A dynamically actuable diffractive optical element (DOE) includes a substrate and a diffraction grating disposed on a first region of a surface of the substrate. The DOE further includes a quantity of a fluid disposed on a second region of the surface of the substrate, a fluid displacer disposed adjacent the second region of the surface of the substrate, and a drive signal source configured to send an electric signal to the fluid displacer. The fluid displacer is configured to, upon receiving the electric signal in a first state, causing a portion of the quantity of the fluid to be displaced from the second region of the surface into grooves of the diffraction grating, and upon receiving the electric signal in a second state, causing the portion of the quantity of the fluid to retract from the grooves of the diffraction grating to the second region of the surface.

A dynamically actuable diffractive optical element (DOE) includes a substrate and a diffraction grating disposed on a first region of a surface of the substrate. The DOE further includes a quantity of a fluid disposed on a second region of the surface of the substrate, a fluid displacer disposed adjacent the second region of the surface of the substrate, and a drive signal source configured to send an electric signal to the fluid displacer. The fluid displacer is configured to, upon receiving the electric signal in a first state, causing a portion of the quantity of the fluid to be displaced from the second region of the surface into grooves of the diffraction grating, and upon receiving the electric signal in a second state, causing the portion of the quantity of the fluid to retract from the grooves of the diffraction grating to the second region of the surface.

A grating collimator and backlight system provide collimated light to illuminate a backlight. The grating collimator includes a light guide configured to guide light as guided light and a light-recycling light source configured to provide light to the light guide and to recycle light received from the light guide. The grating collimator further includes a diffraction grating coupler configured to diffractively redirect the provided light into the light guide as the guided light. The backlight system includes the grating collimator configured to provide collimated output light and the backlight configured to receive the collimated output light. The backlight may be multiview backlight.

A grating collimator and backlight system provide collimated light to illuminate a backlight. The grating collimator includes a light guide configured to guide light as guided light and a light-recycling light source configured to provide light to the light guide and to recycle light received from the light guide. The grating collimator further includes a diffraction grating coupler configured to diffractively redirect the provided light into the light guide as the guided light. The backlight system includes the grating collimator configured to provide collimated output light and the backlight configured to receive the collimated output light. The backlight may be multiview backlight.

An optical module includes first and second transparent substrates and a spacer between the first and second transparent substrates, holding the first transparent substrate in proximity to the second transparent substrate, with first and second diffractive optical elements (DOEs) on respective faces of the first and second transparent substrates. At least first and second capacitance electrodes are disposed respectively on the first and second transparent substrates in proximity to the first and second DOEs. Circuitry is coupled to measure changes in a capacitance between at least the first and second capacitance electrodes.

An eyepiece for projecting an image to an eye of a viewer includes a first planar waveguide positioned in a first lateral plane, a second planar waveguide positioned in a second lateral plane adjacent the first lateral plane, and a third planar waveguide positioned in a third lateral plane adjacent the second lateral plane. The first planar waveguide includes a first diffractive optical element (DOE) coupled thereto and disposed at a first lateral position. The second planar waveguide includes a second DOE coupled thereto and disposed at a second lateral position. The third planar waveguide includes a third DOE coupled thereto and disposed at the second lateral position. The eyepiece further includes an optical filter positioned between the second planar waveguide and the third planar waveguide at the second lateral position.

An eyepiece for projecting an image to an eye of a viewer includes a first planar waveguide positioned in a first lateral plane, a second planar waveguide positioned in a second lateral plane adjacent the first lateral plane, and a third planar waveguide positioned in a third lateral plane adjacent the second lateral plane. The first planar waveguide includes a first diffractive optical element (DOE) coupled thereto and disposed at a first lateral position. The second planar waveguide includes a second DOE coupled thereto and disposed at a second lateral position. The third planar waveguide includes a third DOE coupled thereto and disposed at the second lateral position. The eyepiece further includes an optical filter positioned between the second planar waveguide and the third planar waveguide at the second lateral position.

A camera captures an image of a subject, and a light source illuminates with light a plane intersecting an optical axis of the camera at a prescribed angle. The processor generates guidance information related to a distance between the subject and the light source on the basis of a pixel value distribution of the image of the subject which is illuminated with the light, and outputs the generated guidance information.

A camera captures an image of a subject, and a light source illuminates with light a plane intersecting an optical axis of the camera at a prescribed angle. The processor generates guidance information related to a distance between the subject and the light source on the basis of a pixel value distribution of the image of the subject which is illuminated with the light, and outputs the generated guidance information.

A pupil-replicating lightguide includes a slab of transparent material, a switchable out-coupling grating for out-coupling portions of image light to propagate towards an eyebox, and a switchable tracking grating for redirecting tracking light carrying an eye image towards an eye tracking camera. One of the two gratings may be turned ON while the other is turned OFF, in a time-sequential manner, allowing the combined use of the pupil-replicating lightguide for carrying image light and eye tracking light.