Amplitude and phase of light scattered by micro-scale aggregates of dielectric spheres: Comparison between theory and microwave analogy experiments

Light scattering is a useful diagnostic tool for characterization of particles. Direct scattering measurements for arbitrarily shaped micro-scale particles is difficult due to small-scale limitations. Microwave analogy is a convenient approach to realize such measurements as it enables realization of analogous experiments with larger model particles in a spectral domain where wavelengths are on centimeter scale. In the present study a test model analogous to light scattering by a micro-scale aggregate of dielectric spheres was constructed and experimentally characterized in the microwave regime. Measured amplitude and phase of the scattered field were compared with theoretical predictions obtained from quasi-exact multiple-scattering T-matrix method and discrete dipole approximation (DDA). Excellent agreement demonstrates the validities of both the experiment and the models.