  Metasurfaces are generally designed by placing scatterers in a periodic grid.
We propose and discuss design rules for efficient random and functional
metasurfaces with anisotropic elements. We investigate the impact of the
elements density on the performance of metasurfaces in both periodic and random
cases. Using numerical simulations, we apply our approach to the design of
all-polarization random metalenses at near infrared frequencies. The results
will open a new paradigm in the design of metamaterial and metasurface devices
from lenses to solar energy concentrators.
