CALIBRATION OF THE FORWARD-SCATTERING SPECTROMETER PROBE - MODELING SCATTERING FROM A MULTIMODE LASER-BEAM

Scattering calculations using a more detailed model of the multimode l aser beam in the forward-scattering spectrometer probe (FSSP) were car ried out by using a recently developed extension to Mie scattering the ory. From this model, new calibration curves for the FSSP were calcula ted. The difference between the old calibration curves and the new one s is small for droplet diameters less than 10 mum, but the difference increases to approximately 10% at diameters of 50 mum. When using glas s beads to calibrate the FSSP. calibration errors can be minimized, by using glass beads of many different diameters, over the entire range of the FSSP. If the FSSP is calibrated using one-diameter glass beads, then the new formalism is necessary to extrapolate the calibration ov er the entire range.