Optical patternation: A technique for three-dimensional aerosol diagnostics

A novel technique based on optical patternation is described for three-dime nsional diagnostic studies of aerosols used in analytical spectroscopies. T he aerosol is illuminated with a thin laser light sheet to capture images o f the fluorescence and Lorenz-Mie light-scattering signals from the aerosol field with a charge-coupled detector. These measurements allow for the rap id and nonintrusive elucidation of two-dimensional spray structures, planar mass distributions, and spatial droplet size distributions. The ratio of t he fluorescence image to the Lorenz-Mie image is then utilized to construct a spatially resolved map of the volume-to-surface area mean of the aerosol (Sauter mean diameter). Three-dimensional maps of spray structure, mass di stribution, and droplet size distribution are obtained for the entire aeros ol held by image stacking, The technique is applied to the measurement of t he droplet size over the aerosol field at distances of 5-30 mm from the neb ulizer tip where droplet sizes ranged from 6 to 12 mu m for a direct inject ion high efficiency nebulizer used in inductively coupled plasma spectromet ries.