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Light waves change phase by 180° when they reflect from the surface of a medium with higher refractive index than that of the medium in which they are travelling. [1] A light wave travelling in air that is reflected by a glass barrier will undergo a 180° phase change, while light travelling in glass will not undergo a phase change if it is reflected by a boundary with air.
Thus, whatever phase is associated with reflection on one side of the interface, it is 180 degrees different on the other side of the interface. For example, if r has a phase of 0, r’ has a phase of 180 degrees. Explicit values for the transmission and reflection coefficients are provided by the Fresnel equations
The phase shift of the reflected wave on total internal reflection can similarly be obtained from the phase angles of r p and r s (whose magnitudes are unity in this case). These phase shifts are different for s and p waves, which is the well-known principle by which total internal reflection is used to effect polarization transformations .
Diagram showing the acoustic relationship that results in a seismic polarity reversal. In reflection seismology, a polarity reversal or phase change is a local amplitude seismic attribute anomaly that can indicate the presence of hydrocarbons and is therefore known as a direct hydrocarbon indicator.
Reflection of light is either specular (mirror-like) or diffuse (retaining the energy, but losing the image) depending on the nature of the interface.In specular reflection the phase of the reflected waves depends on the choice of the origin of coordinates, but the relative phase between s and p (TE and TM) polarizations is fixed by the properties of the media and of the interface between them.
This angle is chosen so that each reflection introduces a phase difference of 45° between the components polarized parallel and perpendicular to the plane of reflection. For a given, sufficiently high refractive index , there are two angles meeting this criterion; for example, an index of 1.5 requires an angle of 50.2° or 53.3°.
Ray diagram illustrating the physics of the Goos–Hänchen effect. The Goos–Hänchen effect (named after Hermann Fritz Gustav Goos (1883–1968) and Hilda Hänchen (1919–2013) is an optical phenomenon in which linearly polarized light undergoes a small lateral shift when totally internally reflected.
The overall reflection of a layer structure is the sum of an infinite number of reflections. The transfer-matrix method is based on the fact that, according to Maxwell's equations , there are simple continuity conditions for the electric field across boundaries from one medium to the next.