The invention provides methods and devices for detecting, identifying,
classifying and characterizing particles in a fluid sample. Optical
analyzers are provided having a rotating and/or translating sample
container for measuring the concentrations of fluorescent particles
present in very low concentrations and for characterizing fluorescent
particles on the basis of size, shape, diffusion constant and/or
composition. Scanning optical analyzers are provided using pattern
recognitions data analysis techniques and multichannel detection.