A dental scanning system comprises an intraoral scanner and one or more processors. The intraoral scanner comprises one or more light projectors configured to project a pattern (comprising a plurality of pattern features) on a surface of a dental object, and two or more cameras configured to acquire one or more sets of images, wherein each set of images comprises at least one image from each camera, and wherein each image includes at least a portion of the projected pattern. The processors are configured to determine one or more image features within each set of images, solve a correspondence problem within each set of images such that points in 3D space are determined based on the image features, wherein said points form a solution to the correspondence problem, and wherein the correspondence problem is solved for groups of pattern features, and generate a digital 3D representation of the dental object using the solution to the correspondence problem.

Disclosed are a diffractive optical element, a design method thereof and the application thereof in a solar cell. The design method for a design modulation thickness of a sampling point of the diffractive optical element comprises: calculating the modulation thickness of the current sampling point for each wavelength component; obtaining a series of alternative modulation thicknesses which are mutually equivalent for each modulation thickness, wherein a difference between the corresponding modulation phases is an integral multiple of 2; and selecting one modulation thickness from the alternative modulation thicknesses of each wavelength to determine the design modulation thickness of the current sampling point. In an embodiment, the design method introduces a thickness optimization algorithm into a Yang-Gu algorithm. The design method breaks through limitations to the modulation thicknesses/modulation phases in the prior art and increases the diffraction efficiency, and the obtained diffractive optical element facilitates mass production by a modern photolithographic technique, which greatly reduces the cost. The diffractive optical element may also be applied to the solar cell, which provides an efficient and low-cost way for solar energy utilization.

A defect detection system for an extreme ultraviolet lithography mask comprises an extreme ultraviolet light source (1), extreme ultraviolet light transmission parts (2, 3), an extreme ultraviolet lithography mask (4), a photon sieve (6) and a collection (7) and analysis (8) system. Point light source beams emitted by the extreme ultraviolet light source (1) are focused on the extreme ultraviolet lithography mask (4) through the extreme ultraviolet light transmission parts (2, 3); the extreme ultraviolet lithography mask (4) emits scattered light and illuminates the photon sieve (6); and the photon sieve (6) forms a dark field image and transmits the same to the collection (7) and analysis (8) system. The defect detection system for the extreme ultraviolet photolithographic mask uses the photon sieve to replace a Schwarzchild objective, thereby realizing lower cost, relatively small size and high resolution.

Examples are disclosed that relate to compact optical systems comprising SLMs. One example provides a projection system comprising an illumination stage including a light emitting diode (LED) array. The LED array comprises a plurality of red LEDs, a plurality of green LEDs, and a plurality of blue LEDs. The illumination stage further comprises an illumination stage optical system configured to control an angular extent of light emitted by the LED array and homogenize the light emitted by the LED array. The projection system further comprises an image forming stage configured to form an image from light output by the illumination stage, the image forming stage comprising a spatial light modulator (SLM) configured to spatially modulate the light output by the illumination stage to form an image, and one or more projection optics configured to project the image formed by the spatial light modulator.

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.

A system comprises an intraoral scanning device and a processor. The intraoral scanning device comprises a wand including a probe, one or more light projectors disposed in the probe and configured to project a non-coded structured light pattern comprising pattern features, two or more cameras disposed in the probe and configured to acquire one or more sets of images each including one or more image features of at least a portion of the projected non-coded structured light pattern, and a mirror, wherein a light projector and a camera are positioned to face the mirror. The processor is configured to solve a correspondence problem within each set of images such that points in 3D space are determined based on the one or more image features, wherein said points form a solution to the correspondence problem, and wherein the correspondence problem is solved for one or more pattern features.

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.

A display apparatus for displaying a virtual image (VIMG1) includes a rotating expander device (EPE1) to form light beams (B3.sub.P0,R,B3.sub.P1,R) of output light (OUT1) by expanding light beams (B0.sub.P0,R,B0.sub.P1,R) of input light (IN1), the expander device (EPE1) includes: a waveguide plate (SUB1), an in-coupling element (DOE1) to form first guided light (B1a) and second guided light (B1c) by coupling input light (IN1) into the waveguide plate (SUB1), a first out-coupling element (DOE3a) to form output light (OUT1) by coupling the first guided light (B1a) out of the waveguide plate (SUB1), and a second out-coupling element (DOE3c) to form output light (OUT1) by coupling the second guided light (B1c) out of the waveguide plate (SUB1). The in-coupling element (DOE1) has a first input grating vector (V.sub.1a) and a second input grating vector (V.sub.1c), and an angle (.sub.1ac) between the first and second input grating vectors is between 60 and 120.

A laser processing system includes a laser apparatus configured to output pulse laser light; a diffractive optical element configured to divide the pulse laser light into multiple first diffracted luminous fluxes to be radiated to multiple processing points on a workpiece, and multiple second diffracted luminous fluxes to be radiated to multiple non-processing points on the workpiece; a focusing optical system configured to focus each of the first and second diffracted luminous fluxes at the workpiece; an adjustment mechanism configured to adjust pulse energy of the pulse laser light incident on the diffractive optical element; and a processor configured to control the adjustment mechanism based on parameters including a processing threshold Fth of a fluence for processing the workpiece in such a way that a fluence F.sub.OKm of the first diffracted luminous fluxes at a surface of the workpiece is greater than the processing threshold Fth, and a fluence F.sub.NGm of the second diffracted luminous fluxes at the surface of the workpiece is smaller than or equal to the processing threshold Fth.

A system comprises an intraoral scanning device and a processor. The intraoral scanning device comprises a wand including a probe, one or more light projectors disposed in the probe and configured to project a structured light pattern, wherein the structured light pattern comprises first pattern features of a first type and second pattern features of a second type, and two or more cameras disposed in the probe and configured to acquire one or more sets of images. The processor is configured to solve a correspondence problem within each set of images such that first points in 3D space are determined based on a captured subset of the first pattern features and a corresponding projected subset of the first pattern features and second points in 3D space are determined based on a captured subset of the second pattern features and a corresponding projected subset of the second pattern features.