Combinations of interferometry and optical microscopy has allowed the enhancement of the reflectivity of STOM dielectric prism right angle faces. The set-up consisted of the prism and two mirrors, one of which is semi-transparent. A theoretical model is used to understand the mechanisms presiding at resonance or at anti-resonance, and then to tip-surface coupling using the set-up. A resonant configuration is first located by simulating the moving of the semi-transparent mirror. Different kinds of tips are then classified according to the effects of the perturbation of the resonant state of each tip. One such effect is the broadening of the resonant peak, and the other is the shifting of the position of the resonant peak.