Ophtalmic diffractive lens for the correction of astigmatism.

摘要

The lens comprises diffracting components, the contour of which is delimited by non-degenerate centred conic sections. More precisely, according to the invention, the lens comprises adjacent diffracting components of hyperbolic or elliptical contour whose periodicity in r<2> in two mutually-orthogonal directions X, Y, passing through the axis of the lens and being coincident with the principal axes of the hyperbolae or ellipses is determined respectively by the expressions: DELTA r<2>x = 2 lambda ¦fx¦ , DELTA r<2>y = 2 lambda ¦fy¦ in which: DELTA r<2>x represents the periodicity in r<2> in the direction X, DELTA r<2>y represents the periodicity in r<2> in the direction Y, lambda represents the average wavelength of use, fx represents the desired focal point in the plane X and fy represents the desired focal point in the plane Y. ……