  We investigate the optical properties of periodic composites containing
metamaterial inclusions in a normal material matrix. We consider the case where
these inclusions have sharp corners, and following Hetherington and Thorpe, use
analytic results to argue that it is then possible to deduce the shape of the
corner (its included angle) by measurements of the absorptance of such
composites when the scale size of the inclusions and period cell is much finer
than the wavelength. These analytic arguments are supported by highly accurate
numerical results for the effective permittivity function of such composites as
a function of the permittivity ratio of inclusions to matrix. The results show
that this function has a continuous spectral component with limits independent
of the area fraction of inclusions, and with the same limits for both square
and staggered square arrays.

Optics;Materials Science;Analysis of PDEs