Reticle-Lens System and Method.

The patent application relates to reticles employed in infra-red detector systems, particularly to a reticle-lens system which is effective in reducing back reflectance noise. In a missile seeker system, for example, in which an infra-red detector is used as a guidance feature, a reticle is generally placed in the line of sight of the missile optics before the detecting circuitry. In prior reticles a problem existed when back reflectance in the reticle-lens system caused undesirable background noise. Reflectance background noise is reduced to a minimum by successively depositing a thin film of aluminum on the face of the sapphire reticle substrate, chemically etching a reticle pattern in the aluminum, oxidizing the remaining aluminum and, finally depositing a film of titanium on the oxidized aluminum before etching the final reticle pattern.