Reduced combiner helicopter sight system

Abstract

A helicopter sight system including an illuminated reticle for controllably providing reticle imaging illumination and an active display for controllably providing active display illumination that contains alignment information provided by an electronic aiming system, the active display and the reticle being controlled to provide respective imaging illumination at different times. The reticle illumination and the active display illumination are directed by a color beam combiner along a common axis to a focussing lens system which illuminates a transparent combiner to produce a reticle image and an active display image viewable by the operator of the helicopter. The focussing lens system, the reticle, and the active display are configured so that the reticle image is positioned at optical infinity and the active display image is positioned at less than optical infinity, whereby the reticle image is positioned at a relatively long optical distance so that the focus of the reticle image sufficiently matches the relatively long distance to the target, and whereby the eyebox for viewing the active display image is larger than the eyebox for viewing the reticle image. More particularly, the reticle is positioned at a distance from the focussing lens system that is equal to the focal length of the focussing lens, and the active display is positioned at a distance from the focussing lens system that is less than the focal length of the focussing lens.