Plane of incidence
= Plane of incidence
For a ray meeting an interface at nonzero incidence angle, the plane spanned by the incoming <wavevector> and the surface normal. <transverse electric polarization> has <electric field> perpendicular to this plane, while <transverse magnetic polarization> has <electric field> in it. At exact <normal incidence>, the surface normal and ray alone do not select a unique plane.