The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 21, 1991
Filed:
Feb. 05, 1990
Dominique Baude, Saint Ouen, FR;
Pierre Chavel, Chilly Mazarin, FR;
Denis Joyeux, Les Ulis, FR;
Jean Taboury, Sceaux, FR;
Essilor International-Compagnie Generale, Cedex, FR;
Abstract
The present invention relates to an optical lens for correcting astigmatism. It includes diffractive components whose outlines are delimited by conic section curves having non-degenerate centers. More precisely, in accordance with the invention, the lens includes adjacent diffractive components having hyperbolic or elliptical outlines with a periodicity in r.sup.2 in two mutually orthogonal directions x and y intersecting on the axis of the lens and coinciding with the main axes of the hyperbolas or of the ellipses, which are determined respectively by the equations: .DELTA.r.sub.x.sup.2 =2.lambda..vertline.f.sub.x .vertline.; and .DELTA.r.sub.y.sup.2 =2.lambda..vertline.f.sub.y .vertline.; in which: .DELTA.r.sub.x.sup.2 represents the periodicity in r.sup.2 along the x direction; .DELTA.r.sub.y.sup.2 represents the periodicity in r.sup.2 along the y direction; .lambda. represents the mean utilization wavelength; f.sub.x represents the desired focal length in the X direction; and f.sub.y represents the desired focal length in the Y direction.