Patent ID: 7554663

Claim:
A detector system, comprising: an emitter configured to emit excitation energy into a region of space such that a particle located within said region of space may be exposed to the excitation energy; a detector having a detector input; a changeable filter apparatus including: a first filter disposed in front of a first portion of the detector input; a second filter disposed in front of a second portion of the detector input; and a means for changing a characteristic of the filter apparatus in response to a particle measurement; one or more optical elements being configured such that (a) when the particle is located at a first position within said region and exposed to the excitation energy and produces a first emission, at least a portion of the first emission is directed by the one or more optical elements so that said portion of the first emission passes through the first filter prior to reaching the detector input but substantially no portion of the first emission passes though the second filter, and (b) when the particle is located at a second position within said region and exposed to the excitation energy and produces a second emission, at least a portion of the second emission is directed by the one or more optical elements such that said portion of the second emission passes through the second filter prior to reaching the detector input but not the first filter; and a data processor configured to determine whether the particle is a non-biological particle based, at least in part, on the emissions produced as a result of the particle being exposed to the excitation energy.