Back-scatter by dielectric spheres (Refractive index approx 1.6

This is the authors' abstract. We don't add key points for this paper.

Two independent sets of experimental results are presented on the back-scatter from plexiglass spheres. These are compared with theoretical computations for refractive indices m = 1.60, 1.61 and 1.61-0.0025i. Forα(ratio of perimeter to wavelength)≤ 7.5, the upper limit of the experimental data, the theoretical values are practically identical to one another and agreement with experiment is excellent. Forα >7.5, the theoretical values diverge from one another. The small absorption coefficient has an increasingly important effect as the spheres grow larger, but even atα 100, the cross section remains above its asymptotic value. Except for the interval30< α <40, plexiglass spheres have larger cross sections than metal ones between6 < α < 60. This is due to the focusing action of the dielectric sphere and the back surface reflection.