Dust particle counter

Abstract

The utility model belongs to the technical field of metering detection, and provides a dust particle counter which comprises a laser light source, a detection cavity, a detection unit and a light absorption assembly, wherein the laser light source and the light absorption assembly are coaxial; an axisymmetric plano-concave reflector group taking the optical axis as a symmetric axis is arranged in the detection cavity; the detection units are arranged on the two sides of the axisymmetric plano-concave reflector group. According to the utility model, by utilizing the light convergence characteristic of the axisymmetric plano-concave reflector group, the peak illuminance in the detection cavity can be effectively improved, and the intensity of light signals scattered by dust particles is enhanced, so that the light signal collection efficiency is greatly improved, and the detection unit can capture clearer and more accurate light signals; the powerful guarantee is provided for accurately measuring the quantity and the particle size of dust particles. Meanwhile, the axisymmetric plano-concave reflector group is simple in structure, compared with a complex optical system, the axisymmetric plano-concave reflector group is low in installation and debugging difficulty, and manufacturing and maintenance cost is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of metrology and testing technology, and in particular relates to a dust particle counter. Background Technology

[0002] The working principle of a dust particle counter is mainly based on the principle of light scattering, involving optical systems, laser technology, and photoelectric conversion, among other optical and electronic technologies. The dust particle counter emits light through a light source. When dust particles pass through the measurement cavity, they scatter the light. A photodetector then converts the light signal into an electrical signal. After amplification, discrimination, and counting by electronic circuitry, the relevant data of the dust particles is finally obtained.

[0003] Currently, as the performance of the light source decays during use, dust particles cause changes in light intensity, affecting the accurate detection of particle scattered light signals and reducing measurement accuracy. Furthermore, the integration and accuracy of the optical system and photoelectric conversion system are insufficient. Due to the large size and complex internal structure of the equipment, it is difficult to maintain the calibration of optical components and the stability of the optical path in the long term. The conversion sensitivity and accuracy of the photodetector to weak scattered light signals are easily interfered with, resulting in low detection accuracy. Utility Model Content

[0004] In view of this, the present invention provides a dust particle counter, which aims to solve the problem of low detection accuracy in the prior art.

[0005] The first aspect of this utility model provides a dust particle counter, comprising:

[0006] Laser source, detection cavity, detection unit, and light absorption assembly;

[0007] The laser source and the light absorption component are coaxial; the detection cavity is equipped with an axisymmetric plano-concave mirror group with the optical axis as the axis of symmetry; the detection unit is located on both sides of the axisymmetric plano-concave mirror group.

[0008] In one possible implementation, the dust particle counter also includes a signal processing system; the detection unit is connected to the signal processing system.

[0009] In one possible implementation, the detection unit includes two photodetectors;

[0010] Two photodetectors are symmetrically positioned on either side of the symmetrical plano-concave reflector group.

[0011] In one possible implementation, the dust particle counter also includes a differential amplifier circuit and a signal processing system; two photodetectors are connected to the signal processing system via the differential amplifier circuit.

[0012] In one possible implementation, the light-absorbing component is a gradient refractive index light trap device.

[0013] In one possible implementation, the dust particle counter also includes an air inlet and an air outlet.

[0014] In one possible implementation, a filter is installed at the air outlet.

[0015] In one possible implementation, a temperature control system is incorporated within the laser source.

[0016] In one possible implementation, the laser source operates in pulse-driven mode.

[0017] In one possible implementation, the laser source is a near-ultraviolet semiconductor laser tube.

[0018] The dust particle counter provided in this embodiment includes: a laser source, a detection cavity, a detection unit, and a light absorption component; wherein, the laser source and the light absorption component are coaxial; an axisymmetric plano-concave mirror group with the optical axis as the axis of symmetry is arranged inside the detection cavity; the detection unit is arranged on both sides of the axisymmetric plano-concave mirror group. This invention utilizes the light-converging characteristics of the axisymmetric plano-concave mirror group to effectively increase the peak illuminance in the detection cavity, thereby enhancing the intensity of the light signal scattered by dust particles, greatly improving the light signal collection efficiency, and ensuring that the detection unit can capture clearer and more accurate light signals, providing a strong guarantee for the accurate measurement of the number and size of dust particles. At the same time, the axisymmetric plano-concave mirror group has a simple structure, and compared to complex optical systems, its installation and debugging are less difficult, reducing manufacturing and maintenance costs. It is also more stable in optical path construction, effectively reducing the impact of external interference on the optical path, avoiding detection errors caused by optical path offset or shaking, and thus improving the overall accuracy and reliability of the dust particle counter. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the dust particle counter provided in this embodiment of the utility model;

[0021] Figure 2 This is a schematic diagram of the optical path of a single plano-concave mirror;

[0022] Figure 3 This is a schematic diagram of the peak illuminance of a single plano-concave reflector provided in an embodiment of this utility model;

[0023] Figure 4 This is a schematic diagram of the optical path of the axisymmetric plano-concave reflector provided in this embodiment of the utility model;

[0024] Figure 5 This is a schematic diagram of the peak illuminance of the axisymmetric plano-concave reflector provided in this embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of the structure of a dust particle counter provided in another embodiment of the present invention;

[0026] Figure 7 This is a schematic diagram of the structure of a dust particle counter provided in another embodiment of this utility model. Detailed Implementation

[0027] In the following description, specific details such as particular system structures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the present invention. However, those skilled in the art will understand that the present invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0028] Figure 1 This is a flowchart illustrating the implementation of the dust particle counter provided in this embodiment of the utility model. Figure 1 As shown, the dust particle counter includes:

[0029] 1. Laser source; 2. Detection cavity; 3. Detection unit; and 4. Light absorption component.

[0030] The laser source 1 is coaxial with the light absorption component 4; the detection cavity 2 is equipped with an axisymmetric plano-concave mirror group 5 with the optical axis as the axis of symmetry; the detection unit 3 is located on both sides of the axisymmetric plano-concave mirror group 5.

[0031] Laser source 1 serves as the starting point for the entire detection system, emitting light that propagates along the optical axis to illuminate the dust particle detection. Light absorption component 4 absorbs the light after the detection process, preventing light reflection and interference signals, thus ensuring the purity of the detection environment. In this optical path system, detection cavity 2 is the core detection area. The axisymmetric plano-concave mirror group 5, with the optical axis as its axis of symmetry, is a core component for optimizing the optical path and improving detection performance. Detection units 3 are symmetrically distributed on both sides of the axisymmetric plano-concave mirror group 5, used to capture the light signals scattered by dust particles and convert them into electrical signals for subsequent analysis and processing.

[0032] Figure 2 This is a schematic diagram of the optical path of a single plano-concave mirror; Figure 3This is a schematic diagram of the peak illuminance of a single plano-concave reflector provided in an embodiment of this utility model; Figure 4 This is a schematic diagram of the optical path of the axisymmetric plano-concave reflector provided in this embodiment of the utility model; Figure 5 This is a schematic diagram of the peak illuminance of the axisymmetric plano-concave reflector provided in this embodiment of the present invention; as shown... Figures 2-5 As shown, when the light emitted from the laser source enters the detection cavity, a single plano-concave mirror can only converge the light in a limited way once. Some light rays still diverge after reflection, making it difficult to form a high-intensity focus in the detection area, thus limiting the peak illuminance. The axisymmetric plano-concave mirror group is different. The light first illuminates the plano-concave mirror on one side, and after reflection from the concave surface, it converges towards the center of the optical axis. Simultaneously, some light rays continue to illuminate the symmetrically distributed plano-concave mirrors on the other side, are reflected again, and further converge towards the center of the optical axis. Through this process of multiple reflections and symmetrical convergence, the light can form a highly concentrated focus within the detection area, significantly increasing the light energy density in that area and thus significantly improving the peak illuminance.

[0033] During operation, the light emitted by the laser source 1 enters the detection cavity 2, where the axisymmetric plano-concave reflector group 5 fully utilizes its unique optical properties. Based on the axisymmetric design and concave reflection principle, this group can converge the light, much like a magnifying glass focusing sunlight, converging the originally divergent light towards the center of the optical axis, significantly increasing the peak illuminance within the detection cavity. When dust particles enter the detection cavity 2 and pass through the area with enhanced illuminance, they scatter stronger light signals. Compared to the weak light signals scattered by dust particles in traditional structures, the enhanced light signals are more easily captured by the detection units 3 located on both sides. After receiving clear and accurate light signals, the detection units 3 can more precisely convert them into electrical signals, thus providing high-quality raw data for subsequent accurate measurement of the number and size of dust particles, greatly improving the efficiency of light signal collection and detection accuracy.

[0034] From a structural design perspective, the axisymmetric plano-concave mirror assembly 5 has significant advantages. Its simple and clear structure eliminates the need for assembling and adjusting numerous precision optical components compared to some complex optical systems. During manufacturing, it reduces assembly difficulty and process requirements associated with complex structures, lowering the defect rate and effectively controlling manufacturing costs. In equipment maintenance, the simple structure facilitates inspection and calibration, allowing technicians to quickly locate and resolve potential optical problems, reducing maintenance costs and time. Furthermore, the design with the optical axis as the axis of symmetry endows the mirror assembly with excellent optical path stability. In actual working environments, equipment may be affected by external factors such as vibration and temperature changes. The axisymmetric plano-concave mirror assembly 5, with its symmetrical and stable structure, can effectively resist these external interferences, minimizing optical path deviation or wobbling. This high stability ensures that light always propagates and converges along the predetermined optical path, avoiding detection errors caused by optical path instability. This further guarantees the accuracy and reliability of the overall detection results of the dust particle counter, enabling the equipment to operate stably and accurately in various complex environments.

[0035] The light absorption component 4 can be a light trap, an absorption filter, etc., and is not limited here.

[0036] In some embodiments, the dust particle counter further includes a signal processing system; the detection unit is connected to the signal processing system.

[0037] In this embodiment of the invention, light is emitted by a laser source 1. When dust particles pass through the detection cavity 2, they scatter the light. The detection unit 3 then converts the optical signal into an electrical signal. After amplification, discrimination, and counting by the signal processing system, the dust particles are counted. The light emitted by the laser source 1 is absorbed by the light absorption component 4 to avoid stray light interference.

[0038] In some embodiments, the detection unit is at least one photodetector; preferably, the detection unit includes two photodetectors; the two photodetectors are axially symmetrically arranged on both sides of the axially symmetrical plano-concave reflector group.

[0039] In some embodiments, the dust particle counter further includes a differential amplifier circuit and a signal processing system; two photodetectors are connected to the signal processing system via the differential amplifier circuit.

[0040] In this embodiment of the invention, the axisymmetric plano-concave reflector group converges the light emitted from the laser source, increasing the peak illuminance within the detection cavity and causing dust particles to scatter stronger light signals. The symmetrically distributed photodetectors on both sides can uniformly and comprehensively capture these scattered light signals, avoiding signal omissions or detection blind spots caused by unilateral detection. Simultaneously, the symmetrical arrangement ensures that the two photodetectors operate under the same optical environment, resulting in good consistency and comparability of the received light signals.

[0041] When dust particles pass through the detection cavity, their scattered light is received by photodetectors on both sides, which convert the optical signal into an electrical signal. At this point, the two photomultiplier tubes in the differential amplifier circuit amplify their respective electrical signals. Traditional single photodetectors amplify both the signal and interference signals such as environmental noise. However, the innovative dual photomultiplier tube differential amplification technology significantly improves signal gain by differentially processing the electrical signals output by the two photomultiplier tubes. The differential amplifier amplifies the difference between the two electrical signals while suppressing common-mode signals (such as electromagnetic interference in the environment and thermal noise from the photodetectors themselves). Because the two photodetectors are in the same environment and receive optical signals symmetrically, the impact of common-mode noise on them is essentially the same and is effectively canceled out during the differential process, while the difference signal actually generated by the scattered light from the dust particles is amplified. This technology achieves a significant increase in signal gain, significantly enhancing the originally weak scattered light signal from dust particles, greatly improving signal detection sensitivity, and enabling the detection of even smaller and weaker dust particles. Even a very small number of dust particles passing through the detection cavity can have their scattered light signals accurately captured and amplified.

[0042] The advantages of this design are not only reflected in the improved signal detection sensitivity, but also in the enhanced accuracy and reliability of the detection results. High sensitivity enables the dust particle counter to detect a wider range of particle sizes and lower concentrations of dust particles, meeting the demands for high-precision detection. Meanwhile, the differential amplification technology suppresses noise, reducing detection errors and ensuring that the detection data accurately reflects the dust particle situation in the environment. Whether in pharmaceutical workshops with extremely high cleanliness requirements, electronic semiconductor cleanrooms, or research laboratories requiring precise air quality monitoring, the combination of this detection unit design and dual photomultiplier tube differential amplification technology provides an efficient and accurate solution for dust particle detection.

[0043] In some embodiments, the light absorption component 4 is a gradient refractive index light trap device.

[0044] In this embodiment of the invention, the built-in gradient refractive index light trap device is the core component ensuring detection accuracy. Through its unique structural design and the synergistic effect of the light-absorbing coating, it effectively suppresses stray light interference, significantly improving the accuracy and reliability of detection. The gradient refractive index light trap device utilizes the characteristics of gradient refractive index materials, whose refractive index exhibits a continuous and gradually changing distribution in space. When light enters the device, it bends due to the gradient change in the material's refractive index, propagating towards the region with higher refractive index. This characteristic alters the propagation path of stray light upon entering the device, preventing it from interfering with the detection process along its original direction. For example, stray light such as ambient light and scattered light from a laser source (not in the detection direction) is guided deep into the device upon encountering the gradient refractive index light trap device, rather than being directly reflected or scattered to the detection unit. Simultaneously, the shape design of the gradient refractive index light trap device also enhances its ability to capture stray light. Common structures such as cones and multi-layered nested structures cause light to reflect multiple times internally, with each reflection accompanied by energy loss, further weakening the intensity of stray light.

[0045] The light-absorbing coating plays a crucial role in suppressing stray light interference. This coating is typically made of special materials with high absorptivity, and its microstructure is carefully designed to maximize light absorption efficiency. When stray light reaches the surface of the light-absorbing coating after multiple reflections, the coating absorbs the vast majority of the light. This is because the molecular structure of the coating material interacts with photons, converting their energy into energy forms such as molecular vibrations and rotations, thus dissipating the light energy. In this way, stray light is rapidly absorbed upon contact with the coating, preventing it from being reflected back to the detection area and interfering with the detection unit.

[0046] Figure 6 This is a schematic diagram of the structure of a dust particle counter provided in another embodiment of this utility model. (See diagram below.) Figure 6 As shown, in some embodiments, the dust particle counter further includes an air inlet 6 and an air outlet 7.

[0047] Figure 7 This is a schematic diagram of the structure of a dust particle counter provided in another embodiment of this utility model. (See diagram below.) Figure 7 As shown, in some embodiments, a filter 8 is provided at the air outlet.

[0048] In some embodiments, a temperature control system is provided inside the laser light source 1.

[0049] In this embodiment of the utility model, the integrated temperature control system in the dust particle counter is a key technical module for ensuring the stable operation of the laser tube. Through precise temperature control and excellent power stability, it ensures that the laser tube works in a constant temperature environment, effectively avoiding power drift caused by temperature fluctuations, improving power stability, significantly enhancing the detection accuracy and reliability of the equipment, avoiding detection errors caused by laser tube temperature and power fluctuations, and effectively ensuring environmental cleanliness monitoring and quality control.

[0050] In some embodiments, the laser source 1 operates in pulse-driven mode.

[0051] In this embodiment of the invention, the application of pulse drive mode in the technological innovation of the dust particle counter achieves a reduction in average optical power while ensuring detection accuracy, effectively solving the energy consumption and cost problems caused by high-power operation, and ensuring that detection performance is not affected.

[0052] The pulse-driven mode outputs laser light in short pulses by periodically turning the laser source on and off. Unlike traditional devices where the laser source emits light continuously and stably, in pulse-driven mode, the laser source emits light with high instantaneous power for extremely short time intervals (pulse width), followed by a brief off state (pulse interval). By precisely controlling parameters such as pulse width, pulse frequency, and peak power, although the instantaneous power of the laser source may be high during each pulse cycle, the overall average optical power is significantly reduced because it is off for most of the time. For example, through optimized settings, the laser source's operating time can be significantly reduced while ensuring that dust particles can effectively scatter light and be captured by the detection unit.

[0053] The pulse-driven mode fully utilizes the characteristics of light scattering detection. The core of a dust particle counter lies in capturing the light signal scattered by dust particles. Under pulse-driven conditions, when a laser pulse irradiates a dust particle, the instantaneous high-energy laser is sufficient to cause the particle to produce sufficiently strong scattered light. Even during the period when the laser is off, the detection unit can still accurately record and analyze the light signal scattered by dust particles in each pulse cycle thanks to its rapid response and signal processing capabilities. Simultaneously, in conjunction with other high-precision components in the equipment, such as the axisymmetric plano-concave reflector group for enhanced light focusing and the dual photomultiplier tube differential amplification technology for precise signal processing, it further ensures that even with a reduction in average optical power, the number and size information of dust particles can still be accurately detected.

[0054] In some embodiments, the laser source 1 is a near-ultraviolet semiconductor laser tube.

[0055] In this embodiment of the invention, the 390-420nm near-ultraviolet semiconductor laser tube has unique advantages. The laser energy in this wavelength range is relatively high, and the interaction between photon energy and dust particles with a diameter of 0.1-0.3μm is more effective. Compared to lasers of other wavelengths, near-ultraviolet photons can be absorbed and scattered more efficiently by dust particles in this size range, thereby generating a stronger scattered light signal. Simultaneously, the near-ultraviolet semiconductor laser tube is characterized by its small size, low power consumption, and long lifespan, making it easy to integrate into a dust particle counter. This reduces the overall energy consumption and maintenance costs of the device while ensuring stable light source output.

[0056] In addition, the dust particle counter of this invention also includes an intelligent operation and maintenance system connected to the signal processing system; the intelligent operation and maintenance system has a built-in self-calibration program, its lithium battery pack supports disassembly and standby fast charging, and supports Modbus connection, which can remotely control and read device data.

[0057] Built-in self-calibration is a key technology for ensuring the long-term stable and accurate detection of dust particle counters. As the equipment is used over time, the laser tube inevitably experiences power attenuation, and environmental contaminants such as dust and impurities easily adhere to the surface of optical components, affecting the light signal intensity and optical path stability, leading to detection errors. The self-calibration program works in conjunction with a sophisticated algorithm and sensor to achieve automatic compensation. On one hand, the high-precision optical power sensor inside the equipment monitors the output power of the laser tube in real time. Once laser attenuation is detected, the self-calibration program immediately starts, automatically adjusting laser drive parameters such as current and voltage according to a preset calibration model and algorithm to restore the laser power to the standard level. On the other hand, to address optical contamination, the program uses a reference optical path or a periodically executed calibration optical path to compare the light signal difference between the detection optical path and the reference optical path to determine the degree of optical component contamination. When contamination is detected causing a decrease in light signal intensity or optical path deviation, the self-calibration program automatically corrects the detection data, compensating for signal loss caused by contamination through algorithms, ensuring consistently accurate and reliable detection results without frequent manual intervention. This effectively reduces equipment maintenance costs and calibration difficulty, extending the stable service life of the equipment.

[0058] The removable lithium battery pack and standby fast charging design greatly enhance the device's flexibility and battery life. The removable lithium battery pack eliminates the device's dependence on a fixed power source, allowing users to quickly replace the battery with a spare when the device's power is low, ensuring uninterrupted testing. This is especially suitable for scenarios such as long-term outdoor testing and mobile testing.

[0059] Modbus connectivity enables remote intelligent management of dust particle counters. As a widely used communication protocol, Modbus allows for stable connections between the device and host computers, control centers, or other intelligent terminals.

[0060] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be included within the protection scope of this utility model.

Claims

1. A dust particle counter, characterized in that, include: Laser source, detection cavity, detection unit, and light absorption assembly; The laser source is coaxial with the light absorption component; the detection cavity is provided with an axisymmetric plano-concave mirror group with the optical axis as the axis of symmetry; the detection unit is located on both sides of the axisymmetric plano-concave mirror group.

2. The dust particle counter according to claim 1, characterized in that, The dust particle counter also includes a signal processing system; the detection unit is connected to the signal processing system.

3. The dust particle counter according to claim 1, characterized in that, The detection unit includes two photodetectors; Two photodetectors are symmetrically arranged on both sides of the symmetrical plano-concave reflector group.

4. The dust particle counter according to claim 3, characterized in that, The dust particle counter also includes a differential amplifier circuit and a signal processing system; two photodetectors are connected to the signal processing system via the differential amplifier circuit.

5. The dust particle counter according to claim 1, characterized in that, The light absorption component is a gradient refractive index light trap device.

6. The dust particle counter according to claim 1, characterized in that, The dust particle counter also includes an air inlet and an air outlet.

7. The dust particle counter according to claim 6, characterized in that, A filter is installed at the air outlet.

8. The dust particle counter according to claim 1, characterized in that, The laser source is equipped with a temperature control system.

9. The dust particle counter according to claim 1, characterized in that, The laser source operates in pulse-driven mode.

10. The dust particle counter according to claim 1, characterized in that, The laser source is a near-ultraviolet semiconductor laser tube.

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