Spherical gradient-index lens designs for video-disk pickup lens or the like
AssigneeCorning Glass Works
InventorDuncan T. Moore
Life of this patent
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Abstract
Spherical singlet lenses of gradient index design, suitable for use as video disk lenses or the like, are provided wherein all orders of spherical abberation are sufficiently reduced to provide diffraction-limited axial imaging. This imaging is achieved without resorting to sixth-order refractive index profile control; only the profile parameters N.sub.00, N.sub.10 and N.sub.20 defining the radial index profile N(r) in the profile function: N(r)=N.sub.00 +N.sub.10 r.sup.2 +N.sub.20 r.sup.2 together with the surface curvatures and thickness of the lens, are used to control lens properties.
Claims6
A singlet lens having a thickness t and including opposing first and second refracting surfaces having spherical curvatures C.sub.1 and C.sub.2, respectively, and a radial refractive index gradient wherein the refractive index N of the lens varies with radial distance r from the optical axis of the lens approximately according to the power series expansion formula:
- N(r)=N.sub.00 +N.sub.10 r.sup.2 +N.sub.20 r.sup.4
- wherein the lens parameters C.sub.1, C.sub.2, t, N.sub.00, N.sub.10 and N.sub.20 are within the following ranges:
- 0.09.ltoreq.C.sub.1 .ltoreq.0.14 mm.sup.-1
- -0.04.ltoreq.C.sub.2 .ltoreq.0.05 mm.sup.-1
- 8.ltoreq.t.ltoreq.15 mm
- 1.35.ltoreq.N.sub.00 .ltoreq.1.9
- -0.0045.ltoreq.N.sub.10 .ltoreq.-0.0030 mm.sup.-2
- -1.times.10.sup.-4 .ltoreq.N.sub.20 .ltoreq.-1.times.10.sup.-7 mm.sup.-4
Dependencies are inferred from the claim text.