Abstract: A method for measurement of the size distribution of particles suspended in a gas or in a liquid. The particle suspension is illuminated by a collimated beam of substantially white light. Part of the light scattered by the particles is collected by a lens and is passed through a slit placed in the focal plane of the lens. The light transmitted by the slit is made to pass through a dispersive element which causes spectral decomposition of the processed light in a direction perpendicular to the slit. A spatial filter is placed in the exit plane of the dispersive element; the transmittance of this filter is a function of position on the filter. The light transmitted by the filter is measured by a photodetector. The photodetector output is measured as different spatial filters are switched in place. A computer, microprocessor, or analog device acts on the measured values and produces the particle size distribution as an output.

Abstract: A method for measurement of the size distribution of particles suspended in a gas or in a liquid. The particle suspension is illuminated by a collimated beam of nearly monochromatic light. Part of the light scattered by the particles is collected by a lens and is passed through a spatial filter placed in the focal plane of the lens. The light transmitted by the filter is measured by a photodetector. The photodetector output is measured as different spatial filters are switched in place. A computer, microprocessor, or analog device acts on the measured values and produces the particle size distribution as an output. The data reduction algorithm consists of a linear transformation of the measured data vector, followed by the construction of a linear combination of basis functions for the size distribution. The spatial filters consist of transparencies with non-uniform transmittance functions.

Abstract: A method for measurement of the size distribution of particles suspended in a gas or in a liquid. The particle suspension is illuminated by a collimated beam of colored light, which is produced by passing a collimated beam of substantially white light through a spectral filter which has spatial sections of narrow spectral passband in the blue, green and red. Part of the light scattered by the particles is collected by a lens and is passed through a spatial filter placed in the focal plane of the lens. The light transmitted by the filter is measured by a photodetector. The photodetector output is measured as different spatial filters are switched in place. A computer, microprocessor, or analog device acts on the measured values and produces the particle size distribution as an output. The data reduction algorithm consists of a linear transformation of the measured data vector, followed by the construction of a linear combination of basis functions for the size distribution.