Fig. 6.

(a) Incidence angle ($\theta$) versus beam displacement in mm averaging data from six experiments using airborne illumination or fiber optic illumination. (b) Penetration depth of the evanescent field calculated using Eq. (3) and the incidence angle measured in A. Parameters used in Eq. (3) are: $\lambda =514.5\mathrm{nm}$, $n_g=1.516$, and $n_w=1.334$.