An optical device includes a first zone including a first plurality of nanoscale elements. The first plurality of nanoscale elements has a first optical dispersion profile and a first orientation. The optical device has a second zone including a second plurality of nanoscale elements. The second plurality of nanoscale elements has a second optical dispersion profile and a second orientation. The first orientation and the second orientation are configured according to constructive interference for a plurality of wavelengths and a focal length.