DISCRETE-DIPOLE-APPROXIMATION-BASED LIGHT-SCATTERING CALCULATIONS FORPARTICLES WITH A REAL REFRACTIVE-INDEX SMALLER THAN UNITY

To assess the efficiency and accuracy of light-scattering calculations based on the discrete dipole approximation (DDA) for particles with a real relative refractive index smaller than unity, differential scatt ering cross sections and scattering efficiency factors were calculated for spherical particles. We performed the calculations for oxide part icles and voids embedded in glass and silicon, using the exact scatter ing theory (Mie scattering) and the DDA. A comparison of the results s hows that the DDA is applicable in the above refractive-index regime, and the conditions under which DDA-based calculations can provide scat tering data with good accuracy are discussed. (C) 1996 Optical Society of America