Directional display apparatus

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;
• a first additional polariser arranged on the same side of the spatial light modulator as the display polariser, the first additional polariser being a linear polariser;
• at least one first polar control retarder arranged between the first additional polariser and the display polariser;
• a second additional polariser, the second additional polariser being a linear polariser;
• and
• at least one second polar control retarder, wherein either:
• the second additional polariser is arranged on the same side of the spatial light modulator as the first additional polariser outside the first additional polariser, and the at least one second polar control retarder is arranged between the first additional polariser and the second additional polariser;
• or
• the display device further comprises a backlight arranged to output light, the spatial light modulator comprises a transmissive spatial light modulator arranged to receive output light from the backlight, said display polariser is an input display polariser arranged on the input side of the spatial light modulator, and the display device further comprises an output display polariser arranged on the output side of the spatial light modulator, the second additional polariser is arranged on the output side of the spatial light modulator, and the at least one second polar control retarder is arranged between the second additional polariser and the output display polariser,
• wherein each of the at least one first polar control retarder and the at least one second polar control retarder comprises a respective switchable liquid crystal retarder comprising a layer of liquid crystal material and two surface alignment layers disposed adjacent to the layer of liquid crystal material and on opposite sides thereof, one of the surface alignment layers being arranged to provide homogenous alignment in the adjacent liquid crystal material and the other of the surface alignment layers being arranged to provide homeotropic alignment in the adjacent liquid crystal material.