A particle counter optical train
By designing and optimizing the polarization optical path of the particle counter optical path system, the problem of low signal-to-noise ratio in the existing technology has been solved, and high-precision detection of smaller gas particles has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- QINGDAO ZHONGRUI INTELLIGENT INSTR
- Filing Date
- 2025-06-24
- Publication Date
- 2026-07-14
Smart Images
Figure CN224500327U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of gas detection, and in particular to a particle counter optical path system. Background Technology
[0002] Optical particle counters are core instruments for measuring the particle size and concentration distribution of particulate matter in the air. They operate based on Mie scattering theory: when particles pass through a photosensitive area with the airflow, they are irradiated by a laser, generating scattered light whose intensity is positively correlated with particle size. A photodetector converts the scattered light into electrical pulse signals, enabling particle size resolution and counting. These devices are widely used in cleanroom environmental monitoring (semiconductors, biomedicine), ambient air quality assessment, and industrial process control. Their resolution and counting accuracy directly affect the reliability of the monitoring results.
[0003] The key indicator in the current particle counter optical path system is the signal-to-noise ratio (SNR) of the particle signal. The higher the SNR, the higher the accuracy of the detection signal. By suppressing optical noise interference and increasing the intensity of the light scattering signal, a high SNR optical path system can be built.
[0004] Currently, most existing particle counters use laser diodes as the laser source. Through beam shaping, a gas particle detection area with relatively concentrated energy is formed in the photosensitive region to detect gas particles. This method uses only the energy emitted by a laser diode. Due to limitations such as the size of the laser diode and the chip damage threshold, it cannot emit lasers of higher intensity, and therefore cannot detect smaller gas particles.
[0005] 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
[0006] In response to the problems pointed out in the background art, this utility model proposes a particle counter optical path system that can realize the detection of gas particles with smaller diameters.
[0007] To achieve the above-mentioned objectives, the present invention employs the following technical solution:
[0008] In some embodiments of this application, a particle counter optical path system is provided, comprising:
[0009] The light source is configured to emit linearly polarized light;
[0010] An aspherical lens is disposed on the light-emitting side of the light source;
[0011] A polarizing beam splitter is disposed on the side of the aspherical lens facing away from the light source. The polarizing beam splitter is configured to transmit horizontally polarized linearly polarized light and reflect vertically polarized linearly polarized light.
[0012] A quarter-wave plate is disposed on the side of the polarizing beam splitter opposite to the aspherical lens;
[0013] The photodetector is configured to detect the scattered light signal of particles flowing through the photosensitive region.
[0014] In some embodiments of this application, a light-absorbing barrel is also included, which is disposed below the polarizing beam splitter.
[0015] In some embodiments of this application, the photodetector includes a photodetector, a Manning mirror group, and a second spherical reflector. The photodetector and the Manning mirror group are disposed on one side of the photosensitive region, and the second spherical reflector is disposed on the other opposite side of the photosensitive region.
[0016] In some embodiments of this application, the distance between the second spherical reflector and the photosensitive area is equal to the radius of curvature of the second spherical reflector.
[0017] In some embodiments of this application, a first aperture and a second aperture are further included, wherein the first aperture and the second aperture are disposed on opposite sides of the photosensitive region.
[0018] In some embodiments of this application, a first spherical reflector is also included, which is disposed on the side of the photosensitive region opposite to the quarter-wave plate.
[0019] In some embodiments of this application, the distance between the first spherical mirror and the photosensitive area is equal to the radius of curvature of the first spherical mirror.
[0020] In some embodiments of this application, the light source is a laser diode.
[0021] Compared with the prior art, the advantages and positive effects of this utility model are:
[0022] The particle counter optical path system of this application enhances the light scattering signal intensity by using a polarizing beam splitter and a quarter-wave plate to increase the laser intensity in the photosensitive region; and by using an angle-sensitive coated spherical mirror to suppress optical noise and increase signal intensity, effectively improving the signal-to-noise ratio of the system. This enables the detection of smaller particles and improves the counting accuracy of the device.
[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 This is a schematic diagram of a particle counter optical path system according to some embodiments;
[0026] Figure 2 This is an optical path diagram of a polarizing beam splitter according to some embodiments.
[0027] Figure label:
[0028] 1. Light source; 2. Aspherical lens; 3. Polarizing beam splitter; 4. Quarter-wave plate; 5. Photodetector; 6. Manning lens group; 71. First aperture; 72. Second aperture; 8. First spherical mirror; 9. Light-absorbing barrel; 10. Second spherical mirror; 20. Photosensitive area. Detailed Implementation
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] In some embodiments of this application, a particle counter optical path system is provided, with reference to... Figure 1 It includes a light source 1, which is configured to emit linearly polarized light. For example, the light source 1 is a laser diode. The light source 1 is capable of emitting linearly polarized light with a polarization ratio of 100:1.
[0036] The particle counter optical path system also includes an aspherical lens 2, which is disposed on the light-emitting side of the light source 1. After the linearly polarized light emitted from the light source 1 passes through the aspherical lens 2, the beam is focused at the photosensitive region 20, forming a concentrated light spot at the photosensitive region 20, so that when the particles pass through the photosensitive region 20, a high-energy light scattering signal is generated.
[0037] The particle counter optical path system also includes a polarizing beam splitter 3, which is disposed on the side of the aspherical lens 2 away from the light source 1. The polarizing beam splitter 3 is configured to pass horizontally polarized linear light and reflect vertically polarized linear light.
[0038] Specifically, the polarizing beam splitter 3 is placed behind the aspherical lens 2, as close as possible to the aspherical lens 2, and at a 45° angle to the plane of the aspherical lens 2. Its function is to allow horizontally polarized linearly polarized light (P-ray) to pass through and reflect vertically polarized linearly polarized light (S-ray), such as... Figure 2 As shown.
[0039] The particle counter optical path system also includes a quarter-wave plate 4, which is located on the side of the polarizing beam splitter 3 away from the aspherical lens 2.
[0040] Specifically, the quarter-wave plate 4 is placed after the polarizing beam splitter 3, close to the polarizing beam splitter 3, and perpendicular to the optical axis. When the laser passes through the quarter-wave plate 4, its phase is deflected by 45°, and its polarization direction is between horizontal and vertical polarization. After the laser returns through the first spherical mirror 8, it passes through the quarter-wave plate 4 again, and its phase is deflected by 45° again. At this time, the laser polarization direction changes from the initial horizontal polarization (P-light) to vertical polarization (S-light). After irradiating the polarizing beam splitter 3, total internal reflection occurs, reflecting the laser into the light-absorbing barrel 9, preventing the laser from escaping and generating stray light, and at the same time avoiding the laser returning to the light source 1 along the original path and causing damage to the light source 1.
[0041] The particle counter optical path system also includes a photodetector, which is configured to detect the scattered light signal of particles flowing through the photosensitive region 20.
[0042] The particle counter optical path system of this application utilizes a combination of a polarizing beam splitter 3 and a quarter-wave plate 4 to deflect the polarization state of the laser emitted by the laser diode by 45° before illuminating the photosensitive area 20. The laser then returns to the photosensitive area 20 via a first spherical mirror 8, increasing the laser intensity in the photosensitive area 20. Passing again through the quarter-wave plate 4, the laser polarization state is further deflected by 45°, at which point it is perpendicular to the polarization state of the laser emitted by the laser diode. After passing through the polarizing beam splitter 3, the laser is reflected into the light-absorbing container 9. Using this combination of lenses can double the light energy of the photosensitive area 20 of the particle counter, providing a solution for detecting small-diameter gas particles.
[0043] In some embodiments of this application, the particle counter optical path system further includes a light-absorbing barrel 9, which is disposed below the polarizing beam splitter 3. The light-absorbing barrel 9 is used to receive reflected laser light and prevent laser escape from generating stray light.
[0044] In some embodiments of this application, the photodetector includes a photodetector 5, a Manning mirror group 6, and a second spherical mirror 10. The photodetector 5 and the Manning mirror group 6 are disposed on one side (e.g., the upper side) of the photosensitive area 20, and the second spherical mirror 10 is disposed on the other opposite side (e.g., the lower side) of the photosensitive area 20.
[0045] The photodetector 5 and the Manning mirror group 6 are placed on one side above the photosensitive area 20, with the Manning mirror group 6 placed close to the photosensitive area 20 and the photodetector 5 placed close to the Manning mirror group 6, so as to receive information such as the intensity of light from the particles in the photosensitive area 20.
[0046] Using the Mankind lens group 6, the signal of the photosensitive area 20 is imaged 1:1 onto the photosensitive surface of the photodetector 5. The high-intensity signal is collected and processed by subsequent circuitry to achieve the detection of small-diameter gas particles.
[0047] In some embodiments of this application, the distance between the second spherical reflector 10 and the photosensitive region 20 is equal to the radius of curvature of the second spherical reflector. This doubles the intensity of the light signal generated when a particle passes through the photosensitive region 20, which is then imaged onto the photosensitive surface of the photodetector 5 by the Menkin lens group 6, thereby achieving particle light signal detection.
[0048] The second spherical mirror 10, employing an angle-sensitive coating process, is placed below the photosensitive area 20 at a distance equal to the radius of curvature of the second sphere. The light beam from the photosensitive area 20 is perpendicularly incident on the surface of the second spherical mirror 10, forming a reflected beam. In other words, the particle image from the photosensitive area 20 is imaged again on the photosensitive area 20 after passing through the second spherical mirror 10, doubling the intensity of the light generated when particles pass through. Because the second spherical mirror 10 uses an angle-sensitive coating process, the reflectivity of light intensity information in non-central regions is low, thus stray light signals from other regions cannot be reflected for image enhancement. This method can effectively increase the particle signal intensity by approximately one time and suppress the increase in optical noise intensity, thereby improving the signal-to-noise ratio and enhancing the performance of particle counting instruments.
[0049] In some embodiments of this application, the particle counter optical path system further includes a first aperture 71 and a second aperture 72, which are disposed on opposite sides of the photosensitive region 20. The placement of the first aperture 71 and the second aperture 72 on opposite sides of the photosensitive region 20 effectively reduces the intensity of stray light generated during the two laser transmission processes, thus improving the signal-to-noise ratio of the particle counting sensor.
[0050] Using the first aperture 71 and the second aperture 72 effectively reduces stray light in the photosensitive area 20, keeping optical noise at a low level. At the same time, stray light generated at the edges of the two apertures cannot be imaged by the second spherical mirror 10, thus keeping the stray light intensity at a low level.
[0051] In some embodiments of this application, the particle counter optical path system further includes a first spherical mirror 8, which is disposed on the side of the photosensitive region 20 opposite to the quarter-wave plate 4. The distance between the first spherical mirror 8 and the photosensitive region 20 is equal to the radius of curvature of the first spherical mirror 8.
[0052] The first spherical mirror 8 is placed after the photosensitive area 20, and the distance between the first spherical mirror 8 and the photosensitive area 20 is equal to the radius of curvature of the first spherical mirror 8. This allows the laser to converge again at the photosensitive area 20 after passing through the first spherical mirror 8, thereby doubling the laser intensity and detecting smaller gas particles.
[0053] The particle counter optical path system of this application enhances the light scattering signal intensity by using a polarizing beam splitter 3 and a quarter-wave plate 4 to increase the laser intensity of the photosensitive region 20; and by using an angle-sensitive coated spherical mirror to suppress the intensity of optical noise and excessive signal intensity, effectively improving the signal-to-noise ratio of the system. This enables the detection of smaller particles and improves the counting accuracy of the device.
[0054] 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.
[0055] 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 optical path system, characterized in that, Including: The light source is configured to emit linearly polarized light; An aspherical lens is disposed on the light-emitting side of the light source; A polarizing beam splitter is disposed on the side of the aspherical lens facing away from the light source. The polarizing beam splitter is configured to transmit horizontally polarized linearly polarized light and reflect vertically polarized linearly polarized light. A quarter-wave plate is disposed on the side of the polarizing beam splitter opposite to the aspherical lens; The photodetector is configured to detect the scattered light signal of particles flowing through the photosensitive region.
2. The particle counter optical path system according to claim 1, characterized in that, It also includes a light-absorbing barrel, which is disposed below the polarizing beam splitter.
3. The particle counter optical path system according to claim 1, characterized in that, The photodetector includes a photodetector, a Manning mirror group, and a second spherical reflector. The photodetector and the Manning mirror group are disposed on one side of the photosensitive area, and the second spherical reflector is disposed on the opposite side of the photosensitive area.
4. The particle counter optical path system according to claim 3, characterized in that, The distance between the second spherical reflector and the photosensitive area is equal to the radius of curvature of the second spherical reflector.
5. The particle counter optical path system according to claim 1, characterized in that, It also includes a first aperture and a second aperture, which are disposed on opposite sides of the photosensitive region.
6. The particle counter optical path system according to claim 1, characterized in that, It also includes a first spherical mirror, which is disposed on the side of the photosensitive region opposite to the quarter-wave plate.
7. The particle counter optical path system according to claim 6, characterized in that, The distance between the first spherical mirror and the photosensitive area is equal to the radius of curvature of the first spherical mirror.
8. The particle counter optical path system according to claim 1, characterized in that, The light source is a laser diode.