OptipediaSPIE Press books opened for your reference.

Brewster's Law


Excerpt from Field Guide to Polarization

Around 1812 Brewster discovered that for different glasses the p-polarized ray (in the plane of the paper) vanished completely at a particular angle of incidence i. Furthermore, by rotating the analyzing calcite crystal through 90°, the s-polarized ray (directed out of the plane of the paper) became extinguished. He then discovered that the refracted ray angle r was simply related to the incident ray angle i by

equation_1

Brewster's_Law

Snell’s law of refraction between the two media is

equation_2

where n1 and n2 are the refractive indices of the media, respectively. For air n1 = 1 and for glass n2 = n. Substituting the first equation into Snell’s law leads to

equation_3

This equation is known as Brewster’s law. Its immediate practical use was that it enabled the refractive index of glass to be determined by reflection rather than by refraction; the measurement of the refractive angle r by transmission is difficult. The result of this discovery was that it led to the rapid development and measurement of new optical glasses.

Citation:

E. Collett, Field Guide to Polarization, SPIE Press, Bellingham, WA (2005).



View SPIE terms of use.
Excerpt from
Edward Collett
Member: $35.70
Non-Member: $42.00