A high-resolution liquid particle counting device and its optical path debugging method

Abstract

This invention discloses a high-resolution liquid particle counting device and its optical path debugging method, belonging to the field of liquid particulate matter detection. The liquid particle counting device includes a light source module, which includes a laser and its shaping mirror assembly; a flow control module, located at the rear end of the light source module and including a flow control housing with a flow control chamber inside, the detection area being located at the center of the second cavity of the flow control chamber; a forward collection module, located at the rear end of the flow control module, for collecting forward scattered light; and a side collection module, located on the side of the flow control module, for collecting side scattered light. This invention increases particle size resolution and improves detection accuracy through the integrated detection of forward and side scattered light.

Description

Technical Field

[0001] This invention relates to a high-resolution liquid particle counting device and its optical path adjustment method, belonging to the field of liquid particulate matter detection. Background Technology

[0002] Currently, in the semiconductor industry, the chip exposure pattern masking and chip bridge defects caused by particulate contamination on the wafer surface during photolithography result in significant economic losses annually. To reduce particulate contamination, liquid particle counters are commonly used to detect particle concentration in the ultrapure water system of the immersion lens in DUV lithography machines. These counters can rapidly count the number of insoluble particles in the carrier liquid and infer particle size based on the signal strength received by the detector. Liquid particle counters employing photoresist and light scattering methods are widely used as common optical particle counters. However, photoresist liquid particle counters are generally unsuitable for samples with particle sizes smaller than 1 micrometer due to their limited resolution, making accurate detection of ultrafine particles difficult. Therefore, light scattering liquid particle counters are widely used for detecting submicron and nanometer-scale liquid particles.

[0003] For the detection of nanoscale particles, according to Mie theory, the intensity of scattered light from spherical particles is directly proportional to the intensity of incident light and inversely proportional to the sixth power of the particle size. However, for the detection of particles in liquids, the molecular scattering generated by the liquid increases synchronously with the intensity of the incident light source, limiting the improvement of the signal-to-noise ratio. This results in the inability to detect target particles with smaller diameters, thus limiting the lower detection limit of the equipment.

[0004] Therefore, existing technologies often use macroscopic flow channels to keep the incident laser away from the wall surface to reduce interference from stray light. However, due to the diffraction effect of light during propagation, the target particle is illuminated by different light intensities when passing through the center or edge of the light beam, thus introducing systematic errors. Furthermore, due to the diffraction of light during propagation, the light intensity distribution in the actual detection area of ​​the device is uneven, resulting in a reduction in particle size resolution. At the same time, most existing liquid particle counting devices only collect forward or side-scattered light from the particles for detection. For example, the corner scattering liquid particle technology device disclosed in Chinese invention patent application No. 202311184232.2 only uses forward-scattered light detection. This further reduces the particle size resolution when the liquid particle counter inverts the particle size, and can only roughly divide the particle size into a few relatively wide particle size channels based on the scattering signal, thus affecting the detection accuracy. Summary of the Invention

[0005] To address the problems of low particle size resolution in existing light scattering liquid particle counting devices due to diffraction effects, and the fact that most of them use unidirectional scattered light detection, further reducing particle size resolution and resulting in only coarse particle size classification and low detection accuracy, this invention provides a high particle size resolution liquid particle counting device. The technical solution is as follows: A high particle size resolution liquid particle counting device, the liquid particle counting device comprising: The light source module includes a laser and a shaping lens group. The shaping lens group includes a beam expander, a collimator, and a focusing lens. Each lens of the shaping lens group is arranged sequentially along a direction perpendicular to the optical axis of the laser. The flow control module is located at the rear end of the light source module and includes a flow control housing. The flow control housing has a first light-transmitting window and a second light-transmitting window on its front and rear sides, respectively. The flow control housing has a flow control chamber inside, which is divided into a first chamber and a second chamber by a third aperture. The detection area is located at the center of the second chamber. A forward collection module is located at the rear end of the flow control module and is used to collect forward scattered light. It includes a forward collection mirror group and a forward collection sensor. The forward collection mirror group is located between the flow control module and the forward collection sensor. The forward collection mirror group includes a first condenser cup and a second condenser cup. A lateral collection module is provided on the side of the flow control module for collecting lateral scattered light. It includes a lateral collection mirror group and a lateral collection sensor, with the lateral collection mirror group located between the flow control module and the lateral collection sensor.

[0006] Furthermore, a first aperture is provided between the beam expander and the collimating lens, and a second aperture is provided between the collimating lens and the focusing lens.

[0007] Furthermore, the laser emits a circular light spot with a diameter of 0.5~3mm and a divergence angle of less than 20mrad.

[0008] Furthermore, the focal points of the beam expander lens and the collimating lens coincide, and the aperture of the beam expander lens is designed to match the circular spot of the laser. Its aperture is 3~5mm, which can achieve the beam expansion effect of a circular spot smaller than 3mm.

[0009] Furthermore, a light trap is provided between the first and second condenser cups. The light trap is used to absorb the forward transmitted light. The angle subtended by the light trap at the center of the second chamber is much larger than the laser divergence angle, so as to ensure that all the forward transmitted light is absorbed by the light trap.

[0010] Furthermore, the focal point of the first condenser cup coincides with the center of the second chamber, and the focal point of the second condenser cup coincides with the measurement center of the forward collecting sensor.

[0011] Furthermore, the particle to be detected enters the detection area along the Y direction. When the lower limit of the target particle size is 40 nm, the side-scattered light collection angle can be set to 40° to 140° and the forward-scattered light collection angle can be set to 5° to 35°. When the lower limit of the target particle size is 200 nm, the forward scattering effect of the particle is enhanced, and the side-scattered light collection angle can be set to 30° to 150° and the forward-scattered light collection angle can be set to 5° to 25°.

[0012] Furthermore, the laser and the shaping lens assembly are respectively mounted on the first displacement stage, and the forward collection module and the lateral collection module are respectively mounted on the second and third displacement stages. The positions of the devices on the first, second, and third displacement stages can be adjusted along the X, Y, and Z directions.

[0013] Furthermore, the beam expander and the collimator are mounted on the first displacement stage via a first fine-tuning mechanism, and their positions in the X and Y directions are adjusted by the first fine-tuning mechanism. The focusing lens is mounted on the first fine-tuning mechanism via a second fine-tuning mechanism, and its position in the Z direction is adjusted by the second fine-tuning mechanism.

[0014] Secondly, the present invention also discloses an optical path debugging method for assembling and debugging the liquid particle counting device described in the above technical solution, the method comprising: Step 1: First, install the flow control module and its forward collection mirror group and side collection mirror group. Ultrapure water is introduced into the flow control module. Install the debugging camera close to the rear end of the forward collection mirror group. The sensitive wavelength of the debugging camera is selected in conjunction with the laser. The receiving surface of the debugging camera is larger than the spot diameter emitted by the laser. Step 2: Install the laser, align the laser with the optical axis of the flow control module, and use the first displacement stage to adjust the position of the laser along the X and Y directions until the debugging camera presents a complete circular light spot, avoiding the light from shining on the edge of the aperture. Step 3: Install the shaping lens assembly, which is aligned with the optical axis of the laser. Use the first fine-tuning mechanism to fine-tune the position of the shaping lens assembly along the X and Y directions, and move it until the debugging camera presents a complete circular light spot. Step 4: Coarsely locate the position of the positive collection sensor, then install the debugging camera on the second displacement stage, and use the second displacement stage to drive the debugging camera to adjust along the X, Y, and Z directions, so that the center of the light spot in the X and Y directions coincides with the center of the debugging camera, and the debugging camera is located at the focal point of the light spot in the Z direction. Step 5: Fine-tune the position of the positive collection sensor. Replace the debugging camera with the positive sensor and observe the voltage signal of the positive collection sensor. By fine-tuning the position of the second displacement stage in the X and Y directions to the point where the voltage signal of the positive collection sensor is at its maximum, the fine-tuning of the positive collection sensor is completed. Step 6: Coarsely locate the position of the lateral collection sensor. Install the debugging camera on the third displacement stage so that the center of the debugging camera roughly coincides with the center of the lateral collection sensor. Introduce fluorescent particles or fine particles into the flow control module and use the scattered light of the particle swarm to display the laser path. Observe the laser path in the debugging camera. Adjust the position of the third displacement stage along the X direction to make the laser path image clear. Combine the adjustment of the second fine adjustment mechanism and the Z direction position of the third displacement stage to make the Z direction position of the laser beam waist center clearly converge to the center of the debugging camera. Then move the position of the third displacement stage along the Y direction so that the Y direction position of the laser beam waist center appears in the center of the debugging camera. Step 7: Fine-tune the position of the lateral collection sensor. Replace the debugging camera with the lateral collection sensor. By fine-tuning the position of the third displacement stage in the Y and Z directions to the point where the voltage signal of the lateral collection sensor is at its maximum, the adjustment of the lateral collection sensor is completed.

[0015] The beneficial effects of this invention are: By configuring a laser, a shaping mirror assembly, a flow control module, a forward collection module, and a side collection module, the light emitted by the laser is shaped sequentially by the shaping mirror assembly and then enters the test area at the center of the second chamber through the first light transmission window of the flow control module. The forward scattered light from the test area passes through the second light transmission window of the second chamber and is then collected by the forward collection mirror assembly and the forward collection sensor. The side scattered light from the test area passes through the third light transmission window of the second chamber and is then collected by the side collection mirror assembly and the side collection sensor. Through the integrated detection of forward and side scattered light, the particle size resolution is increased, and the detection accuracy is improved. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention; Figure 2 This is Embodiment 1 of the present invention. Figure 1A schematic diagram of the structure of an optical element; Figure 3 This is a schematic diagram of the light source module according to Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the flow control module according to Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the flow control module and the forward collection module according to Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of the flow control module and the lateral collection module according to Embodiment 1 of the present invention; Figure 7 This is a processing logic diagram of the liquid particle counting device according to Embodiment 1 of the present invention; Figures 8 to 11 This describes the particle situation near the detection area when the liquid particle counting device of Embodiment 1 of the present invention is performing particle detection; Figures 12 to 16 This describes the light spot status during the optical path debugging process of the liquid particle counting device in Embodiment 2 of the present invention; Figure 17 This is a schematic diagram of the irradiation of particles along the Z-direction and the laser polarized along the X-direction in Embodiment 1 of the present invention. Figure 18 yes Figure 17 The distribution of scattered light from 200nm PSL particles under the given conditions; Figure 19 yes Figure 17 The scattered light distribution of 100nm PSL particles under the given conditions; Figure 20 yes Figure 17 The scattered light distribution of 40nm PSL particles under the given conditions; Explanation of reference numerals in the attached figures: 100. Liquid particle counting device; 101. Light source module; 102. Flow control module; 103. Lateral collection module; 104. Forward collection module; 01. Laser; 02. Shaping lens assembly; 03. First displacement stage; 04. First fine-tuning mechanism; 05. Second fine-tuning mechanism; 06. First chamber; 07. Second chamber; 08. Forward collecting lens assembly; 09. Forward collecting sensor; 10. Second displacement stage; 11. Lateral collecting lens assembly; 12. Lateral collecting sensor; 13. Third displacement stage; 21. Beam expander; 22. First reshaping stop; 23. Collimating lens; 24. Second reshaping stop; 25. Focusing lens; 26. First light transmission window; 27. Third reshaping stop; 28. Second light transmission window; 29. ​​First condenser cup; 30. Second condenser cup; 31. Light trap; 80. Original laser beam; 81. Converging beam; 82. Laterally collected beam; 83. Forwardly collected beam; 84. Beam expander beam; 85. Edge beam; 86. Collimated beam; 87. First diverging beam; 88. Second diverging beam; 89. Final incident beam; 90. Detection area; 91. Forwardly scattered beam; 92. Laterally scattered beam; 93. Scattered beam . Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0019] Example 1 This embodiment provides a high particle size resolution liquid particle counting device, see [link / reference] Figure 1 , Figure 2 The liquid particle counting device 100 includes a light source module 101, a flow control module 102, and a forward collection module 104 arranged sequentially along the Z direction. The liquid particle counting device 100 also includes a lateral collection module 103, which is located on the side of the flow control module 102.

[0020] Specifically, the light source module 101 includes a laser 01 and a shaping lens assembly 02. The laser 01 emits a raw laser beam 80, which forms a circular spot with a diameter of 0.5~3mm and a divergence angle of less than 20mrad. The shaping lens assembly 02 includes a beam expander 21, a collimator 23, and a focusing lens 25. The lenses of the shaping lens assembly 02 are arranged sequentially along a direction perpendicular to the optical axis of the laser 01.

[0021] The flow control module 102 includes a flow control housing. A first light-transmitting window 26 and a second light-transmitting window 28 are respectively provided on the front and rear sides of the flow control housing. A flow control chamber is located inside the flow control housing. The flow control chamber is divided into a first chamber 06 and a second chamber 07 by a third aperture 27. The detection area 90 is located at the center of the second chamber 07. In this application, the flow rate through the flow control chamber is a large flow rate, for example, 1000 ml / min. Therefore, this application designs a wide-diameter flow cell to provide a detection flow rate that can accommodate this higher efficiency.

[0022] A forward collection module 104 is located at the rear end of the flow control module 102 and is used to collect forward scattered light 82 from the detection area. It includes a forward collection mirror group 08 and a forward collection sensor 09. The forward collection mirror group 08 is located between the flow control module 102 and the forward collection sensor 09. The forward collection mirror group 08 includes a first condenser cup 29 and a second condenser cup 30.

[0023] The lateral collection module 103 is located on the side of the flow control module 102 and is used to collect lateral scattered light 83 from the detection area. It includes a lateral collection mirror group 11 and a lateral collection sensor 12. The lateral collection mirror group 11 is located between the flow control module 102 and the lateral collection sensor 12.

[0024] After the laser 01 emits the original laser beam 80, it is shaped and converged by the shaping mirror group 02, which blocks edge light and extracts the center of the original laser beam 80 with uniform light intensity as much as possible, focusing the light into a converged beam 81 that is incident on the center of the flow control module 102. Since a third shaping aperture 27 is provided between the first chamber 06 and the second chamber 07 of the flow control module 102, stray light is further blocked by the third shaping aperture 27, improving the beam quality and forming the final incident beam 89. Particle detection occurs in the second chamber 07 and is finally incident. The light beam 89 is focused at the center of the second chamber 07 to form the detection area 90. When particles flow through the detection area 90, scattering occurs. Within a certain angle, the forward-scattered light is collected by the forward-collecting mirror group 08 of the forward-collecting module 104, that is, the forward-scattered light beam 91 is converged into the forward-collecting light beam 83, which illuminates its forward-collecting sensor 09. Within a certain angle, the lateral-scattered light is collected by the lateral-collecting mirror group 11 of the lateral-collecting module 103, that is, the lateral-scattered light beam 92 is converged into the lateral-collecting light beam 82, which illuminates its lateral-collecting sensor 12. The forward-collecting sensor 09 and the lateral-collecting sensor 12 can collect scattered light from different directions in the detection area, thereby increasing the particle size resolution and improving the detection accuracy. Due to the diffraction of light, there will inevitably be a non-uniform distribution of light intensity in the detection area. Through the shaping mirror group 02 on the original laser beam 80 and the third shaping aperture 27 on the converged light beam 81, the uniform light intensity area at the center of the laser beam is extracted and the interference of stray light is suppressed.

[0025] For details, see Figure 3 The shaping lens group 02 is used to block stray areas at the edges of the original laser beam and extract the central uniform intensity position. The beam expander 21 and collimator 23 have the same focal point. The aperture of the beam expander is designed to match the circular spot of the laser, with an aperture of 3~5mm, which can achieve the beam expansion effect of a circular spot smaller than 3mm. After the original laser beam 80 passes through the beam expander 21 and collimator 23, it emits a beam expanded parallel beam 86, which is then focused by the focusing lens 25. The focal length of the focusing lens 25 is greater than the distance from the right end face of the second fine-tuning mechanism 05, where the shaping lens group 02 is located, to the center of the second chamber 07. It also leaves a certain adjustment margin so that the converging light 81 can be adjusted to converge to the center of the second chamber 07.

[0026] Preferably, a first aperture 22 is provided between the beam expander 21 and the collimator 23, and a second aperture 24 is provided between the collimator 23 and the focusing lens 25. The first aperture 22 blocks the edge rays 85 during the beam expansion process of the beam expander 21, extracting the central region of the light. The second aperture 24 blocks the first diverging ray 87 of the collimator 23. This first diverging ray 87 is generated by the diffraction of the original laser ray 80 through the beam expander 21, the first shaping aperture 22, and other effects.

[0027] See Figure 4 In the flow control module 102, the first light-transmitting window 26 and the second light-transmitting window 28 are arc-shaped windows, with both sides of their surfaces designed with the center of curvature of the second chamber 07 as the center of curvature, reducing the refraction and scattering of the converging light 81 entering the flow control module 102 and the forward-scattering light 91. The second diverging light 88 of the second chamber 07 is either caused by the scattering effect of the liquid medium when the converging light 81 passes through the first chamber 06, or by the diffraction effect of the converging light 81 during its propagation from the light source module 101 to the flow control module 102, or by other possible reasons.

[0028] Preferably, the particle to be detected enters the detection area along the Y direction. When the lower limit of the target particle size is 40 nm, the side-scattered light collection angle can be set to 40° to 140° and the forward-scattered light collection angle can be set to 5° to 35°. When the lower limit of the target particle size is 200 nm, the forward scattering effect of the particle is enhanced, and the side-scattered light collection angle can be set to 30° to 150° and the forward-scattered light collection angle can be set to 5° to 25°.

[0029] Preferably, both the third aperture 27 and the flow control chamber of the flow control module 102 are made of pure, light-absorbing materials. For example, using NG1 or other clean materials with added light-absorbing components can avoid false counting caused by particle shedding and further reduce the intensity of stray light in the chamber.

[0030] See Figure 5 The forward collection module 104 is used to convert the forward scattered light 91 into an electrical signal. Specifically, the forward scattered light 91 is converted into parallel light after interacting with the second condenser cup 30 of the forward collection mirror group. The light is then focused onto the forward collection sensor 09 by the first condenser cup 29, and the optical signal is converted into an electrical signal by the forward collection sensor 09.

[0031] Specifically, the forward-collecting mirror assembly is integrated with the flow control module, and both the first condenser cup 29 and the second condenser cup 30 have parabolic surfaces. The focal point of the second condenser cup 30 is located at the center of the second chamber 07. (If possible...) The focal length of the first condenser (29) is 10 to 15 times that of the second condenser (30), as its... The magnification of the forward collecting mirror group is... The forward-collecting sensor 09, on the other hand, is a single-area optoelectronic device, such as an avalanche diode (APD). The area size of the forward-collecting sensor 09... Smaller, such as If its surface element size matches the magnification M of the forward collecting mirror group 08, then the length of the detection area is... Ensure that only the center of the 90% detection area is approximately 30%. Up to 50 The scattered light from the region can be received by the forward-collecting sensor 09, enabling particle detection at a location with relatively uniform light intensity at the center of the incident light 89.

[0032] Preferably, a light trap 31 is also provided between the first condenser cup 29 and the second condenser cup 30. The light trap 31 can be made of light-absorbing material or coated with light-absorbing substance to absorb strong forward transmitted light. To reduce the influence of forward transmitted light, the light trap 31 is positioned at a half-angle relative to the center of the second chamber 07. Much larger than the laser divergence angle, to ensure that all forward-transmitted light rays are absorbed by the light trap 31, which can be used as follows: .

[0033] Preferred, see Figure 6 In the lateral collection module 103, to increase the lateral collection angle, its lateral collection lens group 11 uses an immersion lens, which can be a commercially available standard product. The immersion lens consists of an immersion lens, a parabolic lens, and a meniscus lens, in sequence. The purpose of using an immersion lens is to increase the numerical aperture of the lateral collection lens group 11. If the numerical caliber can be achieved For example, you can choose to be .

[0034] In this example, the light convergence length of the lateral collecting mirror group 11 and the front collecting mirror group 08 is relatively large compared to the size of the flow chamber. To save space, plane mirrors can be used to fold the front scattered light 83 and the lateral scattered light 82 to achieve a dense arrangement.

[0035] Preferred, see Figure 1 As shown, the laser 01 and the shaping mirror group 02 are respectively mounted on the first displacement stage 03, and the forward collection module 104 and the lateral collection module 103 are respectively mounted on the second displacement stage 10 and the third displacement stage 13. The positions of the devices on them along the X, Y and Z directions can be adjusted by the first displacement stage 03, the second displacement stage 10 and the third displacement stage 13.

[0036] Preferably, the beam expander 21, collimator 23, second fine-tuning mechanism 05 and focusing lens 25 are mounted on the first displacement stage 03 via the first fine-tuning mechanism 04, and their positions in the X and Y directions are adjusted by the first fine-tuning mechanism 04. The focusing lens 25 is mounted on the first fine-tuning mechanism 04 via the second fine-tuning mechanism 05, and its position in the Z direction can be adjusted by the second fine-tuning mechanism 05.

[0037] Specifically, in this application, laser 01 is a linearly polarized laser, and the intensity of the scattered light when the particle is irradiated by the laser can be described by Mie scattering: , In the formula: The intensity of the incident light; The wavelength of the incident light; Particle size; The particle size is a dimensionless parameter. The relative refractive index; See Figure 17 The particles are irradiated by a laser beam incident along the Z-axis and polarized in the X-axis. Figure 17 Under the conditions of particle size distribution and laser irradiation, the particle scattered light distributions for 40nm, 100nm, and 200nm polystyrene (n=1.59) particles are as follows: Figures 18 to 20 As shown (the intensity of scattered light in the figure has been normalized): ): As can be seen from the pattern in the figure, for large-diameter particles (represented by 200 nm), the scattered light is mainly forward scattering. As the particle size decreases, the scattered light gradually transitions from forward scattering to uniform scattering. Simultaneously, it can be observed that when particles are irradiated by a linearly polarized laser, the scattered light follows its polarization direction. No scattered light is generated. To avoid interference from the forward transmitted light, this application includes a forward collection module and a side collection module. The lateral collection module is positioned at the saddle point of the scattered light distribution to maximize the reception of scattered signals from small-diameter particles. Combined with other structural designs in this application (flow cell, collection lens), this ultimately enables the detection of particles as small as 40 nm. If circularly polarized light is used to illuminate the particles, Figure 17 The energy of the y-axis polarized light will not produce scattered light in the direction of the lateral collection module of this application. The linearly polarized laser and the lateral collection module are arranged in conjunction to maximize the utilization of particle scattering signals.

[0038] In liquid particle counting devices, simply adding a lateral collection module 103 increases the problem of light intensity non-uniformity due to the large detection area; therefore, in this embodiment, the present invention proposes... Figure 7The diagram illustrates a processing logic that uses forward-scattered light to constrain the collection range of lateral-scattered light, thereby reducing the error caused by the uneven light intensity distribution in the detection area.

[0039] See Figures 8 to 11 The liquid particle counting device described in this embodiment of the invention uses... Figure 7 The logic chain shown completes particle counting and channel division. Possible abnormalities within the flow chambers of this logic chain are as follows: Figure 8 , Figure 9 Figure 11 As shown. After the liquid particle counting device 100 is powered on, the forward collection module 104 and the lateral collection module 103 continuously collect pulse data. When a particle passes through the flow chamber from a position away from the detection area, as shown... Figure 8 As shown, if no scattered light signal is received by the sensors on both sides or is limited by spatial relationships, the received signal of the sensors is less than the trigger threshold, and neither sensor will trigger. When the forward collection module 104 is triggered, it indicates that the particle to be measured has passed near the laser axis Z of the detection area. The two cases are as follows: Figure 9 , Figure 10 As shown: In one scenario, the particle to be tested passes outside the detection area along the laser axis Z, corresponding to... Figure 9 In the scenario shown, when the forward collection module 104 is triggered but the lateral collection module 103 is not triggered, the optical signal pulse is not recorded, and the liquid particle counting device 100 resumes continuous detection. Another scenario is when the particle to be tested passes through the detection area (i.e., the detection region), corresponding to... Figure 10 As shown, the forward collection module 104 is triggered at the same time, and the lateral collection module 103 is also triggered at the same time, and the light pulse signal is recorded.

[0040] Preferably, the triggering order of the forward collection module 104 and the lateral collection module 103 can be adjusted. After swapping the triggering order, i.e., when the lateral collection module 103 is triggered while the forward collection module 104 is not triggered, the situation is as follows: Figure 11 As shown, when the particle to be tested passes through the flow chamber near the detection area, i.e., near the waist radius X, the optical pulse signal is not recorded.

[0041] Preferably, to reduce the differences caused by uneven light intensity distribution in the detection area, the forward collection module sensor 09 is smaller in size, which also means that the triggering of the forward collection module 104 is more stringent. Therefore, using Figure 7 The forward collection module is triggered first, followed by the lateral collection module, to reduce redundant steps in the program.

[0042] Preferably, when the forward collection module 104 and the lateral collection module 103 are triggered simultaneously, the signal pulses from both sides are synchronously recorded and imported into the Pulse Height Analysis (PHA) system for analysis. The comprehensive analysis by the PHA system is not limited to other inversion algorithms such as averaging the particle size determined independently from the pulse signals from both sides. The comprehensive processing method of signals from both sides adopted in this invention improves the resolution of particle size inversion by the device compared to the single-channel signal processing method.

[0043] In summary, the liquid particle counting device in the above embodiments of the present invention improves the uniformity of light intensity in the detection area through a series of light shaping measures and the positional constraint of the forward collection module 104, thereby improving the accuracy of particle counting and particle size inversion compared to traditional methods. Simultaneously, the integrated pulse processing method proposed in this invention for the forward collection module 104 and the lateral collection module 103 improves the resolution of particle size inversion.

[0044] Example 2 Embodiment 2 of the present invention provides an optical path debugging method for a liquid particle counting device 100, used to realize the above-mentioned functions of the liquid particle counting device. The optical path debugging method of this embodiment can be implemented in conjunction with a camera or beam profiler, or other optical detection equipment sensitive to the wavelength range of the selected laser. This embodiment takes camera debugging as an example; see [link to documentation]. Figures 11 to 15 The method includes: Step 1: Install the flow control module 102 and its forward collecting mirror group 08 and side collecting mirror group 11. At the same time, install the debugging camera at the second focusing cup 30, which is close to the outermost part of the forward collecting mirror group 08. The receiving surface of the debugging camera is larger than the aperture of the laser beam. Ultrapure water is introduced into the flow control module.

[0045] Step 2: Install laser 01, aligning it with flow control module 102. After installing laser 01 on the first displacement stage 03, use the first displacement stage 03 to adjust its X and Y position. During movement, observe the morphology of the emitted light spot on the opposite side of the flow chamber using a calibration camera. Due to the limitation of the third aperture 27, the calibration camera will display a circular outline light spot. When the first displacement stage 03 is adjusted so that the calibration camera displays a complete circular light spot or the maximum intensity point is located at the center of the aperture, it indicates that laser 01 and flow control module 102 are aligned, meaning that laser 01 is installed successfully.

[0046] Step 3: Install orthopedic lens assembly 02, see [link / reference] Figure 12 , Figure 13 The reshaping lens assembly 02 is installed and aligned with the optical axis of the laser 01. The reshaping lens assembly 02 is mounted on the first fine-tuning mechanism 04. The first fine-tuning mechanism 04 is used to fine-tune the position of the reshaping lens assembly 02 in the X and Y directions. The camera spot is continuously observed. When the spot moves from... Figure 12 The morphology moved to Figure 13 When the complete circular light spot of the described shape is obtained, it indicates that the laser 01, the shaping lens group 02 and the flow control module 103 have been aligned. At this time, it also indicates that the final incident light 89 has entered the center of the second chamber 07, but its beam waist, i.e., the position in the z-direction, still needs to be calibrated later.

[0047] Preferably, the power of the laser 01 is usually greater than the exposure capability of the calibration camera, or after adding the shaping lens group 02, the light intensity of the spot on the opposite side of the flow chamber is greater than the exposure capability of the calibration camera through focusing. A filter of the corresponding wavelength can be installed before the calibration camera to protect the calibration camera, which has little impact on the calibration results.

[0048] Preferably, due to the divergence angle of the final incident light, the light spot may extend beyond the receiving surface of the adjustment camera. In this case, the adjustment camera can be moved to observe the entire edge morphology of the light spot, ensuring that the edges of the light spot are rounded and complete.

[0049] Step 4: Coarsely locate the position of sensor 09 in the forward direction, see [link / reference] Figure 14 , Figure 15 A forward collection sensor 09 is installed after the flow control module. First, the test camera and its fixture are mounted on the second displacement stage 10. The fixture is a jig designed to fit the dimensions of the test camera; this fixture is a prior art structure and its purpose is to assist in mounting the test camera on the second displacement stage 10. The center of the test camera needs to be approximately aligned with the center of the forward collection sensor 09. Specifically, the second displacement stage 10 is used to adjust the position of the test camera along the Z-direction until the light spot is minimized, i.e., the test camera is moved to the focal point of the light spot. Then, the second displacement stage 10 is used to control the position of the test camera along the X and Y directions so that the center of the light spot appears at the center of the test camera, completing the coarse adjustment of the center position of the forward collection sensor 09.

[0050] Step 5: Fine-tune the center position of the forward collecting sensor 09. First, replace the debugging camera and its fixture with the forward collecting sensor. Then, fine-tune the position of the second displacement stage 10 and the forward collecting sensor 09 on its upper end, and monitor the voltage signal of the forward collecting sensor 09. This voltage signal reflects the intensity of scattering by pure water molecules in the detection area and the alignment between the sensor and the point where the scattered light converges. Move the second displacement stage 10 along the X, Y, and Z directions to the maximum value of the output voltage signal. This indicates that the focal point of the forward collecting mirror group 08 has converged onto the forward collecting sensor 09. This completes the fine-tuning of the forward collecting sensor 09, thus completing the adjustment of the forward collecting optical path.

[0051] Step 6: Coarsely locate the position of sensor 12 by lateral positioning (see below). Figure 16First, install the debugging camera and corresponding tooling on the third displacement stage 13, so that the center of the debugging camera roughly coincides with the center of the lateral collection sensor 12. Introduce a high concentration of fluorescent particles or nano- or micron-sized particle groups into the flow control module 102, utilizing the scattering effect of the particle groups to display the laser profile and determine the alignment of the optical path of the lateral collection module. Preferably, the aforementioned nano- or micron-sized particle groups are stably injected into the flow control module using a syringe pump, and a bubble filter is added before entering the flow control module 102 to ensure that the laser profile is continuously and stably displayed in the debugging camera.

[0052] To observe the laser profile in the adjustment camera, firstly, the third displacement stage 13 moves along the X-direction to make the laser profile in the adjustment camera clearly visible. Then, by adjusting the second fine-tuning mechanism 05 and the third displacement stage 13 in the Z-direction, the center of the laser beam waist in the Z-direction is clearly converged to the center of the adjustment camera. Next, the third displacement stage 13 is moved along the Y-direction to make the center of the laser beam waist in the Y-direction appear at the center of the adjustment camera; this completes the coarse adjustment of the lateral light collection path.

[0053] Step 7: Fine-tune the position of the lateral collection sensor 12. Replace the debugging camera with the lateral collection sensor 12. Fine-tune the center position of the lateral collection sensor 12, and fine-tune the third displacement stage 13. Observe the voltage signal of the lateral collection sensor 12 at this time, and adjust its position along the Y and Z axes to the point where the voltage signal is maximum. This completes the fine-tuning of the lateral collection sensor 12. At this point, the optical path debugging of the lateral collection optical path and all optical paths of the liquid particle counting device is completed.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high particle size resolution liquid particle counting device, characterized in that, The liquid particle counting device includes: The light source module includes a laser and a shaping lens group. The shaping lens group includes a beam expander, a collimator, and a focusing lens. Each lens of the shaping lens group is arranged sequentially along a direction perpendicular to the optical axis of the laser. The flow control module is located at the rear end of the light source module and includes a flow control housing. The flow control housing has a first light-transmitting window and a second light-transmitting window on its front and rear sides, respectively. The flow control housing has a flow control chamber inside, which is divided into a first chamber and a second chamber by a third aperture. The detection area is located at the center of the second chamber. A forward collection module is located at the rear end of the flow control module and is used to collect forward scattered light. It includes a forward collection mirror group and a forward collection sensor. The forward collection mirror group is located between the flow control module and the forward collection sensor. The forward collection mirror group includes a first condenser cup and a second condenser cup. A lateral collection module is provided on the side of the flow control module for collecting lateral scattered light. It includes a lateral collection mirror group and a lateral collection sensor, with the lateral collection mirror group disposed between the flow control module and the lateral collection sensor. When the particle to be tested passes through the laser axis of the detection area, the forward collection module is triggered. When the particle to be tested passes through the detection area, the lateral collection module is also triggered, and the optical signal pulses on both sides are recorded synchronously and imported into the pulse height analysis system for analysis. When the particle to be tested does not pass through the detection area, the lateral collection module is not triggered, and the optical signal pulse is not recorded.

2. The high particle size resolution liquid particle counting device according to claim 1, characterized in that, A first aperture is provided between the beam expander and the collimating lens, and a second aperture is provided between the collimating lens and the focusing lens.

3. The high particle size resolution liquid particle counting device according to claim 1, characterized in that, The laser emits a circular light spot with a diameter of 0.5 to 3 mm and a divergence angle of less than 20 mrad.

4. The high particle size resolution liquid particle counting device according to claim 1, characterized in that, The focal point of the beam expander lens coincides with that of the collimating lens. The aperture of the beam expander lens is designed to match the circular spot of the laser. Its aperture is 3~5mm, which can achieve the beam expansion effect of a circular spot smaller than 3mm.

5. The high particle size resolution liquid particle counting device according to claim 1, characterized in that, A light trap is provided between the first and second condenser cups. The light trap is used to absorb the forward transmitted light. The angle subtended by the light trap at the center of the second chamber is much larger than the laser divergence angle, so as to ensure that all the forward transmitted light is absorbed by the light trap.

6. The high particle size resolution liquid particle counting device according to claim 5, characterized in that, The focal point of the first condenser cup coincides with the center of the second chamber, and the focal point of the second condenser cup coincides with the measurement center of the positive collection sensor.

7. The high particle size resolution liquid particle counting device according to claim 1, characterized in that, The particle to be detected enters the detection area along the Y direction. When the lower limit of the target particle size is 40 nm, the side-scattered light collection angle can be set to 40° to 140° and the forward-scattered light collection angle can be set to 5° to 35°. When the lower limit of the target particle size is 200 nm, the forward scattering effect of the particle is enhanced, and the side-scattered light collection angle can be set to 30° to 150° and the forward-scattered light collection angle can be set to 5° to 25°.

8. The high particle size resolution liquid particle counting device according to claim 1, characterized in that, The laser and the shaping lens assembly are respectively mounted on the first displacement stage, and the forward collection module and the lateral collection module are respectively mounted on the second displacement stage and the third displacement stage. The positions of the devices on the first displacement stage, the second displacement stage, and the third displacement stage can be adjusted along the X, Y, and Z directions.

9. A high particle size resolution liquid particle counting device according to claim 8, characterized in that, The beam expander and the collimator are mounted on the first displacement stage via a first fine-tuning mechanism, and their positions in the X and Y directions are adjusted by the first fine-tuning mechanism. The focusing lens is mounted on the first fine-tuning mechanism via a second fine-tuning mechanism, and its position in the Z direction is adjusted by the second fine-tuning mechanism.

10. An optical path adjustment method, applied to the high particle size resolution liquid particle counting device according to any one of claims 1 to 9, characterized in that, The method includes: Step 1: First, install the flow control module and its forward collection mirror group and side collection mirror group. Ultrapure water is introduced into the flow control module. Install and debug the camera close to the rear end of the forward collection mirror group. Step 2: Install the laser, aligning it with the optical axis of the flow control module; Step 3: Install the shaping lens assembly, which is aligned with the optical axis of the laser; Step 4: Coarsely locate the position of the positive collection sensor, then install the debugging camera on the second displacement stage and adjust the position of the debugging camera so that the debugging camera is located at the focal point of the light spot; Step 5: Fine-tune the position of the positive collection sensor. Replace the debugging camera with the positive collection sensor and adjust its position to the point where the voltage signal of the positive collection sensor is at its maximum. Step 6: Coarsely locate the position of the lateral collection sensor, install the debugging camera on the third displacement stage, introduce fluorescent particles or fine particles into the flow control module, and adjust so that the laser center beam waist position appears in the center of the debugging camera. Step 7: Fine-tune the position of the lateral collection sensor. Replace the debugging camera with the lateral collection sensor and adjust its position to the point where the voltage signal of the lateral collection sensor is at its maximum.

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