Wide angle objective having non-spherical surfaces

Claim 1

IN AN OPTICAL OBJECTIVE COMPRISING A SYSTEM OF LENSES THAT HAVE AT LEAST HALF THE OPTICAL SURFACES THEREOF FORMED AS NON-SPHERICAL SURFACES, EACH OF SAID OPTICAL SURFACES BEING ALIGNED ON A COMMON OPTICAL AXIS AND HAVING AN ARC THEREON THAT INTERSECTS SAID OPTICAL AXIS AND IS CONCENTRIC ABOUT A COMMON CENTRAL AXIS THAT IS PERPENDICULAR TO SAID COMMON OPTICAL AXIS, MEANS FOR PROVIDING A FIRST APERTURE FORMED CENTRALLY WITHIN SAID SYSTEM OF LENSES AND DEFINING A SLOT EXTENDING IN PARALLEL ALIGNMENT WITH SAID COMMON CENTRAL AXIS, AND MEANS FOR PROVIDING A SECOND APERTURE BETWEEN AN ADJACENT PAIR OF OPTICAL SURFACES DEFINING A SLOT EXTENDING SUBSTANTIALLY NORMAL TO SAID FIRST APERTURE AND BEING DISPLACED FROM AND CONCENTRIC ABOUT SAID COMMON CENTRAL AXIS, SAID SYSTEM FORMING AN IMAGE ON THE SHORT CONJUGATE SIDE OF THE OBJECTIVE, THE IMPROVEMENT OF TWO ADJACENT NON-SPHERICAL SURFACES FORMED ON THE IMAGE SIDE OF SAID COMMON CENTRAL AXIS, BEING SPACED BY AN AIR SEPARATION, SAID SPACED SURFACES BEING FURTHER FORMED SO THAT EACH SPACED SURFACE HAS LESS CURVATURE IN THE PLANE CONTAINING THE COMMON CENTRAL AXIS AND THE COMMON OPTICAL AXIS THAN IN A PLANE PERPENDICULAR TO THE COMMON CNETRAL AXIS AND CONTAINING THE COMMON OPTICAL AXIS SO AS TO INCREASE THE USEFUL FIELD IN THE PLANE CONTAINING THE COMMON CENTRAL AXIS AND THE COMMON OPTICAL AXIS.