Brewster window is a transparent optical plate which titled at Brewster's angle to reach a minimum loss of P-polarized beam. Brewster's angle is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. When unpolarized light is incident at this angle, the light that is reflected from the surface is therefore perfectly polarized.  PHYO can make the Brewster windows based on different design request in size and coating. The reflection rate of s-polarized of the Brewster window is up to 22 % for UV Fused Silica and 26% for H-K9L at 1064 nm.