The window is applied to isolate different physical environments while allowing light to pass through an anti-reflection coating is typically applied to windows to minimize losses due to reflections.

The protective windows are used to protect scan lenses from backsplatter and other workplace hazards. 

The Brewster windows are uncoated substrates used in an optical system at Brewster’s Angle.While virtually all of the p component of polarization is transmitted by a Brewster Window, most of the s component is reflected.A Brewster Window causes polarized laser output.