  Dispersion is an important factor of optical materials. Due to the effect of
techniques and equipment in the manufacturing process of optical materials, the
inhomogeneity of the material may be caused. In this paper, microsphere optical
media are used to replace the inhomogeneous zones, and Huygens'principle is
used to study the dispersion caused by the material inhomogeneity. First, we
study the effect of a single inhomogeneous zone, and then the effect of a thin
medium with a large number of inhomogeneous zones. It is deduced that the
dispersion law of a macro-optical medium is also consistent with Cauchy
formula. Finally, it is pointed out that Huygens'principle is suitable for
studying the interaction between light and particles.
