Evaluation of the Forward Scattering Spectrometer Probe. Part III: Time Response and Laser Inhomogeneity Limitations

Abstract
The electronic response time of the Forward Scattering Spectrometer Probe (FSSP) has been evaluated and is shown to affect the measurement of droplet size. The size of droplets are underestimated when airspeeds exceed 50 m s−1 and size distributions are broadened as a result of nonuniformities in the laser beam of the probe. A processing scheme that requires a detailed knowledge of a probe's optical and electronic characteristics is described that compensates for the measurement errors caused by the probe's electronic and optical limitations. Abstract The electronic response time of the Forward Scattering Spectrometer Probe (FSSP) has been evaluated and is shown to affect the measurement of droplet size. The size of droplets are underestimated when airspeeds exceed 50 m s−1 and size distributions are broadened as a result of nonuniformities in the laser beam of the probe. A processing scheme that requires a detailed knowledge of a probe's optical and electronic characteristics is described that compensates for the measurement errors caused by the probe's electronic and optical limitations.