Patent ID: 9360410
Filing Date: 2016-06-07
CPC Classification: G01N

Claim Text:
1. A method comprising: holding a liquid sample in the sample cell a particle analyzer, the liquid sample including (1) particles of a lower size range that are resolvable by dark-field imaging, (2) particles of an intermediate size range that are resolvable by dark-field imaging and by bright-field imaging, and (3) particles of an upper size range that are resolvable by bright-field imaging, the particle analyzer including the sample cell, a dark-field light source, a bright-field light source, an imaging system and a processing system; illuminating the liquid sample in the sample cell with the dark-field light source in a dark-field geometry to produce a scattered light; detecting the scattered light with the imaging system to capture a dark-field image frame in which the particles of the lower size range and the particles of the intermediate size range are resolved; analyzing the dark-field image frame with the analysis module of the processing system to locate images of the particles of the lower size range and the particles of the intermediate size range; analyzing the images of the particles of the lower size range and the particles of the intermediate size range from the dark-field image frame with the analysis module of the processing system to determine relative sizes of the particles of the lower size range and the particles of the intermediate size range; illuminating the liquid sample in the sample cell with the bright-field light source in a bright-field geometry to produce a transmitted light; detecting the transmitted light with the imaging system to capture a bright-field image frame in which the particles of the intermediate size range and the particles of the upper size range are resolved; analyzing the bright-field image frame with the analysis module of the processing system to locate images of the particles of the intermediate size range and the particles of the upper size range; analyzing the images of the particles of the intermediate size range and the particles of the upper size range from the bright-field image frame with the analysis module of the processing system to determine absolute sizes of the particles of the intermediate size range and the particles of the upper size range; comparing the dark-field image frame and the bright field image frame with the processing system to identify corresponding images of the particles of the intermediate size range located in both the dark-field image frame and the bright-field image frame; comparing the relative sizes and the absolute sizes of the particles of the intermediate size range that were determined by analyzing the corresponding images with the analysis module to determine a calibration curve; applying the calibration curve to the relative sizes of the particles of the lower size range with the analysis module to determine calibrated sizes of the particles of the lower size range; and determining the particle size distribution of the liquid sample from the calibrated sizes of the particles of the lower size range, and the absolute sizes of the particles of the intermediate size range and the particles of the upper size range with the processing system.