DE112017003592T5 - Material processing using a laser with variable beam shape - Google Patents

Abstract

In various embodiments, workpieces are processed, for. By welding or cutting while changing the shape and / or one or more other parameters of the laser processing beam. The shape and / or one or more other parameters of the laser processing beam may be varied based on one or more properties of the workpiece.

Description

Related Applications

This application claims the benefit and the priority of the provisional filed on July 15, 2016 U.S. Patent Application No. 62 / 362,824 and submitted on September 9, 2016 U.S. Patent Application Serial No. 15 / 261,096 the entire disclosures of which are hereby incorporated by reference herein.

Technical part

In various embodiments, the present invention relates to the machining (eg, welding or cutting) of materials using high power laser devices having mouldable beams and / or variable beam polarizations.

background

High power lasers are used in many applications for cutting, etching, annealing, welding, drilling and soldering. As with any material processing, efficiency can be a critical limiting factor in terms of effort and time; the lower the efficiency, the higher the cost and / or the slower the operation of the laser used to process a particular material. The brightness and polarization of the laser beam can affect efficiency, and various materials (such as copper, aluminum, steel, etc.) react differently to beam polarization during processing. In addition, the thicknesses of these materials can affect their polarization reaction. That is, the type of cutting or welding can vary with the beam polarization, depending on the material and thickness. Thus, for example, a linearly polarized machining beam can be absorbed differently depending on the orientation of the polarization of the beam with respect to the cutting surface. For this reason, laser processing systems sometimes use circularly or randomly polarized laser powers to avoid directional polarization reactions. While this approach avoids the efficiency-degrading results of unfavorable polarization orientations, it also forecasts the benefits of favorable orientations.

In addition, high power laser systems often include a laser emitter whose laser light is coupled into a fiber (or simply a "fiber") and an optical system that focuses the laser light from the fiber to the workpiece to be machined. The optical system is typically designed to produce the highest quality laser beam or, correspondingly, the lowest beam parameter product (BPP) beam. The BPP is the product of the divergence angle (half angle) of the laser beam and the radius of the beam at its narrowest point (ie the beam waist, the minimum spot size). The BPP quantifies the quality of the laser beam and how well it can be focused on a small spot and is typically expressed in millimeter-milliradian (mm-mrad) units. (The BPP values given herein are in units of mm-mrad unless otherwise specified.) A Gaussian beam has the lowest possible BPP, indicated by the wavelength of the laser light divided by pi. The ratio of the BPP of an actual beam to that of an ideal Gaussian beam at the same wavelength is denoted M ² , which is a wavelength-independent measure of the beam quality.

While techniques like WBC have succeeded in producing laser-based systems for a variety of applications, the challenges of material processing remain. For example, lasers with beam shapes optimized for cutting a particular material in a particular thickness may not be suitable for different materials, materials of different thickness, and materials of different thicknesses. Welding processes present similar challenges. In addition, because of the limited spatial extent of conventional, highly focused laser beams, welding processes typically require relative movement between the laser beam and the parts to be welded, which may require complex and expensive robotics, mobile portals, and / or other equipment. Techniques have been developed that use multiple movable-beam laser systems (see, for example, US Pat U.S. Patent No. 9,335,551 the entire disclosure of which is incorporated herein by reference), but the use of multiple laser systems is often very expensive. Therefore, there is a need for individual laser systems suitable for a wider variety of material processes.

In many applications of laser processing, the desired beam spot size, divergence and beam quality can vary depending on e.g. B. on the type of processing and / or the nature of the material to be processed. To make such changes to the BPP and / or the shape of the laser beam, must often Replacing and / or realigning the exit optics system or fiber with other components is a time-consuming and expensive process that may even result in unintentional damage to the sensitive optical components of the laser system.

Accordingly, there is also a need for improved systems and techniques for increasing the efficiency of laser processing operations that utilize the different responses to beam polarization and / or other beam characteristics (eg, BPP and / or beam shape) that characterize different materials and material thicknesses.

Summary

According to the embodiments of the present invention, laser systems with mouldable output beams are used to optimize and simplify the tasks of material processing, such as cutting and welding of metallic materials. For example, according to embodiments of the invention, the output beam shape of the laser system is changed (eg, from a Gaussian-focused spot beam to a large-area ring beam) because the thickness of a part and / or the angle of the part presented to the laser beam changes. In further exemplary embodiments, the output beam of the laser system is changed during a welding process (eg, spot welding, butt welding, or lap welding) so that large-area welds occur without (or with minimal) relative movement between the laser beam and the workpiece (s) to be machined ,

Embodiments of the invention also provide systems and techniques for altering and optimizing the polarization and / or other properties (eg, BPP, shape) of a beam during processing and maintaining the optimum properties of the beam throughout processing - e.g. B. with varying beam paths or changes in the type or thickness of the material.

Embodiments of the invention may alter the polarization of the beam as the thickness of the workpiece changes and / or for workpieces of varying thickness. For example, the circularity (ie the degree of change from linear to elliptical to circular, with any number of ellipses of different dimensions and curvatures between completely linear and fully circular) of the polarization of the beam can be changed to make the beam more circular (e.g. B. linear to elliptical, less circular ellipse to more circular ellipse, elliptical to circular, etc.) as the thickness of the workpiece increases. (In various embodiments, the circularity of the polarization is inversely proportional to the eccentricity of the elliptical polarization, with an eccentricity of 0 representing the circular polarization and an eccentricity of 1 representing the linear polarization). In various embodiments, the polarization state of the beam is changed, at least in part, by the use of a Babinet Soleil compensator, which allows stepless polarization of arbitrary eccentricity. Embodiments of the invention may also vary the polarization of the beam from linear to radial, e.g. B. to allow the focusing of the beam to a smaller spot size.

Embodiments of the present invention are typically used to machine a workpiece such that the surface of the workpiece is physically altered and / or that a feature is formed on or within the surface, as opposed to optical techniques that probe only one surface with light (eg reflection measurements). Exemplary processes according to the embodiments of the invention are cutting, welding, drilling and soldering. Various embodiments of the invention also process workpieces at one or more locations or along a one-dimensional processing path, rather than flood the entire or substantially all of the workpiece surface with radiation from the laser beam.

Embodiments of the present invention use optical elements capable of forming laser beams to obtain desired spatial beam profiles that alter the beam quality (particularly BPP) and / or the shape of the beam. In particular, the change in the optical geometry of optical elements can be utilized by moving or shifting their position across or along the optical axis of the laser beam to vary the shape and / or the BPP. In embodiments of the invention, there are optical elements in the beam path with switchable states, which generate different beam deflections or diffractions depending on the position. The use of optical elements according to embodiments of the present invention allows for variation of shape and / or BPP regardless of shape, quality, wavelength, bandwidth and number of beams corresponding to the input laser beam (s). The controllable variable shape output beam and / or BPP can be used to machine a workpiece in applications such as welding, cutting, drilling, and the like. As used herein, the change in the "shape" of a laser beam refers to the change in shape and geometrical extent of the beam (eg, at a point where the beam intersects a surface). Shape changes may be accompanied by changes in the beam size, the angular intensity distribution of the beam and the BPP, but mere changes in the beam BPP are not necessarily sufficient to change the shape of the laser beam and vice versa (see, for example 21 representing two beams of different shapes but the same BPP).

An advantage of the variable shape and / or BPP is the improved performance of the laser application for various types of machining techniques or different types of materials being processed. Embodiments of the invention may also utilize various techniques for varying BPP and / or shape of laser beams as described in U.S. Patent Application Serial No. 14 / 632,283, filed February 26, 2015, U.S. Patent Application Serial No. 14 / 747,073, filed Jun. 23, 2015, US Patent Application Serial No. 14 / 852,939, filed September 14, 2015, US Patent Application Serial No. 15 / 188,076, filed June 21, 2016, and US Patent Application Serial No. US Pat Serial No. 15 / 479,745, filed April 5, 2017, the disclosures of each of which are incorporated herein by reference in their entirety. In addition, the different beam intensity distribution induced by optical elements (refractive optics) alters the beam quality and thus the BPP. By using the displacement (eg motorized displacement) of the optical elements, which have different effective optical geometries in the beam path, dynamic shape changes and / or BPP can be realized in real time.

Laser beam forming is the process of redistributing the intensity (irradiance) and phase of the beam. The intensity distribution defines the beam profile, such. Gaussian, Bessel, Ring, Multimode, Rectangle, Hood, Ellipse or Circular, and various intensity profiles may be critical and necessary for certain laser material processing techniques. (As used herein, an "annular" beam is annular, ie with less or substantially no beam intensity in a central portion surrounded by a region of higher beam intensity, but not necessarily circular, ie "ring-shaped" beams may be oval or otherwise quasi-continuous.) In embodiments of this invention, the optical element is in the delivery system which delivers the laser beam to the workpiece and focuses the laser. The delivery system may be configured and / or packaged, for example, as at least a portion of a cutting head or welding head. Embodiments of the invention vary the beam quality to allow a controllably variable shape and / or BPP at the workstation (and / or on the workpiece thereon). The variable shape and / or BPP module may include one or more optical elements, a motorized translation stage, a collimator lens and a focusing lens. Embodiments of the invention may include one or more of several types of refractive optics because the optical elements are used to vary the shape and / or the BPP.

Embodiments of the invention vary the beam quality by dynamically changing the position of one or more optical elements in the optical path of the laser beam. In one embodiment, the beam profile is adjusted by adjusting the beam position to the optical element. Depending on the desired beam profile and thus BPP, the optical elements can have different geometries. An optical element according to the embodiments of the invention has a planar surface and a flat top conical surface (i.e., cut). Another optical element according to the embodiments of the invention has a planar surface and a spherical surface with a flat top. Another optical element according to the embodiments of the invention is a meniscus lens. The diverging light beams from the beam delivery fiber are directed at the optical element (s) to redistribute the beam intensity within the optical elements. Other optical elements according to embodiments of the invention are paired positive and negative axicon lenses. In further embodiments, the optical elements include plied, complementary phase-plate lenses, one of which has a partially convex surface and a partially concave curved surface. The edges of the optical elements may be rounded off to suppress diffraction effects. The benefits of dynamic variation of BPP with the automated movement of optical elements can be applied, for example, to laser cutting applications on round or square cuts where BPP changes are required during free-form cutting. These advantages can also be applied to laser drilling applications that use the ability to vary both BPP and focal length. Automated motor control of closed loop optical elements in accordance with embodiments of the invention provides reliable and repeatable performance and allows precise control of the optical position, thereby enabling accurate BPP variation.

In so doing, "optical elements" may refer to lenses, mirrors, prisms, grids, and the like that redirect, reflect, flex, or otherwise optically manipulate electromagnetic radiation unless otherwise specified. Therein, beam emitters, emitters or laser emitters or lasers include an electromagnetic beam generating device such as semiconductor elements that generate an electromagnetic beam but may not be self-sustaining. These include fiber lasers, disk lasers, non-solid state lasers, etc. In general, each emitter includes a back reflective surface, at least one optical gain medium, and a front reflective surface. The optical gain medium enhances the enhancement of electromagnetic radiation that is not limited to a particular portion of the electromagnetic spectrum but may be visible, infrared and / or ultraviolet light. An emitter may include multiple beam emitters or consist essentially of a plurality of beam emitters, such as a diode bar configured to emit multiple beams. The input beams received in the embodiments may be single-wavelength or multi-wavelength beams combined using various techniques known in the art. In addition, the references to "lasers", "laser emitters" or "beam emitters" herein include not only single diode lasers but also diode bars, laser arrays, diode bar arrays and single arrays of surface emitting lasers (VCSELs).

Embodiments of the invention may be used with wavelength beam combinatorial (WBC) systems that include a plurality of emitters, such as one or more diode bars combined using a dispersive element to form a multi-wavelength beam. Each emitter in the WBC system individually resonates and is stabilized by wavelength-specific feedback from a common, partially-reflecting output coupler which is filtered by the dispersive element along a beam combination dimension. Exemplary WBC systems are in the filed on February 4, 2000 U.S. Patent No. 6,192,062 , submitted on 8 September 1998 U.S. Patent No. 6,208,679 , submitted on 25 August 2011 U.S. Patent No. 8,670,180 and that submitted on 7 March 2011 U.S. Patent No. 8,559,107 described in detail, the entire disclosure of which is incorporated herein by reference. Multi-wavelength output beams of WBC systems may be used as input beams in conjunction with embodiments of the present invention for e.g. B. BPP, shape and / or polarization control can be used.

In one aspect, embodiments of the invention include a method of machining a workpiece. A machining path is defined by causing a relative movement between a laser output beam and the surface of the workpiece. The thickness of the workpiece along a direction parallel to the laser power beam varies along the machining path. The laser output beam physically changes the surface of the workpiece along at least a portion of the processing path. During the relative movement between the laser output beam and the surface of the workpiece, the shape of the laser output beam is at least partially changed by the thickness of the workpiece.

Embodiments of the invention may include one or more of the following in a variety of combinations. The shape of the laser exit beam may be varied with increasing thickness of the workpiece between a focused point and an annulus. The shape of the laser output beam may be varied as the thickness of the workpiece increases between a focused point and a diffuse point (eg, a point having a diameter greater than the diameter of the focused point). A diameter and / or BPP of the laser output beam may be increased with increasing thickness of the workpiece. An angle between the laser output beam and the surface of the workpiece may be changed (eg, by tilting the incoming laser output beam, tilting the workpiece, and / or angled topology on the surface of the workpiece), thereby paralleling the thickness of the workpiece along the direction to change the laser output beam. The thickness of the workpiece along the direction parallel to the laser exit beam may vary, at least in part, by an angular change between the laser exit beam and the surface of the workpiece (eg, by tilting the incident laser exit beam, tilting the workpiece, and / or angled topology on the surface of the workpiece ). The shape of the laser exit beam may be kept substantially constant while maintaining an angle between the laser exit beam and the surface of the workpiece (eg, the laser exit beam may not be inclined with respect to the surface of the workpiece, or the topology of the surface of the workpiece may be one) have substantially constant angles to the incident laser exit beam). The thickness of the workpiece can be measured during the relative movement between the laser output beam and the surface of the workpiece. The shape of the laser exit beam can be changed depending on the composition of the workpiece. The laser output beam may consist of several wavelengths.

In another aspect, embodiments of the invention include a system for machining a workpiece. The system includes, consists essentially of or consists of a beam emitter for emitting a laser output beam, a positioning device for varying a position of the laser output beam with respect to the workpiece, means for changing a shape of the laser output beam, and a controller coupled to the positioning device and the shape changing means for (i) operating the beam emitter so that the laser output beam travels a path over at least a portion of the workpiece to physically change its surface, and (ii) changing the shape of the laser output beam based at least in part on a thickness of the workpiece of the way.

Embodiments of the invention may include one or more of the following in a variety of combinations. The beam emitter may include, consist essentially of, be disposed within, or be coupled to a machining head from which the laser output beam is emitted (eg, via a fiber optic cable). The shape changing means may include (i) one or more optical elements within the machining head and (ii) a second controller for, substantially consists of, or consists of, a position of at least one of the optical elements within the machining head. The second controller may be discrete and separate from the controller, or the controller and the second controller may be parts of a single control system. The controller may be configured to vary an output power of the beam emitter along the path. The controller may be configured to vary the shape of the laser output beam based on a composition of the workpiece. The system may include a database containing a plurality of data sets each relating a laser output beam shape to workpiece parameters. The workpiece parameters may include, consist essentially of or consist of the workpiece thickness and / or the workpiece composition. The beam emitter may include a beam source emitting a plurality of discrete input beams, focusing optics for focusing the plurality of input beams onto a dispersive element, a dispersive element for receiving and diffusing the received focused beams, and a partially reflective output clutch positioned to receives the scattered beams, transmits a portion of the scattered beams as a laser output beam through them, and reflects a second portion of the scattered beams back to the dispersive element. The laser output beam may consist of several wavelengths.

In yet another aspect, embodiments of the invention include a method of joining a first and a second workpiece to a processing station. The first and the second workpiece overlap and / or are close to each other at the processing point. A laser output beam is focused and / or placed near the processing location to melt a portion of the first or second workpiece to connect the first and second workpieces together. During bonding, the shape of the laser exit beam is changed without causing relative movement between the laser exit beam and the first and second workpieces.

Embodiments of the invention may include one or more of the following in a variety of combinations. The shape of the laser exit beam can be varied between a focused point and an annulus. The shape of the laser output beam may be varied between a focused point and a diffuse point (eg, a point having a diameter greater than the diameter of the focused point). The laser output beam may consist of several wavelengths.

In another aspect, embodiments of the invention include a method of joining a first and a second workpiece to a weld having a spatial extent greater than the minimum spot size using a laser power beam focusable to a minimum spot size. The laser output beam is focused and / or arranged on the first and / or the second workpiece to cause its at least partial melting and / or at least partial melting of a binder (eg, a brazing material, a brazing material, or a flux) or between the first and the second workpiece is arranged. Without causing relative movement between the laser power beam and the first and second workpieces, a shape of the laser power beam is varied to increase a size of the weld or joint.

Embodiments of the invention may include one or more of the following in a variety of combinations. The shape of the laser exit beam can be varied between a focused point and an annulus. The shape of the laser output beam may be varied between a focused point and a diffuse point (eg, a point having a diameter greater than the diameter of the focused point). The laser output beam may consist of several wavelengths.

In one aspect, embodiments of the invention include a system for machining a workpiece. The system includes, consists essentially of or consists of a beam emitter, a positioning device for varying a position of a beam of the beam emitter relative to the workpiece, a variable polarizer for varying a polarization of the beam, a beamformer for varying a beam shape, and a controller. coupled to the positioning device, the polarizer and the beamformer to operate the beam emitter, cause the beam to traverse a path over at least a portion of the workpiece for processing thereof and at least partially polarize and / or shape the beam along the path varies based on one or more properties of the workpiece.

Embodiments of the invention may include one or more of the following in a variety of combinations. The controller may be configured to maintain a linear polarization of the beam having a polarization direction that is approximately parallel to the path as the beam traverses the path. The controller may be configured to vary an eccentricity of the polarization of the beam based at least in part on a thickness of the workpiece. The controller may be configured to vary the polarization of the beam between a linear polarization state and a radial polarization state. The variable polarizer may include, consist essentially of, or consist of a wave plate. The variable polarizer may include, consist essentially of, or consist of a wave plate and a rotary element, the rotary element being actuated by the controller. The wave plate may include, consist essentially of, or consist of a half-wave plate and / or a quarter wave plate. The beam can be linearly polarized. The controller may operate the rotating member to maintain a direction of polarization parallel to the web. The variable polarizer may include, consist essentially of, or consist of a compensator plate, a solid birefringent wedge disposed over the compensator plate, and a movable birefringent wedge disposed over the solid birefringent wedge. The variable polarizer may include a compensator plate, a solid birefringent wedge disposed over the compensator plate, a movable birefringent wedge disposed over the fixed birefringent wedge, and a displacement element, the displacement element being actuated by the controller. The variable polarizer may include, substantially consist of or consist of a radial polarization converter.

The system may include a memory accessible to the controller for storing data corresponding to the path and a database for storing polarization data for a plurality of materials. The controller may be configured to query the database to obtain the polarization data for a material of the workpiece and to vary the polarization of the beam based at least in part on the polarization data. The path can include at least one change of direction. The workpiece may have at least two sections of different thicknesses. The workpiece may have at least two sections that contain, consist essentially of, or consist of different materials. The beam emitter may include, consist essentially of, or consist of a radiation source emitting a plurality of discrete input beams, focusing optics for focusing the plurality of input beams onto a dispersive element, a dispersive element for receiving and diffusing the received focused beams, and a beam emitter partially reflecting output clutch positioned to receive the scattered beams, transmit a portion of the scattered beams as a beam of the beam emitter therethrough, and reflect a second portion of the scattered beams back to the dispersive element. The beam (eg the output processing beam) of the beam emitter may consist of several wavelengths.

The beamformer may include a collimating lens for collimating a beam received from the beam emitter, a focusing lens for receiving the collimated beam, and for focusing the beam on the workpiece interposed between the radiation source and the collimating lens, an optical element for receiving the beam and changing it Form and a lens manipulation system for changing a position of the optical element within a beam path include, consist essentially of or consist of such. The controller may be configured to control the lens manipulation system to vary the shape of the beam. The optical element may include, consist essentially of, or consist of a lens having (i) a first surface in the shape of a truncated cone and (ii) opposite the first surface a second surface that is substantially planar. The optical element may comprise a lens, consisting essentially of a lens or consisting of a lens having (i) a first surface in the form of a spherical segment and (ii) opposite the first surface a second surface which is substantially planar , The optical element may include, consist essentially of or consist of a meniscus lens. The Lens processing system may be configured to position the optical element transverse to the center within the beam path. The system may include a second optical element disposed between the focusing lens and the workpiece. The lens processing system may be configured to change a position of the second optical element within the beam path. The second optical element may include, consist essentially of, or consist of a lens having (i) a first surface in the shape of a truncated cone and (ii) opposite the first surface a second surface which is substantially planar. The second optical element may include a lens, consisting essentially of a lens, or consisting of a lens having (i) a first surface with the shape of a spherical segment and (ii) a second surface substantially planar with respect to the first surface is. The second optical element may include, consist essentially of or consist of a meniscus lens.

The beamformer may include a collimating lens for collimating a beam received from the beam emitter, a focusing lens for receiving the collimated beam, and focusing the beam on the workpiece located between the beam source and the collimating lens, consisting essentially of, or consisting of first and second optical elements for receiving the beam and changing its shape, and a lens manipulation system for changing (i) a position of the first optical element within a beam path, (ii) a position of the second optical element within the beam path, and / or ( iii) a distance between the first and the second optical element. The controller may be configured to control the lens manipulation system to vary the shape of the beam. The first optical element may include, consist essentially of or consist of a double concave axicon lens. The second optical element may include, consist essentially of or consist of a double convex axicon lens. The lens processing system may be configured to change the distance between the first and second optical elements in the range of about 0 mm to about 20 mm. The first optical element may comprise a lens having (i) a first surface that is substantially planar, and (ii) opposite the first surface, a second surface having (a) a first portion that is convexly curved, and (b) a second section, which is essentially flat, includes, essentially consists of, or consists of. The second optical element may comprise a lens having (i) a first surface that is substantially planar, and (ii) opposite the first surface, a second surface having (a) a first portion that is concavely curved, and (b) a second section, which is essentially flat, includes, essentially consists of, or consists of. The lens processing system may be configured to position the first optical element and / or the second optical element transversely of the center within the beam path.

In one aspect, embodiments of the invention relate to a system for machining a workpiece. In various embodiments, the system includes a beam emitter, a positioning device for varying a position of a beam of the beam emitter relative to the workpiece, a variable polarizer for varying a polarization of the beam, and a controller coupled to the positioning device and the polarizer for operating the beam emitter causing the beam to traverse a path across at least a portion of the workpiece for processing thereof and maintain a uniform polarization of the beam with respect to the workpiece along the path.

In various embodiments, the variable polarizer includes a waveplate and a rotary member, wherein the rotary member is actuated by the controller. For example, the wave plate may be one or more half wave plates, one or more quarter wave plates, or a combination thereof. For example, the beam may be linearly polarized, with the controller operating the rotation element to maintain a polarization direction parallel to the path.

In some embodiments, the system further includes a memory accessible to the controller for storing data corresponding to the path and a database for storing polarization data for a plurality of materials. The controller is configured to query the database to obtain the polarization data for a material of the workpiece, and the polarization data determines the consistent polarization of the beam. The path can include at least one change of direction.

The radiation emitter can emit a variety of rays. The radiation emitter may be at least one laser and / or at least one polarized fiber.

In another aspect, the invention relates to a method of machining a workpiece. In various embodiments, the method includes the steps of operating a beam emitter to direct a beam passing a path along the workpiece about the workpiece to process, the beam having an output polarization; and altering the output polarization along at least a portion of the path to maintain uniform polarization of the beam with respect to the workpiece throughout its processing.

The step of machining the workpiece may include one or more steps: cutting, welding, soldering, drilling, or etching the workpiece. The step of altering may include directing the beam through a wave plate and varying a rotation angle of the wave plate with respect to the beam. For example, the wave plate may be one or more half wave plates and / or one or more quarter wave plates. For example, the beam may be linearly polarized, and the modifying step maintains a polarization direction of the beam parallel to the path.

In some embodiments, the method further comprises the steps of storing data corresponding to the path, storing polarization data for a plurality of materials, and querying the database to obtain the polarization data for a material of the workpiece, wherein the polarization data is the consequent Determine polarization of the beam. The path can include at least one change of direction.

In one aspect, embodiments of the invention include a laser delivery system to receive and alter a spatial power distribution of a radiation beam from a radiation source and to focus the radiation with the altered spatial power distribution onto a workpiece. The laser system basically includes or consists of a collimating lens for collimating the radiation beam, a focusing lens for receiving the collimated beam and focusing the beam on the workpiece, an optical element for receiving the radiation beam and changing its spatial power distribution, a lens manipulation system for changing a Position of the optical element within a path of the radiation beam and a controller for controlling the lens manipulation system to achieve a desired changed spatial power distribution on the workpiece. The optical element may be disposed between the radiation source and the collimator lens (i.e., optically downstream of the radiation source and optically upstream of the collimator lens).

Embodiments of the invention may include one or more of the following in a variety of combinations. The optical element may include, consist essentially of, or consist of a lens having (i) a first surface in the shape of a truncated cone and (ii) opposite the first surface a second surface that is substantially planar. The first surface may face the radiation source. The first surface may face away from the radiation source. The optical element may comprise a lens, consisting essentially of a lens or consisting of a lens having (i) a first surface in the form of a spherical segment and (ii) opposite the first surface a second surface which is substantially planar , The first surface may face the radiation source. The first surface may face away from the radiation source. The optical element may include, consist essentially of or consist of a meniscus lens. The meniscus lens may be a positive meniscus lens. The meniscus lens may be a negative meniscus lens. The optical element may include, consist essentially of, or consist of fused silica and / or zinc sulfide. The lens processing system may be configured to position the optical element transversely of the center within the beam path.

The laser delivery system may include a second optical element disposed in the path of the radiation beam. The second optical element may be disposed between the focusing lens and the workpiece (i.e., located optically downstream of the focusing lens and optically upstream of the workpiece). The lens processing system may be configured to change a position of the second optical element within the beam path. The second optical element may include, consist essentially of, or consist of a lens having (i) a first surface in the shape of a truncated cone and (ii) opposite the first surface a second surface which is substantially planar. The first surface may face the radiation source. The first surface may face away from the radiation source. The second optical element may include a lens, consisting essentially of a lens, or consisting of a lens having (i) a first surface with the shape of a spherical segment and (ii) a second surface substantially planar with respect to the first surface is. The first surface may face the radiation source. The first surface may face away from the radiation source. The second optical element may include, consist essentially of or consist of a meniscus lens. The meniscus lens may be a positive meniscus lens. The meniscus lens may be a negative meniscus lens. The second optical element may include, consist essentially of, or consist of fused silica and / or zinc sulfide.

The radiation source may include or consist essentially of a beam emitter emitting a plurality of discrete beams, focusing optics for focusing the plurality of beams onto a dispersive element, a dispersive element for receiving and diffusing the received focused beams, and a partially reflecting beam Output clutch positioned to receive the scattered beams, transmit a portion of the scattered beams therethrough as a radiation beam, and reflect a second portion of the scattered beams back to the dispersive element. The radiation beam can consist of several radiation wavelengths. The focusing optics may include or consist essentially of one or more cylindrical lenses, one or more spherical lenses, one or more spherical mirrors, and / or one or more cylindrical mirrors. The dispersive element may include or consist essentially of a diffraction grating (eg, a transmissive diffraction grating or a reflective diffraction grating).

In another aspect, embodiments of the invention include a laser delivery system to receive and alter a spatial power distribution of a radiation beam from a radiation source and to focus the radiation with the altered spatial power distribution onto a workpiece. The laser delivery system essentially comprises or consists of a collimating lens for collimating the radiation beam, a focusing lens for receiving the collimated beam and focusing the beam onto the workpiece, first and second optical elements for receiving the radiation beam, and changing the spatial power distribution thereof; a lens manipulation system for changing (i) a position of the first optical element within a path of the radiation beam, (ii) a position of the second optical element within the path of the radiation beam, and / or (iii) a distance between the first and second optical elements, and a controller for controlling the lens manipulation system to achieve a targeted altered spatial power distribution on the workpiece. The first and / or the second optical element may be disposed between the radiation source and the collimator lens (i.e., optically downstream of the radiation source and optically upstream of the collimator lens).

Embodiments of the invention may include one or more of the following in a variety of combinations. The first optical element may include, consist essentially of or consist of a double concave axicon lens. The second optical element may include, consist essentially of or consist of a double convex axicon lens. The first optical element may be arranged optically upstream of the second optical element. The first optical element may be arranged optically downstream of the second optical element. The lens processing system may be configured to control the distance between the first and second optical elements in the range of about 0 mm to about 50 mm, in the range of about 0 mm to about 20 mm, in the range of about 2 mm to about 50 mm, or Range from about 2 mm to about 20 mm. The first optical element may comprise a lens having (i) a first surface that is substantially planar, and (ii) opposite the first surface, a second surface having (a) a first portion that is convexly curved, and (b) a second section, which is essentially flat, includes, essentially consists of, or consists of. The second optical element may comprise a lens having (i) a first surface that is substantially planar, and (ii) opposite the first surface, a second surface having (a) a first portion that is concavely curved, and (b) a second section, which is essentially flat, includes, essentially consists of, or consists of. The first optical element may be arranged optically upstream of the second optical element. The first optical element may be arranged optically downstream of the second optical element. The second surface of the first optical element may face the second surface of the second optical element. The first surface of the first optical element may face the first surface of the second optical element. The first surface of the first optical element may face the second surface of the second optical element. The second surface of the first optical element may face the first surface of the first optical element. The lens processing system may be configured to position the first optical element and / or the second optical element transversely of the center within the beam path. The first optical element may include, consist essentially of, or consist of fused silica and / or zinc sulfide. The second optical element may include, consist essentially of, or consist of fused silica and / or zinc sulfide.

The radiation source may include or consist essentially of a beam emitter emitting a plurality of discrete beams, focusing optics for focusing the plurality of beams onto a dispersive element, a dispersive element for receiving and diffusing the received focused beams, and a partially reflecting beam Output coupling, which is positioned so that it receives the scattered rays, a part of the scattered rays as Radiation beam transmits through them and reflects a second part of the scattered rays back to the scattering element. The radiation beam can consist of several radiation wavelengths. The focusing optics may include or consist essentially of one or more cylindrical lenses, one or more spherical lenses, one or more spherical mirrors, and / or one or more cylindrical mirrors. The dispersive element may include or consist essentially of a diffraction grating (eg, a transmissive diffraction grating or a reflective diffraction grating).

In yet another aspect, embodiments of the invention include a laser delivery system for receiving and changing a spatial power distribution of a radiation beam from a radiation source and for focusing the radiation with the altered spatial power distribution onto a workpiece. The laser delivery system essentially comprises or consists of one or more divergence-enhancing optical elements for increasing divergence of the radiation beam, a focusing lens for receiving the radiation beam, and focusing the beam onto the workpiece, at least one optical element for receiving the radiation beam and changing it spatial power distribution, a lens manipulation system for changing a position of the at least one optical element within a path of the radiation beam and a controller for controlling the lens manipulation system to achieve a desired altered spatial power distribution on the workpiece.

Embodiments of the invention may include one or more of the following in a variety of combinations. The focusing lens may be optically disposed behind one or more divergence-enhancing optical elements. The at least one optical element can be arranged optically upstream of the focusing lens. The one or more divergence enhancing optical elements may include, consist essentially of, or consist of a triple collimator. The triple collimator may include (i) a first plano-concave lens, (ii) a second meniscus lens, and (iii) a third plano-convex lens, consisting essentially of, or consisting of. The first plano-concave lens may be optically disposed upstream of the second meniscus lens. The second meniscus lens may be optically placed in front of the third plano-convex lens. The at least one optical element may be arranged optically downstream of the first plano-concave lens. The at least one optical element may be arranged optically upstream of the second meniscus lens and / or the third plano-convex lens. The at least one optical element may comprise a lens, consisting essentially of a lens or consisting of a lens having (i) a first surface in the form of a truncated cone and (ii) opposite the first surface a second surface which is substantially planar is. The at least one optical element may comprise a lens, consisting essentially of a lens or consisting of a lens having (i) a first surface in the form of a spherical segment and (ii) opposite the first surface a second surface which is substantially planar is. The at least one optical element may include, consist essentially of or consist of a meniscus lens (eg, a positive meniscus lens or a negative meniscus lens). The lens processing system may be configured to position at least one optical element transverse to the center within the beam path.

The at least one optical element may include, substantially consist of or consist of a first optical element and a second optical element. The first optical element and the second optical element may be separated by a gap therebetween. The lens processing system may be configured to include (i) a position of the first optical element within a path of the radiation beam, (ii) a position of the second optical element within the path of the radiation beam, and / or (iii) a distance between the first and second optical To change element. The first optical element may include, consist essentially of or consist of a double concave axicon lens. The second optical element may include, consist essentially of or consist of a double convex axicon lens. The first optical element may be arranged optically upstream of the second optical element. The first optical element may be arranged optically downstream of the second optical element. The lens processing system may be configured to control the distance between the first and second optical elements in the range of about 0 mm to about 50 mm, in the range of about 0 mm to about 20 mm, in the range of about 2 mm to about 50 mm, or Range from about 2 mm to about 20 mm. The first optical element may comprise a lens having (i) a first surface that is substantially planar, and (ii) opposite the first surface, a second surface having (a) a first portion that is convexly curved, and (b) a second section, which is essentially flat, includes, essentially consists of, or consists of. The second optical element may comprise a lens having (i) a first surface that is substantially planar, and (ii) opposite the first surface, a second surface having (a) a first portion that is concavely curved, and (b) a second section, which is essentially flat, includes, essentially consists of, or consists of. The first optical element may be arranged optically upstream of the second optical element. The first optical element may be arranged optically downstream of the second optical element. The second surface of the first optical element may face the second surface of the second optical element. The first surface of the first optical element may face the first surface of the second optical element. The first surface of the first optical element may face the second surface of the second optical element. The second surface of the first optical element may face the first surface of the first optical element. The lens processing system may be configured to position the first optical element and / or the second optical element transversely of the center within the beam path. The first optical element may include, consist essentially of, or consist of fused silica and / or zinc sulfide. The second optical element may include, consist essentially of, or consist of fused silica and / or zinc sulfide.

The radiation source may include or consist essentially of a beam emitter emitting a plurality of discrete beams, focusing optics for focusing the plurality of beams onto a dispersive element, a dispersive element for receiving and diffusing the received focused beams, and a partially reflecting beam Output clutch positioned to receive the scattered beams, transmit a portion of the scattered beams therethrough as a radiation beam, and reflect a second portion of the scattered beams back to the dispersive element. The radiation beam can consist of several radiation wavelengths. The focusing optics may include or consist essentially of one or more cylindrical lenses, one or more spherical lenses, one or more spherical mirrors, and / or one or more cylindrical mirrors. The dispersive element may include or consist essentially of a diffraction grating (eg, a transmissive diffraction grating or a reflective diffraction grating).

These and other objects as well as the advantages and features of the present invention disclosed herein will become more apparent by reference to the following description, the accompanying drawings and the claims. Moreover, it should be understood that the features of the various embodiments described herein are not mutually exclusive and may be in various combinations and permutations. As used herein, the term "substantially" means ± 10%, and in some embodiments, ± 5%. The term "consists essentially of" means excluding other materials that contribute to the function unless otherwise defined herein. However, these other materials may coexist or individually in trace amounts. Herein, the terms "radiation" and "light" are used interchangeably unless otherwise specified. Here, "downstream" or "optically downstream" is used to indicate the relative placement of a second element that a light beam strikes upon encountering a first element, the first element being "upstream" or "optically upstream" of the second element is. Here, the "optical distance" between two components is the distance between two components, which is actually traversed by light rays; the optical distance may or may not be equal to the physical distance between two components, e.g. By reflections from mirrors or other changes in the direction of propagation experienced by the light traveling from one component to the other.

list of figures

• 1 ein herkömmliches Verfahren zum Schneiden einer Kurve aus Material veranschaulicht, wobei die Polarisation des Schneidstrahls fixiert ist;
• 2A eine exemplarische Anpassung der Polarisation entsprechend dem Schneidweg im Material gemäß verschiedenen Ausführungsformen der Erfindung veranschaulicht;
• 2B eine exemplarische Anpassung der Polarisation in Abhängigkeit von der Dicke des Materials gemäß verschiedenen Ausführungsformen der Erfindung veranschaulicht;
• 2C eine exemplarische Anpassung der Polarisation von linearer Polarisation zu radialer Polarisation gemäß verschiedenen Ausführungsformen der Erfindung veranschaulicht;
• 3A-3G exemplarische Systeme zur Variation der Strahlpolarisation veranschaulichen, die zumindest teilweise auf der Bearbeitungsrichtung oder der Materialdicke gemäß den verschiedenen Ausführungsformen der Erfindung basieren;
• 4A ein Verfahren zum Schneiden oder Schweißen eines Materials mit einem automatisch einstellbaren Polarisationsstrahl gemäß verschiedenen Ausführungsformen der Erfindung veranschaulicht;
• 4B-4D Diagramme der Schnittgeschwindigkeit als Funktion der Werkstückdicke sind, die Laserstrahlen mit kontrollierter Polarisation gemäß verschiedenen Ausführungsformen der Erfindung mit herkömmlichen unpolarisierten Strahlen vergleichen;
• 5 ein schematisches Diagramm eines Laserstrahlabgabesystems gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 6 ein schematisches Diagramm eines optischen Flachkegelelements gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 7A ein Diagramm der BPP-Variation als Funktion des Abstands eines optischen Flachkegelelements aus Quarzglas von einer Strahlenquelle gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 7B ein Diagramm der BPP-Variation als Funktion des Abstands eines optischen Flachkegelelements aus Zinksulfid von einer Strahlenquelle gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 8A ein schematisches Diagramm eines Laserabgabesystems mit einem exzentrischen optischen Element gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 8B-8D Strahlprofile in Abhängigkeit vom exzentrischen Abstand darstellen, der durch das Laserabgabesystem von 8A erzeugt wird;
• 8E ein Diagramm der Bestrahlungsstärke als Funktion der Position für das in 4D dargestellte Zwei-Spitzen-Strahlprofil ist;
• 9 ein schematisches Diagramm eines kugelförmigen optischen Elements mit flacher Oberseite gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 10A ein Diagramm der BPP-Variation als Funktion des Abstands eines kugelförmigen optischen Elements mit flacher Oberseite aus Quarzglas von einer Strahlenquelle gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 10B ein Diagramm der BPP-Variation als Funktion des Abstands eines kugelförmigen optischen Elements mit flacher Oberseite aus Zinksulfid von einer Strahlenquelle gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 11A-11C Strahlprofile in Abhängigkeit vom exzentrischen Abstand darstellen, der durch ein Laserabgabesystem mit dem optischen Element der 9 gemäß verschiedenen Ausführungsformen der Erfindung erzeugt wird;
• 11D ein Diagramm der Bestrahlungsstärke als Funktion der Position für das in 11C dargestellte Zwei-Spitzen-Strahlprofil ist;
• 12A ein schematisches Diagramm eines Abschnitts eines Laserabgabesystems mit zwei optischen Elementen mit Axiconlinse gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 12B und 12C geometrische Designparameter von Axiconlinsen gemäß verschiedenen Ausführungsformen der Erfindung darstellen;
• 13 ein Diagramm der BPP-Variation als Funktion des Spaltabstandes zwischen positiven und negativen Axiconlinsen gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 14 Strahlprofile in unterschiedlichen Spaltabständen zwischen positiven und negativen Axicon-Linsen entsprechend den verschiedenen Ausführungsformen der Erfindung zeigt;
• 15 Strahlprofile in unterschiedlichen Spaltabständen zwischen positiven und negativen Axicon-Linsen zeigt, die gemäß den verschiedenen Ausführungsformen der Erfindung quer zur Strahlengangrichtung versetzt sind;
• 16A ein schematisches Diagramm eines Abschnitts eines Laserabgabesystems mit Zweiphasenplattenlinsen gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 16B und 16C geometrische Entwurfsparameter von Phasenplattenlinsen gemäß verschiedenen Ausführungsformen der Erfindung darstellen;
• 16D ein Diagramm von BPP als Funktion des Innendurchmessers von Zweiphasenplatten gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 16E ein Diagramm mit optimiertem Innendurchmesser von Zweiphasenplatten als Funktion der Trennung von einer Eingangsfaser-Endkappe gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 16F ein Diagramm der BPP-Variation als Funktion des Spaltabstandes zwischen zweiphasigen Plattenlinsen gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 16G Strahlprofile in unterschiedlichen Spaltabständen zwischen zweiphasigen Plattenlinsen gemäß den verschiedenen Ausführungsformen der Erfindung zeigt;
• 17A ein schematisches Diagramm eines optischen Elements einer Meniskuslinse gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 17B ein Diagramm der BPP-Variation als Funktion des Abstands eines optischen Elements einer Meniskuslinse aus Quarzglas von einer Strahlenquelle gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 18A ein schematisches Diagramm eines partiellen Laserstrahlabgabesystems mit einem Triplettkollimator für erhöhte Strahlablenkung gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 18B ein Diagramm der BPP-Variation als Funktion des Abstands eines kugelförmigen optischen Elements mit flacher Oberseite von einer Strahlenquelle im Laserabgabesystem von 18A gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 18C ein Diagramm der BPP-Variation als Funktion des Abstands eines optischen Elements einer Meniskuslinse von einer Strahlenquelle im Laserabgabesystem von 18A gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 18D ein schematisches Diagramm eines partiellen Laserstrahlabgabesystems mit einem Triplettkollimator für erhöhte Strahldivergenz und optischen Zweiphasenplattenelementen gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 18E ein Diagramm der BPP-Variation als Funktion des Spaltabstandes zwischen den zweiphasigen Plattenlinsen im Laserstrahlabgabesystem von 18D gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 19 ein schematisches Diagramm eines Wellenlängenstrahl-Kombinationslasersystems ist, das zur Versorgung des Eingangsstrahls für Laserstrahlabgabesysteme gemäß verschiedenen Ausführungsformen der Erfindung verwendet werden kann;
• 20 eine schematische Darstellung eines Lasersystems gemäß verschiedenen Ausführungsformen der Erfindung ist;
• 21 eine Reihe von Bildern ist, die exemplarische Strahlformen darstellen, die gemäß den verschiedenen Ausführungsformen der Erfindung verwendet werden;
• 22A und 22B schematische Diagramme von Werkstücken sind, die mit Laserstrahlen unterschiedlicher Form gemäß verschiedener Ausführungsformen der Erfindung bearbeitet werden; und
• 23A-23D eine Reihe von schematischen Diagrammen eines Schweißprozesses unter Verwendung eines Laserstrahls mit mehreren verschiedenen Strahlformen gemäß den verschiedenen Ausführungsformen der Erfindung sind.

In the drawings, like reference characters generally refer to the same parts throughout the several views. Also, the drawings are not necessarily to scale, but are generally directed to illustrating the principles of the invention. In the following description, various embodiments of the present invention will be described with reference to the following drawings, in which:

• 1 a conventional method for cutting a curve of material is illustrated, wherein the polarization of the cutting beam is fixed;
• 2A illustrates an exemplary polarization adjustment corresponding to the cutting path in the material according to various embodiments of the invention;
• 2 B illustrates an exemplary polarization adjustment as a function of the thickness of the material according to various embodiments of the invention;
• 2C illustrates an exemplary polarization to linear polarization to radial polarization polarization according to various embodiments of the invention;
• 3A-3G illustrate exemplary beam polarization variation systems based, at least in part, on the machining direction or material thickness according to the various embodiments of the invention;
• 4A illustrates a method of cutting or welding a material with an automatically adjustable polarizing beam in accordance with various embodiments of the invention;
• 4B-4D Diagrams of cutting speed as a function of workpiece thickness comparing laser beams with controlled polarization according to various embodiments of the invention with conventional unpolarized beams;
• 5 Figure 3 is a schematic diagram of a laser beam delivery system according to various embodiments of the invention;
• 6 Figure 3 is a schematic diagram of a flat cone optical element according to various embodiments of the invention;
• 7A Figure 4 is a graph of BPP variation as a function of the distance of a fused silica optical flat cone element from a radiation source according to various embodiments of the invention;
• 7B Figure 4 is a graph of BPP variation as a function of the distance of a zinc sulfide optical flat cone element from a radiation source according to various embodiments of the invention;
• 8A Figure 3 is a schematic diagram of a laser delivery system with an eccentric optical element according to various embodiments of the invention;
• 8B-8D Represent beam profiles as a function of the eccentric distance, by the laser delivery system of 8A is produced;
• 8E a graph of irradiance as a function of position for the in 4D illustrated two-peak beam profile is;
• 9 Fig. 12 is a schematic diagram of a spherical flat top optical element according to various embodiments of the invention;
• 10A Figure 4 is a graph of BPP variation as a function of the distance of a spherical flat top quartz glass optical element from a radiation source according to various embodiments of the invention;
• 10B Figure 4 is a graph of BPP variation as a function of the distance of a zinc-sulfide flat top spherical optic element from a radiation source according to various embodiments of the invention;
• 11A-11C Represent beam profiles as a function of the eccentric distance, by a laser delivery system with the optical element of 9 is generated according to various embodiments of the invention;
• 11D a graph of irradiance as a function of position for the in 11C illustrated two-peak beam profile is;
• 12A Figure 3 is a schematic diagram of a portion of a laser delivery system having two axicon lens optical elements according to various embodiments of the invention;
• 12B and 12C represent geometric design parameters of axicon lenses according to various embodiments of the invention;
• 13 Figure 4 is a graph of BPP variation as a function of gap spacing between positive and negative axicon lenses according to various embodiments of the invention;
• 14 Shows beam profiles at different gap distances between positive and negative axicon lenses according to the various embodiments of the invention;
• 15 Shows beam profiles in different gap distances between positive and negative axicon lenses, which are offset transversely to the beam path direction according to the various embodiments of the invention;
• 16A FIG. 3 is a schematic diagram of a portion of a laser delivery system having two-phase plate lenses according to various embodiments of the invention; FIG.
• 16B and 16C illustrate geometric design parameters of phase-plate lenses according to various embodiments of the invention;
• 16D Figure 3 is a graph of BPP as a function of the inside diameter of two-phase plates according to various embodiments of the invention;
• 16E Figure 3 is an optimized inner diameter diagram of two-phase plates as a function of separation from an input fiber end cap according to various embodiments of the invention;
• 16F Figure 4 is a graph of BPP variation as a function of gap spacing between biphasic plate lenses according to various embodiments of the invention;
• 16G Shows beam profiles at different gap distances between biphasic plate lenses according to the various embodiments of the invention;
• 17A Figure 3 is a schematic diagram of an optical element of a meniscus lens according to various embodiments of the invention;
• 17B Figure 4 is a graph of BPP variation as a function of the distance of an optical element of a quartz glass meniscus lens from a radiation source according to various embodiments of the invention;
• 18A Figure 3 is a schematic diagram of a partial laser beam delivery system with a triplet collimator for increased beam deflection in accordance with various embodiments of the invention;
• 18B a graph of BPP variation as a function of the distance of a spherical flat top surface optical element from a radiation source in the laser delivery system of 18A according to various embodiments of the invention;
• 18C a graph of BPP variation as a function of the distance of an optical element of a meniscus lens from a radiation source in the laser delivery system of 18A according to various embodiments of the invention;
• 18D Fig. 12 is a schematic diagram of a partial laser beam delivery system with a triplet collimator for increased beam divergence and two-phase optical disk elements according to various embodiments of the invention;
• 18E a graph of BPP variation as a function of the gap distance between the biphasic plate lenses in the laser beam delivery system of 18D according to various embodiments of the invention;
• 19 Figure 4 is a schematic diagram of a wavelength-beam combination laser system that may be used to power the input beam for laser beam delivery systems according to various embodiments of the invention;
• 20 a schematic representation of a laser system according to various embodiments of the invention;
• 21 Fig. 10 is a series of images illustrating exemplary beam shapes used in accordance with various embodiments of the invention;
• 22A and 22B are schematic diagrams of workpieces being processed with laser beams of different shapes according to various embodiments of the invention; and
• 23A-23D are a series of schematic diagrams of a welding process using a laser beam having a plurality of different beam shapes according to the various embodiments of the invention.

Detailed description

Aspects and embodiments generally relate to the field of adjusting the polarization and / or shape of a laser beam used in manufacturing to achieve better manufacturing results including less dross and clean cuts and welds. In various embodiments, the present invention therefore relates to the optimization of the polarization and / or shape of a laser beam with respect to a material to be processed. In particular, polarization adjustment systems and methods can vary the orientation of a waveplate through which the beam passes to selectively vary their polarization, e.g. Based on the geometry, the material and the thickness of the material to be processed and the instantaneous orientation of the beam with respect thereto. The approaches and embodiments described herein may apply to single and dual-beam output systems that use polarization-maintaining optical fibers to direct the output beams from the laser system to a laser beam To deliver laser head. In some cases, these laser systems may be wavelength beam combining systems that produce a multi-wavelength output beam.

Embodiments of the present invention thus represent an optimum polarization direction for a particular material and maintain this direction with respect to the processing direction in the course of processing. This is in contrast to the behavior of systems of the previous class, as in 1 illustrates that do not change the polarization direction. In 1 becomes a tin 100 of the material processed with a linearly polarized beam, the desired cutting path 102 follows, which can be curved. The linear polarization indicated at 104 , maintains a fixed orientation regardless of the different orientation of the beam with respect to the material 100 , In many systems, the optimal beam polarization is parallel to the processing direction. In 1 This occurs only once, and in fact the polarization is disadvantageous in most places perpendicular to the processing direction. This can delay processing, create dross, create an imperfect cut, and so on.

An optimal behavior for the exemplary system is in 2A shown: The polarization orientation 204 of the machining beam remains over the entire processing path 102 parallel to the processing direction. Another optimal behavior for the exemplary system is in 2 B shown: The polarization state 210 of the processing beam changes from linear polarization to elliptical polarization to circular polarization as the thickness of the material increases 100 , In yet another embodiment, which is in 2C is shown, the polarization state changes 210 of the processing beam from linear polarization to radial polarization along the processing path 102 , While the processing paths in the 2 B and 2C In embodiments of the invention, processing paths may include one or more direction changes, as in FIG 2 B shown. In general, processing paths may be curved or linear, and "linear" processing paths may have one or more directional changes, ie, linear processing paths may consist of two or more substantially straight segments that are not necessarily parallel to each other.

A representative system for performing polarization variations according to the embodiments of the present invention is disclosed in U.S.P. 3A-3C shown. In relation to 3A includes the system 300 a laser (or other beam emitter, such as a polarized fiber) 305 and a controller 310 , The control 310 controls the operation of the laser 305 (ie it activates the laser 305 and controls the beam parameters, such. As the intensity, accordingly during processing). The controller also operates a conventional positioning system 315 and a polarization controller 320 , The positioning system 315 may be any controllable optical, mechanical or optical-mechanical system for guiding the beam through a machining path along a two- or three-dimensional workpiece. While editing, the controller can 310 the positioning system 315 and the laser 305 operate so that the laser beam passes through a machining path along the workpiece. The processing path may be provided by a user and in an internal or external memory 325 which can also store parameters related to the type of processing (cutting, welding, etc.) and the beam parameters required to perform this processing. In this regard, a local or remote database 330 a library of materials and thicknesses that guide the system 300 process, and after selecting the material parameters (type of material, thickness, etc.) the controller asks 310 database 330 to obtain the corresponding parameter values. The stored values may include a polarization orientation suitable for the material and / or a suitable state.

As well understood in the plot and scanning technique, the required relative movement between the beam and the workpiece may be by optical deflection of the beam by means of a movable mirror, physical movement of the laser by means of a gantry, a lead screw or other arrangement and / or a mechanical arrangement to move the workpiece instead of (or in addition to the beam). The control 310 In some embodiments, feedback may be provided on the position and / or processing efficiency of the beam with respect to the workpiece from a feedback unit 335 received, which is connected to suitable monitoring sensors. In response to signals from the feedback unit 335 changes the control 310 the path, the composition and / or the polarization of the beam.

In an embodiment incorporated in the 3B and 3C is shown, the polarization adjustment within a laser head component 350 which is usually the last opto-mechanical section of a laser system emitting a beam used in manufacturing. The laser head 350 includes a collimating lens 355 , an adjustable / rotating wave plate 360 and a focusing lens 365 to the beam 370 to be directed to the surface of the workpiece. The wave plate 360 can be a quarter-wave plate, a half-wave plate or another wave plate for rotating the polarization of the beam 370 be. Regarding the 3A-3C turns a conventional electromechanical turning device 375 the wave plate 360 under the control of the controller 310 as the beam passes through the machining path 102 moves, creating a uniform polarization direction of the beam 370 opposite the way 102 is enforced. In other configurations, multiple wave plates can be used and separated by individual rotating devices 375 to be turned around. The use of multiple wave plates can improve the reaction time. The polarization of the beam 370 will be at a first orientation 380a before the encounter with the wave plate 360 and at a second orientation 380b after passing through the wave plate 360 shown.

In an embodiment incorporated in the 3D and 3E is shown, the polarization adjustment also within a laser head component 350 carried out. The laser head 350 includes the collimation lens 355 and the focusing lens 365 to the beam 370 on the workpiece surface, just like the in 3B illustrated laser head 350 , In the embodiment of 3D includes the laser head 350 a babinet soleole compensator 385 between the collimator lens 355 and the focusing lens 365 , As known in the art, the Babinet Soleil Compensator 385 a continuously variable optical retarder capable of changing the polarization of the light traveling through it from linear to circular and any elliptical polarization state therebetween. Included in various embodiments is the Babinet Soleil Compensator 385 essentially consists of or consists of a Kompensatorplatte 386 , a solid birefringent wedge 387 and a movable birefringent wedge 388 , The longitudinal axis of the compensator plate 386 is typically perpendicular to the longitudinal axes of the wedges 387 . 388 , The movement of the wedge 388 in terms of the plate 386 and the wedge 377 changes the polarization state of the carrier 370 in any elliptical state between linear and circular. Regarding the 3A . 3D and 3E displaces a conventional electromechanical displacement device 389 the movable wedge 388 the Babinet Soleil Compensator 385 under the control of the controller 310 as the beam passes through the machining path 102 moved (for example, when the thickness of the workpiece changes), whereby the state of polarization depending on the thickness of the workpiece along the way 102 changes. For example, the circularity (ie the transition from linear to elliptical or circular) of the polarization state of the beam 370 be increased with increasing thickness of the workpiece. The polarization of the beam 370 is in a first state 390a before the encounter with the Babinet Soleil Compensator 385 and in a second state 390b after passing through the Babinet Soleil Compensator 385 shown.

In a further embodiment, which in the 3F and 3G is shown, the polarization adjustment is also within a laser head component 350 carried out. The laser head 350 includes the collimation lens 355 and the focusing lens 365 to the beam 370 on the workpiece surface, just like in the 3B and 3D illustrated laser head 350 , In the embodiment of 3F includes the laser head 350 a radial polarization converter 391 between the collimator lens 355 and the focusing lens 365 , As known in the art, a radial polarization converter 391 include, consist essentially of, or consist of, a glass wave plate that converts linear polarization into radial polarization or azimuthal polarization. For example, the radial polarization converter 391 be a half-wave plate with a continuously varying slow axis direction or a space variant of a quarter-wave plate with radial symmetry. The radial polarization converter 391 may include, substantially consist of or consist of a glass plate with a nanostructured grid, e.g. For example, the S-waveplate radial polarization converter of UAB Altechna of Vilnius, Lithuania, or one of the radial polarization transducers of Edmund Optics Inc. of Barrington, New Jersey, USA. In other embodiments, the radial polarization converter 391 include, consist essentially of, or consist of a liquid crystal in which the liquid crystal molecules are specifically aligned to produce the desired radial or azimuthal polarization, e.g. For example, the Arcopix radial polarization converter available from Arcopix, Neuchâtel, Switzerland.

The movement of the radial polarization converter 391 within the beam path 370 changes the polarization state of the beam 370 from linear to radial or azimuthal or vice versa. In various embodiments, the radially polarized beam is 370 focusable to a smaller spot size than the beam 370 with a linear polarization. With reference to the 3A . 3F and 3G displaces a conventional electromechanical displacement device 389 the radial polarization converter 391 under the control of the controller 310 while the beam passes through the processing path 102 moves and thereby the polarization state along the way 102 changes. The polarization of the beam 370 will be in a first state 392a before hitting the radial polarization converter 391 (ie linear polarization) and in a second state 392b after passing through the radial polarization converter 391 (ie radial polarization) shown.

4A illustrates a representative process 400 to operate the system 300 for performing a cutting operation. In a first step 410 the user programs the desired path into the system 300 with a suitable input device or via file transfer. In step 420 analyzes the controller 310 the curves, features (eg, thickness) and cutting direction of the path, query the database as needed 330 determines how fast the cut can be made, and determines the optimum polarization direction and / or state of the laser beam with respect to the cutting direction. In operation, as in step 430 specified controls the controller 330 the laser 305 and the subsystems 315 . 320 to cut along the preprogrammed path and maintain proper polarization. If the composition and / or thickness of the material being processed changes, the location and type of change can be programmed and the controller 310 can adjust the laser beam parameters (including polarization and / or beam shape) accordingly. It should be noted that the optimal cutting, welding or manufacturing solution is not necessarily the cleanest cut or weld, as additional process steps (eg deburring, grinding and / or polishing) may be required. Thus, the overall optimization can be based on the desired performance, and the present methods and systems are configured to deliver the desired results, no matter what they look like. As already mentioned, cutting is just one example of laser processing that can benefit from the approach of embodiments of the present invention.

The control 310 can be provided either as software, hardware or as a combination thereof. For example, the system may be implemented on one or more conventional server-class computers, such as a PC with a CPU board containing one or more processors, such as the Pentium or Celeron processor family manufactured by Intel Corporation of Santa Clara, California. The 680x0 and POWER PC family of processors manufactured by Motorola Corporation of Schaumburg, Illinois, and / or the ATHLON processor family manufactured by Advanced Micro Devices, Inc. of Sunnyvale, California, USA. The processor may also include a main memory unit for storing programs and / or data associated with the methods described above. The memory may include Random Access Memory (RAM), Read Only Memory (ROM) and / or Flash memory located on commonly available hardware, such as one or more Application Specific Integrated Circuits (ASIC), Field Programmable Gate Arrays (FPGA) ), electrically erasable programmable read only memory (EEPROM), programmable read only memory (PROM), programmable logic device (PLD), or read only memory device (ROM). In some embodiments, the programs may be provided with external RAM and / or ROM, such as optical disks, magnetic disks, and other commonly used memory devices. For embodiments in which the functions are provided as one or more software programs, the programs may be written in any number of high level languages such as FORTRAN, PASCAL, JAVA, C, C ++, C #, BASIC, various scripting languages, and / or HTML. In addition, the software may be implemented in assembly language directed to the microprocessor located on a target computer; For example, the software can be implemented in the Intel 80 × 86 assembly language if it is configured to operate on an IBM PC or PC clone. The software may be embodied on an article of manufacture that includes, but is not limited to, a floppy disk, a jump drive, a hard disk, an optical disk, a magnetic tape, a PROM, an EPROM, an EEPROM, a field programmable gate array, or a CD-ROM.

Although the methods described herein improve processing for linearly polarized beams (delivered over a free-space laser or polarization-maintaining fiber), the methods also work with elliptically polarized beams (dominated by one polarization). For example, a standard multimode fiber beam would probably be elliptically polarized and could benefit from the approaches described herein.

Embodiments of the invention may be advantageous for more efficient cutting of various materials, e.g. As metallic materials used. 4B is a graph of achievable cutting speed as a function of workpiece thickness for a stainless steel workpiece 304 under a nitrogen gas stream. Four different laser systems were used for cutting. First, a laser system according to the embodiments of the invention which operates at 1 kW power and uses a 58 μm polarization-maintaining output optical fiber to produce a linearly polarized laser output beam was used to cut the workpiece in directions parallel and perpendicular to the polarization direction. The trend line 440 shows the achievable cutting speed for the parallel to Cutting direction polarized beam and the trend line 445 The achievable cutting speed for the beam polarized perpendicular to the cutting direction. As shown, the parallel polarized beam is capable of achieving cutting speeds significantly higher than the perpendicular polarized beam, especially for thinner workpieces. The trend lines 450 and 455 represent the data for two different commercially available 1kW laser systems with unpolarized output beams (ie, using output optical fibers that are not polarization-maintaining fibers). As shown, the unpolarized beam is able to cut faster than the perpendicularly polarized beam of the trend line 445 , but slower than the parallel polarized ray of the trend line 440 , The trend line 460 shows data for a 2kW laser with a 100μm output fiber, but also produces an unpolarized beam. As expected, this more powerful laser system is able to achieve faster cutting speeds than the lower power laser systems, although this advantage decreases and even disappears on thinner workpieces than the parallel polarized beam of the trend line 440 at higher speed, although it operates at lower power and with a smaller output fiber.

4C FIG. 12 is a graph of achievable cutting speed as a function of workpiece thickness for a 3003 aluminum workpiece under a nitrogen gas flow. FIG. The laser systems used are the same as the ones above 4B described. As shown, the parallel polarized beam is the trend line 440 the best cutting performance, and the power of the parallel polarized beam is even better than the 2 kW, 100 μm unpolarized beam of the trend line 460 , especially with thinner workpiece thicknesses. As in 4B represents the perpendicularly polarized ray of the trend line 445 the worst performance and emphasizes a beneficial effect of embodiments of the invention, in which the polarization direction is maintained parallel to the cutting direction.

4D Figure 11 is a graph of the achievable cutting speed as a function of workpiece thickness for a brass workpiece under a nitrogen gas flow. The laser systems used are the same as the ones above 4B described. As shown, the parallel polarized beam shows the trend line 440 a fast cutting performance, especially with thinner workpiece thicknesses. The parallel polarized beam passing through the trend line 440 also has a much higher cutting speed than the comparable 1 kW unpolarized beam passing through the trend line 450 is represented. As in the 4B and 4C represents the perpendicularly polarized ray of the trend line 445 the worst performance and was actually unable to achieve significant cutting speeds for the workpiece with a thickness of 3 mm.

Embodiments of the present invention combine or replace polarization adjustments of a beam in response to the workpiece material and / or the physical properties with techniques for beam shaping and / or adjustment of the BPP of the beam. 5 shows a schematic diagram of a laser beam delivery system 500 with beam manipulating optical elements according to embodiments of the present invention. In various embodiments, the laser beam delivery system 500 for example within a laser-based cutting head or welding head (eg cutting head 350 ) and combined with various components therein (eg, optical elements, controls, etc.) to adjust the polarization of the output beam. The jet delivery system 500 may comprise a jet delivery fiber contained in a fiber end cap 505 ends, which is connected to the remaining portions of the laser generating system (eg, a WBC laser system used in 5 not shown), a collimating lens 510 , a focusing lens 515 and an optical element 520 that is between the end cap 505 and the collimation lens 510 is positioned. In various embodiments of the invention with combined beamforming and polarization matching functionality, elements such as collimator lenses 510 and focusing lens 515 between these functionalities, that is, the laser beam delivery system in various embodiments may include various optical elements that facilitate both beamforming and polarization matching. In various embodiments, the optical element is 520 near the fiber end cap 505 arranged to the size of the optical element 520 minimize incident beam. The refraction of a smaller beam can be performed with optics having smaller geometrical dimensions of the optic and can vary the output profile with greater sensitivity. 5 also shows an optional second optical element 525 that is between the focusing lens 515 and a workpiece 530 is arranged. The workpiece 530 For example, it may include or consist essentially of one or more parts (eg, metal parts) through the one through the focusing lens 515 focused beam can be welded, drilled and / or cut. In various embodiments, the first optical element is 520 between the focusing lens 515 and the workpiece 530 arranged and the second optical element 525 eliminated. The optical elements 520 . 525 For example, each may include or substantially consist of a phase plate.

The positions of the first optical element 520 and / or the second optical element 525 may be displaced within the beam profile by use of a lens manipulation system which may, for example, include or consist essentially of one or more mechanized or motorized DeepL displacements 535 that may move along two or three axes. The lens processing system may be based on a controller 540 react. The control 540 may be responsive to a desired target radiation distribution and / or BPP or other measure of beam quality (eg, input by a user and / or based on one or more properties of a workpiece to be machined, such as the distance to the workpiece, composition of the workpiece, the topography of the workpiece, the thickness of the workpiece, etc.) and be configured to the optical element 520 and / or the optical element 525 position so that the manipulated beam 545 the workpiece 530 with the desired radiation distribution or beam quality. The control 540 can be programmed to achieve the desired power distribution and / or output BPP and / or beam quality via a particular optical element positioning as described herein. The control 540 can be provided either as software, hardware or a combination thereof. For example, the system may be implemented on one or more conventional server-class computers, such as a personal computer with a CPU card containing one or more processors, such as the Pentium or Celeron processor family manufactured by Intel Corporation of Santa Clara, California. manufactured 680 × 0 processor family and POWER PC, which is manufactured by the Motorola Corporation of Schaumburg, Illinois, and / or the processor family ATHLON, which is manufactured by Advanced Micro Devices, Inc. of Sunnyvale, California. The processor may also include a main memory unit for storing programs and / or data associated with the methods described herein. The memory may include Random Access Memory (RAM), Read Only Memory (ROM) and / or Flash memory located on commonly available hardware, such as one or more Application Specific Integrated Circuits (ASIC), Field Programmable Gate Arrays (FPGA) ), electrically erasable programmable read only memory (EEPROM), programmable read only memory (PROM), programmable logic device (PLD), or read only memory device (ROM). In some embodiments, the programs may be provided with external RAM and / or ROM, such as optical disks, magnetic disks, and other commonly used memory devices. For embodiments in which the functions are provided as one or more software programs, the programs may be written in any number of high level languages such as FORTRAN, PASCAL, JAVA, C, C ++, C #, BASIC, various scripting languages, and / or HTML. In addition, the software may be implemented in assembly language directed to the microprocessor located on a target computer; For example, the software can be implemented in the Intel 80 × 86 assembly language if it is configured to operate on an IBM PC or PC clone. The software may be embodied on an article of manufacture that includes, but is not limited to, a floppy disk, a jump drive, a hard disk, an optical disk, a magnetic tape, a PROM, an EPROM, an EEPROM, a field programmable gate array, or a CD-ROM.

6 is a schematic diagram of an optical element 600 in the form of a truncated cone (flat cone shape or conical cylindrical shape) according to the embodiments of the invention. For example, the optical element 600 as an optical element 520 and / or optical element 525 in the feeding system 500 be used. The parameters D, d, θ, and H are geometric design parameters for the outer diameter, the inner diameter (which may correspond to the beam size of the beam upon impact with the optical element), the angle of inclination, the maximum sagitta (or "sag" h), and the Defined separation of the outer ring of the beam from the point center of the beam, or the thickness of the optical element 600 , Geometric optics ray tracing may be used to design optical elements in accordance with embodiments of the present invention based on energy conservation, optical path length constancy, and Snell's law. For example, the lens design and its surface profiles may convert the beam profile from a Gaussian to a Bessel laser beam having a desired intensity distribution.

Table 1 contains exemplary design values for exemplary optical elements 600 , including, consisting essentially of or consisting of two different materials, quartz glass and zinc sulfide (eg ZnS MultiSpectral, available from II-VI Inc. of Saxonburg, PA, USA). Table 1 Material of the optical element quartz glass zinc sulfide D (mm) 25 25 d (mm) 8th 8th H (mm) 2 0.85 h (μm) 50 17 Θ (mrad) 5.9 2

7A and 7B are diagrams of BPP at different distances from the fiber end cap 505 to the exemplary optical elements 600 made of quartz glass ( 7A) and zinc sulfide ( 7B) with the design parameters given in Table 1. In the plots, the starting position of the optical element 600 with 25 mm from the end cap 505 accepted. As shown, in both cases the BPP of the beam may be from about 4 to about 12 by shifting the optical element 600 be increased by about 30 mm. The slope of this change in BPP as a function of the shift may be due to changes in the numerical aperture of the fiber exit on the end cap 505 to be changed. The carrier profiles at a distance of 50 mm between the optical element 600 and the fiber end cap 505 are also in the 7A and 7B shown.

A tailored beam profile having two peaks in one axis can be obtained by using the optical element 600 (or other optical elements described herein) positioned transversely to the center in the beam path (ie, partially inserted into the input laser beam), as in FIG 8A shown. Depending on the degree of introduction, the beam profile of the output laser beam can be optimally adapted to a large number of laser applications. In the 8B-8D are the carrier profiles in different eccentric distances (0 mm, 2 mm and 4 mm) for the optical element 600 at a distance of 40 mm to the end cap 505 shown. 8E is a plot of irradiance as a function of position for the in 8D illustrated beam profile, which clearly shows the two-peak nature of the beam profile. In various embodiments, the variation of BPP is at various eccentric positions of the optical element 600 about zero, even if the irradiance changes as a function of position over the beam profile.

Optical elements according to embodiments of the invention may also have a spherical segment (ie, spherical flat top) configuration and may also be used to create a Bessel beam profile. The geometric design of the optical elements 900 according to these embodiments is in 9 shown schematically. The optical element 900 can as an optical element 520 and / or optical element 525 in the feeding system 500 be used. The design parameters are the same as above for the optical flat cone element 600 , with the exception of the radius of curvature R, which also defines the maximum sag (h) and the distance of the resulting annular beam ring from the beam spot center.

Table 2 contains exemplary design values for exemplary optical elements 900 , including, consisting essentially of or consisting of two different materials, quartz glass and zinc sulfide. Table 2 Material of the optical element quartz glass zinc sulfide D (mm) 25 25 d (mm) 8th 8th H (mm) 2 0.85 h (μm) 58 23 R (mm) 1200 3000

10A and 10B are diagrams of BPP at different distances from the fiber end cap 505 to the exemplary optical elements 900 made of quartz glass ( 10A) and zinc sulfide ( 10B) with the design parameters given in Table 2. In the plots, the starting position of the optical element 900 with 25 mm from the end cap 505 accepted. As shown, in both cases the BPP of the beam can be achieved by shifting the optical element 900 increased by about 30 mm (eg about 28 mm - about 32 mm) from about 4 to about 12. The slope of this change in BPP as a function of the shift may be due to changes in the numerical aperture of the fiber exit on the end cap 505 to be changed. The beam profiles at a distance of 50 mm from the optical elements 900 to the fiber end cap 505 are in the 10A and 10B as well as the diagrams of their irradiance as a function of the position for the 50 mm distance between the optical element 900 and the end cap 505 ,

In the 11A-11C are the beam profiles at different eccentric distances (0 mm, 2 mm and 4 mm) for the optical element 900 (ie, as for the optical element 600 in 6A shown) at a distance of 40 mm from the end cap 505 shown. 11D is a plot of irradiance as a function of position for the in 11C illustrated beam profile, which clearly shows the two-peak nature of the intensity of the beam profile. In various embodiments, the variation of BPP is at various eccentric positions of the optical element 900 about zero, even if the irradiance changes as a function of position over the beam profile.

Embodiments of the invention use optical elements to produce annular beam shapes. Embodiments of the invention include one or more optical elements that include, consist essentially of, or consist of axicon lenses. As known in the art, axicon lenses are lenses having at least one conical surface, and such lenses may be used to image a point source into a line segment along the optical axis. The conical surface of the rotation is capable of mixing light from a point source located on the axis of rotation by reflection or refraction, or both. Embodiments of the invention use a combination of a double positive (ie, double convex) axicon lens 1200 and a double negative (ie double concave) axicon lens 1210 between the fiber end cap 505 and the collimator lens 510 , as in 12A and the beam size on the workpiece can be varied with this lens system. As shown, the lenses are 1200 . 1210 in the beam path through a gap distance 1220 separated. θ1 and θ2 are the slope variables of the conical surfaces that are the maximum sags ( h1 and h2 ) and the separation of the annular beam ring from the beam spot center, as in FIGS 12B and 12C shown schematically. In various embodiments of the invention, the conical surfaces of one or both lenses 1200 . 1210 smooth edges and radii of curvature less than about 5 μm.

13 is a diagram showing the control over the BPP of the laser delivery system as a function of the gap distance 1220 between the two axicon lenses 1200 . 1210 represents. As in 13 shown, results in an approximate deviation of the gap distance 1220 of 7mm to a BPP increase from 4 to 12, demonstrating the wide bandwidth of the BPP control enabled by such embodiments of the present invention. The beam profiles depending on the gap distance 1220 between the lenses 1200 . 1210 are in 14 shown, wherein the gap distances are given in millimeters. As shown, the setting of the gap distance 1220 Transform a beam profile with a single tip into one with two, three or more tips. 15 shows similar beam profiles in the event that the two axicon lenses 1200 . 1210 offset in the beam path by 4 mm across the center and by the listed gap distances 1220 (Gap distances are given in millimeters) are separated.

Embodiments of the invention include one or more optical elements that include, consist essentially of, or consist of phase plates having a planar surface and an opposing surface, at least a portion of which is convexly or concavely curved. 16A provides a partial beam delivery system with two such plates 1600 . 1610 through a gap Z are separated. As shown, the plate is 1600 from the fiber end cap 505 through a distance S separated. 16B and 16C put the plates 1600 . 1610 As shown, the plates have 1600 . 1610 an outer diameter D and the convex / concave portions of their surfaces have an inner diameter d who say the maximum H defined (in conjunction with R , see below). The thicknesses of the plates at their outer peripheries (ie the thicknesses between the planar portions of their opposite surfaces) are through H and the radii of curvature of the convex / concave portions are represented by R. As in the 16B and 16C shown, have the plates 1600 . 1610 about the same H . D . d and R although various embodiments of the invention have double plates (ie, one having a partial concave surface and one having a partially convex surface) that differ in one or more of these parameters.

Table 3 contains exemplary design values for exemplary optical elements 1600 . 1610 , including, consisting essentially or consisting of two different materials, quartz glass and zinc sulfide. Table 3 Material of the optical element quartz glass zinc sulfide D (mm) 25 25 d (mm) 5 5 H (mm) 2 1 h (μm) 25 9.3 R (mm) 500 1350

16D and 16E show that according to the embodiments of the invention, the inner diameter d the plates 1600 . 1610 can be optimized to the output BPP of the laser delivery system as a function of distance S from the fiber end cap 505 to maximize. 16D is a graphic of BPP depending on the inside diameter d for plates 1600 . 1610 with a distance S of 40 mm, a gap distance Z of 10 mm and a radius of curvature R of 500. As shown, the resulting BPP becomes at an inner diameter d maximized by about 5 mm; This BPP is essentially independent of changes in the gap distance Z and the radius of curvature R , 16E is a diagram of the optimized inner diameter d (ie, the inner diameter d that maximizes the initial BPP) depending on the distance S between the end cap 505 and the plate 1600 , As shown, an optimized inside diameter d be selected, the BPP of the output beam depending on the distance S maximized.

16F is a diagram of BPP at different gap distances Z between the plates 1600 . 1610 with the design parameters given in Table 3 (with the design parameters of Table 3, both the fused silica and zinc sulfide plates provide 1600 . 1610 the same results). In the plot, the distance becomes S to the end cap 505 adopted with 40 mm. As shown, the BPP of the beam can be increased from about 4 to about 12 by the gap Z between the plates 1600 . 1610 is changed by about 9 mm. Different beam profiles of the output beam as a function of the gap Z (in mm) are in 16G shown, as well as diagrams of their irradiance depending on the position. As shown, the beam shape transitions from a single peak to a broader, multi-track irradiation profile as the beam BPP increases.

Optical elements according to embodiments of the invention may also include, consist essentially of or consist of meniscal lenses. The geometric design for optical elements 1700 according to these embodiments is in 17A shown schematically; As shown in various embodiments, a surface of the optical element is 1700 substantially convexly curved over the entire surface while the opposite surface is concavely curved over a portion of the surface and an inner diameter d Are defined. The optical element 1700 can as an optical element 520 and / or optical element 525 in the feeding system 500 be used. As shown, the optical element 1700 an outer diameter D , an inner diameter d , a thickness H , a maximum say h1 the convex curved surface and a maximum sag h2 have the partially concave curved surface. The radius of curvature R for both surfaces of the optical element 1700 can be about the same, defines the maximum loops h1 and h2 and the separation of the resulting annular jet ring from the beam spot center.

Table 4 contains exemplary design values for exemplary optical elements 1700 , including, consisting essentially of or consisting of two different materials, quartz glass and zinc sulfide. Table 4 Material of the optical element quartz glass zinc sulfide D (mm) 25 25 d (mm) 8th 8th H (mm) 3 1.8 h1 (μm) 87 31 h2 (μm) 9 3.2 R (mm) 900 2500

17B is a diagram of BPP at different distances from the fiber end cap 505 to the exemplary quartz glass optical element 1700 with the design parameters given in Table 4. The plot shows the starting position of the optical element 1700 with 25 mm from the end cap 505 accepted. As shown, the BPP of the beam may be from about 4 to about 12 by shifting the optical element 1700 be increased by about 24 mm. The beam profile at a distance of 46 mm between the optical element 1700 and the fiber end cap 505 is also in 17B as well as a plot of irradiance as a function of position for the 46 mm distance between the optical element 1700 and the end cap 505 ,

Laser beam delivery systems according to embodiments of the present invention may also use different lens arrangements to form larger, more divergent input beams for the BPP variation as a function of movement of the optical elements. 18A represents sections of a laser delivery system 1800 which is a movable optical element 1805 for BPP variation and a triplet collimator for increasing the divergence of the laser beam. As shown, the triplet collimator increases the divergence of the beam from an angle α to an angle β , In various embodiments, the ratio of β to α between about 2 and about 1.5, so z. B. about 1.74. As further described below, this increased divergence allows greater control over BPP with less movement of the optical element 1805 , In various embodiments, the optical element is comprised 1805 essentially consists of or consists of one or more optical elements 600 , optical elements 900 , optical elements 1700 , Phase plates 1600 / 1610 or axicon lenses 1200 . 1210 ,

Triplet collimators for increasing the beam deviation according to the embodiments of the invention may consist of various combinations of lenses. 18A represents such an embodiment, which is a plano-concave lens 1810 , a meniscus lens 1815 (eg a positive meniscus lens) and a plano-convex lens 1820 includes. In various embodiments of the invention, the optical element is 1805 in the beam path between the plano-concave lens 1810 and meniscus lens 1815 arranged. In further embodiments, the optical element 1805 in the beam path between meniscus lens 1815 and plano-convex lens 1820 or even optically downstream of the plano-convex lens 1820 be arranged.

18B is a diagram of BPP at different distances from the fiber end cap 505 to the quartz glass optical element 600 with the design parameters given in Table 1 when in a laser beam delivery system 1800 used in conjunction with a triplet collimator for increased beam divergence. The plot shows the starting position of the optical element 600 with 25 mm from the end cap 505 accepted. As shown, the BPP of the beam can be increased from about 4 to about 12 by the optical element 600 is shifted by only about 16 mm, or by the factor 2 less displacement (ie greater control) compared to the beam guiding system without the triplet collimator of 18A (please refer 7A) , The beam profile at a distance of 21 mm between the optical element 600 and the fiber end cap 505 is also in 18B shown.

18C is a diagram of BPP at different distances from the fiber end cap 505 to the exemplary quartz glass optical element 1700 with the design parameters given in Table 4 when used in a laser beam delivery system 1800 used in conjunction with a triplet collimator for increased beam divergence. The plot shows the starting position of the optical element 1700 with 25 mm from the end cap 505 accepted. As shown, the BPP of the beam can be increased from about 4 to about 12 by the optical element 600 is shifted by only about 12 mm, or by the factor 2 less displacement (ie more control) compared to the beam guiding system without the triplet collimator from 18A (please refer 17B) , The beam profile at a distance of 17.5 mm of the optical element 1700 to the fiber end cap 505 is also in 18C shown.

18D is a schematic of the partial laser beam delivery system 1800 comprising the two-phase optical disk elements described above 1600 . 1610 that within the beam path through a gap distance Z are separated. 18E is a diagram of BPP for different gap distances Z the exemplary quartz glass optical elements 1600 . 1610 with the design parameters given in Table 3 when used in the laser beam delivery system 1800 used in conjunction with a triplet collimator for increased beam divergence. The plot shows the position of the optical element 1600 with 25 mm from the end cap 505 accepted. As shown, the BPP of the beam can be increased from about 4 to about 12 by adjusting the gap distance Z between the optical elements 1600 . 1610 increased by only about 3 mm, or by a factor of 3 less displacement (ie greater control) compared to the beam guiding system without the triplet collimator of 18A (please refer 16F) , The beam profile at a gap distance of 3 mm between the optical elements 1600 . 1610 is also in 18C shown.

Laser systems and laser delivery systems according to embodiments of the present invention and described herein may be used in and / or with WBC laser systems. In particular, in various embodiments of the invention, multi-wavelength output beams of WBC laser systems may be used as input beams for laser beam output systems for varying BPP, beam shape and / or polarization as described herein. 19 shows an exemplary WBC laser system 1900 , one or more lasers 1905 used. In the example of 19 points the laser 1905 a diode bar with four radiation emitters on, the rays 1910 emit (see enlarged input view 1915 However, embodiments of the invention may use diode bars that emit any number of single beams or two-dimensional rows or stacks of diodes or diode bars. In the view 1915 becomes every carrier 1910 characterized by a line, wherein the length or larger dimension of the line represents the slow divergent dimension of the carrier and the height or shorter dimension represents the fast divergent dimension. A collimation optics 1920 Can be used to any beam 1910 to collapse along the fast dimension. Transformation optical system (s) 1925 which may include or consist essentially of one or more cylindrical or spherical lenses and / or mirrors are used to form each beam 1910 along a WBC direction 1930 to combine. The transformation optics 1925 then overlaps the combined beam onto a dispersive element 1935 (which may include or consist essentially of, for example, a reflective or transmissive diffraction grating, a dispersive prism, a prism / grating, a transmission grating, or an echelle grating), and the combined beam will then act as a single output profile an output clutch 1940 transfer. The output clutch 1940 then send the combined beams 1945 as in the initial front view 1950 shown. The output clutch 1940 is typically semi-reflective and serves as a common front facet for all laser elements in this external cavity system 1900 , An external cavity is a laser system in which the secondary mirror is spaced apart from the emission aperture or facet of each laser emitter. In some embodiments, additional optics are placed between the emission aperture or facet and the output coupling or partially reflective surface. The output beam 1945 is a multi-wavelength beam (the wavelengths of the individual beams 1910 combined) and may be used as input beam in the laser beam delivery systems described herein and / or coupled into a fiber optic.

20 Represents a laser system 2000 with a variably shaped output beam used in accordance with various embodiments of the present invention. As shown, the laser system 2000 a laser source 2010 (eg a WBC laser system 1900 , which forms a multi-wavelength output beam) with a glass fiber 2020 is coupled. At the distal end of the fiber 2020 there is a machining head or laser beam delivery system 2030 , The machining head 2030 For example, all or some of the above-described components of the laser beam delivery system may be used 500 include, consist essentially of or consist of. For example, the machining head 2030 a controller (eg controller 540 ) and / or responsive to the output beam shape at a focal point 2040 at or near the surface of a workpiece. In various embodiments, as described herein, the processing head may 2030 include or consist essentially of different optical elements that are shaped and / or movable relative to each other to form an output laser beam having a variable output beam shape. 21 shows a number of different output beam shapes passing through the laser system 2000 are malleable according to the embodiments of the present invention. As shown, the output beam shapes range from highly focused spot beams to diffuse, defocused larger dots to annular beams, depending on the control voltage used within the processing head 2030 is applied (eg via the controller for controlling the position of one or more optical elements therein). As well as in 21 As shown, the BPP of the carrier may also change as the beam shape changes.

The laser system 2000 includes in various embodiments a controller (eg, controller 540 as mentioned above) and / or a positioning system (eg positioning system 315 ). The controller controls the operation of the laser system (ie, it activates the laser and controls the beam parameters, such as intensity and / or output beam shape, optionally during machining). The controller can also operate the positioning system. The positioning system may be any controllable optical, mechanical or optical-mechanical system for guiding the beam through a machining path along a two- or three-dimensional workpiece. During machining, the controller can control the positioning system and the laser system 2000 operate so that the laser beam passes through a machining path along the workpiece and / or that the laser output beam is positioned at a certain point on the workpiece to be machined (eg, a position for a weld). The processing path and / or one or more processing points may be provided by a user and stored in internal or external memory which also includes parameters related to the type of processing (cutting, welding, etc.) and the beam parameters required to perform this processing (eg output beam shape) can store. In this context, a local or remote database may carry a library of materials and thicknesses that the laser system will process, and after selecting the material parameters (type of material, thickness, etc.) the controller may query the database to obtain the corresponding parameter values.

As well understood in the plot and scanning art, any required relative movement between the output beam and the workpiece can be achieved by optical deflection of the beam using a movable mirror, physical movement of the laser using a gantry, lead screw, or other arrangement and / or mechanical arrangement for moving the workpiece instead of (or in addition to the beam) are generated. The controller, in some embodiments, may receive feedback about the beam position and / or the processing efficiency of the beam with respect to the workpiece from a feedback unit connected to appropriate monitoring sensors. In response to signals from the feedback unit, the controller changes the path, position, BPP, and / or shape of the beam.

In addition, the laser system may include one or more systems for sensing the thickness of the workpiece and / or the height of features thereon. For example, the laser system may include systems (or components thereof) for interferometric depth measurement of the workpiece, such as that filed on April 1, 2015 U.S. Patent Application No. 14 / 676,070 , the entire disclosure of which is incorporated herein by reference. This depth or thickness information can be used by the controller to control the output beam shape and to optimize the machining (eg, cutting or welding) of the workpiece, e.g. According to the records in the database corresponding to the type of material to be processed.

22A and 22B show exemplary cutting scenarios according to embodiments of the invention. In various embodiments of the invention, the laser system 2000 used to work in a workpiece 2200 different depths and / or different sizes to cut and / or a uniform cut in a workpiece 2200 to perform with variable thickness. As shown, the output beam shape may have a sharply focused point for flat slices and be varied gradually or substantially abruptly to provide a defocused dot and / or ring shape (and / or point with two or more distinct peaks in intensity) for deeper slices to get through thicker areas on the workpiece 2200 and / or changes in the angle between the machining head 2030 and the workpiece 2200 required are. Such as in 22A illustrated, the output beam, the workpiece 2200 at an angle substantially perpendicular to the surface of the workpiece 2200 and the output beam may be in the form of a highly focused spot to make a relatively flat cut through all or part of the thickness of the workpiece 2200 close. As well as in 22A As shown, the shape of the beam may be changed to a defocused point or an annular shape to increase the width of the workpiece 2200 to cut and / or if the angle between the output beam and the surface of the workpiece 2200 changed (eg decreased), so that the distance through the workpiece 2200 is increased along the output beam direction.

In various embodiments, as in 22B shown, the angle of the machining head 2030 (and thus the output beam) are kept constant (eg, substantially vertical), since the topology, thickness and / or surface angle of the workpiece 2200 during the relative movement between the beam and the workpiece 2200 changes, and the controller controls the beam shape according to the effective thickness of the workpiece 2200 (ie the depth of the cut, which is required to pass through or to a certain distance within the workpiece 2200 to cut), the machining head 2030 is presented at various processing points or via the processing path. For example, the thickness of the workpiece 2200 that the machining head 2030 on the left side of 22B is presented larger than the one on the right side of 22B, z , Due to the topology of the surface, and the beam shape is adjusted accordingly. The machining head 2030 and / or the output beam need not be repositioned to create a uniform angle between the beam and the workpiece surface. In this way complex robotic and / or other equipment for the angular adjustment of the machining head and the associated costs and complexity can be avoided.

In various embodiments of the invention, the laser system is used to weld one or more workpieces while minimizing or largely eliminating the need to scan the output beam across the surface of the workpiece (s). 23A-23D illustrate an exemplary welding sequence according to embodiments of the invention. As shown, an output beam shape becomes 2300 during a spot weld of a larger annular shape ( 23A) to a smaller ring ( 23B) to a larger focused point ( 23C) to a smaller focused point ( 23D) varies to two workpieces 2310 . 2320 without the need for a relative movement between the output beam and the workpieces to connect together. In this way, between the two workpieces 2310 . 2320 a uniform weld larger than the dot size 2300 in 23D (and / or at least as large as the outer limit of the point size 2300 in 23A) formed without the beam is scanned along its surface. In various embodiments, the controller may vary the output power and / or BPP of the beam during the welding process as well as the shape of the output beam. For example, the output power of a highly focused beam shape can be reduced to substantially match the output of a more defocused and / or annular beam to facilitate the formation of spatially uniform welds. In this way, large, uniform single welds on a workpiece can be created solely by changing the beam shape (and in some embodiments also the beam power), thereby eliminating the need to form multiple smaller spot welds over the same area (as well as the need to weld the workpiece) to move each weld relative to the carrier). Although the 23A-23D illustrate an exemplary spot welding process, the embodiments of the invention also include other processing techniques and types of welding, e.g. B. Overlap and spot welds. In addition, the different welding steps with different beam shapes, as in the 23A-23D shown in any order according to embodiments of the invention. While the 23A-23D illustrate a series of four different beam shapes used for a weld, embodiments of the invention may use two, three, or more than four different beam shapes when welding a workpiece.

The terms and expressions used herein are for purposes of description and not limitation, and the use of such terms and expressions is not intended to preclude equivalent ones of the illustrated and described features or portions thereof, but it is recognized that various changes may occur in the context of the claimed invention are possible.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 62362824 [0001]
• US 15/261096 [0001]
• US 9335551 [0005]
• US 6192062 [0017]
• US 6,208,679
• US 8670180 [0017]
• US 8559107 [0017]
• US 14676070 [0094]

Claims (46)

A method of machining a workpiece, the method comprising: Causing relative movement between a laser output beam and the surface of the workpiece to define a machining path, wherein a thickness of the workpiece varies along a direction parallel to the laser output beam along the machining path, the laser output beam physically modifying the surface of the workpiece along at least a portion of the machining path; and meanwhile, changing a shape of the laser output beam based at least in part on the thickness of the workpiece. Method according to Claim 1 wherein the shape of the laser output beam is varied between a focused point and a ring as the thickness of the workpiece increases. Method according to Claim 1 wherein the thickness of the workpiece along the direction parallel to the laser output beam varies at least partially due to a change in an angle between the laser output beam and the surface of the workpiece. Method according to Claim 1 wherein the shape of the laser output beam is changed while keeping an angle between the laser output beam and the surface of the workpiece substantially constant. Method according to Claim 1 further comprising measuring the thickness of the workpiece during the relative movement between the laser output beam and the surface of the workpiece. Method according to Claim 1 wherein the shape of the laser output beam is changed based on a composition of the workpiece. Method according to Claim 1 , wherein the laser output beam consists of several wavelengths. A system for machining a workpiece, the system comprising: a beam emitter for emitting a laser output beam; a positioning device for changing a position of the laser output beam with respect to the workpiece; Means for changing a shape of the laser output beam; and a controller coupled to the positioning device and the shape changing means for causing (i) the beam emitter to operate such that the laser output beam travels a path over at least a portion of the workpiece to physically change its surface and (ii) the shape the laser output beam to change at least partially based on a thickness of the workpiece along the way. System after Claim 8 wherein the beam emitter comprises a machining head from which the laser output beam is emitted, and the shape changing means comprises (i) one or more optical elements within the machining head and (ii) a second controller for changing a position of at least one of the optical elements within the machining head , System after Claim 8 wherein the controller is configured to vary an output power of the beam emitter along the path. System after Claim 8 wherein the controller is configured to vary the shape of the laser output beam based on a composition of the workpiece. System after Claim 8 and further comprising a database containing a plurality of data sets each relating a laser output beam shape to workpiece parameters. System after Claim 12 wherein the workpiece parameters include a workpiece thickness and / or a workpiece composition. System after Claim 8 wherein the beam emitter comprises: a radiation source emitting a plurality of discrete input beams; Focusing optics for focusing the plurality of input beams onto a dispersive element; a dispersive element for receiving and dispersing the received focused beams; and a partially reflecting output clutch positioned to receive the scattered beams, pass a portion of the scattered beams as a laser output beam, and reflect a second portion of the scattered beams back to the dispersive element, the laser output beam being composed of a plurality of wavelengths. A method of joining a first and a second workpiece at a machining point, wherein the first and second workpiece overlap and / or are proximate to each other at the machining point, the method comprising: Focusing a laser output beam near the processing point to melt a portion of the first and / or second workpiece, thereby joining the first and second workpieces; and meanwhile, without causing relative movement between the laser exit beam and the first and second workpieces, changing a shape of the laser exit beam. Method according to Claim 15 wherein the shape of the laser output beam is varied between a focused point and a ring. Method according to Claim 15 , wherein the laser output beam consists of several wavelengths. A method of joining a first and a second workpiece to a weld having a spatial extent greater than the minimum dot size using a laser output beam focusable to a minimum spot size, the method comprising: Focusing the laser output beam on the first and / or the second workpiece to effect its melting; and without causing relative movement between the laser exit beam and the first and second workpieces, varying a shape of the laser exit beam to increase a size of the weld. Method according to Claim 18 wherein the shape of the laser output beam is varied between a focused point and a ring. Method according to Claim 18 , wherein the laser output beam consists of several wavelengths. A system for machining a workpiece, the system comprising: a radiation emitter; a positioning device for varying a position of a beam of the beam emitter relative to the workpiece; a variable polarizer for varying a polarization of the beam; a beam former for varying a shape of the carrier; and a controller coupled to the positioning device, the polarizer, and the beamformer for operating the beam emitter, causing the beam to traverse a path across at least a portion of the workpiece for processing thereof, and along the polarization and / or shape of the beam varies based at least in part on one or more properties of the workpiece. System after Claim 21 wherein the controller is configured to maintain a linear polarization of the beam having a polarization direction that is approximately parallel to the path as the beam traverses the path. System after Claim 21 wherein the controller is configured to vary an eccentricity of the polarization of the beam based at least in part on a thickness of the workpiece. System after Claim 21 wherein the controller is configured to vary the polarization of the beam between a linear polarization state and a radial polarization state. System after Claim 21 wherein the variable polarizer comprises a wave plate and a rotary member, the rotary member being actuated by the controller. System after Claim 25 wherein the wave plate comprises a half wave plate and / or a quarter wave plate. System after Claim 25 wherein the beam is linearly polarized and the controller operates the rotating member to maintain a direction of polarization parallel to the path. System after Claim 21 wherein the variable polarizer comprises a compensator plate, a solid birefringent wedge disposed over the compensator plate, a movable birefringent wedge disposed over the fixed birefringent wedge, and a displacement element, the displacement element being actuated by the controller. System after Claim 21 wherein the variable polarizer comprises a radial polarization converter. System after Claim 21 , further comprising: a memory accessible to the controller for storing data corresponding to the path; and a database for storing polarization data for a plurality of materials, wherein the controller is configured to query the database to obtain the polarization data for a material of the workpiece and to vary the polarization of the beam based at least in part on the polarization data. System after Claim 21 , where the path includes at least one change of direction. System after Claim 21 wherein the beam emitter comprises: a radiation source emitting a plurality of discrete input beams; Focusing optics for focusing the plurality of input beams onto a dispersive element; a dispersive element for receiving and dispersing the received focused beams; and a partially reflecting output clutch positioned to receive the scattered beams, transmit a portion of the scattered beams as a beam of the beam emitter, and reflect a second portion of the scattered beams back to the dispersive element, the beam of the beam emitter being of multiple wavelengths. System after Claim 21 wherein the beamformer comprises: a collimator lens for collimating a beam received from the beam emitter; a focusing lens for receiving the collimated beam and focusing the beam onto the workpiece; disposed between the radiation source and the collimator lens, an optical element for receiving the beam and changing its shape; and a lens manipulation system for changing a position of the optical element within a beam path, wherein the controller is configured to control the lens manipulation system to vary the shape of the beam. System after Claim 33 wherein the optical element comprises a lens having (i) a first surface in the shape of a truncated cone and (ii) opposite the first surface a second surface which is substantially planar. System after Claim 33 wherein the optical element comprises a lens having (i) a first surface in the form of a spherical segment and (ii) opposite the first surface a second surface which is substantially planar. System after Claim 33 wherein the optical element comprises a meniscus lens. System after Claim 33 wherein the lens manipulation system is configured to position the optical element transverse to the center within the beam path. System after Claim 33 further comprising a second optical element disposed between the focusing lens and the workpiece, wherein the lens processing system is configured to change a position of the second optical element within the beam path. System after Claim 38 wherein the second optical element comprises a lens having (i) a first surface in the shape of a truncated cone and (ii) opposite the first surface a second surface which is substantially planar. System after Claim 38 wherein the second optical element comprises a lens having (i) a first surface in the form of a spherical segment and (ii) opposite the first surface a second surface which is substantially planar. System after Claim 38 wherein the second optical element comprises a meniscus lens. System after Claim 21 wherein the beamformer comprises: a collimator lens for collimating a beam received from the beam emitter; a focusing lens for receiving the collimated beam and focusing the beam onto the workpiece; disposed between the radiation source and the collimator lens, first and second optical elements for receiving the beam and changing its shape; and a lens processing system for changing (i) a position of the first optical element within a beam path, (ii) a position of the second optical element within the beam path, and / or (iii) a distance between the first and second optical elements is configured to control the lens manipulation system to vary the shape of the beam. System after Claim 42 wherein (i) the first optical element comprises a double concave axicon lens and (ii) the second optical element comprises a double convex axicon lens. System after Claim 42 wherein the lens manipulation system is configured to change the distance between the first and second optical elements in the range of about 0 mm to about 20 mm. System after Claim 42 wherein: the first optical element comprises a lens having (i) a first surface that is substantially planar and (ii) a second surface opposite the first surface, having (a) a first portion that is convexly curved and (b) a second portion that is substantially planar; and the second optical element comprises a lens having (i) a first surface that is substantially planar, and (ii) a second surface opposite the first surface that (a) has a first portion that is concavely curved, and (b) has a second portion that is substantially planar. System after Claim 42 wherein the lens manipulation system is configured to position the first optical element and / or the second optical element transversely of the center within the beam path.

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