Phase of the reflected wave, ϕ_R, as a function of the incidence angle, θ_I. The vertical dash-dotted and dotted lines correspond to the Critical angle, θ_C, the Brewster angle, θ_B, and the Phase inversion angle, θ_P. The Phase inversion angle separates the reflected waves, that are not accompanied by a transmitted wave, into depletion and enhancement characteristics. The horizontal black dashed lines denote the phases π and 0. One can see that the intersection point of the horizontal blue dashed line, which represents the phase π/2, with the phase of the reflected wave defines the Phase inversion angle, θ_P.