Figure 2
From: Reflected wavefront manipulation based on ultrathin planar acoustic metasurfaces
The generalized Snell's law of reflection and anomalous reflections.
(a) Schematics for the derivation of the angle of reflection. ϕ and ϕ + dϕ are the phases at the two cross points separated by dy along the y direction. θr represents the anomalous reflection angle induced by the discrete phase shifts. (b) Pressure field pattern for the gradient phase profile of 
. The black arrows refer to the theoretical value of the reflected angle.
