Display instrument using optical collimation

Claim 1

A display instrument using optical collimation for projecting data into the observer''s normal line of sight, said instrument comprising: a transparent combining glass positioned in said line of sight and having a surface for reflecting projected images into said line of sight; an optical objective for projecting images of luminous objects focused at infinity onto said surface; means for providing said luminous objects; and a reflectively deflecting prism located between said optical objective and said luminous objects providing means, said prism having an entry face for refracting incident light rays issued from said luminous objects; a reflecting face forming a plane reflective mirror and an exit face comprising the largest face of the prism, said exit face being perpendicular to the optical axis of said optical objective which is positioned parallel and opposite said exit face, said luminous objects being positioned in the focal zone of said objective through said prism, said entry face being perpendicular to the optical axis which extends through said prism to said focal zone, the angles of said prism adjacent to said exit face having predetermined values and the ratio of the angle formed with the reflecting face to that formed with the entry face being equal to 1:2 for providing emerging rays which form with the normal to the exit face angles which are respectively the same as those which the corresponding incident rays issued from said objects make with the normal to the entry face, whereby the diameter of the optical objective is greater than the breadth of the entry face and corresponds to the emergent area of said exit face.