Particle size spectrometer with self-calibration and calibration method

Abstract

This invention discloses a particle size spectrometer with self-calibration and a calibration method, comprising: a housing with a detection cavity inside, and an embedded light source module within the detection cavity; a gas path system positioned in a first direction to allow the particle to be measured to move linearly within the detection cavity with the airflow; an optical system positioned in a second direction, perpendicular to the gas path system, to form a photosensitive measurement area along the movement path of the particle; a signal acquisition and processing system for acquiring the scattered light pulse signal from the particle in the photosensitive measurement area and retrieving the particle size based on the one-to-one correspondence between standard particle pulse signals and particle size; and a controller for controlling and adjusting the gas path system, optical system, signal acquisition and processing system, and embedded light source module. This invention offers the advantages of directly, quickly, and conveniently calibrating particle size measurement accuracy, and features a simple structure requiring no external consumables.

Description

Technical Field

[0001] This invention relates to the field of metrology and calibration technology, and more specifically, to a particle size spectrometer with self-calibration and a calibration method. Background Technology

[0002] Currently, both light scattering and aerodynamic particle size spectrometers measure particle size by detecting the scattering signal of light by particles. However, during long-term use, aging, contamination, or performance drift of optical components such as the light source, lens, and detector can lead to inaccurate measurement results. Therefore, periodic calibration is necessary. Existing calibration methods have the following shortcomings:

[0003] In existing technologies, the external standard particle calibration method requires the use of an external aerosol generator to produce standard particles of known size, such as PSL particles. This method is cumbersome, time-consuming, labor-intensive, and costly, and cannot be frequently performed at the instrument's operating site.

[0004] Built-in particle generator method: As disclosed in prior art document CN101911139B, this method integrates a particle generator and other devices to produce aerosol particles of a predetermined size. The instrument status is verified by analyzing the pulse height distribution generated by these particles. Although it can achieve direct particle size calibration, this system has a complex structure, moving parts and consumables, high maintenance costs, and a relatively slow calibration speed.

[0005] Built-in system gain calibration method: As disclosed in prior art document CN115290518B, this method uses the instrument's own main laser to generate a reference light signal to calibrate the detector's sensitivity by switching the optical path. However, this method can only calibrate the optical frequency and intensity signals received by the detector, and cannot calibrate the particle size.

[0006] Independent reference light source calibration method: As disclosed in prior art document CN111344550A, this method uses independent LEDs and reference detectors to calibrate the gain of the measurement detector. However, this method only focuses on the stability of detector sensitivity and does not involve the simulation and calibration of different particle sizes; its calibration level remains at the signal strength level.

[0007] In summary, at least one of the following technical problems exists:

[0008] The method is cumbersome, time-consuming, labor-intensive, and costly, and cannot be frequently performed at the instrument usage site.

[0009] The system has a complex structure, contains moving parts and consumables, has high maintenance costs, and has a relatively slow calibration speed.

[0010] It can only calibrate the light frequency and light intensity signals received by the detector, focusing only on the stability of the detector's sensitivity, and does not involve the simulation and calibration of different particle sizes. Summary of the Invention

[0011] The main objective of this invention is to provide a particle size spectrometer with self-calibration and a calibration method, to solve the problems of existing methods being cumbersome, time-consuming, labor-intensive, and costly, and unable to be frequently performed at the instrument's operating site. These methods also suffer from complex system structures, the presence of moving parts and consumables, high maintenance costs, and relatively slow calibration speeds. Furthermore, they can only calibrate the optical frequency and intensity signals received by the detector, focusing solely on the stability of detector sensitivity and failing to address at least one of the technical issues related to the simulation and calibration of different particle sizes.

[0012] To achieve the above objectives, according to one aspect of the present invention, a particle size analyzer with self-calibration is provided, comprising:

[0013] The outer casing has a detection cavity inside, and an embedded light source module is installed inside the detection cavity;

[0014] An air path system, wherein the air path system is arranged in a first direction, is used to make the particle to be tested move linearly in the detection cavity with the airflow;

[0015] An optical system is provided, positioned in a second direction and perpendicular to the gas path system, for forming a photosensitive measurement area along the movement path of the particulate matter to be measured.

[0016] The signal acquisition and processing system is used to acquire the scattered light pulse signal of the particles to be measured in the photosensitive measurement area, and to invert the particle size of the particles to be measured based on the one-to-one correspondence between the standard particle pulse signal and the particle size.

[0017] The controller is used to control and regulate the air circuit system, the optical system, the signal acquisition and processing system, and the embedded light source module.

[0018] Preferably, the optical system includes:

[0019] The lens assembly is disposed on the detection cavity;

[0020] A laser that illuminates the lens group;

[0021] A light trap is disposed on the detection cavity, positioned opposite to the lens group, and is used to absorb stray light within the detection cavity.

[0022] The lens group, laser, and optical trap have their axes aligned.

[0023] Preferably, the gas path system includes:

[0024] An air inlet is located on the side of the outer casing and is connected to the outside.

[0025] A high-pressure air intake nozzle is disposed inside the detection chamber and is connected to the air intake port;

[0026] An exhaust nozzle is provided on the side of the housing opposite to the air inlet, and the air outlet is connected to the detection chamber;

[0027] An air pump, which is connected to an air outlet nozzle;

[0028] A flow meter is installed on the pipe connecting the air pump and the air outlet nozzle.

[0029] Preferably, the signal acquisition and processing system includes:

[0030] A concave mirror is disposed on the detection cavity, close to the laser;

[0031] The first detector is positioned opposite to the concave mirror.

[0032] The second detector is disposed in the detection cavity, near the air outlet nozzle;

[0033] A first signal processing module is disposed opposite to a first detector;

[0034] The second signal processing module is configured to be positioned opposite to the second detector.

[0035] Preferably, the embedded light source module includes multiple independently controllable light sources, an optical path shaping component, and a third detector. The independently controllable light sources are multiple light-emitting diodes (LEDs), each of which is independently controlled. The number of independently controllable light sources is determined according to the particle detection range of the particle size spectrometer. Each independently controllable light source simulates the scattered light pulse signals of multiple particles of a specific particle size by adjusting the recording driving parameters multiple times. The optical path shaping component is set on the light output path of each independently controllable light source, specifically a miniature diffuser or optical fiber, and is used to scatter and shape the direct light beam emitted by the LED, making its light intensity spatial distribution closer to the scattered light characteristics of real particles, thereby enhancing the realism of the signal simulation. The multiple embedded optical modules are asymmetrically arranged with the photosensitive detection area as the center, according to the main signal receiving angle of the particle size spectrometer, to ensure that the path of the simulated light signal entering the detector is consistent with the path of the scattered light from real particles.

[0036] Preferably, the third detector is an independent reference detector used to monitor the stability of the output light intensity of the LED itself in real time, so as to realize the self-calibration of the calibration source. The third detector is set to sample the output light intensity of each independent controllable light source at the beginning of each calibration cycle. The controller compares the current sampled value with the initial value of the pre-calibration stage. If the light intensity decay exceeds the preset threshold, an early warning is issued and the pre-stored driving parameters of the light source are automatically updated to ensure the long-term stability of the calibration source itself.

[0037] Preferably, the device also includes a communication module and a temperature and humidity sensor, wherein the temperature and humidity sensor is connected to the controller, and the communication module includes a communication board, which is used for data acquisition, transmission, and networking.

[0038] Preferably, the lens group divides the laser light into a first part and a second part. The first part enters the detection cavity to monitor particulate scattering signals, which are received by a first detector and a first signal processing module. The second part is received by a second detector and a second signal processing module. The second detector is used to detect whether the laser light source has attenuated.

[0039] Preferably, when the particle size analyzer with self-calibration leaves the factory, the second signal processing module monitors the initial light intensity of the laser source corresponding to the second detector signal value. During subsequent use, the second detector provides real-time feedback signals. Once the signal is lower than the threshold, it is determined that the laser source is attenuating. The controller automatically compensates for the counting results based on the attenuation amplitude and corrects the error caused by the fluctuation of the light source in real time.

[0040] According to another aspect of the present invention, a calibration method for a particle size spectrometer with self-calibration is provided, comprising: the calibration process of the particle size spectrometer is mainly divided into two stages: pre-calibration and routine calibration. In the pre-calibration stage, multiple independent and controllable light sources with optical paths receivable by a detector are set up in the detection cavity. For each light source, the instrument is first turned on and standard aerosol particles of known particle size are introduced, and the multidimensional characteristic values ​​of their scattered light pulse signals are measured and recorded. Then, the driving parameters of each light source are adjusted one by one to match the characteristic values ​​of the light pulse signals with those of the standard particles. The standard output light intensity at this time is recorded by a third detector as a health reference value. Finally, the optimal driving parameters, simulated standard particle size values, and health reference values ​​of the light source are stored, and a light source-particle size mapping table is established. This process is repeated to form multiple particle size calibration points covering the measurement range. During routine calibration, after the instrument has been running for a long time, the calibration program is started periodically. First, the sample airflow is stopped to ensure that there are no particles in the detection chamber. Then, a self-check of the light source health is performed. The controller activates each light source in sequence and reads the current output light intensity, which is compared with the pre-stored health benchmark value. For light sources with attenuation exceeding the tolerance, the driving parameters are automatically adjusted or marked as unusable. Then, the pre-stored driving parameters of each light source are called to generate pulse light signals simulating specific particle sizes. The detector measures the current multidimensional feature values, and an environmental correction factor is introduced in combination with the temperature and humidity data in the detection chamber. The deviation of each particle size point after environmental compensation is calculated. Finally, the calibration factor is applied to the measurement algorithm to complete the direct calibration of the particle size measurement accuracy.

[0041] The technical solution of this invention has the following technical effects:

[0042] A scheme is proposed to directly simulate particle size signals through embedded optical modules, establishing a mapping relationship between particle size and pulse signals, rather than indirectly calibrating the sensitivity of the system or detector, thus fundamentally ensuring the accuracy of particle size measurement.

[0043] By adding optical path shaping components and asymmetrical layout, the spatial distribution of LED simulated light is made closer to that of real particle scattered light, which significantly improves the realism of signal simulation and calibration accuracy.

[0044] By introducing a light source health monitoring unit and environmental sensors, real-time monitoring and compensation for changes in the calibration source's own state and the environment are achieved, greatly improving the long-term reliability and environmental adaptability of the self-calibration system.

[0045] The system employs an embedded optical module, resulting in a simple structure, long lifespan, and low maintenance costs.

[0046] By setting multiple light sources corresponding to different particle sizes, the linearity and sensitivity of the entire instrument range can be calibrated at multiple points, resulting in a more comprehensive calibration range and more reliable results. Attached Figure Description

[0047] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0048] Figure 1 A first structural schematic diagram of a particle size spectrometer with self-calibration according to the present invention is shown;

[0049] Figure 2 It shows Figure 1 The second structural view of the particle size spectrometer with self-calibration.

[0050] The above figures include the following reference numerals:

[0051] 1. Housing; 2. Detection cavity; 3. Controller; 4. Communication board; 5. Air inlet; 6. High-pressure air inlet nozzle; 7. Air outlet nozzle; 8. Flow meter; 9. Air pump; 10. Laser; 11. Lens group; 12. Light trap; 13. Embedded optical module; 14. Concave mirror; 15. First detector; 16. First signal processing module; 17. Optical path shaping component; 18. Third detector; 19. Temperature and humidity sensor; 20. Second detector; 21. Second signal processing module. Detailed Implementation

[0052] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0053] like Figures 1 to 2 As shown, this embodiment of the invention provides a particle size spectrometer with self-calibration, comprising: a housing 1, wherein a detection cavity 2 is provided inside the housing 1, and an embedded light source module is provided inside the detection cavity 2; a gas path system, wherein the gas path system is arranged in a first direction for causing the particle to be measured to move linearly within the detection cavity 2 with the airflow; an optical system, wherein the optical system is arranged in a second direction, perpendicular to the gas path system, for forming a photosensitive measurement area along the movement path of the particle to be measured; a signal acquisition and processing system, for acquiring the scattered light pulse signal of the particle to be measured in the photosensitive measurement area, and inverting the particle size of the particle to be measured based on the one-to-one correspondence between the standard particle pulse signal and the particle size; and a controller 3, wherein the controller 3 is used to control and adjust the gas path system, the optical system, the signal acquisition and processing system, and the embedded light source module.

[0054] In this embodiment, the optical system includes: a lens group 11 disposed on the detection cavity 2; a laser 10 irradiating the lens group 11; and a light trap 12 disposed on the body of the detection cavity 2, located opposite to the lens group 11, for absorbing stray light within the detection cavity 2; wherein the axes of the lens group 11, the laser 10, and the light trap 12 coincide. The gas path system includes: an air inlet 5 disposed on the side of the outer casing 1, communicating with the outside; a high-pressure air inlet nozzle 6 disposed within the detection cavity 2, communicating with the air inlet 5; an air outlet nozzle 7 disposed on the side of the outer casing 1 opposite to the air inlet 5, communicating with the detection cavity 2; an air pump 9 connected to the air outlet nozzle 7; and a flow meter 8 disposed on the pipe connecting the air pump 9 and the air outlet nozzle 7. The signal acquisition and processing system includes: a concave mirror 14, which is disposed on the detection cavity 2 and close to the laser 10; a first detector 15, which is disposed opposite to the concave mirror 14; a second detector 20, which is disposed in the detection cavity 2 and close to the exhaust nozzle 7; a first signal processing module 16, which is disposed opposite to the first detector 15; and a second signal processing module 21, which is disposed opposite to the second detector 20.

[0055] Specifically, it includes a housing 1, a detection cavity 2, an air path system, an optical system, a signal acquisition and processing system, an embedded light source module, a controller 3, a communication board 4, and a temperature and humidity sensor 19. The air path system is positioned in a first direction of the detection cavity 2, the optical system is positioned in a second direction of the detection cavity 2, and the signal acquisition and processing system is positioned in a third direction of the detection cavity 2. The first, second, and third directions are perpendicular to each other. When the first direction is horizontal, the second direction is vertical; when the first direction is vertical, the second direction is horizontal. The gas path system includes an inlet module and an outlet module positioned in the first direction of the detection cavity 2, used to make the particles to be measured move linearly within the detection cavity 2 with the airflow; the optical path system includes a laser 10, a lens group 11, and an optical trap 12 arranged sequentially perpendicular to the airflow direction, used to form a photosensitive measurement area along the movement path of the particles to be measured; the signal acquisition and processing system includes a concave mirror 14, a detector, and a signal processing module, used to acquire the scattered light pulse signals of the particles to be measured in the photosensitive measurement area, and to invert the particle size of the particles to be measured based on the one-to-one correspondence between standard particle pulse signals and particle sizes; the embedded optical module 13 includes multiple independently controllable light sources, an optical path shaping component 17, and a third detector 18. The independently controllable light sources are multiple light-emitting diodes (LEDs), each of which can be independently controlled. The number of independently controllable light sources can be determined according to the particle detection range of the particle size spectrometer. By repeatedly adjusting the recording drive parameters, one independently controllable light source can simulate the scattered light pulse signals of multiple particles of a specific size. An optical path shaping component 17 is positioned on the light output path of each independently controllable light source. Specifically, it is a miniature diffuser or optical fiber used to scatter and shape the direct beam emitted by the LED, making its light intensity spatial distribution closer to the scattered light characteristics of real particles, thus enhancing the realism of the signal simulation. Multiple embedded optical modules 13 are asymmetrically arranged around the photosensitive detection area, according to the main signal receiving angles of the particle size spectrometer (such as forward scattering and side scattering), ensuring that the path of the simulated light signal entering the detector is consistent with the path of the scattered light from real particles. The third detector 18 is an independent reference detector. This reference detector is not used for particle size measurement but only for real-time monitoring of the output light intensity stability of the LED itself, achieving "self-calibration" of the calibration source. It is configured to sample the output light intensity of each independently controllable light source at the beginning of each calibration cycle. The controller 3 compares the current sampled value with the initial value of the pre-calibration stage. If the light intensity attenuation exceeds a preset threshold (e.g., 5%), an early warning is issued and the pre-stored driving parameters of the light source are automatically updated, ensuring the long-term stability of the calibration source itself.

[0056] Specifically, controller 3 is used to control and regulate the gas path system, optical system, signal acquisition and processing system, and embedded light source module; controller 3 is also connected to temperature and humidity sensor 19 for monitoring environmental parameters within the detection cavity 2. The communication module is used for the acquisition, transmission, and networking of particle size spectrometer data. The air inlet module includes an air inlet 5 and an air inlet high-pressure nozzle connected in sequence; the air outlet module includes an air outlet nozzle 7, an air pump 9 connected to the air outlet nozzle 7, and a flow meter 8 located in the pipeline connecting the air outlet nozzle 7 and the air pump 9. The air inlet 5 and the air inlet high-pressure nozzle are coaxially arranged at both ends of the detection cavity 2. The air outlet nozzle 7, flow meter 8, and air pump 9 are connected in sequence through pipelines. The flow meter 8 is used to observe the airflow rate of the gas path system, and the air pump 9 controls the pumping volume by adjusting the pressure. The light trap 12 is disposed on the body of the detection cavity 2 at a position relative to the laser 10, and is used to absorb stray light within the detection cavity 2. Lens group 11 splits the light from laser 10 into two parts. Most of the light enters detector cavity 2 to monitor particulate scattering signals, which are received by first detector 15 and first signal processing module 16. A small portion of the light is received by second detector 20 and second signal processing module 21. Second detector 20 detects whether the laser 10 light source has attenuated. At the time of manufacture, the second signal processing module 21 monitors the initial light intensity of the laser 10 light source, corresponding to the signal value of second detector 20. During subsequent use, second detector 20 provides real-time feedback. Once the signal falls below a threshold, it is determined that the laser 10 light source has attenuated, and controller 3 automatically compensates for the counting results based on the attenuation amplitude, thus correcting errors caused by light source fluctuations in real time. Stable laser light source is a crucial prerequisite for completing subsequent calibration.

[0057] Another embodiment of the present invention provides a calibration method for a particle size spectrometer with self-calibration, comprising: the calibration process of the particle size spectrometer is mainly divided into two stages: pre-calibration and routine calibration. In the pre-calibration stage, multiple independent and controllable light sources with optical paths that can be received by detectors are set up in the detection cavity. For each light source, the instrument is first turned on and standard aerosol particles of known particle size are introduced, and the multidimensional characteristic values ​​of their scattered light pulse signals are measured and recorded. Then, the driving parameters of each light source are adjusted one by one to match the characteristic values ​​of the light pulse signals with those of the standard particles. The standard output light intensity at this time is recorded by the third detector 18 as a health reference value. Finally, the optimal driving parameters, simulated standard particle size values, and health reference values ​​of the light source are stored, and a light source-particle size mapping table is established. This process is repeated to form multiple particle size calibration points covering the measurement range. During routine calibration, after the instrument has been running for a long time, the calibration program is started periodically. First, the sample airflow is stopped to ensure that there are no particles in the detection chamber 2. Then, a self-check of the light source health is performed. The controller 3 activates each light source in turn and reads the current output light intensity. It is compared with the pre-stored health benchmark value. For light sources with attenuation exceeding the tolerance, the driving parameters are automatically adjusted or marked as unusable. Then, the pre-stored driving parameters of each light source are called to generate pulse light signals simulating specific particle sizes. The detector measures the current multidimensional feature values. Combined with the temperature and humidity data in the detection chamber 2, an environmental correction factor is introduced to calculate the deviation of each particle size point after environmental compensation. Finally, the calibration factor is applied to the measurement algorithm to complete the direct calibration of the particle size measurement accuracy.

[0058] Specifically:

[0059] Pre-calibration stage:

[0060] Within the detection chamber of the particle size spectrometer, multiple independently controllable light sources are arranged. The optical paths of these light sources are configured to be received by the detector. For each light source, the following operations are performed:

[0061] Step 1: Turn on the particle size spectrometer and record the introduction of a standard aerosol particle of known size into the detection chamber 2;

[0062] Step 2: Measure and record the multidimensional characteristic values ​​of the scattered light pulse signal generated by the standard particle;

[0063] Step 3: Adjust the driving parameters of each light source one by one so that the multidimensional characteristic values ​​of the light pulse signal generated by it match the standard particle signal characteristic values ​​recorded in Step 2;

[0064] Step 4: Record the standard output light intensity of each light source under the optimal driving parameters using the third detector 18, as its health benchmark value;

[0065] Step 5: Store the optimal driving parameters of the light source, the simulated standard particle size value, and the health baseline value at this time, and establish a light source-particle size mapping table;

[0066] The above process is repeated for multiple light sources to establish multiple particle size calibration points covering the measurement range of the instrument;

[0067] Routine calibration phase:

[0068] Step 6: When the particle size spectrometer needs to be calibrated periodically after long-term operation, start the calibration program, stop the sample gas flow, and ensure that there are no particles in the detection chamber 2;

[0069] Step 7: First, perform a self-check of the light source health. Controller 3 activates each light source in turn and reads its current output light intensity through the third detector 18. It compares the current output light intensity with the health benchmark value stored in the pre-calibration stage. If the attenuation of a light source exceeds the tolerance, the driving parameters used for subsequent calibration will be automatically adjusted according to its attenuation ratio, or the light source will be marked as unusable.

[0070] Step 8: Controller 3 sequentially calls the pre-stored driving parameters of each light source to generate pulsed light signals simulating specific particle sizes. The detector receives these light signals and measures their current multidimensional characteristic values.

[0071] Step 9: Controller 3 reads the temperature and humidity data in the current detection cavity 2, compares the measured feature values ​​with the reference feature values ​​stored in the pre-calibration stage, and introduces an environmental correction factor to calculate the deviation of each particle size point after environmental compensation.

[0072] Step 10: Based on the environmentally compensated deviation, calculate and apply the calibration factor to the particle size spectrometer's measurement algorithm to directly calibrate the accuracy of particle size measurement.

[0073] In this embodiment, the particle size spectrometer detects particle sizes ranging from 1 to 30 μm. Three LEDs are installed in the detection cavity 2. By adjusting the driving parameters of the LEDs, the generated pulse signals are compared with the multidimensional characteristic values ​​of the standard particle pulse signals. Pulse signals with particle sizes of 1-10 μm, 11-20 μm, and 21-30 μm are simulated respectively. The driving parameters of the LEDs and the multidimensional characteristic values ​​of the pulse signals (pulse amplitude, pulse width, integral area) are recorded, along with the health benchmark values ​​recorded by the reference detector, to establish a "light source-particle size" mapping table.

[0074] In this embodiment, the system is turned on after prolonged use and calibration is initiated. First, a self-check of the light source's health is performed, revealing an 8% attenuation in the LED light intensity within the simulated 11-20μm range. The system automatically increases the drive current used for subsequent calibration proportionally. Then, under conditions of 25°C and 40% humidity, controller 3 sequentially turns on the LEDs according to the corrected drive parameters, and the detector measures the multidimensional characteristic values ​​of the current pulse signal. The measured values ​​are compared with the reference values ​​from the calibration phase, and the 2% amplitude negative drift caused by the temperature increase is compensated for using an environmental model. The final calculated comprehensive deviation is used to generate a calibration factor, completing the calibration.

[0075] In another embodiment, the particle size spectrometer detects particle sizes ranging from 1 to 30 μm. Thirty LEDs are set in the detection cavity 2. By adjusting the driving parameters of the LEDs, the generated pulse signals are compared with the characteristic values ​​of standard particle pulse signals to simulate pulse signals of 1-30 μm particles and establish a "light source-particle size" mapping table.

[0076] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0077] A scheme is proposed to directly simulate particle size signals through embedded optical module 13, establishing a mapping relationship between particle size and pulse signal, rather than indirectly calibrating the sensitivity of the system or detector, thus fundamentally ensuring the accuracy of particle size measurement.

[0078] By adding the optical path shaping component 17 and the asymmetric layout, the spatial distribution of the LED simulated light is made closer to the scattered light of real particles, which significantly improves the realism of the signal simulation and the accuracy of the calibration.

[0079] By introducing a light source health monitoring unit and environmental sensors, real-time monitoring and compensation for changes in the calibration source's own state and the environment are achieved, greatly improving the long-term reliability and environmental adaptability of the self-calibration system.

[0080] The system employs an embedded optical module 13, resulting in a simple structure, long lifespan, and low maintenance costs.

[0081] By setting multiple light sources corresponding to different particle sizes, the linearity and sensitivity of the entire instrument range can be calibrated at multiple points, resulting in a more comprehensive calibration range and more reliable results.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A particle size spectrometer with self-calibration, characterized in that, include: The outer casing has a detection cavity inside, and an embedded light source module is installed inside the detection cavity; An air path system, wherein the air path system is arranged in a first direction, is used to make the particle to be tested move linearly in the detection cavity with the airflow; An optical system is provided, positioned in a second direction and perpendicular to the gas path system, for forming a photosensitive measurement area along the movement path of the particulate matter to be measured. The signal acquisition and processing system is used to acquire the scattered light pulse signal of the particles to be measured in the photosensitive measurement area, and to invert the particle size of the particles to be measured based on the one-to-one correspondence between the standard particle pulse signal and the particle size. The controller is used to control and regulate the pneumatic system, the optical system, the signal acquisition and processing system, and the embedded light source module; The embedded light source module includes multiple independently controllable light sources, an optical path shaping component, and a third detector. The independently controllable light sources are light-emitting diodes (LEDs), and each light source is independently controlled. The number of independently controllable light sources is determined according to the particle detection range of the particle size spectrometer. Each independently controllable light source simulates the scattered light pulse signals of multiple particles of a specific particle size by adjusting the recording and driving parameters multiple times. The optical path shaping component is set on the light output path of each independently controllable light source, specifically a miniature diffuser or optical fiber, and is used to scatter and shape the direct light beam emitted by the LED, making its light intensity spatial distribution closer to the scattered light characteristics of real particles, thereby enhancing the realism of the signal simulation. The embedded optical module is arranged asymmetrically with the photosensitive measurement area as the center, according to the main signal receiving angle of the particle size spectrometer, to ensure that the path of the simulated light signal entering the detector is consistent with the path of the real particle scattered light.

2. The particle size analyzer with self-calibration as described in claim 1, characterized in that, The optical system includes: The lens assembly is disposed on the detection cavity; A laser that illuminates the lens group; A light trap is disposed on the detection cavity, positioned opposite to the lens group, and is used to absorb stray light within the detection cavity. The lens group, laser, and optical trap have their axes aligned.

3. The particle size analyzer with self-calibration as described in claim 2, characterized in that, The gas path system includes: An air inlet is located on the side of the outer casing and is connected to the outside. A high-pressure air intake nozzle is disposed inside the detection chamber and is connected to the air intake port; An exhaust nozzle is disposed on the side of the housing opposite to the air inlet; An air pump, which is connected to an air outlet nozzle; A flow meter is installed on the pipe connecting the air pump and the air outlet nozzle.

4. The particle size analyzer with self-calibration as described in claim 3, characterized in that, The signal acquisition and processing system includes: A concave mirror is disposed on the detection cavity, close to the laser; The first detector is positioned opposite to the concave mirror. The second detector is disposed in the detection cavity, near the air outlet nozzle; A first signal processing module is disposed opposite to a first detector; The second signal processing module is positioned opposite to the second detector.

5. The particle size analyzer with self-calibration as described in claim 4, characterized in that, The third detector is an independent reference detector used to monitor the stability of the output light intensity of the LED itself in real time, so as to realize the self-calibration of the calibration source. The third detector is set to sample the output light intensity of each independent controllable light source at the beginning of each calibration cycle. The controller compares the current sampled value with the initial value of the pre-calibration stage. If the light intensity decay exceeds the preset threshold, an early warning is issued and the pre-stored driving parameters of the light source are automatically updated to ensure the long-term stability of the calibration source itself.

6. The particle size spectrometer with self-calibration as described in claim 5, characterized in that, It also includes a communication module and a temperature and humidity sensor. The temperature and humidity sensor is connected to the controller. The communication module includes a communication board and is used for data acquisition, transmission, and networking.

7. The particle size analyzer with self-calibration as described in claim 6, characterized in that, The lens group divides the laser light into a first part and a second part. The first part enters the detection cavity to monitor the particulate scattering signal, which is received by a first detector and a first signal processing module. The second part is received by a second detector and a second signal processing module. The second detector is used to detect whether the laser light source has attenuated.

8. The particle size analyzer with self-calibration as described in claim 7, characterized in that, in, When the particle size analyzer with self-calibration leaves the factory, the second signal processing module monitors the initial light intensity of the laser source and the corresponding signal value of the second detector. During subsequent use, the second detector provides real-time feedback. Once the signal is lower than the threshold, it is determined that the laser source is attenuating. The controller automatically compensates for the counting results based on the attenuation amplitude and corrects the error caused by the fluctuation of the light source in real time.

9. A calibration method for a particle size spectrometer with self-calibration, used in the particle size spectrometer with self-calibration as described in claim 8, characterized in that, include: The calibration process for particle size analyzers is divided into two stages: pre-calibration and routine calibration. During the pre-calibration stage, multiple independent and controllable light sources with optical paths that can be received by the detector need to be set up in the detection cavity. For each light source, the instrument is first turned on and standard aerosol particles of known particle size are introduced, and the multidimensional characteristic values ​​of its scattered light pulse signal are measured and recorded. Then, adjust the driving parameters of the light source one by one to match the characteristic value of the light pulse signal with the standard particle. Record the standard output light intensity at this time through the third detector as the health reference value. Finally, store the optimal driving parameters of the light source, the simulated standard particle size value and the health reference value, establish a light source-particle size mapping table, and repeat the process to form multiple particle size calibration points covering the measurement range. During the routine calibration phase, after the instrument has been running for a long time, the calibration program is started periodically. First, the sample airflow is stopped to ensure that there are no particles in the detection cavity. Then, the light source health self-check is performed. The controller activates each light source in sequence and reads the current output light intensity. It is compared with the pre-stored health benchmark value. For light sources with attenuation exceeding the tolerance, the drive parameters are automatically adjusted or marked as unusable. Subsequently, the pre-stored driving parameters of each light source are invoked to generate pulsed light signals simulating specific particle sizes. The detector measures the current multidimensional characteristic values, and an environmental correction factor is introduced by combining the temperature and humidity data inside the detection cavity. The deviation of each particle size point after environmental compensation is calculated. Finally, the calibration factor is applied to the measurement algorithm to complete the direct calibration of the particle size measurement accuracy.

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