In 1801 the wave nature of light was convincingly demonstrated when the British physicist and physician Thomas Young performed his now-famous interference experiment. Young found that light directed through two closely spaced pinholes recombined to produce fringes of brightness and darkness on a screen behind. The bright fringes resulted from light waves of the two holes arriving crest to crest, while the dark areas resulted from light waves arriving trough to crest. This pattern of interference fringes is called an interference pattern, and is a general wave phenomena that arises whenever a series of waves arrive at the same place from two synchronized sources, or from the same source by traversing two different paths.

The Interference Hablet is a visualization of Young's Double Slit Experiment. In the double slit experiment, a single source is split in two, to generate two coherent sources. When the light from the two sources is projected on a screen, an interference pattern is observed.

To explain the origin of the interference pattern, consider the distance traveled from the two sources. At the center of the screen the waves from the two sources are in phase. As we move away from the center, the path traveled by the light from one source is larger than that traveled by the light from the other source. When the difference in path is equal to half a wavelength, destructive interference occurs. Instead, when the difference in pathlength is equal to a wavelength, constructive interference occurs.

This is a classic example of interference effects in light waves. Two light rays pass through two slits, separated by a distance d and strike a screen a distance, L, from the slits. You can change these parameters by dragging their respective scrollbars, and then you can see the result of the interference on the screen.

Author: Serge G. Vtorov

Converted By: Alvil Singh & Tom Jackson (NCSA)

Converted from: http://members.tripod.com/~vsg/interf.htm

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