Patent ID: 9746693
Date: 2017-08-29
CPC Classifications: A61F,G02B,G02C

Claim:
1. A simultaneously bifocal optical system, the said optical system being defined by a first system focal point and a second system focal point and a pupil, said system comprising: a simultaneously bifocal diffractive lens component having a first focal point, a second focal point and a plurality of diffractive zones, the plurality of diffractive zones including a central zone and a plurality of annular concentric zones surrounding the central zone, the lens component having a first optical power P1 and a second optical power P2 associated with the first focal point and the second focal point respectively, the first focal point and the second focal point respectively corresponding to points of convergence of the most luminous orders of diffraction generated by the lens component for a nominal wavelength, the first system focal point and the second system focal point having a position dependent upon a value of the first optical power P1 and the second optical power P2 of the lens respectively, wherein the central zone has a surface area value configured such that a predetermined optical performance optimization parameter φ is optimized, said optical performance optimization parameter φ being considered in the vicinity of the first and second system focal points and varying as a function of a surface area value of the central zone without modifying the operational function of the diffractive zones, said predetermined optical performance optimization parameter φ being such as the brightness and/or the Modulation Transfer Function in the vicinity of the first and second system focal points, whereby the central zone has a surface area value determined as a function of the pupil of the optical system, of the first optical power P1 and of the second optical power P2, and the surface area of the annular zones surrounding the central zone does not change with the optimization parameter φ while the area of the central zone does change with optimization parameter φ.