Optical particle sizer for on-line monitoring of particulate emission from industrial plants

We present a low angle light scattering optical particle sizer (measuring range 1-100 micrometers ) utilizing an innovative scheme that enables the instrument to operate at extinction values as small as 10 -5 . At variance with existing systems, the illuminating beam is properly modulated so to allow a coherent detection scheme to be used. In this way optical and electronic noise can be detected and subtracted from the measured signals therefore increasing the S/N ratio.