where
:<math>\Gamma_{\|} = \frac{ \eta_2(\mathbf{ \hat{k}'' \cdot \hat{n} }) - \eta_1(\mathbf{ \hat{k} \cdot \hat{n} }) } { \eta_2(\mathbf{ \hat{k}'' \cdot \hat{n} }) + \eta_1(\mathbf{ \hat{k} \cdot \hat{n} }) }Â = \frac{\eta_2 \cos\theta'' - \eta_1 \cos\theta} {\eta_2 \cos\theta'' + \eta_1 \cos\theta}Â = \frac{Z_{2\|} - Z_{1\|}} {Z_{2\|} + Z_{1\|}}</math>Â Â :<math>\Gamma_{\perp} = \frac{ \eta_2(\mathbf{ \hat{k} \cdot \hat{n} }) - \eta_1(\mathbf{ \hat{k}'' \cdot \hat{n} }) } { \eta_2(\mathbf{ \hat{k} \cdot \hat{n} }) + \eta_1(\mathbf{ \hat{k}'' \cdot \hat{n} }) }Â = \frac{\eta_2 / \cos\theta'' - \eta_1 / \cos\theta} {\eta_2 / \cos\theta'' + \eta_1 / \cos\theta}Â = \frac{Z_{2\perp} - Z_{1\perp}} {Z_{2\perp} + Z_{1\perp}}</math><!--[[File:frml21.png]]-->
=== Wedge Diffraction From Edges ===