To improve brightness of image information visually recognized by a user while using plastic for a light guide plate. An image display element includes: a substrate made of resin; an incident diffraction grating that diffracts incident light; and an exit diffraction grating that emits the light, the incident diffraction grating being formed on a first surface of the substrate, the exit diffraction grating being formed on a second surface on a side opposite to the first surface of the substrate, and the exit diffraction grating being formed on one surface.

A meta lens assembly includes a first meta lens, a second meta lens arranged on an image side of the first meta lens, and a third meta lens arranged on an image side of the second meta lens, the first meta lens, the second meta lens, and the third meta lens being arranged from an object side of the meta lens assembly to an image side of the meta lens assembly facing an image sensor.

An optical structure is provided. The optical structure includes an optical element and a plurality of protrusions. The optical element has a planarized top surface. The plurality of protrusions are disposed on the planarized top surface, wherein each of the plurality of protrusions independently has a size in the subwavelength dimensions.

Techniques for designing diffractive optical elements (DOEs) such as diffusers and other optical beam shaping elements can include designing a DOE unit cell on a smaller area than the overall area of the DOE, and then distributing the unit cell across the entire surface for the DOE. Height translations are introduced for at least some of the unit cells distributed across the surface, where the height translations correspond to respective phase translations for the intended operational wavelength of the DOE. In some instances, phase wrapping is introduced to translate the height variations among the unit cells into unit cells having sub-unit structures whose heights fall within a range that corresponds to a specified phase range at the operational wavelength.

Disclosed herein are metasurfaces formed on a substrate from a plurality of posts. The metasurfaces are configured to be optically active at one or more wavelengths and in certain embodiments are configured to form lenses having unexpectedly strong focusing power. In particular, the metasurfaces are formed from “low-contrast” materials, including CMOS-compatible materials such as silicon dioxide or silicon nitride. Accordingly, the disclosed metasurfaces are generally CMOS compatible and therefore embody a new paradigm in metasurface design and manufacturing.

An optical element may include a substrate. The optical element may include a first anti-reflectance structure for a particular wavelength range formed on the substrate. The optical element may include at least one layer disposed on a portion of the first anti-reflectance structure. The optical element may include a second anti-reflectance structure for the particular wavelength range formed on the at least one layer. A depth between a first surface of the first anti-reflectance structure and a second surface of the second anti-reflectance structure, a first index of refraction of the first anti-reflectance structure, a second index of refraction of the second anti-reflectance structure, and a third index of refraction of the at least one layer may be selected to form a diffractive optical element associated with a particular phase delay for the particular wavelength.

An image sensor includes a sensor substrate including a plurality of pixels configured to sense light; a color separation lens array including a plurality of pixel corresponding regions facing the plurality of pixels, wherein each pixel corresponding region of the plurality of pixel corresponding regions includes one or more nanoposts, and the one or more nanoposts are configured to form a phase profile that separates incident light for each wavelength, and to concentrate light in different wavelength bands on the plurality of pixels; and a filter array positioned between the sensor substrate and the color separation lens array, and including a plurality of transparent regions altematingly arranged with a plurality of filters corresponding to a single color.

An optical device includes an overcoat layer on a surface-relief grating. The overcoat layer is formed by a process including: depositing a layer of a first resin material that is curable by heat or electromagnetic radiation on a surface-relief grating that includes a plurality of grating ridges and a plurality of grating grooves to at least partially fill the plurality of grating grooves, curing the layer of the first resin material, depositing a layer of a second resin material that is curable by heat or electromagnetic radiation and has a higher flowability than the first resin material on the layer of the first resin material, annealing the layer of the second resin material to allow the second resin material to flow and form a planar top surface, and curing the layer of the second resin material.

An optical device is formed by hot stamping a demetallized hologram to an optically variable foil or to a coating of optically variable ink. In another embodiment a hologram is hot stamped to a banknote or document printed with a color-shifting ink.

A welding torch maintenance apparatus and a welding tip changer are described. The welding torch maintenance apparatus and the welding tip changing apparatus each comprise a first gripping means for fastening the welding torch/diffuser so that the nozzle/welding tip is aligned with the rotational axis, a second gripping means for holding the nozzle/welding tip, the second gripping means rotates about the rotational axis to remove the nozzle/welding tip, and moves along the rotational axis. A drive means is provided for rotating the second gripping means, and a lift system is provided for moving the second gripping along the rotational axis. The welding torch maintenance apparatus further includes a cleaning means which enters the nozzle at the distal end and cleans an interior of the nozzle.