Figure 5.

Intensity of fluorescence emitted by a dipole oriented normal to the film-coated surface in the supercritical band of the BFP, for several different film thicknesses h. Each lower panel is a magnified view of the portion of the BFP indicated in the uppermost panel. These computer-generated images are based on the methods of Axelrod (8) and the following parameters are assumed: dipole oriented normal to the interface, positioned at z = 0, with NA = 1.49; n₁ = 1.33; n₂ = 1.42; n₃ = 1.52. The increasing number of sharp emission peaks in the supercritical zone with increasing h is analogous to the sharp resonances in intensity that are predicted for TIR excitation as a function of film thickness (8).