Brewster dispersing prisms have an apex angle whereby linearly polarized light of a specific wavelength introduced at the Brewster angle has a minimum deflection angle (prism apex angle when light passes through a prism parallel to the bottom face).

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