Editing Jean-Baptiste Biot (section)

=== Polarized light ===

In 1812, Biot turned his attention to the study of [[optics]], particularly the [[polarization (waves)|polarization]] of light. Prior to the 19th century, light was believed to consist of discrete packets called [[wikt:corpuscle|corpuscles]]. During the early 19th century, many scientists began to disregard the [[corpuscular theory]] in favor of the [[wave theory of light]]. Biot began his work on polarization to show that the results he was obtaining could appear only if light were made of corpuscles.

In 1815 he demonstrated that "polarized light, when passing through an organic substance, could be rotated clockwise or counterclockwise, dependent upon the optical axis of the material."<ref>Biot, J. B. (1815) [https://www.biodiversitylibrary.org/item/26553#page/196/mode/1up "Phenomene de polarisation successive, observés dans des fluides homogenes"] (Phenomenon of successive polarization, observed in homogeneous fluids), ''Bulletin des Sciences, par la Société Philomatique de Paris'', 190–192.</ref><ref>[http://micro.magnet.fsu.edu/optics/timeline/people/biot.html Jean-Baptiste Biot – Florida State University]</ref> His work in chromatic polarization and [[rotary polarization]] greatly advanced the field of optics, although it was later shown that his findings could also be obtained using the wave theory of light.<ref>Frankel 2009</ref>

Biot's work on the polarization of light has led to many breakthroughs in the field of optics. [[Liquid crystal displays]] (LCDs), such as television and computer screens, use light that is polarized by a filter as it enters the liquid crystal, to allow the liquid crystal to modulate the intensity of the transmitted light. This happens as the liquid crystal's polarisation varies in response to an electric control signal applied across it. [[Polarizer|Polarizing filters]] are used extensively in photography to cut out unwanted reflections or to enhance reflection.