Abstract: A system and method for measuring small particles suspended in a fluid are disclosed. The system employs optical imaging using diffraction enlargement. A sample of small particles illuminated by a light source is imaged onto a pixel array of detector elements using an imaging optical system having a reduced magnification not sufficient for forming a large enough image of a smallest particle of interest. A low-aperture imaging optics with NA<0.05 is used to add diffraction enlargement to the image corresponding to at least 5 pixels to enable accurate measurement of images of smallest particles of interest, and to increase an optical sampling volume. Suitably programmed processor is used for determining at least a pixel count for each of the diffraction-enlarged images, and for generating a number, size or distribution of particles accounting for pre-determined diffraction enlargement of particle images of different sizes. The method enables analysis of large samples of small particles in one measurement.

Abstract: A particle imaging system and a method provided for analyzing particles in a fluid; the system comprising a means for capturing image data of the fluid within a sample cell, and a means for flow control, a valve and a pump, wherein the fluid within the sample cell is periodically stopped, or slowed down, for image capturing and moved rapidly between image capturing events. Advantageously, the present invention allows to increase exposure times, which is particularly significant for fluorescent imaging at low illumination levels.

Abstract: The present invention relates to the automatic analysis and identification of different species of particles in a liquid sample using both fluorescent tagging and magnification techniques. A light source at a first wavelength is used to induce the tagged particles to emit light at a second wavelength, while the image thereof is captured on a pixel array of a digital camera. A second camera can be used to capture an image of the particles illuminated at the first wavelength, which is separated from the second wavelength by an optical filter. Alternatively, a second light source emitting pulses of light at the second wavelength, which alternate with the first light source.

Abstract: The present invention relates to a method for determining a distribution of a parameter, e.g. cross-sectional area, of a particle population for identifying specific types of particles therein. A plurality of images of the particles are detected on a pixel array and a number of pixels in the form of a pixel count is determined for each of the plurality of images of particles. Weighting factors, e.g. a probability which relate values of the parameter to different pixel counts are used to determine the distribution for the parameter of the particle population. The method depends on the facts that the total population to be analyzed contains many particles and is uniformly distributed, over many frames, throughout the optical sampling volume, and that even when substantial uncertainty exists on the parameter value corresponding any individual image, the statistical information which is obtained from many images may be used to provide accurate distributions.