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.

Techniques disclosed herein relate to a near-eye display system. One example of an eye-tracking system includes a substrate transparent to visible light and infrared light and a reflective holographic grating conformally coupled to a surface of the substrate. The reflective holographic grating is configured to transmit the visible light and reflectively diffract infrared light in a first wavelength range for eye tracking. The refractive index modulation of the reflective holographic grating is apodized in a direction along a thickness of the reflective holographic grating to reduce optical artifacts in the visible light.

Provided is a design method for a diffractive optical element for being used for projecting an oblique line. The method comprises: determining an angle θ between an oblique line and a first direction (S101); according to the angle, determining a first cycle d1 of a diffractive optical element in the first direction and a second cycle d2 of the diffractive optical element in a second direction, wherein the first direction is perpendicular to the second direction, and the first cycle d1 and the second cycle d2 satisfy tgθ=d1/d2 (S102); and obtaining a phase distribution map of the diffractive optical element according to the first cycle d1, the second cycle d2 and a target pattern with an oblique line at 45° (S103). By means of the design method, the visual effect of an optical field projected by means of a diffractive optical element can be improved.

The present invention provides a concave diffraction grating and an optical device using the concave diffraction grating, the concave diffraction grating being capable of preventing deformation of a reflection film due to the influence of temperature, and preventing deterioration in optical characteristic due to temperature. This concave diffraction grating is provided with: a reflection film (22) having a plurality of grating grooves (21); a holding film (25) comprising metal and having one surface on which the reflection film (22) is provided; a concave substrate (24) having a concave surface (24a); and an affixing layer (23) provided between the concave surface (24a) and the other surface of the holding film (25), and affixing the holding film (25) and the reflection film (22) to the concave substrate (24).

A grating structure for a diffractive optic includes grating lines, each of which is approximated by successive segments. Longitudinal axes of the segments each have an angle relative to a first coordinate axis of a reference coordinate system. A first section of a first one of the grating lines is approximated by a first group of the segments, and a second section adjacent to the first section of the first grating line is approximated by a second group of segments. The longitudinal axes of a major portion of the segments of the first group have a first predetermined angle relative to the first coordinate axis of the reference coordinate system, and the longitudinal axes of a major portion of the segments of the second group have a second predetermined angle different from the first predetermined angle relative to the first coordinate axis of the reference coordinate system.

A detection apparatus includes: a substrate; a metal nanostructure on a surface of the substrate and on which immobilized antibodies having a property of binding with a detection object substance are immobilized, the metal microstructure generating a surface plasmon by being irradiated with excitation light; an introducer that introduces labeled antibodies having a property of binding with the detection object substance and labeled with a fluorescent material, and a test solution containing the detection object substance into the metal nanostructure; a light source that irradiates the metal nanostructure with the excitation light from the back surface side of the substrate; and a photodetector that detects the detection object substance based on fluorescence generated from the fluorescent material in response to irradiation of the excitation light. The metal nanostructure includes a light transmissive portion that transmits, to the surface side of the substrate, the excitation light emitted from the back surface side thereof.

A method for producing security elements, security elements, a security document with at least one security element as well as a transfer film with at least one security element, wherein a three-dimensional object is recorded and a surface profile of the three-dimensional object, described by a function F(x,y), is determined, wherein the function F(x,y) describes the distance between the surface profile and a two-dimensional reference surface spanned by co-ordinate axes x and y at the co-ordinate points x and y. A first microstructure is determined in such a way that the structure height of the first microstructure is limited to a predetermined value smaller than the maximum distance between the surface profile and the two-dimensional reference surface, and the first microstructure provides an observer with a first optical perception which corresponds to the surface profile of the three-dimensional object described by the function F(x,y).

The present invention relates in particular to a security element (1) for a valuable document, which comprises an array (R) of at least two contiguous or adjacent lines (2, 2′, 2″), at least one of these lines (2) being raised and having two opposing and at least partially inclined sides (20, 21) that each originate along one of the longitudinal and opposing edges (200, 210) of the line (2), characterised by the fact that the two opposing inclined flanks (20, 21) meet at a single, uninterrupted, sinuous junction area (22), that extends in the longitudinal direction of the line (2), the sides (20, 21) having no discontinuities or interruptions at least in the longitudinal direction.

An eyepiece for use in front of an eye of a viewer includes a waveguide configured to propagate light therein, and a diffractive optical element optically coupled to the waveguide. The diffractive optical element includes a plurality of first ridges protruding from a surface of the waveguide. Each of the plurality of first ridges has a first height and a first width. The diffractive optical element further includes a plurality of second ridges. Each of the plurality of second ridges protrudes from a respective first ridge and has a second height greater than the first height and a second width less than the first width. The diffractive optical element is configured to diffract a portion of a light beam incident on the diffractive optical element toward the eye as a first order transmission.

An optical assembly may include a waveguide and a Bragg grating configured to couple light into or out of the waveguide. The Bragg grating may include a plurality of layer pairs, wherein at least one layer pair comprises a first material having a first refractive index and a second layer having a second refractive index, and wherein properties of the Bragg grating are selected so that the Bragg grating exhibits a substantially similar diffractive efficiency and diffraction angle for light of at least two colors.