Stabilization for privacy display

A display device comprising:

• a spatial light modulator;
• a display polariser arranged on a side of the spatial light modulator, the display polariser being a linear polariser;
• an additional polariser arranged on the same side of the spatial light modulator as the display polariser, the additional polariser being a linear polariser;
• and
• at least one polar control retarder arranged between the additional polariser and the display polariser,
• wherein the at least one polar control retarder comprises a switchable liquid crystal retarder comprising:
• first and second support substrates;
• a liquid crystal layer disposed between the first and second transparent support substrates, the liquid crystal layer comprising non-curable liquid crystal material and cured polymer material, wherein the cured polymer material comprises a cured liquid crystal material;
• electrodes arranged to apply a voltage for controlling the liquid crystal layer, wherein the cured liquid crystal material has an alignment that is aligned with the alignment of the non-curable liquid crystal material in a state in which a predetermined voltage is applied to the electrodes;
• and
• respective liquid crystal alignment layers supported on the first and second support substrates adjacent the liquid crystal layer for aligning the non-curable liquid crystal material, wherein the predetermined voltage is capable of causing the layer of cured liquid crystal material and non-curable liquid crystal material simultaneously to introduce no net relative phase shift to orthogonal polarisation components of light passed by the display polariser along an axis along a normal to the plane of the at least one polar control retarder and to introduce a net relative phase shift to orthogonal polarisation components of light passed by the additional polariser along an axis inclined to the normal to the plane of the at least one polar control retarder.