Viewing device having optical arrangement producing virtual image at infinity

Claim 1

IN A VIEWING DEVICE, AN OPTICAL ARRANGEMENT COMPRISING A FIRST REFLECTOR HAVING A CONCAVE SPECULAR SURFACE OF REVOLUTION INCLUDING FIRST AND SECOND PORTIONS, AND A SECOND REFLECTOR HAVING A CONVEX SPECULAR SURFACE OF REVOLUTION, SAID SURFACES OPPOSING EACH OTHER AND SPACED APART A DISTANCE SUBSTANTIALLY EQUAL TO THE PRIME FOCAL LENGTH OF SAID CONCAVE SURFACE, SAID CONVEX SURFACE HAVING A SHORTER CHORDAL LENGTH IN ONE DIRECTION THAN THE CHORDAL LENGTH IN THE SAME DIRECTION OF SAID CONCAVE SURFACE, WHEREBY LIGHT FROM AN OBJECT TO BE VIEWED PASSING LATERALLY OF ONE SIDE OF SAID SECOND REFLECTOR AND BEING INCIDENT TO SAID SECOND CONCAVE SURFACE PORTION IS FOCUSED ON SAID CONVEX SURFACE FROM WHENCE IT IS REFLECTED TO IMPINGE SAID FIRST CONCAVE SURFACE PORTION AND THEREBY CREATE A VIRTUAL IMAGE OF SAID OBJECT AT INFINITY VIEWABLE LATERALLY OF THE OTHER SIDE OF SAID SECOND REFLECTOR.