For a wavefront traveling through a boundary between two media, the first with a refractive index of n1, and the other with one of n2, the angle of incidence, θ, is related to the angle of refraction, φ, by:
For a wavefront traveling through a boundary between two media, the first with a refractive index of n1, and the other with one of n2, the angle of incidence, θ, is related to the angle of refraction, φ, by: