Sunday, December 5, 2010
MULTI BEAM INTERFEROMETRY -TOPIC
Sponsored links
The interference between two beams which are derived from a single beam either by division of wavefront or by division of amplitude. Here we shall discuss the interference due to many beams which are derived from a single beam by multiple reflections - division of amplitude.
If a plane wave falls on parallel glass plate, then the beam would undergo multiple reflections at the two surfaces and a large number of beams of decreasing amplitudes will emerge on both sides of the plate. These beams on either side interfere to produce interference pattern at infinity. The interference fringes so produced are much sharper than those formed by interference produced by two beams. The interferometers involving multiple beam interference have very high resolving power and have application in high resolution spectroscopy.
FABRY- PEROT INTERFEROMETER
Fabry -Perot interferometer is based on the principle of multiple beam interference. It consists of two plane parallel glass plates A and B whose inside surfaces are silvered. Light from a point S of an extended source falls on plate A at an angle 0. The transmitted light after multiple reflection between the glass plates in the air film is brought to focus at P by the lens L. The intensity of transmitted light is maximum when the path difference between the rays. The interference pattern is concentric rings with O as center. Each ring corresponds to a particular value of 0. The radius of the ring is OP and the fringes are called fringes of constant inclination or Haidinger Fringes.
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment