A REAL-TIME MONITORING-SYSTEM FOR AIRBORNE PARTICLE-SHAPE AND SIZE ANALYSIS

This paper describes a new instrument for the study of airborne partic les. The instrument performs a rapid analysis of the transient spatial intensity distribution of laser light scattered by individual aerosol particles drawn from an ambient environment and uses this to characte rize the particles in terms of both size and shape parameters. Analyse s are carried out at peak particle throughput rates of up to 10,000 pa rticles per second, and semiquantitative data relating to the size and shape (or more correctly asymmetry) spectra of the sampled particles are provided to the user via a graphical display which is refreshed or updated at 5-s intervals, In addition to the real-time display of dat a, continuous data recording allows subsequent replay of measurements at either normal or high speed. Preliminary experimental results are g iven for aerosols of both spherical and nonspherical particle types, a nd these suggest the instrument may find use in environmental monitori ng of aerosols or clouds where some real-time semiquantitative assessm ent of particulate size and shape spectra may be desirable as an aid t o characterizing the aerosol and its constituent particulate species.