating the 1 / 2 wave plate 30, so that the polarization direction of the laser is rotated by 90°.

[0055] The rotating device can employ a conventional rotating mechanism, such as a motor drive. The specific implementation of the rotating device can be easily designed by those skilled in the art based on existing technology, and this application does not impose any specific limitations.

[0056] In some embodiments of this application, the laser source 10 is a laser diode. The laser emitted by the laser diode is linearly polarized light.

[0057] In some embodiments of this application, the photodetector 50 includes a concave reflector 51 and a photodetector 52, with the concave surface of the concave reflector 51 facing the photodetector 52. The concave reflector 51 and the photodetector 52 are disposed on opposite sides of the photosensitive region 70, with the concave surface of the concave reflector 51 facing the photosensitive region 70, to collect the scattered light signal from aerosol particles.

[0058] For example, the concave mirror 51 has a collection angle of more than 125° for the scattered light signal.

[0059] In some embodiments of this application, the width of the laser beam 11 within the photosensitive region 70 after being compressed by the aspherical lens 20 along its long axis is less than 0.02 mm.

[0060] After being compressed by the aspherical lens 20, the short axis of the laser beam 11 has a width range of 0.08-1.02 mm within the photosensitive area 70.

[0061] In other words, the aspherical lens 20 focuses the laser beam 11 emitted by the laser source 10. Since the laser beam 11 has a larger divergence angle along its major axis, it converges faster after passing through the aspherical lens 20. Its beam waist position is a thin line with a width of less than 0.02 mm at the photosensitive area 70. The laser beam 11 converges more slowly along its minor axis, and its beam waist position at the photosensitive area 70 has a spot width of 0.08-1.02 mm, for example, 1 mm.

[0062] Based on the Mie scattering theory, this application adjusts the laser polarization state by adding a 1 / 2 waveplate 30. When the angle between the incident light vibration surface and the scattering surface is adjusted to 90°, the collected particle size signal is significantly increased, which can effectively distinguish the particle signal of small particle size (e.g., 0.3 micrometers) from the noise signal, thereby solving the problem of low signal intensity when detecting small particles.

[0063] In the description of the above embodiments, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0064] The above are merely specific embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A particle counter, characterized in that, Including: A laser source is configured to emit a laser beam into a detection optical chamber, the laser beam having a major axis and a minor axis; An aspherical lens is disposed on the light-emitting side of the laser source, and the aspherical lens is configured to compress the laser beam; A light collecting unit is disposed at the light emission point of the laser source, the light collecting unit is disposed opposite to the aspherical lens, and the light collecting unit is configured to collect laser light and stray light in the detection light chamber; A half-wave plate is disposed between the aspherical lens and the light collecting part, and the half-wave plate is configured to rotate the polarization direction of the laser beam by 90°; An air inlet is configured to provide an aerosol flow into the detection optical chamber, the aerosol flow passing through the laser beam; The photoelectric detection unit is configured to detect the scattered light signal from aerosol particles.

2. The particle counter according to claim 1, characterized in that, The laser source emits a first wavelength laser, and the half-wave plate is coated with a first wavelength dielectric film.

3. The particle counter according to claim 2, characterized in that, The laser source emits 808nm laser light, and the half-wave plate is coated with an 808nm dielectric film.

4. The particle counter according to claim 1, characterized in that, The laser source is a laser diode.

5. The particle counter according to claim 1, characterized in that, The photoelectric detection unit includes a concave reflector and a photodetector, with the concave surface of the concave reflector facing the photodetector.

6. The particle counter according to claim 5, characterized in that, The concave reflector collects scattered light signals at an angle greater than 125°.

7. The particle counter according to claim 1, characterized in that, After being compressed by the aspherical lens, the width of the laser beam along its long axis within the photosensitive area is less than 0.02 mm.

8. The particle counter according to claim 1, characterized in that, After being compressed by the aspherical lens, the width of the laser beam along its short axis within the photosensitive area ranges from 0.08 to 1.02 mm.

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