Particle measurement systems and methods

Abstract

A method according to one embodiment includes generating light fringes using a light source; directing a particle through the light fringes; detecting light scattered by the particle as the particle passes through the light fringes using at least one light detector; and determining at least one property of the particle. A system according to one embodiment includes a light source for generating light fringes; a sampling mechanism for directing particles through the light fringes; and at least one light detector for detecting light scattered by each of the particles as the particles pass through the light fringes

Description

FIELD OF THE INVENTIONThe present invention relates to particle measurement, and more particularly to systems and methods for more efficient particle measurement.BACKGROUNDProperties of small particles, such as size, density and fluorescence, are critical for many applications, but the small size makes measurement difficult. A potentially lethal anthrax spore, for example, has a diameter of one thousandth of a millimeter, a mass of one trillionth of a gram, and is completely invisible to the naked eye. Nonetheless, if anthrax spores were to suddenly appear in a subway it is clearly important to rapidly and accurately detect them. This is a significant challenge. Different applications have different requirements, but the more information an instrument can provide about the particles, the better. Similarly, the speed and accuracy of virtually any such instrument should be maximized while the size, cost and complexity are kept to a minimum. It would thus be desirable to provide a syst...

AI Technical Summary

Benefits of technology

The patent describes a system and method for detecting particles as they pass through light fringes. The system includes a light source, a sampling mechanism, and a light detector. The light source generates light fringes, which the sampling mechanism directs particles through. The light detector detects the light scattered by the particles as they pass through the light fringes. The system can determine properties of the particles by analyzing the light scattered. The technical effect of this invention is a more precise and accurate method for detecting particles and analyzing their properties.

Problems solved by technology

Properties of small particles, such as size, density and fluorescence, are critical for many applications, but the small size makes measurement difficult.

This is a significant challenge.

As the mean spacing between particles becomes comparable to the spacing between lasers, however, the system becomes increasingly confused by coincident particles, crossing particles and related phenomena.

Unfortunately, high particle loads must be dealt with in many applications.

To handle such loads the lasers can be moved closer together (reducing sizing accuracy) or more lasers can be used (increasing cost).

The BioAerosol Mass Spectrometry (BAMS) system developed at LLNL uses six lasers to achieve both high accuracy and a high analysis rate, but the system is complex and expensive.

Optical techniques include measuring the total amount of light scattered from a particle, the spatial pattern of scattered light and other scattered light properties, but very few techniques measure both sizes simultaneously.

At least a few instruments, such as the APS, ATOFMS and BAMS, are in theory capable of making such measurements, but generally in these instruments the physical size measurement is rather inaccurate being based upon the total amount of light scattered from a particle in a laser beam.

The fluorescence signal produced and detected is very weak and accurate quantification is a challenge.

General Dynamic's Biological Agent Warning System (BAWS) uses a randomly-fired, pulsed laser to deposit more energy into a particle, which does produce more fluorescence, but cost is increased.

The BAMS system uses an even more powerful pulsed laser triggered by a separate tracking system and carefully designed optics to collect as much fluorescence as possible, but the result is a very expensive system.

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