US Patent 8687040 Optical device with electrically variable extended depth of field

A system and method for providing an optical device with a variable extended depth-of-field (EDOF). The optical device includes an optically transparent liquid crystal layer, an optically transparent phase mask, optically aligned with the liquid crystal layer and separated therefrom by an optically transparent substrate, an optically transparent index-matching layer, disposed adjacent to one surface of the phase mask, and having a refractive index substantially matching that of the phase mask; and a pair of electrodes for generating an electric field acting on said liquid crystal layer to change the depth of field of the imaging system in proportion to the amplitude of a signal applied to the electrodes.