Disclosed are optical devices suitable as security devices for document authentication, which comprise at least one two-dimensional array of elongate laser-modified tracks extending within a document substrate that have a distinct optical refractive index compared to the unmodified substrate, which can exhibit excellent diffractive effects. Also disclosed are the use of such devices for document authentication and methods for their production.

A method is disclosed for dividing a composite material in which a brittle material layer and a resin layer are laminated, including: irradiating the resin layer with a laser beam L1 oscillated from a CO.sub.2 laser source along scheduled dividing lines DL of the composite material to form a processing groove along the scheduled dividing lines; and irradiating the brittle material layer with a laser beam L2 oscillated from an ultrashort pulsed laser source along the scheduled dividing lines to form a processing mark along the scheduled dividing lines. In the resin removing step, in a region IS where the scheduled dividing lines intersect, the laser beam oscillated from the CO.sub.2 laser source is not irradiated multiple times, or an irradiation amount of the laser beam is decreased relative to an irradiation amount in a region other than a region where the scheduled dividing lines intersect.

A method is disclosed for dividing a composite material in which a brittle material layer and a resin layer are laminated, including: irradiating the resin layer with a laser beam L1 oscillated from a CO.sub.2 laser source along scheduled dividing lines DL of the composite material to form a processing groove along the scheduled dividing lines; and irradiating the brittle material layer with a laser beam L2 oscillated from an ultrashort pulsed laser source along the scheduled dividing lines to form a processing mark along the scheduled dividing lines. In the resin removing step, in a region IS where the scheduled dividing lines intersect, the laser beam oscillated from the CO.sub.2 laser source is not irradiated multiple times, or an irradiation amount of the laser beam is decreased relative to an irradiation amount in a region other than a region where the scheduled dividing lines intersect.

A golf club head has a striking face with a plurality of scorelines including a first scoreline and a second scoreline adjacent thereto. The striking face also has a plurality of auxiliary grooves each spaced from the scorelines. In a first imaginary vertical plane, a first path is formed by a first intersection between the first imaginary vertical plane and the striking face, and the auxiliary grooves have a first concentration no less than 0.17 measured between the first and second scorelines. A second imaginary vertical plane is horizontally spaced from the first imaginary plane. A second path is formed in the second imaginary vertical plane by a second intersection between the second imaginary vertical plane and the striking face. The auxiliary grooves in the second imaginary vertical plane have a second concentration that is different from the first concentration measured between the first and second scorelines.

A golf club head has a striking face with a plurality of scorelines including a first scoreline and a second scoreline adjacent thereto. The striking face also has a plurality of auxiliary grooves each spaced from the scorelines. In a first imaginary vertical plane, a first path is formed by a first intersection between the first imaginary vertical plane and the striking face, and the auxiliary grooves have a first concentration no less than 0.17 measured between the first and second scorelines. A second imaginary vertical plane is horizontally spaced from the first imaginary plane. A second path is formed in the second imaginary vertical plane by a second intersection between the second imaginary vertical plane and the striking face. The auxiliary grooves in the second imaginary vertical plane have a second concentration that is different from the first concentration measured between the first and second scorelines.

A grain-oriented electrical steel sheet incudes a groove formed on a surface and a solidified alloy layer formed under the groove, wherein the solidified alloy layer includes particles of a certain average diameter.

The present application relates to a method of laser ablation of a metal-ceramic substrate, in which a laser is used under process conditions in which the formation of solid metal particles on the metal-ceramic substrate, which can separate from metal particles released by laser ablation near the ablation edge, is essentially avoided. Further the present application relates to a ceramic-metal substrate comprising a ceramic substrate and a metallization on at least one side of the ceramic substrate, wherein the ceramic substrate and the metallization have flush cutting edge.

A method for processing a transparent workpiece comprises forming an optically modified region in or on a transparent workpiece and forming a contour in the transparent workpiece, the contour comprising a plurality of defects in the transparent workpiece positioned laterally offset from the optically modified region. Forming the contour comprises directing a primary laser beam comprising a quasi-non diffracting beam oriented along a beam pathway onto the transparent workpiece such that a first caustic portion of the primary laser beam is directed into the transparent workpiece, thereby generating an induced absorption within the transparent workpiece to produce a defect within the transparent workpiece and a second caustic portion of the primary laser beam is modified by the optically modified region. Further, translating the transparent workpiece and the primary laser beam relative to each other along a contour line and laterally offset from the optically modified region.

A method for processing a transparent workpiece comprises forming an optically modified region in or on a transparent workpiece and forming a contour in the transparent workpiece, the contour comprising a plurality of defects in the transparent workpiece positioned laterally offset from the optically modified region. Forming the contour comprises directing a primary laser beam comprising a quasi-non diffracting beam oriented along a beam pathway onto the transparent workpiece such that a first caustic portion of the primary laser beam is directed into the transparent workpiece, thereby generating an induced absorption within the transparent workpiece to produce a defect within the transparent workpiece and a second caustic portion of the primary laser beam is modified by the optically modified region. Further, translating the transparent workpiece and the primary laser beam relative to each other along a contour line and laterally offset from the optically modified region.

A method of removing an insulating coating layer of coil wiring includes: a fragmentation step in which a line-shaped region of the insulating coating layer, which separates a removal-planned portion and a remain-planned portion of the insulating coating layer, is removed; a laser irradiation step in which laser light which transmits through the insulating coating layer but which is absorbed by a coil wiring is irradiated from a side of an outer surface of the removal-planned portion toward a boundary of the coil wiring with the insulating coating layer, to carbonize a boundary portion between the insulating coating layer and the coil wiring of the removal-planned portion by generation of heat of the coil wiring; and a coating turn-over step in which air is blown onto the removal-planned portion to turn over and blow off the removal-planned portion.