Unidirectional grating-based backlighting includes a light guide and a diffraction grating at a surface of the light guide. The light guide is to guide a light beam and the diffraction grating is configured to couple out a portion of the guided light beam using diffractive coupling and to direct the coupled-out portion away from the light guide as a primary light beam at a principal angular direction. The diffraction grating is to further produce a secondary light beam directed into the light guide at an opposite one of the principal angular direction. The unidirectional grating-based backlighting further includes an angularly selective reflective layer within the light guide adjacent to the light guide surface that is configured to reflectively redirect the diffractively produced, secondary light beam out of the light guide in the direction of the primary light beam.

An optical source for an extreme ultraviolet (EUV) photolithography tool includes a light-generation system including a light-generation module; an optical amplifier including a gain medium associated with a gain band, the gain medium configured to amplify light having a wavelength in the gain band; and a wavelength-based optical filter system on a beam path between the light-generation module and the optical amplifier, the wavelength-based optical filter system including at least one optical element configured to allow light having a wavelength in a first set of wavelengths to propagate on the beam path and to remove light having a wavelength in a second set of wavelengths from the beam path, the first set of wavelengths and the second set of wavelengths including different wavelengths in the gain band of the optical amplifier.

The present invention provides a projector, wherein the projector includes a light-emitting device, a lens module having a diffuser part and a lens part, and a DOE. In the operations of the projector, the light-emitting device is arranged for generating at least one laser beam, and the at least one laser beam passes through the diffuser part and the DOE to illuminate a field of view, and the at least one laser beam passes through the lens part and the DOE to generate a plurality of dots.

A system for an extreme ultraviolet (EUV) light source includes a light-generation system configured to emit one or more light beams onto a beam path; one or more optical amplifiers, each of the one or more amplifiers including a gain medium on the beam path, each gain medium being configured to amplify the one or more light beams to produce one or more amplified light beams; and one or more diffractive optical elements on the beam path, where each of the one or more diffractive optical elements has a plurality of focal lengths, and each focal length of the diffractive optical element is associated with a particular polarization state.

A diffractive optical element is configured to provide desired diffracted light and is excellent in durability. The diffractive optical element shapes light from a light source, wherein the diffractive optical element is provided with a diffractive layer having a periodic structure having low refractive index portions and high refractive index portions, and the high refractive index portions of the periodic structure include one having an aspect ratio of 2 or more.

To protect observer's eyes while forming a clear illumination pattern on a desired region to be illuminated. An illumination device includes a light source that emits coherent light, a collimating optical system that enlarges and collimates a beam diameter of the coherent light emitted from the light source, and a diffractive optical element that diffracts the coherent light collimated by the collimating optical system into a predetermined diffusion angle space. The diffractive optical element has a plurality of element diffractive optical portions and has a function to illuminate the region to be illuminated defined at a predetermined position and having predetermined size and shape to form the desired illumination pattern. Each of the plurality of element diffractive optical portions has a function to illuminate at least a part of the region to be illuminated, and diffractive characteristics of the element diffractive optical portions are different from each other.

An apparatus for intraoral scanning includes an elongate handheld wand that has a probe. One or more light projectors and two or more cameras are disposed within the probe. The light projectors each has a pattern generating optical element, which may use diffraction or refraction to form a light pattern. Each camera may be configured to focus between 1 mm and 30 mm from a lens that is farthest from the camera sensor. Other applications are also described.

A handheld wand comprises a probe at a distal end of the elongate handheld wand. The probe includes a light projector and a light field camera. The light projector includes a light source and a pattern generator configured to generate a light pattern. The light field camera includes a light field camera sensor, the light field camera sensor comprising an image sensor comprising an array of sensor pixels, and an array of micro-lenses disposed in front of the image sensor such that each micro-lens is disposed over a sub-array of the array of sensor pixels.

An imaging optical unit comprises a plurality of minors for imaging an object field into an image field. The imaging optical unit has an image-side numerical aperture greater than 0.55. Each mirror is configured so that it can be measured by a testing optical unit having at least one DOE with a predetermined maximum diameter for test wavefront generation. For the complete measurement of all reflection surfaces of the minors, a maximum number of DOEs of the testing optical unit and/or a maximum number of DOE test positions of the at least one DOE of the testing optical unit comes into play, which is no more than five times the number of minors in the imaging optical unit. The result is an imaging optical unit in which a testing-optical measurement remains manageable even in the case of a design with an image-side numerical aperture which is relatively large.

An optical device is disclosed for use in an augmented reality or virtual reality display, comprising a waveguide (12; 22; 32) and an input diffractive optical element (H0; H3; 34) positioned in or on the waveguide, configured to receive light from a projector and couple it into the waveguide so that it is captured within the waveguide under total internal reflection. The input diffractive optical element has an input grating vector (G0; G.sub.ig) in the plane of the waveguide. The device includes a first diffractive optical element (H1; H4) and a second diffractive optical element (H2; H5) having first and second grating vectors (G2, G3; GV1, GV2) respectively in the plane of the waveguide, wherein the first diffractive optical element is configured to receive light from the input diffractive optical element and to couple it towards the second diffractive optical element, and wherein the second diffractive optical element is configured to receive light from the first diffractive optical element and to couple it out of the waveguide towards a viewer. The input grating vector, the first grating vector and the second grating vector have different respective magnitudes, and wherein a vector addition of the input grating vector, the first grating vector and the second grating vector sums to zero.