Optimization of response functions of light scattering instruments for size evaluation of aerosol particles

Response functions of light scattering instruments for size evaluation of aerosol particles depend on the polarization and wavelength distribution of the radiation illuminating the particles, size, and shape of the illumination and collection aperture, spectral transmission of the radiation through the instrument, spectral sensitivity of the photodetector, and the optical properties of the particle material. Analytical expressions of response functions as a function of all these parameters are derived, and satisfactory agreement between theoretical and experimental response functions was obtained. Extensive calculations of response functions show that diameter distributions of airborne particles of unknown optical properties can be evaluated with great accuracy by low angle scattering of polychromatic radiation of continuous wavelength distribution.