Patent ID: 7636199

Claim:
An optical device for superposing images, constructed to be positioned in front of an optical module, the optical device having an objective and a photosensitive or photoemissive surface positioned in the focal plane of said objective, said device comprising at least an image source and an optical combiner, said combiner: being formed of two optical parts assembled via an approximately plane common face; wherein the combiner has the general form of a plate with plane parallel faces, said common face being inclined at around 45 degrees to said plane faces; wherein said combiner has an entrance face and a opposing face that are approximately perpendicular to said plane faces; wherein the opposing face has approximately the form of a reflecting spherical surface and in that the common face has a weakly reflective coating, the reflection coefficient of this coating being less than 10% in the spectral band used by the photosensitive surface; and said combiner being constructed to be positioned in front of the objective such that the plane parallel faces are approximately perpendicular to the optical axis of said objective.