US Patent 10247515 Holographic sight with optimized reflection and image angles

A holographic gun sight has a housing with a viewing end and an opposing target end, a viewing path being defined from the viewing end to the target end. A light source projects a light beam along a path to illuminate a reflection-type holographic optical element (HOE). The HOE reconstructs an object beam with an image of a reticle. The absolute difference between the incidence angle of the light beam on the HOE and the object beam angle is greater than zero and less than or equal to 30 degrees.