Wideband Integrated Bioaerosol Sensor (WIBS-4A) - Droplet Measurement Technologies. Dectection of Fluorescent Biological Aerosol Particle (FBAP) number concentrations. Single particle analysis using dual wavelength (280nm and 370nm by xenon lamps) excitation on two parallel broadband visible-wavelength detectors (310-400nm and 420-650nm). Particles are classified by a combination of fluorescence excitation and emission characteristics, as well as their optical size measured by forward-scattering using a 635nm continuous-wave diode laser.