label any fluorescence target species present in the sample a first light source 3 emits a first pulse of light at wavelength u03bb 1 which reflects off of optical filter 4 into the optical excitation zone 2 any fluorescently tagged particles in the excitation zone 2 will then emit light at a fluorescence emission wavelength u03bb 2 which passes through the optical filter 4 to the digital camera 6 the optical filter 4 permits only a narrow band of wavelengths at or near the fluorescent wavelength u03bb 2 to pass to the digital camera 6 a magnification system 7 is provided for forming a clearer image on the pixel array of the camera 6 the number intensity and location of pixels which detect fluorescent signals are recorded by system software at alternating periods of time a second light source 8 emits a second pulse of light at wavelength u03bb 2 i e within the bandpass of the optical filter 4 but outside the range of wavelengths that will induce fluorescence from the particles as a result any particle having adequate contrast will produce an image on the pixel array in the digital camera 6 during continuous work the pulsing light sources 3 and 8 are synchronized with the digital camera 6 the number intensity and location of pixels which detect signals are also recorded by the system software in computerized control 10 each of the images is measured with respect to several parameters e g area maximum dimension minimum dimension perimeter length circularity average contrast contrast variation sphericity aspect ratio perimeter heywood diameter smallest circle enclosing the particle feret diameter convex perimeter roughness and fractal dimension at least four parameters are measured however six eight ten even sixteen different parameters can be measured since a larger number of parameters.