Optical systems and methods are provided, which combine see-through view of the real world and display source images using a conical optical combiner cut to have flat surfaces normal to the viewer line of sight. The conical shape minimizes interferences in the view of the real world as the edges of the optical combiner are tangent to the viewer vision field of view and the inner part of the optical combiner is semitransparent. Additionally, the optical system comprises a beam splitter, a shutter(s) for attenuating or blocking the see-through path and may employ polarizing element to improve the contrast between the scene observation and the projected display and thus enabling selective viewing of either. The system may also be configured to enable diopter adjustment and virtual display distance adjustments.