DIFFRACTIVE TRIFOCAL LENS Russian patent published in 2014 - IPC G02B3/10 

FIELD: physics, optics.

SUBSTANCE: diffractive lens comprises an optical element having a first optical surface having a profile comprising a plurality of concentric annular zones. The optical thickness of the lens changes monotonically within each zone and a distinct step in optical thickness occurs at the junction between the zones. The height of the steps differs between at least some adjacent zones. A pattern of step height differences between two or more adjacent zones repeats periodically from the centre to the edge of the lens so as to form diffraction order efficiencies of the optical element. The method of manufacture involves modelling an optical element having a periodic profile pattern; calculating from the model a diffractive efficiency distribution for light propagating through the optical element; selecting dimension parameters to achieve desired diffractive efficiencies for at least three corresponding diffraction orders of the lens; and forming a periodic surface profile pattern.

EFFECT: improving operation of a multifocal lens at far, intermediate and near distances by directing the required level of light energy to corresponding diffraction orders.

24 cl, 7 dwg