Varför har kupolen på F-22 Raptor en guldkant? [duplicera]

För att minska flygplanets radartvärsnitt (RCS), är F22-kapslarna belagda med ett tunt lager av indiumtennoxid (ITO), vilket ger den en gyllene nyans.

Från boken F-22 Raptor av Bill Sweetman:

The F22 Raptor canopy ... comprises two sheets of polycarbonate, sandwiched between two layers of optical glass, fusion bonded in an autoclave and drape formed over a canopy blank ... A metallic coating of indium-tin-oxide is added to the canopy to reflect the radar waves, giving it a golden tint.

De används i stealthflygplan för att minska RCS. Från globalsecurity.org :

A window member composed of a transparent resin or inorganic glass with a transparent conducting film such as gold or ITO (indium tin oxide) coated thereon, is used as an electromagnetic wave shield window for stealth aircraft. Applying such transparent conducting film enables, while maintaining transparency to visible radiation, both a radio wave stealth property which scatters radio waves in various directions so as not to be detected by radar, and an electromagnetic wave shield property which prevents harmful electromagnetic waves, except for visible radiation, from invasion into an aircraft.

Denna teknik används i andra flygplan som EA6B Prowler.