Relation between refractive index in ordinary and extraordinary rays in double refraction in calcite crystal
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What is the explanation of the extraordinary ray of double refraction?
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John Purcell, Author of "Mind, Matter and the Universe"
Answered Aug 28, 2016 · Author has 5.4kanswers and 7.9m answer views
Some crystals, like calcite, refract light differently depending on the polarisation of the beam. Unpolarised light contains light that is closest to one polarisation, and light that is closest to the other. For example, you can think of unpolarised light as consisting of one set of waves that are waving roughly up and down, and another that are waving roughly side to side.
The actual situation is a bit more complicated because ordinary light is a whole rambling collection of waves doing all kinds of things, you but get the idea.
So calcite is actually separating the light into two beams based on its polarisation.
Both obey the normal laws of refraction, just with two different refractive indices, one for each polarisation of the beam. This ultimately has to do with the crystal structure of calcite. Light aligned with one crystal plane can get through it faster than light aligned at ninety degrees to this plane.
If you take one lens of some polaroid sunglasses and examine the images produced by a calcite crystal, for example placing the crystal over some text and looking at the doubled text, you can filter out one or the other image depending on how you rotate the lens.
Still have a question? Ask your own!
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John Purcell, Author of "Mind, Matter and the Universe"
Answered Aug 28, 2016 · Author has 5.4kanswers and 7.9m answer views
Some crystals, like calcite, refract light differently depending on the polarisation of the beam. Unpolarised light contains light that is closest to one polarisation, and light that is closest to the other. For example, you can think of unpolarised light as consisting of one set of waves that are waving roughly up and down, and another that are waving roughly side to side.
The actual situation is a bit more complicated because ordinary light is a whole rambling collection of waves doing all kinds of things, you but get the idea.
So calcite is actually separating the light into two beams based on its polarisation.
Both obey the normal laws of refraction, just with two different refractive indices, one for each polarisation of the beam. This ultimately has to do with the crystal structure of calcite. Light aligned with one crystal plane can get through it faster than light aligned at ninety degrees to this plane.
If you take one lens of some polaroid sunglasses and examine the images produced by a calcite crystal, for example placing the crystal over some text and looking at the doubled text, you can filter out one or the other image depending on how you rotate the lens.
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