Laser Induced Fluorescence (LIF) could permit fast early warning systems either for point or stand-off detection if a reliable classification of warfare biological agents versus biological or non-biological fluorescing background can be achieved. In order to improve LIF discrimination capability, a new system is described in which the fluorescence pattern is enriched by the use of multiple wavelength delayed excitation while usual spectral fluorescence analysis is extended to time domain to use both aspects as criteria for classification. General considerations and guidelines for the system design are given as well as results showing good discrimination between background and simulants.
Optical chamber for aerosol particle fluorescence measurements is designed. With the designed chamber, UV-induced fluorescent spectrum of single particles can be measured. The design includes two-nozzle flow system, with sheath air flow and virtual impactor concentrator integrated into the chamber. The operation of the flow system was verified with computational fluid dynamics (CFD). The chamber is intended to be used with pulsed UV-laser source, and it includes triggering of the laser pulse to hit individual particles.