In optics, a perfect mirror is a mirror that reflects light (and electromagnetic radiation in general) perfectly, and does not transmit or absorb it.[1]
General
editDomestic mirrors are not perfect mirrors as they absorb a significant portion of the light which falls on them.
Dielectric mirrors are glass or other substrates on which one or more layers of dielectric material are deposited, to form an optical coating. A very complex dielectric mirror can reflect up to 99.999% of the light incident upon it, for a narrow range of wavelengths and angles. A simpler mirror may reflect 99.9% of the light, but may cover a broader range of wavelengths.
Almost any dielectric material can act as a perfect mirror through total internal reflection. This effect only occurs at shallow angles, however, and only for light inside the material. The effect happens when light goes from a medium with a higher index of refraction to one with a lower value (like air).
A new type of dielectric "perfect mirror" was developed in 1998 by researchers at MIT.[2][3] These unusual mirrors are very efficient reflectors over a broad range of angles and wavelengths, and are insensitive to polarization. A version of the perfect mirror that was developed at MIT for military use is used by OmniGuide in laser surgery.[4]
See also
editReferences
edit- ^ The Pearson Guide To The B.Sc. (Nursing) Entrance Examination. Pearson Education India. September 2007. ISBN 9788131713389.
- ^ "MIT researchers create a 'perfect mirror'". MIT. 27 November 1998. Archived from the original on May 14, 2011. Retrieved 2012-11-18.
- ^ Fink, Yoel; Winn, Joshua N.; Fan, Shanhui; Chen, Chiping; Michel, Jurgen; Joannopoulos, John D.; Thomas, Edwin L. (November 26, 1998). "A Dielectric Omnidirectional Reflector". Science. 282 (5394): 1679–1682. doi:10.1126/science.282.5394.1679. Retrieved 2008-09-22.
- ^ "From military device to life-saving surgery tool". CNN. December 19, 2008. Retrieved 2008-12-19.
External links
edit- Perfect mirror debuts (2013)
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