An optical device, comprising a first electrode layer and a second electrode layer provided at a distance (d) from the first electrode layer, which first and second electrode layer are light transmitting, and wherein the first electrode layer extends substantially parallel to the second electrode layer; wherein the optical device further comprises, in between the first and the second electrode layers: - a diffractive optical structure adjacent to the first electrode layer and comprising a Fresnel lens structure with multiple sloped surfaces (11, 11a, 11b) sloped relative to at least the first electrode layer; and - a liquid crystalline, 'LC', material filling a space between the Fresnel lens structure and the second electrode layer, wherein, in an off state, substantially all LC molecules of said LC material are oriented in an upright direction and, in an on state, a majority of the LC molecules are oriented in a laying direction, substantially parallel to a preferred alignment direction, the preferred alignment direction being parallel to the first electrode layer, and; wherein the multiple sloped surfaces of the Fresnel lens structure are adapted to provide, in the off state, a pretilt angle (α) to those LC molecules of the liquid crystalline material that are in contact with the multiple sloped surfaces such that projections (Npxy) of orientation vectors (Np) of those LC molecules on the first electrode layer, lie within a range of 60 degrees from the preferred alignment direction, resulting in the said majority of LC molecules to switch substantially parallel to the preferred alignment direction in the on-state, thereby compensating for the difference in slope angles of each of the multiple sloped surfaces; wherein the pretilt angle (α) is the angle between a surface normal vector of the sloped surface, and the orientation vector of those LC molecules in contact with the sloped surface and wherein the slope angle is the angle between the sloped surface and the preferred alignment direction in a plane that comprises the preferred alignment direction and a direction perpendicular to said first electrode layer. wherein the optical device further comprises, in between the first and the second electrode layers: - a diffractive optical structure adjacent to the first electrode layer and comprising a Fresnel lens structure with multiple sloped surfaces (11, 11a, 11b) sloped relative to at least the first electrode layer; and - a liquid crystalline, 'LC', material filling a space between the Fresnel lens structure and the second electrode layer, - a diffractive optical structure adjacent to the first electrode layer and comprising a Fresnel lens structure with multiple sloped surfaces (11, 11a, 11b) sloped relative to at least the first electrode layer; and - a liquid crystalline, 'LC', material filling a space between the Fresnel lens structure and the second electrode layer, wherein, in an off state, substantially all LC molecules of said LC material are oriented in an upright direction and, in an on state, a majority of the LC molecules are oriented in a laying direction, substantially parallel to a preferred alignment direction, the preferred alignment direction being parallel to the first electrode layer, and; wherein the multiple sloped surfaces of the Fresnel lens structure are adapted to provide, in the off state, a pretilt angle (α) to those LC molecules of the liquid crystalline material that are in contact with the multiple sloped surfaces such that projections (Npxy) of orientation vectors (Np) of those LC molecules on the first electrode layer, lie within a range of 60 degrees from the preferred alignment direction, resulting in the said majority of LC molecules to switch substantially parallel to the preferred alignment direction in the on-state, thereby compensating for the difference in slope angles of each of the multiple sloped surfaces; wherein the pretilt angle (α) is the angle between a surface normal vector of the sloped surface, and the orientation vector of those LC molecules in contact with the sloped surface and wherein the slope angle is the angle between the sloped surface and the preferred alignment direction in a plane that comprises the preferred alignment direction and a direction perpendicular to said first electrode layer.