Patent ID: 8186837
Filing Date: 2012-05-29
Classification: G02B

Abstract:
1. An apparatus for displaying an image comprising: a wide-angle lens and a screen; wherein said wide angle lens forms an erect image of an external scene at said screen, wherein said wide-angle lens incorporates an image inverter, wherein said image inverter comprises upper and lower components, wherein said upper component is operative to provide a vertical inversion to light incident above a predetermined angle of incidence and said lower component is operative to provide a vertical inversion to light incident below a predetermined angle of incidence, wherein each said component comprises an input surface that admits light from said external scene, a reflecting surface and an exit surface, wherein said components are symmetrically disposed about an axis of symmetry of said apparatus wherein said reflecting surfaces are disposed back to back and substantially overlap, wherein each said component is divided into first and second optical elements disposed in sequence, wherein said first element has a first surface that provides said input surface and a second surface, wherein said second element has a first surface of the same shape as said second surface of the first element and a second surface that provides said exit surface, wherein said second surface of said first element and said first surface of the second element are separated by an air gap, and wherein said second surface of said first element operates as a total internal reflection surface for light from said external scene incident in directions that do not intercept said reflecting surface.