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Double Refraction 2

Double refraction, or birefringence, occurs when a single ray of unpolarized light enters an anisotropic medium and splits into two rays: the ordinary ray, which travels unchanged, and the extraordinary ray, which is refracted at an angle. This phenomenon can be demonstrated using materials like glass and calcite, where calcite reveals two images of a pencil mark when oriented correctly. The ordinary and extraordinary rays are polarized at right angles, with their refractive indices differing based on direction, affecting their speed in the medium.

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15 views6 pages

Double Refraction 2

Double refraction, or birefringence, occurs when a single ray of unpolarized light enters an anisotropic medium and splits into two rays: the ordinary ray, which travels unchanged, and the extraordinary ray, which is refracted at an angle. This phenomenon can be demonstrated using materials like glass and calcite, where calcite reveals two images of a pencil mark when oriented correctly. The ordinary and extraordinary rays are polarized at right angles, with their refractive indices differing based on direction, affecting their speed in the medium.

Uploaded by

j0dkl0pu9s
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Phenomena Of Double

Refraction
B.Tech-I
Double refraction, also called birefringence, an
optical property in which a single ray of
unpolarizedlight entering an anisotropic medium is
split into two rays, each traveling in a different
direction. One ray (called the extraordinary ray) is
bent, or refracted, at an angle as it travels through
the medium; the other ray (called the ordinary ray)
passes through the medium unchanged.
Double refraction

Double refraction can be observed by


comparing two materials, glass and calcite.
If a pencil mark is drawn upon a sheet of
paper and then covered with a piece of
glass, only one image will be seen; but if
the same paper is covered with a piece
of calcite, and the crystal is oriented in a
specific direction, then two marks will
become visible.
The Figure shows the phenomenon of double refraction through a calcite
crystal. An incident ray is seen to split into the ordinary ray CO and
the extraordinary ray CE upon entering the crystal face at C. If the incident ray
enters the crystal along the direction of its optic axis, however, the light ray will
not become divided.
In double refraction, the ordinary ray and the
extraordinary ray are polarized in planes vibrating at
right angles to each other.
Furthermore, the refractive index (a number that
determines the angle of bending specific for each
medium) of the ordinary ray is observed to be constant
in all directions;
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.
Because the speed of light waves in a medium is equal
to their speed in a vacuum divided by the index of
refraction for thatwavelength, an extraordinary ray can
move either faster or slower than an ordinary ray.

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