Patent ID: 7342728

Claim:
Fresnel lens comprising: a first face lying in a plane; and opposite this face, a second face parallel to the first face; and including circular concentric refractive structures, each refractive structure being defined by: a first surface intended to form a refractive diopter and making a first angle with the said plane and a second surface without optical purpose and making a second angle with the normal to the said plane, each said structure being intended to be illuminated by a beam making an entrance angle different from zero degrees with the normal to the said plane, the directions of said beam and of said normal being substantially different, wherein the second face has at least two zones of refractive structures distributed between the centre of the concentric refractive structures and the periphery of the Fresnel lens: a first zone close to the centre, in which: the first angle of each first surface is such that the refractive structures refract the said beam along a direction making a zero angle relative the optical axis of said lens and the second angle of each second surface is equal to the said entrance angle; a second zone in which: the first angle of each first surface is such that the refractive structures refract the said beam along a direction making a non-zero angle smaller than a maximum value relative to the optical axis and the second angle of each second surface is equal to the said entrance angle.