Due to the irregular, non-spherical shape of some aerosols, the desire to incorporate angular scattering data into the standard total and backscatter data was acknowledged.
Intensive R&D has resulted in the latest advancement of the nephelometer into a commercially available polar nephelometer.
The backscatter shutter can be set to any angle between 10 through to 90° at up to 17 different positions. When the backscatter shutter is positioned at a specific angle the nephelometer measures the light scattering from that angle through to 170°.
For example, a scattering angle set to 20° will measure all scattering between 20° to 170°. A scattering angle set to 30° will measure all scattering between 30° to 170°. Thus the difference between these two angles will give the light scattering for the polar segment of 20° to 30°.
Each measurement cycle also includes a measurement without the backscatter active or a 0° angle measurement.
This is the first commercially available instrument of its type and is receiving a great deal of attention from researchers who recognise its potential for studying the light scattering effects of aerosols and in its ability to improve the derivation of the aerosol asymmetry parameter (g). Analysing smaller angles will also offer a greater understanding of the particle size.