Three element objective lens with ellipsoidal, hyperbolic, and parabolic surfaces
AssigneeEastman Kodak Company
InventorPaul Lewis Ruben
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Abstract
An objective lens comprising three elements, a front positive biconvex element, a middle negative biconcave element and a rear positive biconvex element. The first two elements are made of inexpensive plastic materials. Aberration correction at a high relative aperture is improved by the use of aspheres on selected surfaces of the first and second elements.
Claims6
A three element objective lens comprising a front positive biconvex element having two aspheric surfaces, a middle negative biconcave element having two aspheric surfaces and a rear positive biconvex element wherein said aspheric surfaces are from front to rear, an ellipsoid, a hyperboloid, and two paraboloids.
A three element lens comprising a front positive biconvex element, a middle negative biconcave element and a rear positive biconvex element, said front element having two aspheric surfaces and said middle element having at least one aspheric surface wherein the lens focal length F, radii of curvature R, thicknesses T, air spaces S, vertex curvatures C and conic constants K, as numbered by subscript from front to rear, are as defined by the following relationships:
- 11 .ltoreq. F .ltoreq. 14 9 .ltoreq. R.sub.5 .ltoreq. 11 9 .ltoreq.-R.sub.6 .ltoreq. 11 3 .ltoreq. T.sub.1 .ltoreq. 5 0.8 .ltoreq. T.sub.2 .ltoreq. 0.9 2 .ltoreq. T.sub.3 .ltoreq. 3 0.8 .ltoreq. S.sub.2 .ltoreq. 1.5 0.9 .ltoreq. S.sub.3 .ltoreq. 1.5 0.13 .ltoreq. C.sub.1 .ltoreq. 0.16 0.06 .ltoreq.-C.sub.2 .ltoreq. 0.08 0.08 .ltoreq.-C.sub.3 .ltoreq. 0.09 0.21 .ltoreq. C.sub.4 .ltoreq. 0.24 .75 .ltoreq.-K.sub.1 .ltoreq. .85 17 .ltoreq.-K.sub.2 .ltoreq. 26.
Dependencies are inferred from the claim text.