A device includes a waveguide, an in-coupling element, and an out-coupling element coupled with the waveguide. The waveguide, the in-coupling element, and the out-coupling element are configured to deliver a plurality of portions of an image light to an eye-box of the device. At least one of the in-coupling element or the out-coupling element includes a polarization selective diffractive element. The polarization selective diffractive element includes a grating including a plurality of microstructures defining a plurality of grooves filled with a passive optically anisotropic material having a first effective refractive index along a groove direction of the grooves and a second effective refractive index along an in-plane direction perpendicular to the groove direction. One of the first effective refractive index or the second effective refractive index substantially matches with a refractive index of the microstructures.

Fiducial patterns that produce 2D Barker code-like diffraction patterns at a camera sensor are etched or otherwise provided on a cover glass in front of a camera. 2D Barker code kernels, when cross-correlated with the diffraction patterns captured in images by the camera, provide sharp cross-correlation peaks. Misalignment of the cover glass with respect to the camera can be derived by detecting shifts in the location of the detected peaks with respect to calibrated locations. Devices that include multiple cameras behind a cover glass with one or more fiducials on the cover glass in front of each camera are also described. The diffraction patterns caused by the fiducials at the various cameras may be analyzed to detect movement or distortion of the cover glass in multiple degrees of freedom.

Diffraction-based imaging systems are described. Aspects of the technology relate to imaging systems having one or more sensors inclined at angles with respect to a sample plane. In some cases, multiple sensors may be used that are, or are not, inclined at angles. The imaging systems may have no optical lenses and are capable of reconstructing microscopic images of large sample areas from diffraction patterns recorded by the one or more sensors. Some embodiments may reduce mechanical complexity of a diffraction-based imaging system. A diffractive imaging system comprises a light source, a sample support configured to hold a sample along a first plane, and a first sensor comprising a plurality of pixels disposed in a second plane that is tilted at an inclined angle relative to the first plane. The first sensor is arranged to record diffraction images of the light source from the sample.

In an optical system, a first optical section having positive power, a second optical section provided with a first diffractive element and having positive power, a third optical section having positive power, and a fourth optical section provided with a second diffractive element and having positive power are disposed along a light path of image light emitted from an image light generation device. A first intermediate image of the image light is formed between the first optical section and the third optical section, a pupil is formed in the vicinity of the third optical section, a second intermediate image of the image light is formed between the third optical section and the fourth optical section, and the fourth optical section collimates the image light to form an exit pupil. The first diffractive element and the second diffractive element are in a conjugate relation or a roughly conjugate relation.

A device includes an array of light sources configured to emit light beams, and a metasurface including a plurality of nanostructures and configured to receive and deflect the light beams emitted by the array of light sources. The metasurface includes a plurality of regions. Nanostructures in different regions of the plurality of regions are configured to deflect center light rays (with peak intensity) of the light beams into different directions towards a target, such as display optics of a near-eye display. In some embodiments, nanostructures in each region of the plurality of regions are configured to deflect center light rays of light beams of two or more different colors into a same direction or similar directions towards the target.

A waveguide apparatus includes a planar waveguide and at least one optical diffraction element (DOE) that provides a plurality of optical paths between an exterior and interior of the planar waveguide. A phase profile of the DOE may combine a linear diffraction grating with a circular lens, to shape a wave front and produce beams with desired focus. Waveguide apparati may be assembled to create multiple focal planes. The DOE may have a low diffraction efficiency, and planar waveguides may be transparent when viewed normally, allowing passage of light from an ambient environment (e.g., real world) useful in AR systems. Light may be returned for temporally sequentially passes through the planar waveguide. The DOE(s) may be fixed or may have dynamically adjustable characteristics. An optical coupler system may couple images to the waveguide apparatus from a projector, for instance a biaxially scanning cantilevered optical fiber tip.

In a 3D imaging method using scanning-type coherent diffraction, a 2D photodetector detects diffraction of a coherent beam emitted from a light source that moves in a scanning manner toward a sample object to obtain multiple 2D diffraction data distributions; and a processor converts the 2D diffraction data distributions into multiple 3D intensity distributions in a reciprocal space, performs one or more iterations based on a sample function, a light source function and the 3D intensity distributions to obtain a phase-retrieval sample function, and generates a 3D reconstruction image of the sample object based on the phase-retrieval sample function.

A retina scanning type display apparatus includes a scanning portion, a deflection member, and a light flux diameter expanding element. An incidence angle range in a first incidence direction with respect to an eye from the deflection member is broader than an incidence angle range in a second incidence direction, and, in the light flux diameter expanding element, an expanding magnification of light flux diameter in a first expanding direction, which corresponds to the first incidence direction, is greater than an expanding magnification of light flux diameter in a second expanding direction, which corresponds to the second incidence direction. In addition, in the scanning mirror, a width in a first scanning direction, which corresponds to the first expanding direction, is narrower than a width in a second scanning direction, which corresponds to the second expanding direction.

An image projection device includes: a light source that emits a laser beam; a control unit that generates an image light beam, and controls emission of the image light beam; a scan unit that scans the image light beam to convert it into scan light; a first light converging unit that is disposed before a user's eye, converges the scan light at a first convergence point near a pupil, and then irradiates the retina with the scan light to project the image on the retina; and a second light converging unit that converges the scan light at a second convergence point before the first light converging unit, and then irradiates the first light converging unit with the scan light; wherein a scan angle of the scan light is substantially the same size as a convergence angle at which the scan light converges to the first convergence point.

In an optical element, a first diffraction grating, second diffraction grating, a third diffraction grating, and a fourth diffraction grating are formed in each of a first surface of a first substrate, a fourth surface of a second substrate, a fifth surface of a third substrate, and an eighth surface of a fourth substrate. Each substrate is fixed by (a first adhesive layer, second adhesive layer, and a third adhesive layer) adhesive layers including a gap material. A first filler with a refractive index equal to that of the first substrate and the second substrate is filled between the first substrate and the second substrate and a third filler formed of air or a medium with a refractive index equal to that of air is filled between the second substrate and the third substrate.