Anamorphic directional illumination device with selective light-guiding

An anamorphic near-eye display apparatus comprising:

• an illumination system comprising a spatial light modulator, the illumination system being arranged to output light;
• and
• an optical system arranged to direct light from the illumination system to a viewer's eye, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the spatial light modulator comprises pixels distributed in the lateral direction, and the optical system comprises:
• a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the spatial light modulator and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction;
• an extraction waveguide arranged to receive light from the transverse anamorphic component;
• a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide being arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction;
• and
• a light reversing reflector that is arranged to reflect light guided along the extraction waveguide in the first direction to form light that is guided along the extraction waveguide in a second direction opposite to the first direction,
• wherein:
• the extraction waveguide comprises:
• a front guide surface;
• a polarization-sensitive reflector opposing the front guide surface;
• and
• an extraction element disposed outside the polarization-sensitive reflector,
• the extraction element comprising:
• a rear guide surface opposing the front guide surface;
• and an array of extraction features;
• the anamorphic near-eye display apparatus is arranged to provide light guided along the extraction waveguide in the first direction with an input linear polarization state before reaching the polarization-sensitive reflector;
• and
• the optical system further comprises a polarization conversion retarder disposed between the polarization-sensitive reflector and the light reversing reflector, wherein the polarization conversion retarder is arranged to convert a polarization state of light passing therethrough between a linear polarization state and a circular polarization state, and the polarization conversion retarder and the light reversing reflector are arranged in combination to rotate the input linear polarization state of the light guided in the first direction so that the light guided in the second direction and output from the polarization conversion retarder has an orthogonal linear polarization state that is orthogonal to the input linear polarization state;
• the polarization-sensitive reflector is arranged to reflect light guided in the first direction having the input linear polarization state and to pass light guided in the second direction having the orthogonal linear polarization state, so that the front guide surface and the polarization-sensitive reflector are arranged to guide light in the first direction, and the front guide surface and the rear guide surface are arranged to guide light in the second direction;
• and
• the array of extraction features is arranged to extract light guided along the extraction waveguide in the second direction towards an eye of a viewer through the front guide surface, the array of extraction features being distributed along the extraction waveguide so as to provide exit pupil expansion in the transverse direction;
• wherein the polarization conversion retarder has a retardance of a quarter wavelength at a wavelength of visible light.