An optical device, comprising: —a first electrode layer; —a second electrode layer provided at a distance from the first electrode layer; —the first and second electrode layer being light transmitting; wherein the optical device further comprises, in between the first and the second electrode layers: o a diffractive optical element adjacent to the first electrode layer and comprising at least one sloped surface; and o a liquid crystalline material filling a space between the sloped surface and the second electrode layer; the liquid crystalline material having a pretilt that compensates for a slope angle of the at least one sloped surface.