Method and apparatus for particle measurement employing optical imaging
US7379577B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 10, 2004 |
| Grant date | May 27, 2008 |
| Priority date | — |
| Expiry date | Dec 5, 2026 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N15/0227
- WIPO fieldMeasurement
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.