Particle measurement system and method

Abstract

To provide a new optical system for analyzing particle size and concentration.SOLUTION: An optical system for analyzing particle size and concentration comprises: at least one laser that generates an illumination beam; a focusing lens that focuses the illumination beam on particles that move relatively to the illumination beam at known or predefined angles through a focal region of the focusing lens; and at least two forward-looking detectors that detect interactions of particles with the illumination beam in the focal region of the focusing lens. The focusing lens is a cylindrical lens forming a focal region that is: (i) narrow in a direction of relative motion between the particles and the illumination beam; and (ii) wide in a direction perpendicular to a plane defined by an optical axis of the system and the direction of relative motion between the particles and the illumination beam. Each of the two forward-looking detectors includes two segmented linear arrays of detectors.SELECTED DRAWING: Figure 6

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims priority to and benefit of U.S. Provisional Patent Application No. 62 / 577,403, filed October 26, 2017, which is incorporated herein by reference in its entirety. [Technical Field]

[0002] The present invention relates to the field of particle size and concentration measurement, and more particularly to the use of optical methods for measuring particle size and concentration, and achieving improved detection sensitivity or improved characterization of the measured particles. [Background technology]

[0003] Publications and other references mentioned herein are numerically referenced in the text below and are each grouped in a bibliography appended immediately before the claims.

[0004] Many techniques exist for particle size and concentration analysis (PSA), which can be reviewed in the books "Introduction to Particle Size Analysis" by Terry Alan (1) and "Particle Size Analysis" by N. Stanley-Wood and Roy W. Lines (10).

[0005] The most commonly used techniques are optical, based on the interaction of laser radiation with the particles being measured. Especially as we approach the submicron particle size range, where Mie scattering dominates, most of these techniques suffer from inaccuracies due to the effects of the real and imaginary components of the particle's refractive index. For example, some techniques, such as those based on Fraunhofer diffraction analysis, overestimate the size of light-absorbing particles due to energy loss caused by absorption, while at high concentrations, particles are known to be underestimated due to secondary scattering, etc. Furthermore, the ability to detect individual nanometer-scale particles is very limited due to the signal decay as the sixth power of the radius r, presenting challenges in sensitivity and dynamic range.

[0006] An optical technique less sensitive to these challenges is known as Time of Transition (TOT). In this technique, the interaction of a scanned, focused laser beam with particles is analyzed in the time domain rather than the amplitude domain, making it less sensitive to changes in refractive index. A detailed description of this technique is provided in the paper "Improvements in Accuracy and Speed ​​Using the Time-of-Transition Method and Dynamic Image Analysis For Particle Sizing" by Bruce Weiner, Walter Tscharnuter, and Nir Karasikov (2). In this approach, a digital deconvolution algorithm of a known laser beam profile derives size from the interaction signal. Concentration is derived from the number of interactions per unit time within a known volume of the focused laser beam using the principles of digital confocality.

[0007] In TOT technology, particles interact with a focused, scanning laser beam. To measure smaller particles, a smaller focused spot must be used. However, according to the diffraction law of a Gaussian laser beam, if the beam waist is D, the beam divergence is proportional to λ / D, where λ is the wavelength of the laser. As a result, the Rayleigh range and depth of focus decrease as λ increases or D decreases (depth of focus is

number

[0008] Improvements can be achieved by using shorter wavelengths, which result in lower divergence for a given focus and a correspondingly longer Rayleigh range, but this may be limited to a factor of two because wavelengths that are too short result in absorption of the laser light by the optics and, in the case of particles in a liquid, by the liquid itself.

[0009] A prior patent assigned to some of the applicants of the present application (U.S. Pat. No. 7,746,469, which is incorporated herein by reference in its entirety) introduces new techniques and means to somewhat decouple two conflicting requirements, namely, the ability to resolve small particles and the ability to measure low concentrations, using measurements based on the interaction of single particles with a structured laser beam.

[0010] The method presented in U.S. Patent No. 7,746,469 is based on synthetic beam generation. The limitations described therein are due to the inherent Gaussian beam profile of the laser beam, and are somewhat addressed by the proposed synthetically generated beam, in which spatial resolution can be achieved with lower beam divergence. Other energy distributions can be synthetically generated and used for particle measurement. One specific reference describing this technique is reference (3). This book deals with the generation of three-dimensional optical structures used in the present invention. This book explains the principles and techniques used and also provides several examples. In particular, the described dark line beam is the primary focus of the previous invention. Other relevant references are (4)-(9).

[0011] A dark line beam is a laser beam with a typical Gaussian envelope, except for a singular point in the center of the beam: a dark spot or line. Its main advantage for PSA (particle size analysis) comes from the fact that the dark line central spot / line is narrower than a classical Gaussian spot but has the same divergence, potentially resulting in greater sensitivity to the location and structure of interfering objects while maintaining a sufficient Gaussian beam volume for concentration measurements and for larger particle interactions. Dark line beams can be generated by converting conventional laser beams using optical elements (usually diffractive elements) or by specially designing the laser resonator to emit dark line beams. These laser modes are typically members of sets known as Gauss-Laguerre and Gauss-Hermitt modes.

[0012] Referring to Figure 1, Figure 1 is a schematic diagram of a chart 101 showing the intensity curve of a Gaussian beam. The horizontal axis represents the position from the center of the beam, for example, in microns or 10^(-6) meters. The vertical axis represents the beam light intensity, for example, in relative units.

[0013] In chart 101, for example, reference numeral 10 denotes the shape of a beam with a Gaussian profile, reference numeral 12 denotes the shape of the first lobe of the dark line beam, and reference numeral 12' denotes the shape of the second lobe of the dark line beam; the two lobes are 180 degrees out of phase, but because this chart shows intensity, they are not shown in chart 101. Reference numeral 14 denotes the spacing between the two lobes; because the two lobes are 180 degrees out of phase, there is a zero-energy singularity between the two lobes. Reference numeral 16 denotes the width of the beam at an intensity of e^(-2), and reference numeral 18 denotes the spacing between the peaks of the two lobes.

[0014] 1 shows a comparison of the intensity curve of a Gaussian beam 10 with that of a dark line beam generated from the Gaussian beam 10. The dark line beam has two lobes 12, 12' and a singular dark line 14 between the two lobes. The double-headed arrows indicate, respectively, (i) the maximum width of the Gaussian beam 14 is ≈2WO, as shown at 16, where WO is the waist of the Gaussian beam, and (ii) the maximum width or peak spacing between the peaks of the dark line lobes 12, 12' is ≈2WO, as shown at 18.

number

[0015] Dark line beams can be generated in a manner that maintains a sharply defined energy distribution over a wider depth of field, thus providing a better tradeoff between size and concentration when implemented in a scanning laser probe measurement technique, or TOT. Furthermore, dark line beams provide additional information not available in TOT, allowing for more accurate measurements. Several methods for achieving these configurations are contemplated and covered in the references listed in the bibliography of U.S. Patent No. 7,746,469, which are incorporated herein by reference in their entireties.

[0016] The optical setup described in U.S. Patent No. 7,746,469 includes a single forward detector. Particle size is measured by the modulation depth of the dark line for small particles and by the interaction width for large particles. The optical setup also includes a scanner. Because the scanning speed is much higher than the particle speed, the particle speed is assumed to be negligible. Therefore, particle size can be determined from the beam speed, the interaction width and modulation depth of the interaction signal, and the width of the beam.

[0017] The subject of U.S. Patent Application Publication No. 2015 / 0260628, which is incorporated herein by reference in its entirety, is a method and apparatus for measuring particle size and concentration that improves upon the method described in U.S. Patent No. 7,746,469.

[0018] Referring to Figure 2, Figure 2 is a schematic illustration of a system. Figure 2 schematically illustrates a measurement system described in U.S. Patent Application Publication No. 2015 / 0260628. The system shown in Figure 2 includes a laser 20 that generates a Gaussian beam, spherical lenses 22, 24 that collimate the beam and act as a beam expander 26, a phase mask 28 that converts the Gaussian laser beam into a structured dark line beam with a linear singularity, a beam splitter 30 that collects backscattered light, a condenser lens 32 that focuses the dark line beam into a cuvette 34 through which liquid or air containing particles 36 flows in the direction of arrow Y, and two horizontal forward detectors 38, 40 (rotated relative to the plane of the paper for clarity). Note that in the case of particles in air, the particle-carrying air flow does not necessarily need to be confined within the cuvette. Backscattered radiation from particles 36 within the focus of collecting lens 32 is collected by collecting lens 32, essentially collimated, reflected by beam splitter 30, and directed through collecting lens 42, which focuses the radiation through pinhole 44 onto backscatter detector 46.

[0019] Referring to Figure 3, a schematic diagram illustrating detector positioning is shown. Figure 3 illustrates the relative positions of detectors 38 and 40 relative to the illumination dark beam pattern. In Figure 3, the Z axis is the optical axis perpendicular to the paper, the Y direction is the particle flow direction perpendicular to the Z direction within the paper, and the X direction is also perpendicular to the Z direction within the paper. As shown, two detectors are positioned in the XY plane at different positions in the Y direction, parallel to the dark line singularity, one on each side of the dark line 14, symmetrically. Detector 38 is positioned to partially cover intensity lobe 12, and detector 40 is positioned symmetrically to partially cover intensity lobe 12' of the dark line beam. Referring to Figure 3, as particles traverse the beam from top to bottom, the output intensity pattern is altered, and the detectors detect a phase shift. Essentially, minute scattering from a small particle traversing one lobe interacts with the second lobe in a homodyne mode. This results in greater sensitivity and additional information because scattering is spatially separated before detection, rather than integrated.

[0020] The detector spacing can be optimized, modified, or configured for sensitivity by matching it to the maximum intensity gradient of the dark line beam. For various analytical purposes, the detector signals can be recorded (a) as separate signals, (b) as the differential signal of the two detector signals, or (c) as the sum of the two detector signals. By subtracting the two detector signals, common noise, such as laser noise, is removed, thereby improving the sensitivity of measurements over those made using the system of U.S. Pat. No. 7,746,469.

[0021] The detected signal is the result of the phase difference, the size dependence of which is typically r^2.5.

[0022] The signal dependence of r^2.5 is shown in the table below and in graphs 1401 and 1402 on PSL (polystyrene latex) beads in FIG. [Table 1]

[0023] The delay between the signals from the two forward detectors 38, 40 is used to derive information about the position along the optical axis Z where the particle interaction occurred. This improves accuracy because, if the position along the beam propagation direction is known, the corresponding beam profile at that position is known, leading to greater precision when determining particle size based on the interaction signal and deconvolving the beam profile. Alternatively, the delay can be used to reject particles that do not interact with the beam at the focal point. In U.S. Patent No. 7,746,469, the rejection of measurements of particles that do not pass through the focal point of the dark line beam is based on the slope of the interaction signal, which is less accurate. This requires knowledge of the particle's relative velocity. In U.S. Patent Application Publication No. 2015 / 0260628, velocity can be derived without scanning based on the transit time between the two lobes of the two detectors (e.g., the known distance between the lobes divided by the time between the signals). This typically results in lower noise and higher sensitivity than using a scanned beam.

[0024] The backscatter detector 46 detects backscatter due to particle interaction with the dark line beam through the pinhole 44. Because of the pinhole 44, detection is confocal, and only particles traveling exactly within the focus of the dark line beam are detected by the backscatter detector 46. The signal from the backscatter detector provides additional information, including information about particle size via intensity, width, and modulation, the particle's reflective properties, and fluorescence produced by the illumination beam (if an appropriate wavelength is selected), and when combined with the signals from the two forward detectors, can function as a high-resolution one-dimensional confocal scanning microscope and / or reveal information that can be used to characterize specific particles and / or classify individual particles by clustering the nature of their interaction.

[0025] Another improvement over the apparatus of U.S. Patent Application Publication No. 2015 / 0260628 is that the use of two forward detectors in the system described eliminates the need for scanning and allows measurements to be made using a stationary beam to measure particle velocity, as explained above. This is achieved by measuring the velocity of particles passing through a focal zone where the gap between the lobes is known (delay between the signals of the two detectors = 0). This is easily accomplished when the particles are small compared to the gap, but for larger particles, the gap will appear as a gradual signal ramp with a plateau midway between the rise and fall times.

[0026] One limitation of the methods described in U.S. Pat. No. 7,746,469 and U.S. Patent Application Publication No. 2015 / 0260628 is that the spot size of the illumination beam is still highly focused, resulting in a low degree of interaction with particles, and the methods are typically effective for relatively high particle concentrations. Summary of the Invention

[0027] It is therefore an object of the present invention to outline systems and methods that provide accurate particle size and concentration measurements for low-concentration contaminants in clear liquids and gases, while retaining the advantages of the above-mentioned techniques, and / or to facilitate size sensitivity down to the sub-20 nm range as required in clean liquids and air in the semiconductor and pharmaceutical industries.A further object of the present invention is to outline and describe several configurations for improved detection sensitivity down to and even below 7 nm PSL.

[0028] Further objects and advantages of the present invention will become apparent as the description proceeds.

[0029] The present invention covers various aspects for improving the performance of particle detection based on interaction with a dark line beam, including, for example, provisions and mechanisms for detection at low concentrations, provisions and mechanisms for determining or detecting or inferring more information using multiple wavelengths, provisions and mechanisms for different beam profiles, provisions and mechanisms for improved sensitivity using dual-path and multi-path detection, provisions and mechanisms for noise reduction through polarization, including provisions and mechanisms for creating delays between two polarizations or between two polarization components, provisions and mechanisms for more information due to clustering-backscattering, multicolor interactions, provisions and mechanisms for phase and amplitude separation analysis, and / or provisions and mechanisms for detection under low signal-to-noise ratios (SNRs) using pattern recognition.

[0030] In one aspect, a particle detection system is provided that includes: i) a flow cell for flowing a fluid containing particles; ii) a light source for generating a beam of electromagnetic radiation; iii) a beam shaping optical system for receiving the beam of electromagnetic radiation, the beam shaping optical system for generating an anamorphic beam and directing at least a portion of the anamorphic beam through the flow cell; iv) at least one photodetector array in optical communication with the flow cell and the light source, the light source directing the beam of electromagnetic radiation to an optical lens to generate the anamorphic beam, and at least a portion of the anamorphic beam directed through the flow cell is provided to the at least one optical detector array that measures interactions between at least a portion of the anamorphic beam and particles present in the flow cell, thereby generating a plurality of individual signals corresponding to elements of the at least one optical detector array; and v) an analyzer for generating a differential signal from the individual signals indicative of the particles.

[0031] The beam shaping optical system may include one or more cylindrical lenses. At least one photodetector array may be positioned to receive the forward-propagating electromagnetic radiation.

[0032] In one aspect, a particle detection system is provided that includes: a) a flow cell for flowing a fluid containing particles; b) a light source for generating a beam of electromagnetic radiation; c) an optical steering system in optical communication with the flow cell and the light source for directing the beam through the flow cell at least twice, wherein a particle in the flow cell interacts with a different portion of the beam on each separate path through the flow cell; d) an optical detection system for receiving the electromagnetic radiation from the flow cell onto at least one optical detector array for generating a plurality of individual signals from interaction with the beam; and e) an analyzer for generating a differential signal from the individual signals indicative of the particle.

[0033] The light steering system can direct the beam through the flow cell at least 4 times, at least 6 times, or optionally at least 8 times. The light steering system can include a half wave plate, a quarter wave plate, or both to change the polarization state of the beam.

[0034] The analyzer can analyze the differential signal in the time domain, the analyzer can count particles based on the differential signal, and the analyzer can characterize the size of the particles.

[0035] The beam of electromagnetic radiation may be a Gaussian beam, a non-Gaussian beam, a structured non-Gaussian beam, a dark line beam, or a structured dark line beam. The anamorphic beam may be a top-hat beam, a Gaussian beam, or a structured dark line beam.

[0036] The particle detection systems and methods described herein may further include at least one backscatter detector in optical communication with the flow cell. The backscatter detector may detect reflectance of the particles. The backscatter detector may detect fluorescence of the particles. The backscatter detector may be used to determine whether the particles are biological or non-biological.

[0037] The at least one photodetector array may be a segmented linear detector array. The differential signal may be generated in analog form by the particle detection system.

[0038] The particle detection systems and methods described herein may further include a processor. The differential signals may be generated by the processor. The processor may compare each output differential signal to a pre-generated library of known signals corresponding to particles to determine whether each output signal corresponds to a particle detection event or laser noise. The processor may convert each output differential signal to the frequency domain using a Fourier transform or a fast Fourier transform.

[0039] In one aspect, a method for detecting particles is provided, the method including: i) providing at least one photodetector array in optical communication with a flow cell; ii) generating one or more electromagnetic radiation beams; iii) shaping the one or more electromagnetic radiation beams using a beam shaping optical system to generate an anamorphic beam, wherein at least a portion of the anamorphic beam is directed through the flow cell and provided to the at least one photodetector array; iv) flowing a fluid through the flow cell, thereby generating an interaction between the anamorphic beam and particles present in the fluid; v) detecting an interaction between the particles in the flow cell and the anamorphic beam using the at least one photodetector array, thereby generating a detector output signal corresponding to an element of the at least one photodetector array; vi) generating a differential signal based on two or more of the detector output signals; and vii) analyzing the differential signal to detect and / or determine one or more characteristics of the particles.

[0040] In one aspect, a method for detecting particles is provided, the method including: i) providing at least one photodetector array and a flow cell for flowing particles; ii) generating at least one beam of electromagnetic radiation and directing the beam to a light steering system; iii) directing the beam using the light steering system such that the beam passes through the flow cell at least two times; iv) flowing a fluid through the flow cell, thereby generating interactions between the beam and particles in the fluid, wherein the interactions between the particles and the beam occur at different portions of the beam for each individual pass; v) directing the beam to at least one photodetector array to generate a plurality of detector signals from the interactions between the particles and the beam; vi) generating a differential signal based on the plurality of detector signals; and vii) analyzing the differential signal to detect and / or determine one or more properties of the particles.

[0041] The step of analyzing the differential signal may be performed in the time domain. The beam of electromagnetic radiation may be a Gaussian beam, a non-Gaussian beam, a structured non-Gaussian beam, a dark line beam, or a structured dark line beam. The anamorphic beam may be a top-hat beam, a Gaussian beam, a structured non-Gaussian beam, or a structured dark line beam.

[0042] The beam shaping optical system may include one or more cylindrical lenses. The at least one optical detector array may be a segmented linear detector array.

[0043] Analyzing the differential signal may include comparing the differential signal to a pre-generated library of known signals corresponding to particles to determine whether the differential signal corresponds to a particle detection event or laser noise. Analyzing the differential signal may include converting the differential signal to the frequency domain using a Fourier transform or a fast Fourier transform. Analyzing the differential signal may include characterizing the particles, for example, counting the particles, determining the size of the particles, or both.

[0044] Furthermore, additional embodiments and systems described herein may be usefully incorporated into the methods described herein.

[0045] As used herein, "anamorphic beam" refers to a beam of electromagnetic radiation characterized by having independent optical power in two or more spatial dimensions. An anamorphic beam may have different optical powers in two or more spatial dimensions. An anamorphic beam may have different independent optical powers in two spatial dimensions corresponding to the cross-sectional area of ​​a flow cell (e.g., the xy plane through which particles pass when flowing in the z direction).

[0046] "Photodetector array" refers to a group or array of individual detector elements, for example, a one- or two-dimensional array of photodetectors or photodiodes.

[0047] All the above and other features and advantages of the present invention will be further understood through the following illustrative and non-limiting description of embodiments of the invention, with reference to the accompanying drawings. [Brief explanation of the drawings]

[0048] [Figure 1] FIG. 1 shows two-dimensional intensity profiles of a Gaussian beam and a dark line beam. [Figure 2] FIG. 1 is a schematic diagram of a prior art particle monitoring system. [Figure 3]FIG. 3 is a diagram illustrating the position in the detector plane of the front detector of the system of FIG. 2 relative to an illumination dark line beam pattern. [Figure 4] 1 shows a schematic of one embodiment of a particle monitoring system of the present invention, with an elongated focal zone and collection optics projecting lobes onto a detector array, connected to a DAQ (data acquisition board or subsystem). [Figure 5] 3 shows a schematic representation of two lobes of a beam in a detector plane partially covered by a dual detector array in accordance with the present invention, where each pair in the array functions as detectors 38 and 40 in FIG. [Figure 6] FIG. 1 is a schematic diagram illustrating one embodiment of an optical setup for detecting and measuring the size and concentration of small particles on the surface of a wafer or other surface in accordance with the present invention. [Figure 7] 7A and 7B are schematic diagrams illustrating the scanning directions used in the optical setup of FIG. 6 according to the present invention; [Figure 8A] 1 is a diagram showing a schematic diagram of a light-collecting optical system having a line focus that performs a Fourier transform (FT) in the Y direction and forms an image in the X direction according to the present invention. [Figure 8B] 1 is a diagram showing a schematic diagram of a light-collecting optical system having a line focus that performs a Fourier transform (FT) in the Y direction and forms an image in the X direction according to the present invention; [Figure 8C] 1 is a diagram showing a schematic diagram of a light-collecting optical system having a line focus that performs a Fourier transform (FT) in the Y direction and forms an image in the X direction according to the present invention; [Figure 9] FIG. 1 shows a schematic diagram of a system implementing a modified setup based on the method of US Patent Application Publication No. 2015 / 0260628 with two wavelengths or multiple wavelengths, in accordance with the present invention. [Figure 10] 1A-1C are schematic diagrams illustrating single-path detection schemes and improved dual-path and multi-path detection schemes in accordance with the present invention; [Figure 11] FIG. 1 shows a labeled photograph of an exemplary embodiment of an embodiment of a dual path system in accordance with the present invention. [Figure 12] FIG. 1 is a schematic diagram illustrating a fluorescence detection scheme in accordance with the present invention. [Figure 13] FIG. 10 is a schematic diagram illustrating an approach to further enhance SNR via polarization in accordance with the present invention. [Figure 14] 1A-1C are schematic diagrams showing two graphs illustrating signal dependence according to the present invention; [Figure 15] FIG. 1 shows an example of an interaction detected in one channel according to the present invention. [Figure 16] 10A-10C are diagrams illustrating an example of a differential signal showing the difference between the upper and lower PDA elements according to the present invention. [Figure 17] FIG. 10 shows the matching pattern shapes detected by the algorithm according to the present invention. [Figure 18] FIG. 4 illustrates filter parameters according to the present invention. [Figure 19] FIG. 1 illustrates an interaction scatter plot generated in accordance with the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0049] The inventors modified the optical system of Figure 2 by specifically changing lens 32 from a spherical lens to a cylindrical lens to improve the sensitivity of the measurement to low concentrations of contaminants in transparent liquids or gases. The optical energy distribution of one embodiment of the present invention, shown schematically in Figure 5, includes a line focus with a dark singularity. Other optical designs to achieve higher levels of anamorphic beam profiles, including top-hat line distributions in the X direction, are part of this invention. The focused beam interacts with particles in the same manner as described above for the circular focus and is then projected onto the detector array, thus achieving parallel detection by multiple detector pairs of the configuration shown and described in Figure 3. Additional cylindrical focusing optics, shown schematically in Figure 4, can be used between the focal zone and the detector to match the beam profile to the detector size. This lens can be used, for example, to create an image in the X direction and a Fourier transform in the Y direction. An example of such a lens design is shown schematically in Figure 8A, with Figure 8B further illustrating the X direction imaging on a 4 mm detector and Figure 8C further illustrating the Y direction Fourier transform.

[0050] As a result, if the Z axis is the optical axis in the plane of the paper, the Y axis is the direction of particle flow perpendicular to the Z direction, and the X direction is perpendicular to the plane of the paper, as in Figures 2 and 4, the focal point of the illumination beam at the location of interaction with the particle will be very sharp in the Y direction and a relatively very thin line in the X direction, ideally with a top-hat distribution along the X direction, which is the direction of the dark line singularity (optical design to achieve a flat energy distribution in a preferred direction). Exemplary, but non-limiting, dimensions for the focal point used in a system built and tested by the inventors are a 1 micron dark line beam in the Y direction and a 120 micron top-hat in the X direction. In the particular embodiment of the system built and used by the inventors to test the method, the detector array included 32 pairs of SiPIN photodiode detector elements. Thus, for the front detector, each pair of elements formed an image of 120 / 32 ≈ 4 microns.

[0051] In the X direction, the detector sees the image of the beam, and in the exemplary embodiment described above where the detector array is 4 mm long, the 120 micron width of the focal zone is magnified to 4 mm. In the Y direction, the forward scatter detector in Figure 3 or the backscatter detector in Figure 6 (see herein below) sees the Fourier transform (far field) of the beam.

[0052] Since the particles are flowing in the Y direction and interact only with the narrow side of the beam, it is possible to broaden the focus in this direction without affecting the spatial resolution in the Y direction.

[0053] Based on the singularity and homodyne approach described in U.S. Pat. No. 7,746,469 and U.S. Patent Application Publication No. 2015 / 0260628, the 120×1 μm 2There are significant SNR and contrast challenges when trying to detect 10 to 20 nanometer particles in the focal region of a 10-nm particle. To overcome this problem in the present invention, the two forward horizontal detectors 38 and 40 shown in Figure 2 are replaced by two segmented matched linear array detectors 38* and 40* in the system shown in Figure 5.

[0054] Figure 5 symbolically illustrates the position of detector arrays 38*, 40* relative to the peak intensity regions of the dark line 14 and the two lobes 12, 12' of the dark line beam in the detector plane. Measurements are performed using signals from corresponding pairs of detector elements (e.g., 1a, 1b in Figure 5) across the dark line. In this way, parallel detection is facilitated in pairs within the array while maintaining the same spatial resolution, achieving the same SNR as long as the laser power density in the focal zone is similar to that of Figure 2. In this way, the interaction rate of the focused beam is typically increased by a factor corresponding to the number of detector pairs.

[0055] In the new invention, the backscatter detector 46 shown in FIG. 2 can be expanded to detector 46*, which can be either a single detector like the backscatter detector 46 in the prior art system, but it is advantageous to use two detectors 46*a and 46*b to measure a differential signal and thereby reduce the effects of random noise. In this embodiment of the system, the two detectors 46*a and 46*b, which can be incorporated into a system like that of FIG. 2, can be simply single detectors or dual detectors, with high sensitivity detectors such as PMTs or APDs covering the image of a line focus. Backscatter is in the dark field, so a detector array to reduce background shot noise is typically unnecessary. Nevertheless, segmented linear arrays similar to the forward detectors 38* and 40* can be considered for other advantages, such as high sensitivity continuous area or flow mapping, and / or improved detection rate and clustering, similar to forward detector arrays.

[0056] Figure 6 shows a specific embodiment where particles are located on the surface of a Si wafer. The wafer is reflective, so the detector array 58 is spatially equivalent to the forward scattering, where the beam is reflected back and passes through the particle twice. In this configuration, the detector array 58 measures the sum of the forward scattering and back scattering reflected from the wafer after passing through the particle twice. Using a line focus and a segmented linear array detector to measure the backscattered beam as described above is particularly useful for low particle concentrations because the line focus provides a larger coverage area. Typically, full wafer coverage for detecting particles 10 nm or smaller can be achieved in a few minutes, consistent with a rate of 10 to 20 wafers per hour, while achieving excellent resolution. An example embodiment involves a 0.5 mm top hat width and a 1 m / sec scanning speed of the wafer relative to the beam. This results in a detection area of ​​500 mm^2 / sec, and for a 300 mm wafer, complete coverage takes less than 3 minutes.

[0057] DAQ: A dedicated data acquisition system (DAQ) and algorithms were developed by the inventors to process the output from the detectors. The output of each photodiode is fed into one of 64 input channels of the DAQ, which includes, among other things, a low-noise preamplifier, components to provide a trigger output, a buffer, and an interface board between the two detectors of each pair to allow multiplexing of the output signals or transfer of separate events.

[0058] In one embodiment, for example, a DAQ system includes four boards, with detectors 1, 2, 3, and 4 channeled to different acquisition boards and channels 5, 6, 7, and 8 channeled to the same acquisition board. The system utilizes an algorithm for smart sequencing of detector elements and their connections to the DAQ. Typically, thresholding is performed in the DAQ, and only packets of a configurable duration before and after a threshold trigger event are transferred to a computer or processor for further processing. Because each packet is accompanied by a precise timestamp, the concentration of an event can be calculated based on the number of interactions and the known zone / volume of the interaction. This approach is effective for low concentrations, where it is unlikely that more than two of four adjacent detector pairs will encounter an interaction. This topology of the DAQ means that, for example, if a large particle passes through a detector and signals are generated by up to four sets of adjacent detector elements, the data collection is divided so that the signal from the first set of elements goes to channel 1, the signal from the second set of elements goes to channel 2, the signal from the third set of elements goes to channel 3, the signal from the fourth set of elements goes to channel 4, the signal from the fifth set of elements goes again to channel 1, the signal from the sixth set of elements goes again to channel 2, etc. In this way, information can be collected about large particles whose interactions are recorded on multiple channels with close timestamps.

[0059] The data transferred to an external processor or computer for further processing is efficient and contains only interaction information. At low concentrations, most of the time there are no interactions and no data passes the threshold to be transferred to the processor. The concentration limit is such that two particles cannot statistically pass in front of the detector at the same time, or the algorithm can detect this and ignore all measurements other than single particle detection.

[0060] At higher concentrations, an interaction signal is present most of the time, so a strategy is to transfer all data to an external processor for analysis. A relevant embodiment for detecting high concentrations is a differential preamplifier that subtracts between the two detectors of each pair. This embodiment allows for an initial threshold for the interaction signal. This is relevant when a large tail of particles is to be detected, such as in CMP applications (chemical mechanical polishing slurries). In this case, the interaction is optically filtered by the interaction strength, eliminating the interaction of a large amount of small particles.

[0061] Another advantage of differential signals is the rejection of common noise, allowing for lower threshold levels and therefore improved sensitivity to small particles.

[0062] Of course, all the advanced DAQ features mentioned above can be applied to differential signals, allowing for further processing.

[0063] The signal discrimination algorithm is capable of determining particle size, type and concentration. A description of the algorithm follows:

[0064] Pattern matching for low SNR: FIG. 15 shows an example 1501 of an interaction detected on one of the channels.

[0065] It can be seen that the positive and negative channels (positive and negative channels are readouts from two detectors in a single pair on the PDA) have a particular relative structure.

[0066] FIG. 16 shows an example differential signal 1601 that is the difference between them, for example, the difference between the upper and lower PDA elements.

[0067] The differential signal is less noisy than the two detected channels (positive and negative). To detect similar signals in lower SNR conditions, we used matched filter-based pattern recognition and performed a convolution of the differential signal with a bank of filters.

[0068] y k (t)=x(t)*h k (t) where x(t) is the differential signal, hk(t) is the specific matching filter, and yk(t) is the output. All filters hk(t) are normalized to unit energy.

[0069] Because the shape of the signal x(t) depends on the beam structure, particle size, and location of the interaction in XYZ space relative to the focus, we create a number of matching filters hk(t) that can be substituted in the future if different interactions occur.

[0070] To detect the different signals, variable delay and width of the matching filter is used, as shown in example 1701 of FIG. 17, which shows the matching pattern shape in the algorithm.

[0071] In practice, filter banks provide a non-orthogonal basis spanning the signal subspace. The main ideas are outlined in papers related to sparse signal representation. A relevant review is the publication by Alfred M. Bruckstein, David L. Donoho, and Michael Elad, "From Sparse Solutions of Systems of Equations to Sparse Modeling of Signals and Images," SIAM Review (2009) - Society for Industrial and Applied Mathematics, Volume 51, Number 1, pp. 34-81, which is incorporated herein by reference in its entirety.

[0072] The present invention may express the response of each sensor as the derivative of a Gaussian function such as:

number

[0073] Since there are two lobes interacting with each other, the total filter response h(t) is

number

[0074] Since the interaction can occur anywhere on the Z axis, the algorithm accommodates this by using a different delay parameter m and width parameter σ. To detect from an unknown Z distance, a set of filters h(t) is generated, where k represents a certain pair {m, σ}. Each filter is designed to have specific delay and width parameters for the positive and negative data channels, as described and shown in example 1801 of Figure 18, which illustrates the filter parameters.

[0075] The absolute value of each output signal yk(t) is calculated and the maximum value is compared to a threshold (which can be set, for example, by the analysis software). The filter parameters that produced the maximum response above the threshold are used as delay and width indicators. The amplitude is taken from the maximum value yk(t).

[0076] Based on the best-matching filter parameters for all interactions, a histogram is calculated or generated, such as example 1901 in FIG. 19 showing an interaction scatter plot.

[0077] The method of the present invention is suitable for measuring airborne and liquid-borne samples and has been successfully tested by the inventors in both cases. The experimental setup used electrospray to generate nanoparticles. The results are shown in the table below. [Table 2]

[0078] Some examples of applications in which the method of the present invention can be used include monitoring the quality of ultrapure water or other liquids in the pharmaceutical and semiconductor industries, and monitoring ambient air in clean rooms. Note that in the case of airborne particles, the airflow carrying the particles may (but need not) be confined within a cuvette, and the particle velocity can be determined by intrinsic interaction information, as explained above.

[0079] In addition to measuring airborne and liquid-borne particles, the systems and methods of the present invention can be used to detect and measure the size and concentration of small particles on a surface. An illustrative example of the application of the methods to such measurements can be found in the semiconductor industry, where it is very important to detect and identify the presence, concentration, and size of dust and other small particles on the surface of bare wafers or reticles used as substrates in the manufacturing process.

[0080] FIG. 6 shows a schematic diagram of one embodiment of an optical setup for detecting and measuring the size and concentration of microparticles on the surface of a wafer 54. Light emitted by a laser 20 passes through a beam isolator 48, focusing optics 50 (with or without measures to create a dark line singularity), and a beam splitter 52 before reaching the wafer 54. Light reflected from the surface of the wafer 54 is split into two parts by the beam splitter 52. The first part passes through the focusing lens 50 and is absorbed by the beam isolator 48. The second part of the reflected light passes through the focusing optics 56 and is detected by a segmented forward linear detector array 58. The optical signal from the detector includes reflected forward scattering and back scattering, as described above. FIG. 6 shows only the elements necessary to illustrate this application of the method. Not shown are the optical elements used to form the dark line beam or linear focus. The detector array 58 may include two detector arrays (dual arrays), as in FIGS. 4 and 5.

[0081] FIG. 7 shows a schematic of the scanning directions used in the optical setup of FIG. 6. The Z axis is the incident light axis, the X axis is the dark beam direction, and the Y axis is the scanning direction. The wafer 54 is placed on an XY scanning stage. An optional tip-tilt Z stage can be used to ensure that the imaged portion of the wafer is in focus. The methodology and focus feedback sensor may be implemented based on common practices as known in the motion control industry.

[0082] During the scan, the wafer 54 moves in the Y direction so that the (stationary) dark line beam 60 effectively moves over the surface of the wafer 54 in the direction of the arrow. Raster, meander, or other scanning patterns can be applied to cover the entire surface of the wafer. In practice, since the position of the array is known via closed-loop control of the scanning stage, an image or map of the contamination can be created.

[0083] The methods described in U.S. Pat. No. 7,746,469, U.S. Patent Application Publication No. 2015 / 0260628, and the present patent application can be practiced with many modifications and improvements, such as those described below.

[0084] (1) Using other beam profiles: Although the method is described using a dark line beam to interact with particles, it can be implemented using other non-Gaussian structured beams or even Gaussian beams, mutatis mutandis, using the same optical setup. When using a dark line beam, the background signal is low, and the background shot noise is correspondingly low. However, the spot size of a Gaussian beam is small for a given numerical aperture, so the interaction signal can be high in some configurations. Thus, in some cases, a better signal-to-noise ratio (SNR) can be obtained with a Gaussian beam.

[0085] Research has shown that dark line beams can be very effective by optimizing the photodiode detector, power, and spot size. The dark line beam must be large enough that the detector receives 50% of each lobe of the beam. For the dark line beam to be effective, the signal must be strong enough not to be limited by detector noise / DAQ resolution. Beam divergence requires more laser power.

[0086] Analysis of gold vs. PSL, dark line beam vs. Gaussian beam: Gold vs. PSL: The data suggest that the signal produced by PSL is mostly due to phase enhancement, while the signal produced by gold also has a strong component of obscuration.

[0087] Dark line beam vs. Gaussian beam experiment: The interaction signal with the dark line beam is 2.66 times stronger than the interaction with the Gaussian beam.

[0088] (2) Use of multiple wavelengths: Instead of using a single illumination laser as described above, an embodiment of the optical system includes two or more illumination lasers, each with a different wavelength, all of which have the same focal zone and share a portion of their measurement cross section. Therefore, by rapidly switching between them and synchronizing detection to the switching rate, it is possible not only to detect when a nanoparticle passes through the beam, but also to better characterize what type of particle it is based on additional spectral information.

[0089] Another embodiment of this multi-wavelength method and system uses a dichroic beam splitter and two detectors, allowing signals at both wavelengths to be obtained in parallel without the need to switch between lasers.The dark line beam measurement method is extended to two dark line beams with different wavelengths (λ1, λ2) directed along the same optical path and focused at the center of the cuvette, as shown in system 901 in Figure 9.

[0090] In the case of a chromatic objective, each wavelength has a different focal zone along the optical axis, thereby increasing the cross section of detection.

[0091] With an achromatic objective, it is possible to think of the particle-beam interaction as two separate interactions for the same particle, each probing the particle's refractive index at a different wavelength, improving the SNR and the ability to characterize particles based on their spectral behavior.

[0092] (3) Use of polarized light: In other embodiments of the invention, polarizing optics are included to improve the performance of the system and allow for the investigation of particle properties revealed by polarized light.

[0093] Detection through crossed polarizers allows detection of the birefringence signal from the particles while reducing background noise.

[0094] (4) Use of dual-path / multi-path detection schemes: Another embodiment of the present invention employs dual or multiple passes of the beam through the particles to improve the signal level: the same beam is redirected to interact with the same particles in the cuvette, thereby increasing the SNR.

[0095] This is illustrated in FIG. 10, which shows a single-pass setup 1001, a double-pass (or dual-pass) setup 1002, and a multi-pass (or multi-path) setup 1003, according to some embodiments of the present invention.

[0096] In the embodiment shown in FIG. 10, for example, symbol 1 indicates a laser (e.g., laser transmitter, laser generator, laser beam source), symbol 2 indicates an isolator, symbol 3 indicates a beam expander, symbol 4 indicates a mirror, symbol 5 indicates a phase mask, symbol 6 indicates a half-wave plate, symbol 7 indicates a mirror, symbol 8 indicates an objective lens, symbol 9 indicates a cuvette, symbol 10 indicates a focusing optic, symbol 11 indicates a detector, symbol 12 indicates a polarizing beam splitter, symbol 13 indicates a mirror, symbol 14 indicates a quarter-wave plate, and symbol 15 indicates a semi-transparent mirror.

[0097] A description of the improvements between single-pass, dual-pass, and multi-pass is given below.

[0098] Scatter calculation: For particles that are very small compared to the beam diameter, the signal increases each time the beam interacts with a particle.

number

[0099] For semi-transparent mirrors, t 2 +r 2 = 1 can be claimed.

[0100] Therefore, we can write signal = 2S(1 + r).

[0101] Since we know that both forward and backward scattering are expressed as 1, we can write S = S (forward scattering) + S (backward scattering).

[0102] For small particles, forward and backward scattering have similar amplitudes, so by choosing r→1, up to 8 times better SNR can be achieved in some embodiments.

[0103] Another explanation relates to the generation of standing waves as a result of the interaction of the propagating and reflected beams. This produces energy peaks and nulls along the optical axis. The peak energy is higher, providing a higher power density and a higher SNR. The peak is narrow along the optical axis Z, but this can be fully compensated for by elongating the beam in the X direction.

[0104] A labeled photograph of a representative embodiment of a dual path setup according to the present invention is shown in FIG.

[0105] (5) Fluorescence detection: In another embodiment of the present invention, fluorescence detection is possible. The concept and setup is shown in system 1201 in Figure 12 according to the present invention.

[0106] By using illumination with a shorter wavelength, e.g., 405 nm from a laser L, fluorescence is generated from living organisms, and the additional detection herein will function as a high spatial resolution flow cytometer, allowing for better clustering and separation between inorganic and organic matter.

[0107] (6) Polarization, delay, and interference detection: In the interferometric detection techniques introduced above, the signal falls off (approximately) with the third power of particle size, while the scattering signal falls off with the sixth power. By analyzing dark field instead of bright field, the SNR can be significantly improved. Furthermore, phase and amplitude can be analyzed separately by aligning the analyzer.

[0108] Another embodiment is described herein. In a dark-beam (DB) dual-path common-path interferometer system, an incident beam (pump) passes through calcite and is split into two beams, one parallel-polarized and one perpendicularly polarized, with a short time delay. The perpendicularly polarized beam (leading beam) interacts with the particle, while the other beam does not. The two beams are recombined by a second crystal, and the interference of the two beams is monitored at (or by) a detector (dark field).

[0109] Figure 13 illustrates a schematic of an approach to further enhance SNR via polarization in accordance with the present invention. System 1301 of Figure 13 illustrates a schematic of polarization enhancement to a dual-path or multi-path detection scheme in accordance with the present invention.

[0110] In Figure 13, for example, symbol 1 represents a laser, symbol 2 represents an isolator, symbol 3 represents a beam expander, symbol 4 represents a mirror, symbol 5 represents a phase mask, symbol 6 represents a half-wave plate, symbol 7 represents a mirror, symbol 8 represents a BS polarizer (for example, a beam splitter polarizer, or a polarizing beam splitter, or a combination of a beam splitter and a polarizer), symbol 9 represents a quarter-wave plate, symbol 10 represents a polarizing plate, symbol 11 represents a detector, symbol 12 represents a quarter-wave plate, symbol 13 represents a polarizing plate, symbol 14 represents calcite or calcite crystal, symbol 15 represents an objective lens, symbol 16 represents a cuvette, symbol 17 represents a focusing optical system, symbol 18 represents calcite or calcite crystal, and symbol 19 represents a mirror.

[0111] As shown in Figure 13, in a dark-beam dual-path common-path interferometer, a 45-degree polarized beam from the vertical direction passes through a calcite and splits into two orthogonally polarized beams with a short time delay (Δt). The vertically polarized beam, defined by the fast optical axis of the calcite, travels forward. At time t, a single nanoparticle, with a phase shift between the two polarizations, interacts with the beam. Both beams are recombined by a second calcite, and the interference is monitored by a detector.

[0112] Since this interferometer operates in dark field, the detection resolution is limited by photon noise. Also, since the amplitude and phase response of the scattered field are decoupled in this system, the information hidden in the phase (scattering) and amplitude (absorption) can be extracted by simply adjusting the angle between the polarizer and the quarter-wave plate.

[0113] The interferometer operates in homodyne mode, but can also operate in reflection mode (heterodyne mode), in which case only one calcite crystal is required.

[0114] Some embodiments of the present invention include an optical system for particle size and concentration analysis, the optical system including: (a) at least one laser that generates an illumination beam; (b) a focusing lens that focuses the illumination beam onto a particle moving at a known angle relative to the illumination beam through a focal region of the focusing lens; and (c) at least two forward detectors that detect interactions of the illumination beam with the particle within the focal region of the focusing lens, wherein the focusing lens is a cylindrical lens that forms a focal region that is (i) narrow in the direction of relative motion between the particle and the illumination beam and (ii) wide in a direction perpendicular to a plane defined by the optical axis of the system and the direction of relative motion between the particle and the illumination beam; and each of the two forward detectors includes two segmented linear array detectors.

[0115] In some embodiments, the system is configured to operate on reflection from a surface to detect particles on the surface.

[0116] In some embodiments, the system is configured to operate on reflection from the wafer surface to detect particles on the wafer surface.

[0117] In some embodiments, the system further includes a backscatter detector for performing backscatter detection and / or for determining the focus of the path of the particles through the cuvette.

[0118] In some embodiments, the system further includes a backscatter detector for performing color analysis of the particles.

[0119] In some embodiments, the system further comprises a backscatter detector for performing fluorescence detection that allows for distinguishing between organic and inorganic particles.

[0120] In some embodiments, the system further includes a dichroic mirror for detecting both backscatter and fluorescence.

[0121] In some embodiments, the system further comprises a particle velocity measurement unit for determining particle velocity based on the time of flight of particles passing through two peaks of the dark line beam.

[0122] In some embodiments, the system is configured to operate in a dual-pass mode that enhances detection through the superposition of two interactions of the particle with the propagating and reflected beams.

[0123] In some embodiments, the two mirrors create a cavity that allows multiple paths for the signal, thereby allowing for an enhanced signal.

[0124] In some embodiments, the system utilizes cross-polarized light to (i) remove laser background signals, (ii) benefit from particle birefringence, and (iii) enable dark-field detection.

[0125] In some embodiments, the system further includes a data acquisition subsystem for the dual array with periodicity of detection to enable detection of small and large particles.

[0126] In some embodiments, the system further comprises a pattern matching unit for performing pattern matching of (i) the synthetically generated array of potential interactions with (ii) the actual interactions, and for utilizing pattern matching to enable particle detection at lower SNR ratios.

[0127] In some embodiments, the system utilizes a dark line beam.

[0128] In some embodiments, the system utilizes a Gaussian beam.

[0129] In some embodiments, the system utilizes both a dark line beam and a Gaussian beam.

[0130] In some embodiments, the system utilizes multiple different wavelengths.

[0131] In some embodiments, the system utilizes multiple different wavelengths with a chromatic objective to enhance the interaction volume.

[0132] In some embodiments, the system utilizes multiple different wavelengths with an achromatic objective to derive more information about the particles.

[0133] In some embodiments, the system is configured as a dual-path setup including a dark-field (DB) dual-path and common-path interferometer. An incident beam (pump) passes through a calcite crystal and is split into two beams with a short delay: a parallel-polarized beam and a perpendicular-polarized beam. The perpendicular-polarized beam (leading beam) interacts with the particles, while the parallel-polarized beam does not. The two beams are recombined by a second crystal, and the interference of the two beams is monitored by a detector (dark-field layout).

[0134] The system(s) of the present invention may optionally include or be implemented utilizing suitable hardware and / or software components, such as processors, processor cores, central processing units (CPUs), digital signal processors (DSPs), GPUs, circuits, integrated circuits (ICs), controllers, memory units, registers, accumulators, storage devices, input units (e.g., touch screens, keyboards, keypads, styluses, mice, touch pads, joysticks, trackballs, microphones), output units (e.g., screens, touch screens, monitors, display units, audio speakers), acoustic sensor(s), optical sensor(s), wired or wireless modems or transceivers or transmitters or receivers, GPS receivers or GPS elements or other location-based or position-determining units or systems, network elements (e.g., routers, switches, hubs, antennas), and / or other suitable components and / or modules. The system(s) of the present invention may optionally be implemented by utilizing co-located components, remote components or modules, "cloud computing" servers or devices or storage, client / server architectures, peer-to-peer architectures, distributed architectures, and / or other suitable architectures or system or network topologies.

[0135] According to embodiments of the present invention, calculations, operations and / or decisions may be performed locally within a single device, by or between multiple devices, and may be performed both locally and partially remotely (e.g., on a remote server), optionally utilizing a communication channel to exchange raw data and / or processed data and / or processing results.

[0136] Although some of the discussion herein relates to wired links and / or wired communications for demonstration purposes, some embodiments are not limited in this respect and may utilize wired and / or wireless communications, may include one or more wired and / or wireless links, may utilize one or more components of wired and / or wireless communications, and / or may utilize one or more methods or protocols or standards of wireless communications.

[0137] Some embodiments may be implemented using a special purpose machine or device that is not a general purpose computer, or using a non-general purpose computer or machine. Such a system or device may utilize or include one or more components or units or modules that are not part of a "general purpose computer," such as a cellular transceiver, a cellular transmitter, a cellular receiver, a GPS unit, a graphics processing unit (GPU), a position determination unit, an accelerometer(s), a gyroscope(s), a device orientation detector or sensor, a device position detector or sensor, or the like.

[0138] Some embodiments may be implemented as or by using an automated method or process, or a machine-implemented method or process, or a semi-automated or partially automated method or process, or a set of steps or operations that can be performed or carried out by a computer or machine or system or other apparatus.

[0139] In some embodiments, the implementation may be using code or program code or machine-readable instructions or machine-readable code that may be stored on a non-transitory storage medium or non-transitory storage article (e.g., CD-ROM, DVD-ROM, physical memory unit, physical memory unit), which when executed by a processor or machine or computer, causes such processor or machine or computer to perform the methods or processes as described herein. Such code or instructions may be or include, for example, one or more of software, software modules, applications, programs, subroutines, instructions, instruction sets, computational code, words, values, symbols, strings, variables, source code, compiled code, interpreted code, executable code, static code, dynamic code, high-level programming languages, low-level programming languages, object-oriented programming languages, visual programming languages, compiled programming languages, interpreted programming languages, including, but not limited to, code or instructions in C, C++, C#, Java, JavaScript, SQL, Ruby on Rails, Go, Cobol, Fortran, ActionScript, AJAX, XML, JSON, Lisp, Eiffel, Verilog, hardware description languages ​​(HDL), BASIC, Visual BASIC, Matlab, Pascal, HTML, HTML5, CSS, Perl, Python, PHP, machine language, machine code, assembly language, etc.

[0140] For example, discussions herein utilizing terms such as "processing," "computing," "calculating," "determining," "establishing," "analyzing," "checking," "detecting," "measuring," etc. may refer to operation(s) and / or process(es) of a processor, computer, computing platform, computing system, or other electronic or computing device that may automatically and / or autonomously manipulate and / or transform data represented as physical (e.g., electron) quantities in registers and / or accumulators and / or memory units and / or storage units into other data, or perform other suitable operations.

[0141] As used herein, the terms "plurality" and "plurality" include, for example, "a plurality" or "two or more." For example, "a plurality of items" includes two or more items.

[0142] References to "one embodiment," "an embodiment," "demonstrative embodiment," "various embodiments," "some embodiments," and / or similar terms may indicate that the described embodiment(s) may optionally include a particular configuration, structure, or feature, but not all embodiments necessarily include the particular configuration, structure, or feature. Further, repeated use of the phrase "in one embodiment" does not necessarily, but possibly, refer to the same embodiment. Similarly, repeated use of the phrase "some embodiments" does not necessarily, but possibly, refer to the same set or group of embodiments.

[0143] As used herein, and unless otherwise specified, the use of ordinal adjectives such as "first," "second," "third," "fourth," etc., merely indicates that different instances of such similar items or objects are being referred to and is not intended to imply that the items or objects so described must be in a particular given order, whether temporally, spatially, sequentially, or in any other manner of ordering.

[0144] Some embodiments may be used in combination with one-way and / or two-way wireless communication systems, cellular radiotelephone communication systems, mobile phones, cellular phones, radiotelephones, personal communication system (PCS) devices, PDAs or handheld devices incorporating wireless communication capabilities, mobile or portable global positioning system (GPS) devices, devices incorporating GPS receivers or transceivers or chips, devices incorporating RFID elements or chips, multiple-input multiple-output (MIMO) transceivers or devices, single-input multiple-output (SIMO) transceivers or devices, multiple-input single-output (MISO) transceivers or devices, devices with one or more internal and / or external antennas, digital video broadcasting (DVB) devices or systems, multi-standard wireless devices or systems, wired or wireless handheld devices such as smartphones, wireless application protocol (WAP) devices, etc.

[0145] Some embodiments may include or be implemented by using "apps" or "applications" that may be downloaded or obtained, free of charge or for a fee, from an "app store" or "application store," or that may be pre-installed on a computing or electronic device, or that may otherwise be delivered and / or installed on such a computing or electronic device.

[0146] Any features, operations, components and / or features described herein with reference to one or more embodiments of the invention may be combined or utilized in combination with one or more other features, operations, components and / or features described herein with reference to one or more other embodiments of the invention.

[0147] Thus, the present invention may include any possible or suitable combination, rearrangement, assembly, reassembly, or other utilization of some or all of the modules or functions or components described herein, even if some or all of the modules or functions or components described herein are discussed in different places or in different sections of the above discussion, or are shown in different drawings or across multiple drawings.

[0148] While certain features of several exemplary embodiments of the invention have been illustrated and described herein, various modifications, substitutions, changes, and equivalents may occur to those skilled in the art. It is therefore intended that the claims cover all such modifications, substitutions, changes, and equivalents.

[0149] Bibliography / References: The following publications are incorporated herein by reference in their entirety, and embodiments of the present invention may optionally include or utilize any of the components, systems, methods and / or operations described in any of the following publications: [Explanation of symbols]

[0150] 20...laser, 48...beam isolator, 50...collecting lens, 52...beam splitter, 54...wafer, 56...collecting optics, 58...forward linear detector array.

Claims

1. 1. An optical system for particle detection, comprising: (a) a flow cell for causing a fluid containing particles to flow along a flow direction; (b) a light source for generating a beam of electromagnetic radiation in a direction of propagation; (c) a beam shaping optical system positioned to receive the beam of electromagnetic radiation, the beam shaping optical system for generating an anamorphic beam comprising a top-hat beam and directing at least a portion of the top-hat beam through the flow cell; (d) a first forward detector and a second forward detector configured to detect light that has interacted with one or more particles in the flow cell, respectively, the first forward detector configured to detect light from a first region of the flow cell, thereby generating a first signal, and the second forward detector configured to detect light from a second region of the flow cell located downstream of the first region along the flow direction, thereby generating a second signal; and (e) an analyzer that receives the first signal from the first forward detector and the second signal from the second forward detector, the analyzer generating a differential signal from the first signal and the second signal that is characteristic of the one or more particles; Equipped with the first forward detector and the second forward detector collectively comprise a pair of segmented linear detector arrays, and the differential signal is generated from corresponding pairs of detector elements of the segmented linear detector arrays.

2. 2. The optical system of claim 1, wherein interaction of the top-hat beam with the one or more particles produces light that is transmitted, scattered, or both along the propagation direction, and at least a portion of the light that is transmitted, scattered, or both along the propagation direction is detected by the first forward detector and the second forward detector.

3. The optical system of claim 1 , wherein the light source comprises a laser and the beam shaping optical system comprises a diffractive element for generating the anamorphic beam.

4. The optical system of claim 1 , wherein the anamorphic beams, including the top-hat beam, are characterized by different optical powers in two or more spatial dimensions.

5. The optical system of claim 1 , wherein the anamorphic beam, including the top-hat beam, is characterized by different optical powers in two spatial dimensions corresponding to cross-sectional areas of the flow cell.

6. The optical system of claim 1 , wherein the anamorphic beam passes through the flow cell once.

7. The optical system of claim 1 , wherein the anamorphic beam is directed to interact twice with the first region and the second region of the flow cell.

8. The optical system of claim 1 , wherein the anamorphic beam is directed to interact with the first region and the second region of the flow cell more than once.

9. The optical system of claim 1 , wherein the first forward detector and the second forward detector comprise one or more segmented linear detector arrays.

10. The optical system of claim 1 , wherein the differential signal is the difference between the first signal and the second signal.

11. 2. The optical system of claim 1, wherein the analyzer generates a sum signal from the first signal and the second signal characteristic of the one or more particles, the sum signal being the sum of the first signal and the second signal.

12. The optical system of claim 1 , wherein the analyzer analyzes the differential signal in the time domain.

13. The optical system of claim 1 , wherein the analyzer counts the one or more particles based on the differential signal.

14. The optical system of claim 1 , wherein the analyzer characterizes a size of the one or more particles based on the differential signal.

15. 10. The optical system of claim 1, wherein the analyzer comprises a pattern matching unit for performing pattern matching of (i) an array of synthetically generated potential interactions with (ii) the differential signal.

16. 10. The optical system of claim 1, wherein the analyzer compares the differential signal to a pre-generated library of known signals corresponding to particles to determine whether the differential signal corresponds to a particle detection event or laser noise.

17. The optical system of claim 1 , wherein the differential signal is transformed by the analyzer into the frequency domain using a Fourier transform or a fast Fourier transform.

18. 1. An optical system for particle detection, comprising: (a) a flow cell for causing a fluid containing particles to flow along a flow direction; (b) a light source for generating a beam of electromagnetic radiation in a direction of propagation; (c) a beam shaping optical system positioned to receive the beam of electromagnetic radiation, the beam shaping optical system for generating an anamorphic beam comprising a top-hat beam and directing at least a portion of the top-hat beam through the flow cell; (d) a first forward detector and a second forward detector configured to detect light that has interacted with one or more particles in the flow cell, respectively, the first forward detector configured to detect light from a first region of the flow cell, thereby generating a first signal, and the second forward detector configured to detect light from a second region of the flow cell located downstream of the first region along the flow direction, thereby generating a second signal; and (e) an analyzer that receives the first signal from the first forward detector and the second signal from the second forward detector, the analyzer generating a differential signal from the first signal and the second signal that is characteristic of the one or more particles; Equipped with the analyzer comprises a pattern matching unit for performing pattern matching of (i) an array of synthetically generated potential interactions with (ii) the differential signal; An optical system wherein the pattern matching is performed using convolution of the differential signal with a bank of variable delay and variable width matching filters according to equation (1). y ｋ (t)=x(t)*h ｋ (t)・・・(1) where x(t) is the differential signal and h ｋ (t) is the specific matching filter normalized to unit energy, and y ｋ (t) is the output signal.

19. 20. The optical system of claim 18, wherein the average sensor response is expressed by equation (2). [Equation 1] where f σ，ｍ where (t) is the average sensor response, m is the delay parameter, σ is the width parameter, t is the time parameter, and the amplitude value is ignored.

20. The anamorphic beam contains two interacting lobes, with a total filter response h σ，ｍ 20. The optical system of claim 19, wherein (t) is expressed by equation (3). [Equation 2] where each interacting lobe is assumed to be symmetric around zero, and f σ，ｍ (t) and f －σ，ｍ (t) is the average sensor response to each interacting lobe, m is the delay parameter, σ is the width parameter, and t is the time parameter.

21. 1. An optical system for particle detection, comprising: (a) a flow cell for causing a fluid containing particles to flow along a flow direction; (b) a light source for generating a beam of electromagnetic radiation in a direction of propagation; (c) a beam shaping optical system positioned to receive the beam of electromagnetic radiation, the beam shaping optical system for generating an anamorphic beam comprising a top-hat beam and directing at least a portion of the top-hat beam through the flow cell; (d) a first forward detector and a second forward detector configured to detect light that has interacted with one or more particles in the flow cell, respectively, the first forward detector configured to detect light from a first region of the flow cell, thereby generating a first signal, and the second forward detector configured to detect light from a second region of the flow cell located downstream of the first region along the flow direction, thereby generating a second signal; and (e) an analyzer that receives the first signal from the first forward detector and the second signal from the second forward detector, the analyzer generating a differential signal from the first signal and the second signal that is characteristic of the one or more particles; Equipped with the analyzer comprises a pattern matching unit for performing pattern matching of (i) an array of synthetically generated potential interactions with (ii) the differential signal; A set of matching filters h ｋ (t) is generated, where k represents a pair {mk, σk}, each filter is designed with m and σ parameters for the positive and negative data channels, and each output signal y ｋ The absolute value of (t) is calculated, the maximum output signal is compared to a threshold, and the filter parameters that produced the maximum output signal above the threshold are used as indices for m and σ, and the amplitude is the maximum value y ｋ (t) and optionally a histogram is calculated and / or generated.

22. The optical system of claim 1 , further comprising an isolator disposed between the light source and the flow cell.

23. The optical system of claim 1 , further comprising a diffractive optical element disposed between the light source and the flow cell.

24. 1. A method for detecting particles in a fluid, comprising: (a) flowing the fluid containing particles along a flow direction through a flow cell; (b) generating a beam of electromagnetic radiation from a light source in a direction of propagation; (c) generating an anamorphic beam from the beam of electromagnetic radiation, the anamorphic beam comprising a top-hat beam, and directing at least a portion of the top-hat beam through the flow cell using a beam shaping optical system; (d) detecting light that has interacted with one or more particles in the flow cell using a first forward detector and a second forward detector, wherein the first forward detector is configured to detect light from a first region of the flow cell, thereby generating a first signal, and the second forward detector is configured to detect light from a second region of the flow cell located downstream of the first region along the flow direction, thereby generating a second signal; (e) analyzing the first signal from the first forward detector and the second signal from the second forward detector to generate a differential signal characteristic of the one or more particles; Including, the first forward detector and the second forward detector collectively comprise a pair of segmented linear detector arrays, and the differential signal is generated from corresponding pairs of detector elements of the segmented linear detector arrays.

25. 25. The method of claim 24, wherein interaction of the top-hat beam with the one or more particles produces light that is transmitted, scattered, or both along the propagation direction, and at least a portion of the light that is transmitted, scattered, or both along the propagation direction is detected by the first forward detector and the second forward detector.

26. 25. The method of claim 24, wherein the differential signal is characteristic of the size of the particle.

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