Multi-focal lens

A lens (200) comprising: a surface (210) having a modulated relief comprising a plurality of regions including a first region (220) and a second region (230), wherein the first region is a region of phase adjustment configured to enlarge a depth of field of the lens, characterized in that the first region (220) has a depth (240) relative to the second region (230) of from about 1.0 microns to about 1.5 microns; and a plurality of nanostructures (260) are formed in the first region (220); wherein a spacing (280) between adjacent nanostructures (260) of the plurality of nanostructures is made smaller than the shortest wavelength in the visible spectrum such that the first region (220) does not substantially diffract visible light.