A liquid crystal optical device for combination with a display unit, wherein the liquid crystal optical device is adapted to operate as a Fresnel lens, the liquid crystal optical device comprising: a first substrate having transparent plural strip electrodes formed to make groups in respective given areas; a lens line (11 p) comprising adjacent given areas, wherein the lens line has a virtual centre-line running parallel to the lens lines, and wherein the lens line and the strip electrodes both extend in a first direction; a second substrate; a transparent common electrode; a liquid crystal layer arranged between the first substrate and the second substrate, in which a retardation distribution is controlled in respective given areas according to voltages to be applied between the common electrode and the strip electrodes; wall spacers provided at boundaries between adjacent given areas, wherein the wall spacers extend between the first substrate and the second substrate; wherein, within a lens line, the width of a given area decreases with distance of the given area from the virtual centre-line of the lens line, the width of a given area being measured in a second direction which is in the plane of the liquid crystal layer and perpendicular to the first direction; wherein within a lens line, the strip electrodes are arranged to have a symmetrical relation with respect to a plane perpendicular to the first and second substrates and containing said virtual centre-line of the lens line; and wherein the liquid crystal optical device is adapted to operate as a Fresnel lens by controlling the voltage applied to the strip electrodes in a given area, with respect to the common electrode, so that within a given area, the voltage increases with distance from the virtual centre-line of the lens line, and the voltage applied to the strip electrode which is closest to the virtual centre-line is zero and characterized in that the common electrode is formed on the second substrate and, acting as a shield electrode, also formed on the whole surface of the wall spacers, wherein the shield electrode suppresses electric field leakage between adjacent given areas. a first substrate having transparent plural strip electrodes formed to make groups in respective given areas; a lens line (11 p) comprising adjacent given areas, wherein the lens line has a virtual centre-line running parallel to the lens lines, and wherein the lens line and the strip electrodes both extend in a first direction; a second substrate; a transparent common electrode; a liquid crystal layer arranged between the first substrate and the second substrate, in which a retardation distribution is controlled in respective given areas according to voltages to be applied between the common electrode and the strip electrodes; wall spacers provided at boundaries between adjacent given areas, wherein the wall spacers extend between the first substrate and the second substrate; wherein, within a lens line, the width of a given area decreases with distance of the given area from the virtual centre-line of the lens line, the width of a given area being measured in a second direction which is in the plane of the liquid crystal layer and perpendicular to the first direction; wherein within a lens line, the strip electrodes are arranged to have a symmetrical relation with respect to a plane perpendicular to the first and second substrates and containing said virtual centre-line of the lens line; and wherein the liquid crystal optical device is adapted to operate as a Fresnel lens by controlling the voltage applied to the strip electrodes in a given area, with respect to the common electrode, so that within a given area, the voltage increases with distance from the virtual centre-line of the lens line, and the voltage applied to the strip electrode which is closest to the virtual centre-line is zero and characterized in that the common electrode is formed on the second substrate and, acting as a shield electrode, also formed on the whole surface of the wall spacers, wherein the shield electrode suppresses electric field leakage between adjacent given areas.