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Created page with "{{Language_sel|LANG=ger|ARTIKEL=Brechung Licht}} {{PSM_Infobox}} Refraction light __FORCETOC__ ==Optical refraction of light – Law of refraction== Refraction refers to the discontinuous change in direction of energy transport at the interface (see: phase boundary surface) between two media into the adjacent medium. Energy transport can occur in the form of electromagnetic waves (e.g. li..."

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{{Language_sel|LANG=ger|ARTIKEL=Brechung Licht}}
{{PSM_Infobox}}
Refraction light
__FORCETOC__

==Optical refraction of light – Law of refraction==

Refraction refers to the discontinuous change in direction of energy transport at the interface (see: [[Phase Boundary Surface|phase boundary surface]]) between two media into the adjacent medium. Energy transport can occur in the form of electromagnetic waves (e.g. light, heat) and sound waves. In optically transparent or translucent (partial light transmission) [[Material & Werkstoff|materials]], an obliquely incident light wave is partially reflected at an interface between medium 1 and 2 and simultaneously refracted depending on the optical properties. The deflection of light rays in the second medium is also referred to as light refraction or refraction [1].

While in the case of [[Reflection Light|reflection]], the angle of incidence ''α''0 of the light beam LW is identical to the angle of exit or reflection ''α''R, the angle of refraction ''β''B differs from the angle of incidence. The decisive factor here is the ratio of the index of refraction (refractive index) ''n''1 and ''n''2 of the two media, whereby the behaviour of refraction is described by SNELLIUS's law of refraction or the generalised law of refraction ('''Fig. 1''') and ('''Eq. 1''') [2, 3].

[[File:Refraction Light Fig-1.jpg|400px]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px" |Optical refraction and reflection at flat interfaces
|}

{|
|-
|width="20px"|
|width="500px"|<math>\frac{\sin \alpha _{0}}{\sin \alpha _{R}}=\frac{n_{1}}{n_{2}}</math>
|(1)
|}

==Determination of the index of refraction==

If the index of refraction transition at the [[Phase Boundary Surface|interface]] is sharp, a kink occurs in the beam path, which typically occurs in optical prisms, for example ('''Fig. 1'''). If the [[Refraction Index|index of refraction]] changes continuously from medium 1 to medium 2, the light is also continuously curved, whereby the incident, reflected and refracted rays also lie in one plane. During refraction, the product ''n''i sin ''α''i remains constant, and this product is then referred to as the invariant of refraction.

==Test methods for determining the index of refraction==

For the optical [[Testing|testing]] of [[Plastics|plastics]], the determination of the index of [[Refraction Index|refraction]] or refractive index is of practical importance. For the examination of plastic powders and test [[Specimen|specimens]], a number of physical measurement methods for determining the index of refraction have been found to be particularly suitable [1].

The most commonly used test methods in practice are:

* determination of the index of refraction by measuring the angle of total reflection with a refractometer on liquid or compact solid media,
* determination of the index of refraction of powdered [[Plastics|plastics]] using the immersion method by changing the embedding liquid,
* index of refraction determination using the temperature and/or wavelength variation method on plastic powders with an embedding agent, and
* index of refraction determination on plane-parallel test [[Specimen|specimens]] (films, plates, thin slices, thin sections) with assumed or measured knowledge of the thickness

==See also==

* [[Reflection Light|Reflection light]]
* [[Light Absorption|Light absorption]]
* [[Light Remission|Light remission]]
* [[Light Transmission|Light transmission]]
* [[Refraction Index|Refraction index]]

==References==

{|
|-valign="top"
|[1]
|Trempler, J.: Optical properties. In: [[Grellmann,_Wolfgang|Grellmann, W.]], [[Seidler,_Sabine|Seidler, S.]] (Eds.): Polymer Testing. Carl Hanser, Munich (2022), 3rd Edition, pp. 299–330 (ISBN 978-1-56990-806-8; E-Book: ISBN 978-1-56990-806-5; see [[AMK-Library]] under A 22)
|-valign="top"
|[2]
|Eichler, J., Eichler, H. J.: Laser – Bauformen, Strahlführung, Anwendungen. Springer, Berlin (2003) 5th Edition, p. 258 (ISBN 3-540-00376-2)
|-valign="top"
|[3]
|Recknagel, A.: Physik – Optik. Technik Publishing, Berlin (1977) 7th Edition
|}

[[Category:Light]]

Refraction Light - Revision history