Patent ID: 7072038

Claim:
A method for identifying unknown particles that are present in a fluid that lies in a containing device that has transparent walls, which includes interrogating particles by directing a light beam ( 104 ) of small width ( 106 ) through the fluid and detecting scattered light by a plurality of detectors ( 112 ) as a result of a single event, which is when a single particle passes through a detect zone ( 114 ) that lies along said beam, and recording the outputs of said detectors for a single event to produce an eventvector, which includes producing multiple ones of said events for particles that are of a known first species to produce multiple ones of said eventvectors for that known first species, producing an event for an unknown particle of an unknown species to produce an eventvector for the unknown particle, and comparing the multiple eventvectors for said known first species to said eventvector for the unknown species to determine whether the unknown particle is of said known first species, characterized by: said step of directing the light beam includes directing the light beam through locations in said fluid that are not in said detection zone, so light is scattered by particles passing through locations in said fluid that lie along said light beam, that are not in said detect zone; said step of detecting scattered light by a plurality of detectors, includes detecting, by each of said detectors, only light that is scattered from said detect zone but not light that is scattered from locations along said light beam that lie in said fluid but that are outside said detect zone, where said detect zone is spaced from said walls of said container device by more than said beam width ( 106 ).