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:
“Removed from its more restrictive sense, masturbation has become an expression for everything that has proved, for lack of human contact, to be void of meaning. We have communication problems, suffer from egocentrism and narcissism, are frustrated by information glut and loss of environment; we stagnate despite the rising GNP.”
—Günther Grass (b. 1927)
“For, the expectation of gratitude is mean, and is continually punished by the total insensibility of the obliged person. It is a great happiness to get off without injury and heart-burning, from one who has had the ill luck to be served by you. It is a very onerous business, this being served, and the debtor naturally wishes to give you a slap.”
—Ralph Waldo Emerson (1803–1882)
“I have been amazed by the Anglo-Saxon’s lack of curiosity about the internal lives and emotions of the Negroes, and for that matter, any non-Anglo-Saxon peoples within our borders, above the class of unskilled labor.”
—Zora Neale Hurston (1891–1960)
“With respect to a true culture and manhood, we are essentially provincial still, not metropolitan,—mere Jonathans. We are provincial, because we do not find at home our standards; because we do not worship truth, but the reflection of truth; because we are warped and narrowed by an exclusive devotion to trade and commerce and manufacturers and agriculture and the like, which are but means, and not the end.”
—Henry David Thoreau (1817–1862)