Dynamic, surface displacement measurements using a proximate, radiating electric dipole

Abstract

Expressions for the optical power radiated by a vertically oriented, electric dipole are developed to understand the dependence of this power on the distance between the dipole and a nearby surface, especially when this distance is varying with time. Results of this analysis assess the conditions under which the power depends linearly on displacement amplitude when this distance has a sinusoidal, time-varying component of fixed amplitude combined with a mean dipole-to-surface distance. The variation in the radiated power with this mean distance is also examined so that comparisons can be made to experimental measurements of near-field optical signals.