Frustrated Total Internal Reflection
See also: attenuated total reflectanceUnder "ordinary conditions" it is true that the creation of an evanescent wave does not affect the conservation of energy, i.e. the evanescent wave transmits zero net energy. However, if a third medium with a higher refractive index than the low-index second medium is placed within less than several wavelengths distance from the interface between the first medium and the second medium, the evanescent wave will be different from the one under "ordinary conditions" and it will pass energy across the second into the third medium. (See evanescent wave coupling.) This process is called "frustrated" total internal reflection (FTIR) and is very similar to quantum tunneling. The quantum tunneling model is mathematically analogous if one thinks of the electromagnetic field as being the wave function of the photon. The low index medium can be thought of as a potential barrier through which photons can tunnel.
The transmission coefficient for FTIR is highly sensitive to the spacing between the high index media (the function is approximately exponential until the gap is almost closed), so this effect has often been used to modulate optical transmission and reflection with a large dynamic range. An example application of this principle is the multi-touch sensing technology for displays as developed at the New York University’s Media Research Lab.
Read more about this topic: Total Internal Reflection
Famous quotes containing the words frustrated, total, internal and/or reflection:
“The parody is the last refuge of the frustrated writer. Parodies are what you write when you are associate editor of the Harvard Lampoon. The greater the work of literature, the easier the parody. The step up from writing parodies is writing on the wall above the urinal.”
—Ernest Hemingway (1899–1961)
“I think that if most guys in America could somehow get their fave-rave poster girl in bed and have total license to do whatever they wanted with this legendary body for one afternoon, at least 75 percent of the guys in the country would elect to beat her up.”
—Lester Bangs (1948–1982)
“What makes some internal feature of a thing a representation could only its role in regulating the behavior of an intentional system.”
—Daniel Clement Dennett (b. 1942)
“If the contemplation, even of inanimate beauty, is so delightful; if it ravishes the senses, even when the fair form is foreign to us: What must be the effects of moral beauty? And what influence must it have, when it embellishes our own mind, and is the result of our own reflection and industry?”
—David Hume (1711–1776)