Brewster windows are uncoated windows used at Brewsters Angle (the angle at which only p-polarized light has zero transmission loss). A series of Brewster Windows used in a laser cavity will ensure linearly polarized output light. Brewsters Angle can be calculated from the following equation:

ß=tan-1(n)     ß=Brewster angle ; n=Reflective index
Material	Brewster angle
ZnSe	67.4°
Ge	76°
GaAs	73°
Bk7	54°