Four-component symmetrical projection objective

Claim 1

A SYMMETRICAL PROJECTION OBJECTIVE FOR USE AT EQUAL CONJUGATES HAVING AN APERTURE OF SUBSTANTIALLY F/5.6, SAID OBJECTIVE COMPRISING A PAIR OF NEGATIVE MENISCUS LENS MEMBERS WHICH ARE DUPLICATES OF EACH OTHER AND ARE CONCAVE TOWARD EACH OTHER, SAID MEMBERS BEING EQUALLY SPACED FROM OPPOSITE SIDES OF AN INTERPOSED DIAPHRAGM AND BEING OPTICALLY ALIGNED ON A COMMON AXIS, EACH OF SAID MEMBERS BEING COMPOSED OF AN OUTER CONVEX-CONCAVO LENS ELEMENT OF POSITIVE POWER DESIGNATED I WHICH LIES IN CONTACT WITH AN INNER CONVEX-CONCAVO NEGATIVE LENS ELEMENT DESIGNATED II, SAID OBJECTIVE BEING FURTHER COMPOSED OF A PAIR OF SINGLET POSITIVE MENISCUS LENS MEMBERS DESIGNATAED III SPACED BETWEEN SAID DOUBLET MEMBERS AND SPACED SYMMETRICALLY FROM EITHER SIDE OF SAID DIAPHRAGM AND BEING CONCAVE THERETO, SAID MEMBERS AND ELEMENTS HAVING LENS PARAMETER VALUES AS SPECIFIED IN THE TABLE HEREBELOW WHEREIN FI, -FII AND FIII DESIGNATE THE FOCAL LENGTHS OF THE LENSES I, II AND III RESPECTIVELY AND THE MINUS (-) SIGN MEANS NEGATIVE FOCAL LENGTH, RI, TO RK AND -RI TO -R5 REPRESENTS THE RADII OF THE SUCCESSIVE LENS SURFACE AND THE MINUS (-) SIGN USED THEREWITH MEANS THAT SUCH RADII ARE CONCAVE TOWARD THE OBJECT SIDE, TI TO T3 REPRESENT THE SUCCESSIVE AXIAL THICKNESSES OF SAID LENSES NUMBERING TOWARD THE DIAPHRAGM, SI, AND S4 REPRESENT THE FRONT AND BACK AIR SPACES, S2 REPRESENTS THE SPACE BETWEEN THE DOUBLET LENS AND THE SINGLET LENS, S3 REPRESENTS THE AIR SPACES AT EITHER SIDE OF THE DIAPHRAGM, AND ND AND V REPRESENT THE REFRACTIVE INDEX AND ABBE