Geometric phase optical element and three-dimensional display apparatus including the same

A three-dimensional display apparatus comprising:

• a light source;
• a light guide plate configured to guide a beam incident from the light source;
• at least one geometric phase optical element configured to change a deflection angle of light incident from the light guide plate;
• and
• a spatial light modulator configured to form a hologram image using light transmitted through the at least one geometric phase optical element,
• wherein the at least one geometric phase optical element comprises a liquid crystal layer in which a liquid crystal is arranged and through which the incident light is transmitted, a first electrode on a surface of the liquid crystal layer, and a second electrode on another surface of the liquid crystal layer,
• wherein, when no voltage is applied to the first electrode and the second electrode, a phase difference, between first light having a first polarization state and second light having a second polarization state perpendicular to the first polarization state, according to an arrangement of the liquid crystal is π and light transmitted through the liquid crystal layer is diffracted by a first deflection angle,
• wherein, when a first voltage is applied to the first electrode and the second electrode, the phase difference according to the arrangement of the liquid crystal is π/2 and the transmitted light is diffracted by a second deflection angle,
• wherein, when a second voltage is applied to the first electrode and the second electrode, the phase difference according to the arrangement of the liquid crystal is 0 and the transmitted light is diffracted by a third deflection angle,
• wherein the first deflection angle is larger than the second deflection angle, and
• wherein the second deflection angle is larger than the third deflection angle.