Conical refraction is an optical phenomenon in which a ray of light, passing through a biaxial crystal along certain directions, is refracted into a hollow cone of light. There are two possible conical refractions, one internal and one external. For internal refraction, there are 4 directions, and for external refraction, there are 4 other directions.
For internal conical refraction, a planar wave of light enters an aperture a slab of biaxial crystal whose face is parallel to the plane of light. Inside the slab, the light splits into a hollow cone of light rays. Upon exiting the slab, the hollow cone turns into a hollow cylinder.
For external conical refraction, light is focused at a single point aperture on the slab of biaxial crystal, and exits the slab at the other side at an exit point aperture. Upon exiting, the light splits into a hollow cone.
This effect was predicted in 1832 by William Rowan Hamilton[1] and subsequently observed by Humphrey Lloyd in the next year.[2] It was possibly the first example of a phenomenon predicted by mathematical reasoning and later confirmed by experiment.[3]
- ^ Hamilton, William R. (1832). "Third Supplement to an Essay on the Theory of Systems of Rays". The Transactions of the Royal Irish Academy. 17: v–144. ISSN 0790-8113. JSTOR 30078785.
- ^ Lloyd, Humphrey (1831). "On the Phenomena Presented by Light in Its Passage along the Axes of Biaxal Crystals". The Transactions of the Royal Irish Academy. 17: 145–157. ISSN 0790-8113. JSTOR 30078786.
- ^ Berry, M. V.; Jeffrey, M. R. (2007-01-01). Wolf, E. (ed.). Chapter 2 Conical diffraction: Hamilton's diabolical point at the heart of crystal optics. Progress in Optics. Vol. 50. Elsevier. pp. 13–50. Bibcode:2007PrOpt..50...13B. doi:10.1016/S0079-6638(07)50002-8. ISBN 978-0-444-53023-3. Retrieved 2024-04-23.