|
Fresnel Lenses
During the height of the Shipping Age in the 18th century, France was looking for a way
to make new lighthouses along the coast of Normandy and Brittany. The lenses that were
used in the lighthouses were huge pieces of glass that were both bulky and expensive.
In 1748, Georges de Buffon realized that only one side of a lens is needed to
bend light. In fact, only the outer surface of the lens is needed. Why do we only need the surface to bend the light?
de Buffon cut away the inside of the lens and left rings with edges on the outside. Later,
Augustin Fresnel modified this idea and the modern Fresnel lens was created. His lenses
were first used on the French coast as a lightweight and less-expensive alternative to
the old, bulky lighthouse lenses.
Below is a schematic cut-away diagram showing how a Fresnel lens is made.
Activities | Readings | Course Info | Home
Page authored by the
ACEPT W3 Group Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287-1504 Copyright © 1995-2000 Arizona Board of Regents. All rights reserved.
Last modified 26 December 1999
Send Questions or Comments to our webmaster
URL: http://acept.asu.edu/PiN/rdg/fresnel/fresnel.shtml
|
|
 Activities
 Readings
 PiN Home
 General Schedule
 Useful Tools
|