Method and apparatus for particle analysis

An aerosol spectrometer combines the features of forced motion instruments and optical particle sizers. The motion of suspended particles in multiple force fields is used to obtain density, diameter, electrical charge, magnetic moment and other physical attributes of individual particles. Measurements are possible without the need for precision size standards. Optical scattering parameters are also extracted, namely scattering magnitude and visibility. This allows calibration of the optical sizer based on independently measured size parameters also without the need for precision standards. Since the optical counter is extremely rapid, it is possible to apply feedback control to the application of force on the particles and to the sample dispensing apparatus as well. Because of the large amount of information extracted from single particle events, and because of the speed with which the measurements are made it is possible to characterize the distribution of particle attributes in an ensemble of particles such as a naturally occurring aerosol or a dispersed powder sample.