A method for laser keyhole welding of metal alloys is disclosed. The method independently adjusts power in a focused center beam and power in a concentric focused annular beam. At the termination of a weld, the power in the center beam is initially ramped up and then ramped down, while the power in the annular beam is ramped down. Increasing the power in the center beam enables a controlled and prolonged contraction of the keyhole and melt pool, thereby preventing undesirable cracking.

A method for laser keyhole welding a stack of metal foils to a metal tab is disclosed. The method independently adjusts power in a focused center beam and power in a focused annular beam to form a weld through all the foils and the tab. The annular beam provides sufficient power to heat the metal to about melting temperature, widen a mouth of a keyhole, and stabilize a melt pool. The center beam provides sufficient additional power to form the keyhole. The power of the annular beam is sustained for a longer time than the power of the center beam. A plurality of such welds is formed to provide mechanical strength and electrical conductivity.

A beam-forming and deflecting optical system for a laser machining device includes at least two optical elements, which are arranged one behind the other in the direction of the laser beam and which are formed by wedges with respective wedge angles, wherein at least one optical element is connected to a drive for the rotation of the optical element about the optical axis, whereby an optical wedge can be rotated relative to the at least one other optical wedge. Also a method for machining a workpiece uses a collimated laser beam. In order to achieve different shapes of the laser beam on the workpiece, each of the optical wedges, which are arranged one behind the other, in each case cover only a part of the laser beam.

A method for processing a transparent workpiece includes directing a laser beam oriented along a beam pathway through an aspheric optical element and the transparent workpiece. The laser beam impinges the aspheric optical element radially offset from a centerline axis of the aspheric optical element by an offset distance of 30% the 1/e.sup.2 diameter of the laser beam or greater. The beam pathway and the transparent workpiece are tilted relative to one another such that the beam pathway has a beam pathway angle of less than 90° relative to an impingement surface at the impingement surface and a portion of the laser beam directed into the transparent workpiece is a laser beam focal line having an internal focal line angle of less than 80° relative to the impingement surface, such that a defect with a defect angle of less than 80° is formed by induced absorption within the transparent workpiece.

In various embodiments, a workpiece is processed utilizing one or more output beams emitted from a step-core optical fiber and formed from one or more input beams that may have non-circular beam shapes. In various embodiments, an input beam may be a variable-power laser beam having a laser-beam numerical aperture (NA) that varies as a function of the power of the laser beam. The step-core optical fiber may have an outer core NA that is greater than or equal to the laser-beam NA at a laser power of approximately 100%, an inner core NA that is less than or equal to the outer core NA, and an inner core NA that is greater than or equal to the laser-beam NA at a power of 50%.

An additive-manufacturing head includes: a ring-shape laser beam forming unit having axicon lenses facing each other and a convex lens between the axicon lenses to form a laser beam entering through the axicon lens into a ring-shape laser beam and emit the ring-shape laser beam from the other axicon lens; a lens moving mechanism to move the convex lens in the optical axis direction of the laser beam; a laser beam emitting unit to emit the ring-shape laser beam toward a workpiece; and a material powder feeding tube having an outlet which is disposed inside the ring-shape laser beam emitted from the laser beam emitting unit and from which material powder is released, to feed the material powder from the outlet toward the workpiece. Accordingly, the additive-manufacturing head capable of freely controlling the size of the laser-beam-irradiated region and the laser beam intensity distribution on the workpiece is provided.

A method and apparatus particularly for additively manufacturing materials that are susceptible to hot cracking. The additive manufacturing process may include a leading energy beam (16) for liquefying a raw material to form a melt pool (20), and a trailing energy beam (17) directed toward a trailing region of the melt pool. The trailing energy beam may be configured to enhance agitation and/or redistribution of liquid in the melt pool to prevent hot cracking, reduce porosity, or improve other characteristics of the solidified part. The method and apparatus also may improve processing parameters, such as adjusting vacuum level to prevent volatilization of alloying agents, or providing a chill plate to control interpass temperature. The process may be used to form new articles, and also may be used to enhance tailorability and flexibility in design or repair of pre-existing articles, among other considerations.

A method for providing a first and a second laser beam, which are spatially offset in relation to an input laser beam. The method includes: providing a laser source for generating the input laser beam; providing a spatial offsetting unit for providing an offset laser beam that can keep the same polarization between the input laser beam and the offset laser beam; providing a separating unit including a first module for separation by polarization in order to obtain, from the offset laser beam: the first laser beam spatially offset by transmission; and the second laser beam spatially offset by reflection, the first and second spatially offset laser beams being suitable for each describing a circle.

An apparatus comprises a multi-clad fiber that includes a light-guiding core surrounded by at least a cladding layer, and an input interface including a first set of input channels in the core configured to receive a first optical fiber, and a second set of input channels in the cladding layer configured to receive a second optical fiber. The apparatus further includes an optical switch module having an input port, a first and a second output port, a first optical path between the input port and the first input channel, and a second optical path between the input port and a second input channel in the second set of input channels. The optical switch module is controllable to switch between the first and the second optical paths. The apparatus also includes a set of laser modules.

The invention, according to an aspect thereof, relates to a device (60) for laser micromachining a sample made of a given material, which includes a focusing module enabling a nondiffracting beam to be generated from a given incident beam, said nondiffracting beam being focused along a focusing cylinder that is oriented generally along the optical axis of the focusing module, means (601) for transmitting at least one first light pulse (11) suitable for generating, after said focusing module focuses in the sample, a plasma of free charges by multiphotonic absorption in a volume of the sample located on the side surface of said focusing cylinder.