I See Double! The Birefringence or Double Refraction of Calcite

[caption id="attachment_8638" align="alignright" width="440"] Image splitting by a calcite crystal.[/caption] Refraction? Yes. But double refraction?? A number of phenomena produce double vision. I personally suffer a degree of double vision. It was caused by pressure damage to my 6th optic nerve. The pressure resulted from a tumor on my pituitary gland. One of the most interesting sources of double vision is caused by the splitting of an image by a calcite crystal. Almost transparent, calcite is a form of calcium carbonate. The phenomenon is birefringence or double refraction. Image Splitting Property Most science loving non-scientists use the term double refraction. Refraction is the bending of light as it leaves one medium to enter another. This bending alters the course the light would have taken if there was no change in…
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