Particle characterization with laboratory nephelometers

In this chapter, we explain the basics of light scattering experimental setups devoted to measuring one or more elements of the scattering matrix as functions of the scattering angle for irregular dust particles. We focus on those apparatus based on the modulation of incoming light. Experimental setups are described for measuring samples of particles comparable in size to the wavelength or much larger. Some practical issues are addressed with hands-on recipes on how to test the performance of the apparatus, how to extrapolate the scattering matrix to angles at which measurements are not possible, and how to average measurements over orientations. Hardware solutions for expanding the angular range of measurements are presented as well.