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AssigneeEssilor International-Compagnie Generale
InventorsDominique Baude, Pierre Chavel, Denis Joyeux, Jean Taboury
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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.
A lens for correcting astigmatism, including adjacent hyperbolic- or elliptical-outline diffractive components whose periodicity in two mutually orthogonal X and Y directions intersecting at the axis of the lens and coinciding with the main axes of the hyperbolas or the ellipses are respectively determined by the equations:
Dependencies are inferred from the claim text.