Laser Detection and Mapping of Biological Simulants III. Dichotomous Sampler Measurements of Aerosol Concentrations as Related to Lidar Signals

Abstract : In a continuing series of investigations on biological aerosol detection by the Laser Cloud Mapper (LCM), reliable measurement of biological aerosol concentrations were found to be critical to LCM data interpretations. The sampling method must give reproducible results under difficult field conditions of rapidly changing environmental parameters. A series of trials were conducted to evaluate the Dichotomous Sampler (DS) as a device for the sampling of biological aerosols and to assess its potential for the estimation of biological aerosol concentrations during LCM trials. Sampled biological aerosols were enumerated as viable cells and provided reliable estimates of viable aerosol concentrations with respect to time. Interpretation of DS and LCM data demonstrated a relationship between cell concentrations and depolarization signal ratios which suggests that this technique has potential for remote biological aerosol detection at the 200-400 viable spores/liter level. Keywords: Laser; LIDAR; Biological aerosol; BW Simulant; Dichotomous sampler; Concentration measurement; Depolarization.