Particle detection device

Abstract

The present invention discloses a particle detection device. The particle detection device includes a light source, a sample pool, a light beam collection unit, a dichroic mirror, a first photoelectric detection unit, a second photoelectric detection unit and a processing unit; the sample pool includes a fluorescent liquid path inlet, a sample liquid path inlet and a liquid path outlet; the light source emits an illumination light beam to the sample pool to generate scattered fluorescence and scattered signal light, the scattered fluorescence is output to the first photoelectric detection unit, and the scattered signal light is output to the second photoelectric detection unit; the processing unit detects and counts the particles to be measured according to the electrical signal of the second photoelectric detection unit, and corrects the measurement result according to the number and particle size of the fluorescent particles and the electrical signal of the first photoelectric detection unit. The present invention adds a fluorescent detection optical path to a conventional light scattering optical path, monitors the state of the light scattering optical path in real time, and uses the fluorescent signal waveform to provide auxiliary information for the light scattering signal processing algorithm, thereby improving the detection accuracy and realizing the detection and counting of ultrafine particles in the liquid.

Description

Technical Field

[0001] The present invention relates to the technical field of particle detection, and in particular to a particle detection device. Background Art

[0002] The semiconductor industry has extremely stringent requirements for the purity of chemicals. Any tiny impurity may have a significant impact on the performance of the final product. Therefore, the detection and counting of nanoparticles in ultra-pure chemicals, especially liquid chemicals, has become an essential key step in semiconductor processing.

[0003] A particle counter is an instrument that uses the principle of light scattering to count particles. Light scattering is related to factors such as particle size, light wavelength, particle refractive index, and particle absorption characteristics of light. For particles with smaller particle sizes, such as particles with a diameter of 20nm or less, the detection accuracy needs to be improved due to weak scattering signals. Summary of the invention

[0004] An embodiment of the present invention provides a particle detection device, which adds a fluorescence detection light path to a conventional light scattering light path. By detecting the fluorescence of additionally added larger-sized known fluorescent particles, the state of the light scattering light path can be monitored in real time, and the fluorescence signal waveform is used to provide auxiliary information for the light scattering signal processing algorithm, thereby improving the detection accuracy and realizing the detection and counting of ultrafine particles (as small as 20nm) in liquid.

[0005] According to one aspect of the present invention, there is provided a particle detection device, comprising a light source, a sample cell, a beam collection unit, a dichroic mirror, a first photodetection unit, a second photodetection unit and a processing unit, wherein the first photodetection unit and the second photodetection unit are both connected to the processing unit;

[0006] The sample pool comprises a fluorescent liquid path inlet, a sample liquid path inlet and a liquid path outlet. The fluorescent sample is injected into the sample pool from the fluorescent liquid path inlet and flows out of the sample pool from the liquid path outlet. The sample to be tested is injected into the sample pool from the sample liquid path inlet and flows out of the sample pool from the liquid path outlet. The fluorescent sample comprises fluorescent particles of known quantity and particle size, and the sample to be tested comprises particles to be tested.

[0007] The light source is used to emit an illumination light beam to the sample pool, the illumination light beam irradiates the fluorescent particles and the particles to be tested to generate scattered fluorescence and scattered signal light respectively, the scattered fluorescence and the scattered signal light are transmitted to the dichroic mirror after passing through the beam collecting unit, the scattered fluorescence is output from the first output end of the dichroic mirror to the first photoelectric detection unit, and the scattered signal light is output from the second output end of the dichroic mirror to the second photoelectric detection unit;

[0008] The processing unit is used to detect and count the particles to be measured according to the electrical signal of the second photoelectric detection unit, and is also used to correct the measurement result according to the number and particle size of the fluorescent particles and the electrical signal of the first photoelectric detection unit.

[0009] Optionally, a beam adjustment unit is further included, and the beam adjustment unit is located on the optical path between the light source and the sample pool. The beam adjustment unit is used to adjust the illumination beam into a flat-top beam and then transmit it to the sample pool.

[0010] Optionally, the beam adjustment unit is connected to the processing unit, and the processing unit is further used to monitor the beam quality of the illumination beam according to the signal intensity of the first photodetection unit, and control the beam adjustment unit to adjust the beam quality of the illumination beam.

[0011] Optionally, the beam adjustment unit includes a fiber coupler, an optical fiber, a motor, a diffuser, and a focusing lens group;

[0012] The optical fiber coupler is used to couple the illumination light beam into the first end of the optical fiber, and the second end of the optical fiber outputs the illumination light beam to the diffuser;

[0013] The motor drives the diffuser to rotate, converts the illumination light beam into the flat-top light beam and transmits it to the focusing lens group;

[0014] The focusing lens group includes at least one lens, and the focusing lens group is used to focus the flat-top beam onto the sample pool.

[0015] Optionally, a light trap is also included, and the light trap is used to absorb the transmitted light beam of the sample pool.

[0016] Optionally, the light source includes a single transverse mode laser.

[0017] Optionally, the output wavelength range of the single transverse mode laser is 360nm~700nm.

[0018] Optionally, the light beam collecting unit includes a collecting lens group and an aperture, and the collecting lens group includes at least one lens.

[0019] Optionally, a filter is further included, and the filter is located between the dichroic mirror and the first photodetection unit.

[0020] Optionally, the processing unit includes a data acquisition card and a computer, and the computer has built-in signal processing software.

[0021] The particle detection device provided by an embodiment of the present invention includes a light source, a sample cell, a light beam collection unit, a dichroic mirror, a first photoelectric detection unit, a second photoelectric detection unit and a processing unit, wherein the first photoelectric detection unit and the second photoelectric detection unit are both connected to the processing unit; the sample cell includes a fluorescent liquid path inlet, a sample liquid path inlet and a liquid path outlet, the fluorescent sample is injected into the sample cell from the fluorescent liquid path inlet and flows out of the sample cell from the liquid path outlet, the sample to be tested is injected into the sample cell from the sample liquid path inlet and flows out of the sample cell from the liquid path outlet, the fluorescent sample includes fluorescent particles of known quantity and particle size, and the sample to be tested includes particles to be tested. The light source emits an illumination beam to the sample pool, and the illumination beam irradiates the fluorescent particles and the particles to be measured to generate scattered fluorescence and scattered signal light respectively. The scattered fluorescence and scattered signal light are transmitted to the dichroic mirror after passing through the beam collection unit, and the scattered fluorescence is output from the first output end of the dichroic mirror to the first photoelectric detection unit, and the scattered signal light is output from the second output end of the dichroic mirror to the second photoelectric detection unit; the processing unit realizes the detection and counting of the particles to be measured according to the electrical signal of the second photoelectric detection unit, and corrects the measurement result according to the number and particle size of the fluorescent particles and the electrical signal of the first photoelectric detection unit. The technical solution of the embodiment of the present invention adds a fluorescence detection optical path to the conventional light scattering optical path, and by detecting the fluorescence of the additional larger size known fluorescent particles, the state of the light scattering optical path can be monitored in real time, and the fluorescence signal waveform is used to provide auxiliary information for the light scattering signal processing algorithm, thereby improving the detection accuracy and realizing the detection and counting of ultrafine particles (as small as 20nm) in the liquid.

[0022] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A structural block diagram of a particle detection device provided by an embodiment of the present invention;

[0025] Figure 2 A structural block diagram of another particle detection device provided by an embodiment of the present invention;

[0026] Figure 3 A structural block diagram of another particle detection device provided by an embodiment of the present invention;

[0027] Figure 4 A structural block diagram of another particle detection device provided by an embodiment of the present invention;

[0028] Figure 5 A structural block diagram of another particle detection device provided by an embodiment of the present invention;

[0029] Figure 6 This is a structural block diagram of another particle detection device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] Figure 1 A structural block diagram of a particle detection device provided by an embodiment of the present invention, refer to Figure 1The particle detection device includes a light source 10, a sample pool 20, a beam collecting unit 30, a dichroic mirror 40, a first photoelectric detection unit 50, a second photoelectric detection unit 60 and a processing unit 70. The first photoelectric detection unit 50 and the second photoelectric detection unit 60 are both connected to the processing unit 70; the sample pool 20 includes a fluorescent liquid path inlet 21, a sample liquid path inlet 22 and a liquid path outlet 23. The fluorescent sample is injected into the sample pool 20 from the fluorescent liquid path inlet 21 and flows out of the sample pool 20 from the liquid path outlet 23. The sample to be tested is injected into the sample pool 20 from the sample liquid path inlet 22 and flows out of the sample pool 20 from the liquid path outlet 23. The fluorescent sample includes fluorescent particles of known quantity and particle size. The sample to be tested has a fluorescence path inlet 21, a sample liquid path inlet 22 and a liquid path outlet 23. The invention comprises particles to be measured; a light source 10 is used to emit an illumination light beam to a sample pool 20, the illumination light beam irradiates the fluorescent particles and the particles to be measured to generate scattered fluorescence and scattered signal light respectively, the scattered fluorescence and the scattered signal light are transmitted to a dichroic mirror 40 after passing through a beam collecting unit 30, the scattered fluorescence is output from a first output end of the dichroic mirror 40 to a first photoelectric detection unit 50, and the scattered signal light is output from a second output end of the dichroic mirror 40 to a second photoelectric detection unit 60; a processing unit 70 is used to detect and count the particles to be measured according to the electrical signal of the second photoelectric detection unit 60, and is also used to correct the measurement result according to the number and particle size of the fluorescent particles and the electrical signal of the first photoelectric detection unit 50.

[0033] Among them, the particle detection device provided by the embodiment of the present invention is a particle counter, which is an instrument that uses the principle of light scattering to count particles. Light scattering is related to factors such as particle size, light wavelength, particle refractive index, and particle absorption characteristics of light. However, as far as the intensity of scattered light and particle size are concerned, there is a basic rule, that is, the intensity of particle scattered light increases with the increase of the surface area of ​​the particle. In this way, a certain flow of gas or liquid containing particles passes through a beam of strong light, causing the particles to emit scattered light, which is projected onto the photomultiplier tube through a focusing lens, converting the light pulse into an electrical pulse, and the number of particles is obtained from the number of pulses. The particle diameter is obtained based on the functional relationship between the intensity of the particle scattered light and the particle size. In this way, the size of the particle can be inferred by measuring the intensity of the scattered light, which is the basic principle of the light scattering particle counter.

[0034] For example, for particles with a diameter of less than 100 nm, the Mie scattering formula can be well approximated by the following Rayleigh light scattering expression:

[0035] ;

[0036] Where I0 is the incident light intensity, d is the particle size, R is the measurement distance, λ is the wavelength of the incident light, m ​​is the complex refractive index of the particle, n is the refractive index of the liquid medium, and θ is the azimuth of the scattered light. According to the above formula, the light scattering cross section (i.e., the probability measure of scattering) of a particle with a diameter of 50nm is approximately 0.001, or 0.1%. The light scattering cross section of a particle with a diameter of 20nm is approximately 0.002%. When a particle takes 0.1msec to pass through a particle with an energy density of 200kW / cm 2 When the light detection area of ​​10μm optical fiber (wavelength of 532nm) is used, the number of scattered photons of particles with a diameter of 30nm is about 5000 and the number of scattered photons of particles with a diameter of 20nm is about 400. Therefore, the scattered light generated by ultrafine particles is very weak.

[0037] In existing particle detection systems, there are many noise factors, such as laser power fluctuations, light scattering from liquid media (caused by molecular thermal motion, basically DC), dark current of photodetectors, light scattering caused by the surface roughness of the detection cell (DC), etc. The light scattering caused by particles is usually a pulse signal. In summary, the existing technology is suitable for processing particles with larger diameters, and can generate strong enough pulse signals to perform height discrimination on the pulse signals, but is not suitable for processing particles with smaller diameters, and cannot generate strong enough pulse signals for height discrimination. That is, the existing counting is suitable for application scenarios with low signal-to-noise ratios.

[0038] During the use of the instrument, slight vibrations may cause the optical path in the instrument to deform, thereby causing baseline fluctuations or a decrease in the signal-to-noise ratio of the light scattering signal. Therefore, in the embodiment of the present invention, an additional fluorescent sample injection channel is added to the sample pool 20 to facilitate the injection of fluorescent particles of known quantity and particle size (the specific quantity and particle size can be selected according to actual conditions) when needed. The fluorescent particles are excited to emit fluorescence in the area illuminated by the illumination light beam in the sample pool 20, wherein the wavelength of the fluorescence is different from the wavelength of the scattered signal light, and the fluorescence is separated by the dichroic mirror in the detection light path and detected by the first photoelectric detection unit 50.

[0039] In a certain embodiment, optionally, the light source 10 includes a single transverse mode laser. In a specific implementation, the light source 10 may also include a laser power supply, which is used to provide energy for the single transverse mode laser. Optionally, the output wavelength range of the single transverse mode laser is 360nm~700nm, which can be designed according to actual conditions during specific implementation. In order to avoid the influence of the fluorescent sample on the sample to be tested, in a specific implementation, the sample pool 20 may include a fluorescent liquid path and a sample liquid path isolated from each other, wherein the material of the sample pool 20 may be quartz, sapphire or fusible polytetrafluoroethylene PFA plastic. The beam collection unit 30 may include a collection lens group, which may be an aspheric lens or a double cemented lens or a combination of the two, for collecting scattered light from a direction at an angle of 90 degrees to the optical axis of the incident laser, and a focus of the collection lens group is located in the detection area of ​​the liquid flow channel of the sample pool 20. The first photoelectric detection unit 50 and the second photoelectric detection unit 60 may include a photomultiplier tube or an avalanche diode and a transimpedance amplifier, and optionally, the processing unit 70 may include a data acquisition card and a computer, and the computer has built-in signal processing software. The data acquisition card is used to convert the analog voltage signal output by the transimpedance amplifier into a digital signal for computer processing. The functions of the signal processing software include correction of baseline drift, frequency domain transformation, cluster analysis, etc., to achieve the detection and counting of the particles to be tested.

[0040] The technical solution of the embodiment of the present invention adds a fluorescence detection light path to the conventional light scattering light path. By detecting the fluorescence of additional larger-sized known fluorescent particles, the state of the light scattering light path can be monitored in real time, and the fluorescence signal waveform is used to provide auxiliary information for the light scattering signal processing algorithm, thereby improving the detection accuracy and realizing the detection and counting of ultrafine particles (as small as 20nm) in liquids.

[0041] Figure 2 A structural block diagram of another particle detection device provided by an embodiment of the present invention, referring to Figure 2 Optionally, the particle detection device further includes a beam adjustment unit 80 , which is located on the optical path between the light source 10 and the sample pool 20 , and is used to adjust the illumination beam into a flat-top beam and then transmit it to the sample pool 20 .

[0042] The beam adjustment unit 80 is used to convert the single transverse mode laser output by the light source 10 into a flat-top beam. It can be understood that the light beam directly output by the light source 10 is usually a Gaussian beam, and the intensity of the Gaussian beam decays from the center to the surroundings. If the Gaussian beam is used as the illumination beam, the sample to be tested cannot be illuminated uniformly, while the flat-top beam has almost uniform energy density in the spot area. The use of the flat-top beam illumination can improve the uniformity of the light-sensitive area, further improve the quality of the scattered light signal, and facilitate software processing.

[0043] Optional, continue to refer to Figure 2 The beam adjustment unit 80 is connected to the processing unit 70, and the processing unit 70 is also used to monitor the beam quality of the illumination beam according to the signal intensity of the first photodetection unit 50, and control the beam adjustment unit 80 to adjust the beam quality of the illumination beam.

[0044] In the embodiment of the present invention, a fluorescence detection optical path is introduced to perform real-time status monitoring. When the light beam quality deteriorates due to vibration or other reasons, the signal intensity acquired by the first photoelectric detection unit 50 will become weaker. Such feedback information can be provided to the processing unit 70. The processing unit controls the light beam adjustment unit 80 to adjust the light beam quality of the illumination light beam to ensure the detection effect of the particles to be measured.

[0045] Figure 3 A structural block diagram of another particle detection device provided by an embodiment of the present invention, referring to Figure 3 Optionally, the beam adjustment unit 80 includes a fiber coupler 81, an optical fiber 82, a motor 83, a diffuser 84 and a focusing lens group 85; the fiber coupler 81 is used to couple the illumination beam into the first end of the optical fiber 82, and the second end of the optical fiber 82 outputs the illumination beam to the diffuser 84; the motor 83 drives the diffuser 84 to rotate, converts the illumination beam into a flat-top beam and transmits it to the focusing lens group 85; the focusing lens group 85 includes at least one lens, and the focusing lens group 85 is used to focus the flat-top beam onto the sample pool 20.

[0046] Among them, the input end of the fiber optic coupler 81 is coupled with the output end of the light source 10, and the output end of the fiber optic coupler 81 is coupled with the first end of the optical fiber 82. The fiber optic coupler 81 is used to couple the output single transverse mode laser of the light source 10 into the optical fiber 82 as much as possible; the optical fiber 82 can be a multi-mode optical fiber, which is used to convert the single-mode laser into a multi-mode laser; the diffuser 84 is fixed on the rotating shaft of the motor 83. After the laser passes through the high-speed rotating diffuser 84, the coherence of the laser is further reduced, and it is converted from a Gaussian beam to an approximately flat-top beam; the focusing lens group 85 can include at least one focusing lens, and its specific lens shape and number can be designed according to actual conditions, which is used to focus the output laser of the diffuser 84, and the focus is located in the detection area of ​​the liquid flow channel of the sample pool 20.

[0047] Figure 4 A structural block diagram of another particle detection device provided by an embodiment of the present invention, referring to Figure 4 Optionally, the particle detection device further includes a light trap 90 , and the light trap 90 is used to absorb the transmitted light beam of the sample pool 20 .

[0048] The light trap 90 is used to absorb the transmitted light beam of the sample pool 20 to avoid interference caused by scattering of the reflected light beam, thereby improving the detection accuracy.

[0049] Figure 5A structural block diagram of another particle detection device provided by an embodiment of the present invention, referring to Figure 5 Optionally, the beam collecting unit 30 includes a collecting lens group 31 and an aperture 32, and the collecting lens group 31 includes at least one lens ( Figure 5 not shown).

[0050] Among them, the collecting lens group 31 can have at least one focusing lens, and its specific lens shape and number can be designed according to actual conditions, and is used to collect more scattered light from a direction that is at an angle of 90 degrees to the optical axis of the incident laser. The light beam collected by the collecting lens group 31 passes through the aperture 32 to filter out part of the stray light and then is incident on the dichroic mirror 40, thereby improving the detection accuracy.

[0051] Figure 6 A structural block diagram of another particle detection device provided by an embodiment of the present invention, referring to Figure 6 Optionally, the particle detection device further includes a filter 100 , and the filter 100 is located between the dichroic mirror 40 and the first photodetection unit 50 .

[0052] The filter 100 is used to filter out the optical fiber other than the scattered fluorescence, so as to improve the accuracy of the first photoelectric detection unit 50 in acquiring the signal.

[0053] It can be understood that the structures in the above different embodiments can be combined with each other to obtain more embodiments. For example, in a certain embodiment, a beam adjustment unit, a light trap and a filter can be included at the same time, and the specific implementation can be designed according to actual conditions.

[0054] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A particle detection device, characterized in that: It includes a light source, a sample cell, a beam collecting unit, a dichroic mirror, a first photoelectric detection unit, a second photoelectric detection unit and a processing unit, wherein the first photoelectric detection unit and the second photoelectric detection unit are both connected to the processing unit; The sample pool comprises a fluorescent liquid path inlet, a sample liquid path inlet and a liquid path outlet, the fluorescent sample is injected into the sample pool from the fluorescent liquid path inlet and flows out of the sample pool from the liquid path outlet, the sample to be tested is injected into the sample pool from the sample liquid path inlet and flows out of the sample pool from the liquid path outlet, the fluorescent sample comprises fluorescent particles of known quantity and particle size, the sample to be tested comprises particles to be tested, and the size of the fluorescent particles is larger than the size of the particles to be tested; The light source is used to emit an illumination light beam to the sample pool, the illumination light beam irradiates the fluorescent particles and the particles to be tested to generate scattered fluorescence and scattered signal light respectively, the scattered fluorescence and the scattered signal light are transmitted to the dichroic mirror after passing through the beam collecting unit, the scattered fluorescence is output from the first output end of the dichroic mirror to the first photoelectric detection unit, and the scattered signal light is output from the second output end of the dichroic mirror to the second photoelectric detection unit; The processing unit is used to detect and count the particles to be measured according to the electrical signal of the second photoelectric detection unit, and is also used to correct the measurement result according to the number and particle size of the fluorescent particles and the electrical signal of the first photoelectric detection unit.

2. The particle detection device according to claim 1, characterized in that: It also includes a beam adjustment unit, which is located on the optical path between the light source and the sample pool, and is used to adjust the illumination beam into a flat-top beam and then transmit it to the sample pool.

3. The particle detection device according to claim 2, characterized in that: The beam adjustment unit is connected to the processing unit, and the processing unit is further used to monitor the beam quality of the illumination beam according to the signal intensity of the first photoelectric detection unit, and control the beam adjustment unit to adjust the beam quality of the illumination beam.

4. The particle detection device according to claim 2, characterized in that: The beam adjustment unit includes a fiber coupler, an optical fiber, a motor, a diffuser, and a focusing lens group; The optical fiber coupler is used to couple the illumination light beam into the first end of the optical fiber, and the second end of the optical fiber outputs the illumination light beam to the diffuser; The motor drives the diffuser to rotate, converts the illumination light beam into the flat-top light beam and transmits it to the focusing lens group; The focusing lens group includes at least one lens, and the focusing lens group is used to focus the flat-top beam onto the sample pool.

5. The particle detection device according to claim 1, characterized in that: Also included is a light trap, which is used to absorb the transmitted light beam of the sample cell.

6. The particle detection device according to claim 1, characterized in that: The light source includes a single transverse mode laser.

7. The particle detection device according to claim 6, characterized in that: The output wavelength range of the single transverse mode laser is 360nm~700nm.

8. The particle detection device according to claim 1, characterized in that: The light beam collecting unit comprises a collecting lens group and an aperture, and the collecting lens group comprises at least one lens.

9. The particle detection device according to claim 1, characterized in that: A filter is also included, and the filter is located between the dichroic mirror and the first photodetection unit.

10. The particle detection device according to claim 1, characterized in that: The processing unit comprises a data acquisition card and a computer, and the computer has built-in signal processing software.

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