Optical Particle Counters are tools widely used by the aerosol science community to provide particle concentration data and frequently size distributions too. These instruments function by delivering a sample airflow through a laser beam and then detecting pulses of scattered light which are interpreted as individual particles. Correct design of the the airflow system can ensure that the particles pass through the beam in single file and that particle coincidences in the beam are minimal. Additionally, the magnitude of the scattered light signal is used to derive optical equivalent size of the particle.

The spatial distribution of light scattered by a particle, often called the scattering profile, is a function of size, shape and orientation of the particle as well the wavelength and polarisation state of the incident light. So by using a laser source with fixed wavelength and polarisation and then carefully controlling the particle orientation, particle size and shape can be characterised.

ASAS Technology was originally an invention from our partner - The University of Hertfordshire. The technology was then further developed and commercialised by Biral in conjunction with Porton Labs (UK Ministry of Defence) for use in military and civil defence biodetection. In fact, Biral’s ASAS devices are in current operation by the British Armed Forces.