Double Refraction
Double Refraction or Birefringence is an optical property in which a ray of light entering a medium is decomposed into two rays, each traveling in a different direction. One ray is bent or refracted called the extraordinary ray and the other passes through the medium unchanged called the ordinary ray. This effect can occur only if the structure of the material is anisotropic.
Anisotropy
Anisotropy is the property of a material to be directionally dependent due to which a material does not behave the same way in all directions. When anisotropic crystals refract light, the resulting rays are polarized along the axis of anisotropy and travel at different velocities giving rise to the phenomenon of double refraction. One of the rays travels with the same velocity in every direction (ordinary ray). The other ray travels with a velocity that is dependent upon the propagation direction (extraordinary ray). The distance of separation between the ordinary and extraordinary ray increases with increasing crystal thickness.
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Description
The figure below shows the phenomenon of double refraction through a crystal. A ray AB incident on the crystal is split into rays BO the ordinary ray and BE the extraordinary ray. The optical axis of the crystal is shown in the figure. If the incident ray enters the crystal along the optical axis the phenomenon of double refraction will not be observed as the light ray will not be splitted.
Anisotropy
Anisotropy is the property of a material to be directionally dependent due to which a material does not behave the same way in all directions. When anisotropic crystals refract light, the resulting rays are polarized along the axis of anisotropy and travel at different velocities giving rise to the phenomenon of double refraction. One of the rays travels with the same velocity in every direction (ordinary ray). The other ray travels with a velocity that is dependent upon the propagation direction (extraordinary ray). The distance of separation between the ordinary and extraordinary ray increases with increasing crystal thickness.
Understanding Index of Refraction Definition is always challenging for me but thanks to all math help websites to help me out.
Description
The figure below shows the phenomenon of double refraction through a crystal. A ray AB incident on the crystal is split into rays BO the ordinary ray and BE the extraordinary ray. The optical axis of the crystal is shown in the figure. If the incident ray enters the crystal along the optical axis the phenomenon of double refraction will not be observed as the light ray will not be splitted.
Fig : Phenomenon of Double Refraction
The ordinary ray obeys the normal laws of refraction. The other refracted ray, called the extraordinary ray, follows different laws. The light in the ordinary ray is polarized at right angles to the light in the extraordinary ray. The refractive index of the ordinary ray is observed to be constant in all directions whereas the refractive index of the extraordinary ray varies according to the direction taken because it has components that are both parallel and perpendicular to the crystal’s optic axis.
The two independent refractive indices of anisotropic crystals are quantified in terms of their birefringence(double refraction), a measure of the difference in refractive index. Thus, the Fig : Phenomenon of Double Refraction
The ordinary ray obeys the normal laws of refraction. The other refracted ray, called the extraordinary ray, follows different laws. The light in the ordinary ray is polarized at right angles to the light in the extraordinary ray. The refractive index of the ordinary ray is observed to be constant in all directions whereas the refractive index of the extraordinary ray varies according to the direction taken because it has components that are both parallel and perpendicular to the crystal’s optic axis.
The two independent refractive indices of anisotropic crystals are quantified in terms of their birefringence(double refraction), a measure of the difference in refractive index. Thus, the birefringence (B, often termed d, or D) of a crystal is defined as:
B = |n(high) – n(low)|
where n(high) is the largest refractive index and n(low) is the smallest. This expression holds true for any part or fragment of an anisotropic crystal with the exception of light waves propagated along the optical axis of the crystal.(B, often termed d, or D) of a crystal is defined as:
B = |n(high) – n(low)|
where n(high) is the largest refractive index and n(low) is the smallest. This expression holds true for any part or fragment of an anisotropic crystal with the exception of light waves propagated along the optical axis of the crystal.
The ordinary ray obeys the normal laws of refraction. The other refracted ray, called the extraordinary ray, follows different laws. The light in the ordinary ray is polarized at right angles to the light in the extraordinary ray. The refractive index of the ordinary ray is observed to be constant in all directions whereas the refractive index of the extraordinary ray varies according to the direction taken because it has components that are both parallel and perpendicular to the crystal’s optic axis.
The two independent refractive indices of anisotropic crystals are quantified in terms of their birefringence(double refraction), a measure of the difference in refractive index. Thus, the Fig : Phenomenon of Double Refraction
The ordinary ray obeys the normal laws of refraction. The other refracted ray, called the extraordinary ray, follows different laws. The light in the ordinary ray is polarized at right angles to the light in the extraordinary ray. The refractive index of the ordinary ray is observed to be constant in all directions whereas the refractive index of the extraordinary ray varies according to the direction taken because it has components that are both parallel and perpendicular to the crystal’s optic axis.
The two independent refractive indices of anisotropic crystals are quantified in terms of their birefringence(double refraction), a measure of the difference in refractive index. Thus, the birefringence (B, often termed d, or D) of a crystal is defined as:
B = |n(high) – n(low)|
where n(high) is the largest refractive index and n(low) is the smallest. This expression holds true for any part or fragment of an anisotropic crystal with the exception of light waves propagated along the optical axis of the crystal.(B, often termed d, or D) of a crystal is defined as:
B = |n(high) – n(low)|
where n(high) is the largest refractive index and n(low) is the smallest. This expression holds true for any part or fragment of an anisotropic crystal with the exception of light waves propagated along the optical axis of the crystal.