Publisher Summary This chapter discusses anti-veiling glare windows for third-generation image intensifiers. The early image intensifiers used glass input windows and S • 1 photocathodes. The development in the 1960s of the much more sensitive S.25 photocathode and of fiber-optic faceplates enabled the 3-stage electrostatic focus intensifier to have sufficient gain and resolution for many night-vision tasks. Prototypes were made and tested in the mid 1970s and it was found that, although performance of the new Gen. 3 goggles systems was superb, there was a problem with veiling glare. Veiling glare was found to be particularly objectionable when a bright light was just off the edge of the field of view. The field of view is generally chosen to be 40º from considerations of human factors. It is important to note that this field of view is determined by the cathode diameter and not by the lens; a larger cathode diameter would result in a wider field of view.