Dust particle counter

Abstract

The invention 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 invention, by utilizing the convergence characteristic of the axisymmetric plano-concave reflector group to light, the peak illuminance in the detection cavity can be effectively improved, so that the intensity of an optical signal scattered by dust particles is enhanced, the optical signal collection efficiency is greatly improved, a detection unit can capture clearer and more accurate optical signals, and the detection accuracy is improved. 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] The present invention belongs to the technical field of metrology and testing, and particularly relates to a dust particle counter. Background Art

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

[0003] Currently, during the use of dust particle counters, as the performance of the light source decays, the light intensity changes, affecting the accurate detection of the particle scattered light signal, reducing the measurement accuracy. Moreover, the integration and accuracy of the optical system and the photoelectric conversion system are insufficient. Due to the large volume and complex internal structure of the device, it is difficult to maintain the calibration of optical elements and the stability of the optical path for a long time. The conversion sensitivity and accuracy of the photodetector to weak scattered light signals are easily interfered with, resulting in a low detection accuracy. Summary of the Invention

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

[0005] The first aspect of the present invention provides a dust particle counter, including:

[0006] A laser light source, a detection chamber, a detection unit, and a light absorption component;

[0007] Among them, the laser light source and the light absorption component are coaxial; an axially symmetric plano-concave mirror group with the optical axis as the axis of symmetry is arranged in the detection chamber; the detection unit is arranged on both sides of the axially symmetric plano-concave mirror group.

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

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

[0010] The two photodetectors are axially symmetrically arranged on both sides of the axially symmetric plano-concave mirror group.

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

[0012] In a possible implementation manner, the light absorption component is a gradient refractive index light trap device.

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

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

[0015] In a possible implementation, a temperature control system is provided inside the laser light source.

[0016] In a possible implementation, the operating mode of the laser light source is a pulse drive mode.

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

[0018] The dust particle counter provided by the embodiment of the present invention includes: a laser light source, a detection cavity, a detection unit, and a light absorption component; wherein, the laser light source and the light absorption component are coaxial; an axially symmetric plano-concave mirror group with the optical axis as the axis of symmetry is arranged in the detection cavity; the detection unit is arranged on both sides of the axially symmetric plano-concave mirror group. By utilizing the light converging characteristics of the axially symmetric plano-concave mirror group, the present invention can effectively increase the peak illuminance in the detection cavity, enhance the intensity of the light signal scattered by the dust particles, thereby greatly improving the light signal collection efficiency, ensuring that the detection unit can capture clearer and more accurate light signals, and providing a strong guarantee for accurately measuring the number and particle size of dust particles. At the same time, the axially symmetric plano-concave mirror group has a simple structure. Compared with a complex optical system, its installation and debugging are less difficult, reducing the manufacturing and maintenance costs. It has better stability in optical path construction, can effectively reduce the influence of external interference on the optical path, and avoid detection errors caused by optical path deviation or shaking, thereby improving the overall detection accuracy and reliability of the dust particle counter. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0020] Figure 1 is a schematic structural diagram of the dust particle counter provided by the embodiment of the present invention;

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

[0022] Figure 3 is a schematic diagram of the peak illuminance of the single plano-concave mirror provided by the embodiment of the present invention;

[0023] Figure 4 It is a schematic optical path diagram of the axially symmetric plano-concave mirror provided by an embodiment of the present invention;

[0024] Figure 5 It is a schematic diagram of the peak illuminance of the axially symmetric plano-concave mirror provided by an embodiment of the present invention;

[0025] Figure 6 It is a schematic structural diagram of the dust particle counter provided by another embodiment of the present invention;

[0026] Figure 7 It is a schematic structural diagram of the dust particle counter provided by still another embodiment of the present invention. Detailed implementation manners

[0027] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present invention. However, those skilled in the art should clearly understand that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present invention.

[0028] Figure 1 It is a flowchart of the implementation of the dust particle counter provided by an embodiment of the present invention. As Figure 1 shown, the dust particle counter includes:

[0029] a laser light source 1, a detection chamber 2, a detection unit 3, and a light absorption component 4;

[0030] Among them, the laser light source 1 and the light absorption component 4 are coaxial; an axially symmetric plano-concave mirror group 5 with the optical axis as the axis of symmetry is arranged in the detection chamber 2; the detection unit 3 is arranged on both sides of the axially symmetric plano-concave mirror group 5.

[0031] The laser light source 1 serves as the light source starting point of the entire detection system, and the emitted light propagates along the optical axis direction to provide illumination for dust particle detection; the light absorption component 4 is used to absorb the light after the detection process to prevent interference signals caused by light reflection and ensure the purity of the detection environment. In this optical path system, the detection chamber 2 serves as the core detection area, and the axially symmetric plano-concave mirror group 5 arranged inside with the optical axis as the axis of symmetry becomes the core component for optimizing the optical path and improving the detection performance. The detection units 3 are symmetrically distributed on both sides of the axially symmetric plano-concave mirror group 5 and are used to capture the light signals scattered by the dust particles 0 and convert them into electrical signals for subsequent analysis and processing.

[0032] Figure 2 It is a schematic optical path diagram of a single plano-concave mirror; Figure 3 It is a schematic diagram of the peak illuminance of the single plano-concave mirror provided by an embodiment of the present invention; Figure 4It is a schematic optical path diagram of the axially symmetric plano-concave mirror provided by an embodiment of the present invention; Figure 5 It is a schematic diagram of the peak illuminance of the axially symmetric plano-concave mirror provided by an embodiment of the present invention; As Figures 2 - 5 shown, when the light emitted by the laser light source enters the detection cavity, the single plano-concave mirror can only perform a relatively limited convergence on the light, and some of the light will still diverge around after reflection, making it difficult to form a high-intensity focus in the detection area, resulting in limited peak illuminance. The axially symmetric plano-concave mirror group is different. The light first irradiates on the plano-concave mirror on one side, converges towards the optical axis center direction after being reflected by the concave surface, and at the same time, some of the light will continue to irradiate on the symmetrically distributed plano-concave mirror on the other side, and is reflected again and further converges towards the optical axis center. Through this process of multiple reflections and symmetric convergence, the light can form a highly concentrated focus in the detection area, greatly increasing the light energy density in this area, thus significantly improving the peak illuminance.

[0033] During the working process, when the light emitted by the laser light source 1 enters the detection cavity 2, the axially symmetric plano-concave mirror group 5 fully exerts its unique optical characteristics. Based on the axially symmetric design and the concave surface reflection principle, this mirror group can converge the light, just like a magnifying glass focusing sunlight, converging the originally diverging light towards the optical axis center, significantly increasing the peak illuminance in the detection cavity. When dust particles enter the detection cavity 2 and pass through the area with enhanced illuminance, they will scatter a stronger optical signal. Compared with the weak optical signal scattered by dust particles under the traditional structure, the enhanced optical signal is more easily captured by the detection units 3 arranged on both sides. After receiving the clear and accurate optical signal, the detection units 3 can more accurately convert it into an electrical signal, thus providing high-quality original data for the subsequent accurate measurement of the number and particle size of dust particles, greatly improving the optical signal collection efficiency and detection accuracy.

[0034] From the perspective of structural design, the axially symmetric plano-concave mirror group 5 has obvious advantages. Its structure is simple and clear. Compared with some complex optical systems, it does not require the combination and debugging of a large number of precision optical components. During the manufacturing process, the assembly difficulty and process requirements caused by the complex structure are reduced, the defective rate during the production process is lowered, thus effectively controlling the manufacturing cost; during the equipment maintenance stage, the simple structure makes the inspection and calibration work more convenient. Technicians can quickly locate and solve possible optical problems, reducing the maintenance cost and maintenance time cost. In addition, the design with the optical axis as the axis of symmetry endows the mirror group with good optical path stability. In the actual working environment, the equipment may be affected by external factors such as vibration and temperature changes. However, due to its symmetric and stable structure, the axially symmetric plano-concave mirror group 5 can effectively resist these external interferences, minimizing the occurrence of optical path deviation or shaking phenomena to the greatest extent. This high stability ensures that the light always propagates and converges along the predetermined optical path, avoiding detection errors caused by unstable optical paths, and further guaranteeing the accuracy and reliability of the overall detection results of the dust particle counter, enabling the equipment to operate stably and precisely in various complex environments.

[0035] The light absorption component 4 can be a light trap, an absorption type filter, etc., which 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 the embodiments of the present invention, light is emitted by the laser light source 1. When dust particles pass through the detection cavity 2, the light will be scattered, and then the detection unit 3 converts the optical signal into an electrical signal. After processing such as amplification, discrimination, and counting by the signal processing system, the counting of dust particles is completed. Among them, the light emitted by the laser light source 1 is absorbed by the light absorption component 4 to avoid interference from stray light.

[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 symmetric plano-concave mirror group.

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

[0040] In the embodiments of the present invention, the axially symmetric plano-concave mirror group converges the light emitted by the laser light source, increasing the peak illuminance in the detection cavity and enabling the dust particles to scatter stronger light signals. The photodetectors symmetrically distributed on both sides can uniformly and comprehensively capture these scattered light signals, avoiding signal omission or detection blind spots caused by single-sided detection. At the same time, the symmetric setting ensures that the two photodetectors operate in the same optical environment, and the received light signals have good consistency and comparability.

[0041] When the dust particles pass through the detection cavity and the scattered light is received by the photodetectors on both sides, the photodetectors convert the light signals into electrical signals. At this time, the two photomultiplier tubes of the differential amplification circuit amplify the corresponding electrical signals respectively. While the traditional single photodetector amplifies the signal, it also amplifies interference signals such as environmental noise. The innovative dual-photomultiplier differential amplification technology realizes a significant increase in signal gain by performing differential processing on the electrical signals output by the two photomultiplier tubes. The differential amplifier amplifies the difference between the two electrical signals while suppressing the common-mode signals (such as electromagnetic interference in the environment and the thermal noise of the photodetector itself). Since the two photodetectors are in the same environment and symmetrically receive the light signals, the influence of the common-mode noise on them is basically the same and is effectively cancelled out during the differential process, while the difference signal truly generated by the scattered light of the dust particles is amplified. Through this technology, a significant increase in signal gain can be achieved, significantly enhancing the originally weak scattered light signals of the dust particles, greatly improving the signal detection sensitivity, enabling the detection of smaller and weaker dust particles, and even when a very small amount of dust particles pass through the detection cavity, the generated scattered light signals can be accurately captured and amplified.

[0042] The advantages of this design are not only reflected in the improvement of signal detection sensitivity but also further ensure the accuracy and reliability of the detection results. The high sensitivity enables the dust particle counter to detect dust particles in a wider particle size range and at lower concentrations, meeting the requirements of high-precision detection; while the suppression of noise by the differential amplification technology reduces the detection error, ensuring that the detection data truly reflects the dust particle situation in the environment. Whether in pharmaceutical workshops, electronic semiconductor clean rooms with extremely high cleanliness requirements or in scientific research laboratories that require precise air quality monitoring, the combination of this detection unit design and the dual-photomultiplier differential amplification technology can provide an efficient and accurate solution for the detection of dust particles.

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

[0044] In the embodiments of the present invention, the built-in gradient refractive index optical trap device is the core component to ensure the detection accuracy. Through the synergistic effect of its unique structural design and the light-absorbing coating, it can effectively suppress the interference of stray light and significantly improve the accuracy and reliability of detection. The gradient refractive index optical trap device utilizes the characteristics of gradient refractive index materials, where the refractive index of the material shows a continuous and gradually changing distribution in space. When light enters the gradient refractive index optical trap device, it will bend due to the gradient change of the material refractive index and propagate towards the region with a higher refractive index. This characteristic causes the propagation path of stray light to be changed after entering the device and no longer propagate in the original direction to interfere with the detection process. For example, ambient light in the environment, scattered light in non-detection directions generated by the laser light source, and other stray lights will be guided deep into the device when encountering the gradient refractive index optical trap device, rather than being directly reflected or scattered to the detection unit. At the same time, the shape design of the gradient refractive index optical trap device also helps to enhance the ability to capture stray light. Common structures such as cones, multi-layer nested structures, etc. After light enters, it will be reflected multiple times inside, and each reflection is accompanied by the loss of light energy, thereby further weakening the intensity of stray light.

[0045] The light-absorbing coating plays a crucial role in suppressing the interference of stray light. The light-absorbing coating is usually made of special materials with high absorption rates, and its microstructure is carefully designed to maximize the light absorption efficiency. When stray light finally reaches the surface of the light-absorbing coating after multiple reflections, the light-absorbing coating will absorb most of the light. This is because the molecular structure of the light-absorbing coating material can interact with photons and convert the energy of photons into energy forms such as molecular vibration and rotation, thereby consuming the light energy. In this way, stray light is quickly absorbed after contacting the light-absorbing coating and cannot be reflected back to the detection area to interfere with the detection unit again.

[0046] Figure 6 It is a schematic structural diagram of a dust particle counter provided by another embodiment of the present invention. As Figure 6 shown, in some embodiments, the dust particle counter further includes an air inlet 6 and an air outlet 7.

[0047] Figure 7 It is a schematic structural diagram of a dust particle counter provided by another embodiment of the present invention. As Figure 7 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 the embodiments of the present invention, in a dust particle counter, the integrated temperature control system is a key technical module to ensure the stable operation of the laser tube. Through precise temperature control and excellent power stability guarantee, it ensures that the laser tube works in a constant temperature environment, effectively avoiding power drift caused by temperature fluctuations, improving power stability by [X], significantly enhancing the detection accuracy and reliability of the device, avoiding detection errors caused by temperature and power fluctuations of the laser tube, and effectively guaranteeing the cleanliness monitoring and quality control of the environment.

[0050] In some embodiments, the operating mode of the laser light source 1 is a pulsed drive mode.

[0051] In the embodiments of the present invention, in the technological innovation of the dust particle counter, the application of the pulsed drive mode realizes a reduction in the average optical power while ensuring the detection accuracy, effectively solving the problems of energy consumption and cost brought by high-power operation, and at the same time ensuring that the detection performance is not affected.

[0052] The pulsed drive mode outputs laser light in the form of short pulses by periodically turning on and off the laser light source. Different from the continuous and stable emission of the laser light source in traditional devices, in the pulsed drive mode, the laser light source emits light with a relatively high instantaneous power within a very short time interval (pulse width), and then enters a short off state (pulse interval). By precisely controlling parameters such as the pulse width, pulse frequency, and peak power, within a complete pulse cycle, although the instantaneous power of the laser light source may be relatively high during each pulse, due to being in the off state for most of the time, the overall average optical power is significantly reduced. For example, through optimized settings, it is possible to significantly reduce the working time ratio of the laser light source while ensuring that dust particles can effectively scatter light and be captured by the detection unit.

[0053] The pulsed drive mode makes full use of the characteristics of light scattering detection. The core of the detection of a dust particle counter is to capture the light signal scattered by dust particles. Under pulsed drive, when the laser pulse irradiates the dust particles, the instantaneous high-energy laser is sufficient to cause the particles to produce a strong enough scattered light. Even during the time period when the laser is in the off state, the detection unit can still accurately record and analyze the light signal scattered by dust particles within each pulse cycle with its fast response and signal processing capabilities. At the same time, in cooperation with other high-precision components in the device, such as the focusing and enhancement of light by the axially symmetric plano-concave mirror group and the precise processing of signals by the dual photomultiplier differential amplification technology, it further ensures that even when the average optical power is reduced, the number and particle size information of dust particles can still be accurately detected.

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

[0055] In the embodiments of the present 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 the photon energy and dust particles with a particle size of 0.1 - 0.3μm is more effective. Compared with lasers of other wavelengths, photons of near - ultraviolet light can be more efficiently absorbed and scattered by dust particles in this particle size range, thereby generating a stronger scattered light signal. At the same time, the near - ultraviolet semiconductor laser tube has the characteristics of small size, low power consumption, and long life, which is convenient to be integrated into the dust particle counter. While reducing the overall energy consumption and maintenance cost of the equipment, it ensures a stable light source output.

[0056] In addition, the dust particle counter of the present invention further 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 functions, and supports Modbus connection, enabling remote control and data reading of the device.

[0057] The built - in self - calibration program is a key technology to ensure the long - term stable and accurate detection of the dust particle counter. As the usage time of the device increases, the laser tube will inevitably experience power attenuation, and the surface of optical components is also prone to attaching pollutants such as dust and impurities due to environmental factors, which will affect the light signal intensity and optical path stability, resulting in detection errors. The self - calibration program works in coordination with precise algorithms and sensors to achieve automatic compensation. On the one hand, the high - precision optical power sensor inside the device will continuously monitor the output power of the laser tube. Once laser attenuation is detected, the self - calibration program will be immediately activated. According to the preset calibration model and algorithm, it will automatically adjust laser drive parameters such as current and voltage to restore the laser power to the standard level. On the other hand, for the problem of optical pollution, the program uses a reference optical path or a regularly executed calibration optical path to compare the light signal differences between the detection optical path and the reference optical path, and judges the degree of optical component pollution. When it detects that the pollution causes a decrease in light signal intensity or an optical path deviation, the self - calibration program will automatically correct the detection data, compensating for the signal loss caused by pollution through algorithms, ensuring that the detection results are always accurate and reliable, without the need for frequent manual intervention, effectively reducing the equipment maintenance cost and calibration difficulty, and extending the stable usage period of the equipment.

[0058] The detachable and standby fast - charging design of the lithium - battery pack greatly improves the flexibility and battery life of the device. The detachable lithium - battery pack breaks the dependence of the device on a fixed power source. Users can quickly replace the spare battery when the device's power is insufficient according to actual usage needs, ensuring that the detection work continues without interruption, especially suitable for scenarios such as long - term outdoor detection and mobile detection.

[0059] The Modbus connection function endows the dust particle counter with the ability of remote intelligent management. Modbus, as a widely used communication protocol, can achieve stable connection between the device and the upper computer, control center or other intelligent terminals.

[0060] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A dust particle counter, characterized in that, Comprising: a laser light source, a detection cavity, a detection unit, and a light absorption component; wherein, the laser light source is coaxial with the light absorption component; an axially symmetric plano-concave mirror group with the optical axis as the axis of symmetry is arranged in the detection cavity; the detection unit is arranged on both sides of the axially symmetric plano-concave mirror group.

2. The dust particle counter according to claim 1, wherein The dust particle counter further comprises a signal processing system; the detection unit is connected to the signal processing system.

3. The dust particle counter according to claim 1, wherein The detection unit comprises two photodetectors; the two photodetectors are axially symmetrically arranged on both sides of the axially symmetric plano-concave mirror group.

4. The dust particle counter according to claim 3, wherein, The dust particle counter further comprises a differential amplifier circuit and a signal processing system; the two photodetectors are connected to the signal processing system through the differential amplifier circuit.

5. The dust particle counter according to claim 1, wherein The light absorption component is a gradient index optical trap device.

6. The dust particle counter according to claim 1, wherein The dust particle counter further comprises an air inlet and an air outlet.

7. The dust particle counter according to claim 6, wherein A filter is arranged at the air outlet.

8. The dust particle counter according to claim 1, characterized in that, A temperature control system is arranged in the laser light source.

9. The dust particle counter according to claim 1, characterized in that, The working mode of the laser light source is a pulse drive mode.

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

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