Brownian motion correction method for particle measurement
Inventors
BANDO, Kazuna • Kondo, Kaoru • TABUCHI, Takuya • KONDO, Sota
Assignees
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Publication Number
US-12625048-B2
Publication Date
2026-05-12
Expiration Date
Abstract
A flow passage is irradiated with irradiation light, and light scattered from a particle contained in a sample passing through a detection region that is formed in a prescribed section is condensed at a position obtained by extending the prescribed section in a flow direction of the sample and captured at a prescribed frame rate. Then movement amount of the particle due to Brownian motion in directions perpendicular to the flow direction on the basis of captured plural frame images. Furthermore, a particle size of the particle is determined by correcting the movement amount using correction values that were obtained in advance corresponding to each of defocus positions for correcting errors of movement amount in the images caused by magnification.
Core Innovation
A particle measuring method irradiates a sample flowing through a flow passage with irradiation light, and condenses light scattered from a particle contained in the sample in a detection region formed in a prescribed section of the flow passage by irradiation with the irradiation light. The condensing is performed at a position obtained by extending the prescribed section in the flow direction of the sample, and a camera captures the condensed scattered light at a prescribed frame rate.
The method calculates a movement amount of the particle due to Brownian motion in two-dimensional directions on a basis of captured plural frame images, and determines a particle size based on the movement amount. A magnification error that occurs due to defocusing during condensing of the scattered light is corrected by correcting the calculated movement amount.
The correction uses correction values obtained in advance corresponding to defocus positions of the frame images. The correction is performed using a correction map that stores correction values corresponding to respective positions on a light receiving surface of the camera, and the correction values are obtained by optical simulation software that calculates magnification errors for predetermined object heights at different defocus positions in the flow direction.
Claims Coverage
The partial content includes two independent claims that cover a particle measuring method and a correction method for a particle measuring device. Across the independent claims, the inventive coverage centers on Brownian-motion-based particle sizing from 2D movement in a flow passage, with defocus-related magnification-error correction using precomputed correction values provided via a correction map and obtained by optical simulation.
Two-dimensional Brownian-motion particle sizing from condensed scattered light
The method irradiates a sample flowing through a flow passage, condenses light scattered from a particle in a detection region at a downstream position, captures condensed scattered light at a prescribed frame rate, calculates a particle movement amount due to Brownian motion in two-dimensional directions from plural frame images, and determines particle size based on the calculated movement amount.
Defocus-dependent magnification-error correction using precomputed correction values and a correction map
The method corrects the calculated movement amount using correction values obtained in advance corresponding to each defocus position of captured frame images to correct for a magnification error due to defocusing at condensing.
Optical-simulation-derived correction values indexed on the camera light receiving surface
The correcting uses a correction map that stores correction values corresponding to respective positions on the light receiving surface of the camera, where the correction values are obtained by optical simulation software that calculates magnification errors for predetermined object heights at different defocus positions in the flow direction.
Correction method for movement amount prior to particle-size determination
The correction method includes correcting the movement amount using correction values to correct for a magnification error that occurs due to defocusing at condensing of scattered light, with correction values obtained in advance corresponding to each defocus position of captured frame images, then determining particle size based on the corrected movement amount.
Overall, the independent claims require capturing condensed scattered light in a flow passage, computing 2D Brownian-motion movement from multiple frames at a prescribed frame rate, determining particle size from the corrected movement amount, and correcting defocus-induced magnification errors using precomputed correction values delivered through a correction map tied to camera light-receiving surface positions, where the correction values are obtained by optical simulation for predetermined object heights at different defocus positions.
Stated Advantages
Improves particle size accuracy by correcting for magnification error caused by defocusing during condensing of the scattered light.
Documented Applications
Measuring and determining particle size for a particle measuring device by outputting the determination result to one of a display screen, a printer, a storage unit, and a network.
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