JP2019523137A - Material processing using lasers with variable beam shapes - Google Patents

Abstract

In various embodiments, the workpiece is processed, for example, via welding or cutting, while the shape of the laser processing beam and / or one or more other parameters are modified. The shape of the laser processing beam and / or one or more other parameters may be varied based on one or more characteristics of the workpiece. According to embodiments of the present invention, a laser system having a formable output beam is utilized to optimize and simplify material processing tasks such as cutting and welding of metallic materials. For example, according to an embodiment of the present invention, the output beam shape of a laser system can vary as the thickness of the part presented to the laser beam and / or the angle of the part varies (eg, from a Gaussian focused spot beam). Modified to a large area annular beam).

Description

(Related application)
This application claims the benefit of US Provisional Patent Application No. 62 / 362,824, filed July 15, 2016, and US Patent Application No. 15 / 261,096, filed September 9, 2016. Priority is claimed and the entire disclosure of each of these is incorporated herein by reference.

  In various embodiments, the present invention relates to material processing (eg, welding or cutting) utilizing a high power laser device having a formable beam and / or variable beam polarization.

  High power lasers are used in many cutting, etching, annealing, welding, drilling, and soldering applications. As in any material processing operation, efficiency can be an important limiting factor in terms of cost and time. That is, the lower the efficiency, the higher the cost and / or the slower the operation of the laser deployed to process a given material. The brightness and polarization of the laser beam can affect the efficiency, and different materials (copper, aluminum, steel, etc.) respond differently to the beam polarization as they are processed. Furthermore, the thickness of these materials can also affect their polarization response. That is, the properties of cutting or welding can vary with beam polarization, depending on the material and its thickness. For example, a linearly polarized processing beam can be absorbed differently depending on the polarization orientation of the beam relative to the cutting front. For this reason, laser-processing systems sometimes utilize a circular or randomly polarized laser output to avoid a directivity-dependent polarization response. That approach avoids undesirable polarization alignment efficiency reduction results, but also eliminates the advantages of preferred alignment.

In addition, high power laser systems often have a laser emitter from which the laser light is coupled into an optical fiber (or simply “fiber”) and the workpiece to be processed from the fiber. And an optical system for focusing on the piece. Optical systems are typically engineered to produce the highest quality laser beam, or in other words, the beam with the lowest beam parameter product (BPP). BPP is the product of the divergence angle (half angle) of a laser beam and the radius of the beam at its narrowest point (ie, beam waist, minimum spot size). BPP quantifies the quality of the laser beam and the degree to which it can be focused on a small spot and is typically expressed in units of millimeter-milliradians (mm-mrad). (The BPP values disclosed herein are in mm-mrad unless otherwise indicated.) The Gaussian beam is the lowest possible BPP determined by the wavelength of the laser light divided by the circumference. Have The BPP of the actual beam at the same wavelength, the ratio for an ideal Gaussian beam is shown as M ^2, which is a wavelength-independent measurement of beam quality.

  Techniques such as WBC have been successful in producing laser-based systems for a variety of applications, but material processing challenges remain. For example, a laser with a beam shape optimized to cut a particular material at a particular thickness may not be suitable for different materials, materials with different thicknesses, and materials with variable thicknesses. The welding process presents similar challenges. In addition, due to the limited spatial range of conventional highly focused laser beams, welding processes typically require relative movement between the laser beam and the part being welded, such as Movement may require complex and expensive robots, mobile gantry, and / or other equipment. Techniques have been developed that utilize multiple laser systems with moving beams (see, eg, US Pat. No. 9,335,551, the entire disclosure of which is incorporated herein by reference) The use of multiple laser systems is often very expensive. Thus, there is a need for individual laser systems that are capable of a wider variety of material processes.

  In many laser processing applications, the desired beam spot size, divergence, and beam quality may vary depending on, for example, the type of processing and / or the type of material being processed. In order to make such changes to the BPP and / or shape of the laser beam, often the output optical system or optical fiber must be replaced and / or realigned with other components, which is time consuming. And expensive processes, which can further lead to inadvertent damage to the fragile optical components of the laser system.

US Pat. No. 9,335,551

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

  According to embodiments of the present invention, a laser system having a formable output beam is utilized to optimize and simplify material processing tasks such as cutting and welding of metallic materials. For example, according to an embodiment of the present invention, the output beam shape of a laser system can vary as the thickness of the part presented to the laser beam and / or the angle of the part varies (eg, from a Gaussian focused spot beam). Modified to a large area annular beam). In other exemplary embodiments, the output beam of the laser system is modified during the welding process (eg, spot welding, butt welding, or lap welding) between the laser beam and the workpiece being processed. Form large area welds without any (or minimal) relative movement.

  Embodiments of the present invention also modify and optimize beam polarization and / or other properties (e.g., BPP, shape) during processing, e.g., beam path variation or material properties throughout the process. Alternatively, systems and techniques are provided that maintain the optimum characteristics of the beam as thickness changes.

  Embodiments of the present invention may modify the polarization of the beam as the thickness of the workpiece changes and / or for different thickness workpieces. For example, the circularity of the polarization of the beam (i.e., varying from linear to elliptical or circular, with any number of elliptical shapes with varying dimensions and curvatures between perfect linear and perfect circular Possible, but can be modified to make the beam more circular as the thickness of the workpiece increases (eg, from linear to elliptical, less circular to more circular elliptical) From oval to circular etc.). (In various embodiments, the circularity of the polarization is inversely proportional to the eccentricity of the elliptical polarization, decentration 0 represents circular polarization, and decentration 1 represents linear polarization.) In various embodiments, the beam The polarization state is modified, at least in part, through the use of a Babenet-Soleil compensator that allows for continuously variable polarization of any eccentricity. Embodiments of the present invention may also vary the polarization of the beam from linear to radial, for example, to provide beam focusing to a smaller spot size.

  Embodiments of the present invention typically allow the surface of the workpiece to be physically modified, as opposed to optical techniques (eg, reflectometry), which simply probe the surface with light. And / or is utilized to process the workpiece such that features are formed on or in the surface. Exemplary processes according to embodiments of the invention include cutting, welding, drilling, and soldering. Various embodiments of the present invention also provide for workpieces in one or more spots or along a one-dimensional processing path, rather than filling all or substantially all of the workpiece surface with radiation from the laser beam. Process.

  Embodiments of the present invention use optical elements that can shape a laser beam and modify the beam quality (in particular, BPP) and / or the shape of the beam to achieve a desired spatial beam profile. More specifically, a change in the optical geometry of the optical element by moving or displacing its position laterally or longitudinally with respect to the optical axis of the laser beam causes the shape and / or BPP to vary. It may be used. In an embodiment of the present invention, the optical element is located in the beam path with a switchable state that produces different beam deflections or diffractions depending on its position. The use of optical elements according to embodiments of the present invention allows variations in shape and / or BPP regardless of the shape, quality, wavelength, bandwidth, and number of beams corresponding to the input laser beam. Output beams with controllably variable shape and / or BPP may be used to process workpieces in applications such as welding, cutting, drilling, and the like. As utilized herein, a change in the “shape” of a laser beam refers to a modification of the shape and geometric range of the beam (eg, at the point where the beam intersects the surface). Shape changes can occur concomitant with changes in beam size, beam angular intensity distribution, and BPP, but mere changes in beam BPP are not necessarily due to changing the laser beam shape and vice versa. Not enough (eg, depicting two beams with different shapes but having the same BPP, see FIG. 21).

  One advantage of variable geometry and / or BPP is improved laser application performance for different types of processing techniques or different types of materials being processed. Embodiments of the present invention can also be found in U.S. Patent Application No. 14 / 632,283, filed February 26, 2015, U.S. Patent Application No. 14 / 747,073, filed June 23, 2015, US patent application Ser. No. 14 / 852,939 filed on Sep. 14, 2015, U.S. Patent Application No. 15 / 188,076 filed on Jun. 21, 2016, and Apr. 5, 2017. Various for varying BPPs and / or shapes of laser beams as described in filed US patent application Ser. No. 15 / 479,745, the disclosure of each of which is incorporated herein by reference in its entirety. The technique may be used. In addition, the different beam intensity distributions induced by the optical elements (refractive optics) modify the beam quality and thus the BPP. By using translations of optical elements with different effective optical geometries in the beam path (eg, motor driven translation), real-time dynamic changes in shape and / or BPP can be achieved.

  Laser beam shaping is a process that redistributes the intensity (irradiance) and phase of the beam. Intensity distributions that define beam profiles such as Gaussian, Bessel, annular, multimode, rectangular, top hat, elliptical or circular, and different intensity profiles may be important and necessary for specific laser material processing techniques. (As utilized herein, an “annular” beam is ring-shaped, ie, has little or substantially no beam intensity in the central portion surrounded by a region of higher beam intensity. However, it is not necessarily circular, i.e. the "annular" beam may be oval or otherwise quasi-annular.) In an embodiment of the invention, the optical element causes the laser beam to be a workpiece Located in a delivery system that delivers and focuses the laser. The delivery system may be configured and / or packaged, for example, as at least part of a cutting head or a welding head. Embodiments of the present invention vary beam quality to allow a controllably variable shape and / or BPP at a workstation (and / or a workpiece disposed thereon). The variable shape and / or BPP module may include one or more optical elements, a motor driven translation stage, a collimating lens, and a focusing lens. Embodiments of the invention may feature any one or more of multiple types of refractive optics for optical elements used to vary shape and / or BPP.

  Embodiments of the present invention vary 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 pointing position on the optical element. The optical elements may have different geometries depending on the desired beam profile and thus BPP. One optical element according to an embodiment of the present invention has a planar surface and a flat top (ie, truncated) conical surface. Another optical element according to an embodiment of the invention has a planar surface and a flat upper spherical surface. Yet another optical element according to an embodiment of the invention is a meniscus lens. The divergent light from the beam delivery fiber is directed toward the optical element to redistribute the beam intensity within the optical element. Other optical elements according to embodiments of the present invention include paired positive and negative axicon lenses. In other embodiments, the optical element includes a pair of complementary phase plate lenses, one of which has a partially convex surface and one of which has a complementary partially concave curved surface. . The edge of the optical element may be rounded to suppress diffraction effects. The advantages of BPP dynamic variation using automated movement of optical elements are applied to laser cutting applications, for example, on round or square cutting angles where BPP changes during free form cutting are required. Also good. Such advantages may also be applied to laser drilling applications that may take advantage of the ability to vary both BPP and focal length. Automated closed-loop motor control of optical elements according to embodiments of the present invention provides reliability and repeatability performance and allows precise control of optical position, thereby providing accurate BPP variation.

  As used herein, "optical element" means a lens, mirror, prism that redirects, reflects, bends, or optically manipulates electromagnetic radiation in any other manner, unless otherwise indicated. , Lattice, and the like. As used herein, a beam emitter, emitter, or laser emitter, or laser generates an electromagnetic beam, but may or may not be self-resonant, any electromagnetic beam generating device, such as a semiconductor element. including. These also include fiber lasers, disk lasers, non-solid state lasers and the like. In general, each emitter includes a back reflective surface, at least one optical gain medium, and a front reflective surface. The optical gain medium is not limited to any particular part of the electromagnetic spectrum, but increases the gain of electromagnetic radiation, which can be visible light, infrared light, and / or ultraviolet light. The emitter may comprise or consist essentially of a plurality of beam emitters, such as diode bars, configured to emit a plurality of beams. The input beams received in the embodiments herein may be single wavelength or multi-wavelength beams that are combined using various techniques known in the art. In addition, references herein to “laser”, “laser emitter”, or “beam emitter” are not only single diode lasers, but also diode bars, laser arrays, diode bar arrays, and single or array Vertical cavity surface emitting laser (VCSEL).

  Embodiments of the present invention may also be utilized with a wavelength beam combining (WBC) system that includes multiple emitters, such as one or more diode bars, that are combined using dispersive elements to form a multi-wavelength beam. Good. Each emitter in the WBC system is stabilized through wavelength specific feedback from a common partially reflected output coupler that resonates individually and is filtered by a dispersive element along the beam coupling dimension. An exemplary WBC system is disclosed in US Pat. No. 6,192,062, filed Feb. 4, 2000, filed Sep. 8, 1998, each of which is incorporated herein by reference in its entirety. U.S. Pat.No. 6,208,679, U.S. Pat.No. 8,670,180 filed August 25, 2011, and U.S. Pat. No. 8,559, filed Mar. 7, 2011. This is described in detail in No. 107. The multi-wavelength output beam of the WBC system may be utilized as an input beam in conjunction with embodiments of the present invention, for example for BPP, shape, and / or polarization control.

  In one aspect, embodiments of the invention feature a method for processing a workpiece. The processing path is defined by creating a relative motion between the laser output beam and the surface of the workpiece. The thickness of the workpiece along the direction parallel to the laser output beam varies along the processing path. The laser output beam physically modifies 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 modified based at least in part on the thickness of the workpiece.

  Embodiments of the invention may include one or more of the following, in any of a variety of combinations. The shape of the laser output beam may be varied between the focused spot and the annulus as the workpiece thickness increases. The shape of the laser output beam may be varied between a focused spot and a diffused spot (eg, a spot having a diameter greater than the diameter of the focused spot) as the thickness of the workpiece increases. The laser output beam diameter and / or BPP may be increased as the thickness of the workpiece increases. The angle between the laser output beam and the surface of the workpiece is modified (eg, through the tilt of the incident laser output beam, the tilt of the workpiece, and / or the angled topology on the surface of the workpiece). Thereby, the thickness of the workpiece along the direction parallel to the laser output beam may be varied. The thickness of the workpiece along the direction parallel to the laser output beam may vary at least in part due to a change in angle between the laser output beam and the surface of the workpiece (eg, incident laser power Via beam tilt, workpiece tilt, and / or angled topology on the workpiece surface). The shape of the laser output beam may be modified while maintaining the angle between the laser output beam and the workpiece surface substantially constant (eg, the laser output beam is tilted with respect to the workpiece surface). Or the surface topology of the workpiece may present a substantially constant angle to the incident laser output beam). The thickness of the workpiece may be measured during the relative movement between the laser output beam and the surface of the workpiece. The shape of the laser output beam may be modified based on the composition of the workpiece. The laser output beam may consist of a plurality of wavelengths.

  In another aspect, embodiments of the invention feature a system for processing a workpiece. The system comprises a beam emitter for emitting a laser output beam, a positioning device for varying the position of the laser output beam relative to the workpiece, means for modifying the shape of the laser output beam, and a positioning device And (i) operating the beam emitter, causing the laser output beam to traverse a path across at least a portion of the workpiece, physically modifying its surface, and (ii) at least Including, consisting essentially of, or consisting of a controller for modifying the shape of the laser output beam based in part on the thickness of the workpiece along the path.

  Embodiments of the invention may include one or more of the following, in any of a variety of combinations. The beam emitter may include a processing head from which the laser output beam is emitted, consists essentially of, consists of, is disposed in, or is coupled to (e.g., via an optical fiber). ) The shape modifying means includes (i) one or more optical elements in the processing head and (ii) a second controller for modifying the position of at least one of the optical elements in the processing head, It may consist essentially of or consist of. The second controller may be separate from and separate from the controller, or the controller and the second controller may be part of a single control system. The controller may be configured to vary the 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 the composition of the workpiece. The system may include a database containing a plurality of records each relating laser output beam shape and workpiece parameters. The workpiece parameter may comprise, consist essentially of, or consist of a workpiece thickness and / or workpiece composition. The beam emitter emits a plurality of discrete input beams, a beam source, focusing optics for focusing the plurality of input beams onto the dispersive element, a focused beam received, and a received focused beam A dispersive element for dispersing and receiving the dispersed beam, transmitting a portion of the dispersed beam therethrough as a laser output beam, and reflecting a second portion of the dispersed beam toward the dispersive element; Including, consisting essentially of, or consisting of a partially reflective output coupler. The laser output beam may consist of a plurality of wavelengths.

  In yet another aspect, embodiments of the invention feature a method of splicing first and second workpieces at a processing point. The first and second workpieces overlap and / or close to each other at the processing point. The laser output beam is focused and / or positioned proximate to the processing point to melt a portion of at least one of the first or second workpieces, thereby causing the first and second workpieces to melt. Join together. During splicing, the shape of the laser output beam is varied without causing relative movement between the laser output beam and the first and second workpieces.

  Embodiments of the invention may include one or more of the following, in any of a variety of combinations. The shape of the laser output beam may be varied between the focused spot and the annulus. The shape of the laser output beam may be varied between a focused spot and a diffused spot (eg, a spot having a diameter larger than the diameter of the focused spot). The laser output beam may consist of a plurality of wavelengths.

  In another aspect, embodiments of the present invention use a laser output beam that can be focused to a minimum spot size to weld the first and second workpieces with a weld having a spatial range greater than the minimum spot size. Characterized by the method of joining. The laser output beam is focused and / or disposed on the first and / or second workpiece and an adhesive (eg, brazing material, solder material, etc.) disposed on or between the first and second workpieces. Or at least partial melting and / or at least partial melting of the flux material). Without causing relative movement between the laser output beam and the first and second workpieces, the shape of the laser output beam is varied, increasing the size of the weld or seam.

  Embodiments of the invention may include one or more of the following, in any of a variety of combinations. The shape of the laser output beam may be varied between the focused spot and the annulus. The shape of the laser output beam may be varied between a focused spot and a diffused spot (eg, a spot having a diameter larger than the diameter of the focused spot). The laser output beam may consist of a plurality of wavelengths.

  In one aspect, embodiments of the invention feature a system for processing a workpiece. The system includes a beam emitter, a positioning device for varying the beam position of the beam emitter relative to the workpiece, a variable polarizer for varying the polarization of the beam, and a beam shaping for varying the beam shape. And a positioning device, a polarizer, and a beam shaper for operating the beam emitter, causing the beam to traverse a path across at least a portion of the workpiece, and at least partially Including, consisting essentially of, or consisting of a controller for varying the polarization and / or shape of the beam along the path based on one or more properties of the workpiece.

  Embodiments of the invention may include one or more of the following, in any of a variety of combinations. The controller may be configured to maintain a linear polarization of the beam having a polarization direction substantially parallel to the path as the beam traverses the path. The controller may be configured to vary the eccentricity of the polarization of the beam based at least in part on the 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 comprise, consist essentially of, or consist of a wave plate. The variable polarizer may comprise, consist essentially of, or consist of a wave plate and a rotating element, the rotating element being operated by a controller. The wave plate may comprise, consist essentially of, or consist of a half wave plate and / or a quarter wave plate. The beam may be linearly polarized. The controller may operate the rotating element to maintain a polarization direction parallel to the path. The variable polarizer includes, consists essentially of, or consists of a compensator plate, a fixed birefringent wedge disposed across the compensator plate, and a movable birefringent wedge disposed across the fixed birefringent wedge. Good. The variable polarizer comprises and consists essentially of a compensator plate, a fixed birefringent wedge disposed across the compensator plate, a movable birefringent wedge disposed across the fixed birefringent wedge, and a translation element. Or it may consist of a translation element operated by a controller. The variable polarizer may comprise, consist essentially of, or consist of a radial polarization converter.

  The system is accessible to the controller and may include a memory 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 polarization data for the workpiece material and vary the polarization of the beam based at least in part on the polarization data. The path may include at least one directivity change. The workpiece may have at least two parts having different thicknesses. The workpiece may have at least two parts comprising, consisting essentially of, or consisting of different materials. The beam emitter emits a plurality of discrete input beams, a beam source, focusing optics for focusing the plurality of input beams onto the dispersive element, a focused beam received, and a received focused beam A dispersive element for dispersing and receiving the dispersed beam, transmitting a portion of the dispersed beam therethrough as a beam emitter beam, and reflecting a second portion of the dispersed beam toward the dispersive element; Including, consisting essentially of, or consisting of a partially reflective output coupler. The beam of the beam emitter (eg, output processing beam) may consist of multiple wavelengths.

  The beam shaper includes a collimating lens for collimating the beam received from the beam emitter, a focusing lens for receiving the collimated beam and focusing the beam toward the workpiece, a beam source and a collimating lens. An optical element for receiving the beam and modifying its shape, and a lens manipulation system for changing the position of the optical element in the beam path, or consisting essentially of It may consist of it. The controller may be configured to control the lens manipulation system and vary the shape of the beam. The optical element includes a lens having (i) a first surface having a frustoconical shape, and (ii) a substantially planar second surface opposite the first surface, and then essentially It may consist of or consist of. The optical element includes a lens having (i) a first surface having a truncated spherical shape and (ii) a substantially planar second surface opposite the first surface, and then essentially It may consist of or consist of. The optical element may comprise, consist essentially of, or consist of a meniscus lens. The lens manipulation system may be configured to position the optical element laterally off-center within the beam path. The system may include a second optical element disposed between the focusing lens and the workpiece. The lens manipulation system may be configured to change the position of the second optical element in the beam path. The second optical element includes a lens having (i) a first surface having a frustoconical shape and (ii) a substantially planar second surface opposite the first surface, and It may consist essentially of or consist of. The second optical element comprises a lens having (i) a first surface having a truncated spherical shape and (ii) a substantially planar second surface opposite the first surface; It may consist essentially of or consist of. The second optical element may comprise, consist essentially of, or consist of a meniscus lens.

  The beam shaper includes a collimating lens for collimating the beam received from the beam emitter, a focusing lens for receiving the collimated beam and focusing the beam toward the workpiece, a beam source and a collimating lens. First and second optical elements disposed between and for receiving the beam and modifying its shape; (i) the position of the first optical element in the path of the beam; (ii) the path of the beam Comprising, consisting essentially of, or consisting of a lens manipulation system for changing the position of the second optical element within and / or (iii) the distance between the first and second optical elements Good. The controller may be configured to control the lens manipulation system and vary the shape of the beam. The first optical element may comprise, consist essentially of, or consist of a double concave axicon lens. The second optical element may comprise, consist essentially of, or consist of a double convex axicon lens. The lens manipulation system may be configured to vary the distance between the first and second optical elements within a range of about 0 mm to about 20 mm. The first optical element has a first surface having (i) a substantially planar first surface, (ii) (a) a convex curved first portion, and (b) a substantially planar second portion. And a second surface opposite to, including, consisting essentially of, or consisting of a lens. The second optical element has (i) a substantially planar first surface, and (ii) (a) a concave curved first portion and (b) a substantially planar second portion. And a second surface opposite to, including, consisting essentially of, or consisting of a lens. The lens manipulation system may be configured to position the first optical element and / or the second optical element laterally off-center within the beam path.

  In one aspect, embodiments of the invention relate to a system for processing a workpiece. In various embodiments, the system includes a beam emitter, a positioning device for varying the beam position of the beam emitter relative to the workpiece, a variable polarizer for varying the polarization of the beam, a positioning device and polarization. The beam emitter is operated to cause the beam to traverse the path across at least a portion of the workpiece, and to consistently polarize the beam with respect to the workpiece along the path. And a controller for maintaining.

  In various embodiments, the variable polarizer comprises a wave plate and a rotating element that is operated by a controller. For example, the wave plate may be one or more half wave plates, one or more quarter wave plates, or some combination thereof. The beam may be linearly polarized using, for example, a controller that operates a rotating element and maintains a polarization direction parallel to the path.

  In some embodiments, the system further comprises 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 and obtain polarization data for the workpiece material, which determines the consistent polarization of the beam. The path may include at least one directivity change.

  The beam emitter may emit a plurality of beams. The beam emitter may be at least one laser and / or at least one polarized fiber.

  In another aspect, the invention relates to a method for processing a workpiece. In various embodiments, the method operates the beam emitter, directs the beam to traverse the path along the workpiece, and processes the workpiece, the beam having an output polarization. And modifying the output polarization along at least a portion of the path to maintain a consistent polarization of the beam relative to the workpiece throughout the process.

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

  In some embodiments, the method further includes storing data corresponding to the path, storing polarization data for a plurality of materials, and querying a database to obtain polarization data for the material of the workpiece. The polarization data comprises determining the consistent polarization of the beam. The path may include at least one directivity change.

  In one aspect, embodiments of the invention feature a laser delivery system for receiving and modifying a spatial power distribution of a radiation beam from a beam source and focusing radiation with the modified spatial power distribution onto a workpiece. To do. The laser system includes a collimating lens for collimating the radiation beam, a focusing lens for receiving the collimated beam and focusing the beam toward the workpiece, and receiving the radiation beam and modifying its spatial power distribution An optical element for controlling, a lens manipulation system for changing the position of the optical element in the path of the radiation beam, and controlling the lens manipulation system to achieve a modified spatial power distribution of the target on the workpiece Or consist essentially of a controller. The optical element may be disposed between the beam source and the collimating lens (ie, disposed optically downstream of the beam source and optically upstream of the collimating lens).

  Embodiments of the invention may include one or more of the following, in any of a variety of combinations. The optical element includes a lens having (i) a first surface having a frustoconical shape, and (ii) a substantially planar second surface opposite the first surface, and then essentially It may consist of or consist of. The first surface may face the beam source. The first surface may face away from the beam source. The optical element includes a lens having (i) a first surface having a truncated spherical shape and (ii) a substantially planar second surface opposite the first surface, and then essentially It may consist of or consist of. The first surface may face the beam source. The first surface may face away from the beam source. The optical element may comprise, 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 comprise, consist essentially of, or consist of fused silica and / or zinc sulfide. The lens manipulation system may be configured to position the optical element laterally off-center within the path of the radiation beam.

  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 (ie, positioned optically downstream of the focusing lens and optically upstream of the workpiece). The lens manipulation system may be configured to change the position of the second optical element in the path of the radiation beam. The second optical element includes a lens having (i) a first surface having a frustoconical shape and (ii) a substantially planar second surface opposite the first surface, and It may consist essentially of or consist of. The first surface may face the beam source. The first surface may face away from the beam source. The second optical element comprises a lens having (i) a first surface having a truncated spherical shape and (ii) a substantially planar second surface opposite the first surface; It may consist essentially of or consist of. The first surface may face the beam source. The first surface may face away from the beam source. The second optical element may comprise, 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 comprise, consist essentially of, or consist of fused silica and / or zinc sulfide.

  The beam source includes: a beam emitter that emits a plurality of discrete beams; a focusing optics for focusing the plurality of beams on the dispersive element; and receiving the focused beam and dispersing the received focused beam A dispersive element and a dispersive beam are positioned to transmit a portion of the dispersive beam as a radiation beam therethrough and reflect a second portion of the dispersive beam toward the dispersive element. May comprise or consist essentially of a partially reflective output coupler. The radiation beam may consist of multiple wavelength radiation. The focusing optics may comprise 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 comprise or consist essentially of a diffraction grating (eg, a transmission diffraction grating or a reflection diffraction grating).

  In another aspect, embodiments of the invention feature a laser delivery system for receiving and modifying a spatial power distribution of a radiation beam from a beam source and focusing radiation with the modified spatial power distribution onto a workpiece. And The laser delivery system includes a collimating lens for collimating the radiation beam, a focusing lens for receiving the collimated beam and focusing the beam toward the workpiece, receiving the radiation beam, and determining its spatial power distribution. First and second optical elements for modification; (i) a position of the first optical element in the path of the radiation beam; (ii) a position of the second optical element in the path of the radiation beam; and / or Or (iii) a lens manipulation system for changing the distance between the first and second optical elements and a controller for controlling the lens manipulation system and achieving a modified spatial power distribution of the target on the workpiece Or consist essentially of. The first and / or second optical element may be disposed between the beam source and the collimating lens (ie, disposed optically downstream of the beam source and optically upstream of the collimating lens).

  Embodiments of the invention may include one or more of the following in any of a variety of combinations. The first optical element may comprise, consist essentially of, or consist of a double concave axicon lens. The second optical element may comprise, consist essentially of, or consist of a double convex axicon lens. The first optical element may be disposed optically upstream of the second optical element. The first optical element may be disposed optically downstream of the second optical element. The lens manipulation system includes first and second optical elements within a range of about 0 mm to about 50 mm, within a range of about 0 mm to about 20 mm, within a range of about 2 mm to about 50 mm, or within a range of about 2 mm to about 20 mm. You may be comprised so that the distance between may be changed. The first optical element has a first surface having (i) a substantially planar first surface, (ii) (a) a convex curved first portion, and (b) a substantially planar second portion. And a second surface opposite to, including, consisting essentially of, or consisting of a lens. The second optical element has (i) a substantially planar first surface, and (ii) (a) a concave curved first portion and (b) a substantially planar second portion. And a second surface opposite to, including, consisting essentially of, or consisting of a lens. The first optical element may be disposed optically upstream of the second optical element. The first optical element may be disposed 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 manipulation system may be configured to position the first optical element and / or the second optical element laterally off-center within the path of the radiation beam. The first optical element may comprise, consist essentially of, or consist of fused silica and / or zinc sulfide. The second optical element may comprise, consist essentially of, or consist of fused silica and / or zinc sulfide.

  The beam source includes: a beam emitter that emits a plurality of discrete beams; a focusing optics for focusing the plurality of beams on the dispersive element; and receiving the focused beam and dispersing the received focused beam A dispersive element and a dispersive beam are positioned to transmit a portion of the dispersive beam as a radiation beam therethrough and reflect a second portion of the dispersive beam toward the dispersive element. May comprise or consist essentially of a partially reflective output coupler. The radiation beam may consist of multiple wavelength radiation. The focusing optics may comprise 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 comprise or consist essentially of a diffraction grating (eg, a transmission diffraction grating or a reflection diffraction grating).

  In yet another aspect, embodiments of the present invention provide a laser delivery system for receiving and modifying a spatial power distribution of a radiation beam from a beam source and focusing radiation with the modified spatial power distribution onto a workpiece. Features. The laser delivery system includes one or more divergence increasing optical elements for increasing the divergence of the radiation beam, a focusing lens for receiving the radiation beam and focusing the beam toward the workpiece, and receiving the radiation beam. At least one optical element for modifying its spatial power distribution, a lens manipulation system for changing the position of at least one optical element in the path of the radiation beam, and controlling the lens manipulation system to modify the target Comprising or essentially consisting of a controller for achieving a spatial power distribution on the workpiece.

  Embodiments of the invention may include one or more of the following in any of a variety of combinations. The focusing lens may be disposed optically downstream of the one or more divergence increasing optical elements. At least one optical element may be disposed optically upstream of the focusing lens. The one or more divergence increasing optical elements may comprise, consist essentially of, or consist of a triple collimator. The triple collimator may comprise, consist essentially of, or consist of (i) a first plano-concave lens, (ii) a second meniscus lens, and (iii) a third plano-convex lens. . The first plano-concave lens may be disposed optically upstream of the second meniscus lens. The second meniscus lens may be disposed optically upstream of the third plano-convex lens. At least one optical element may be disposed optically downstream of the first plano-concave lens. The at least one optical element may be disposed optically upstream of the second meniscus lens and / or the third plano-convex lens. The at least one optical element includes a lens having (i) a first surface having a frustoconical shape and (ii) a substantially planar second surface opposite the first surface; It may consist essentially of or consist of. The at least one optical element includes a lens having (i) a first surface having a truncated spherical shape and (ii) a second substantially planar surface opposite the first surface; It may consist essentially of or consist of. The at least one optical element may comprise, consist essentially of, or consist of a meniscus lens (eg, a positive meniscus lens or a negative meniscus lens). The lens manipulation system may be configured to position the at least one optical element laterally off-center within the path of the radiation beam.

  The at least one optical element may comprise, consist essentially 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 manipulation system may include (i) a position of the first optical element in the path of the radiation beam, (ii) a position of the second optical element in the path of the radiation beam, and / or (iii) first and second. The distance between the optical elements may be changed. The first optical element may comprise, consist essentially of, or consist of a double concave axicon lens. The second optical element may comprise, consist essentially of, or consist of a double convex axicon lens. The first optical element may be disposed optically upstream of the second optical element. The first optical element may be disposed optically downstream of the second optical element. The lens manipulation system includes first and second optical elements within a range of about 0 mm to about 50 mm, within a range of about 0 mm to about 20 mm, within a range of about 2 mm to about 50 mm, or within a range of about 2 mm to about 20 mm. You may be comprised so that the distance between may be changed. The first optical element has a first surface having (i) a substantially planar first surface, (ii) (a) a convex curved first portion, and (b) a substantially planar second portion. And a second surface opposite to, including, consisting essentially of, or consisting of a lens. The second optical element has (i) a substantially planar first surface, and (ii) (a) a concave curved first portion and (b) a substantially planar second portion. And a second surface opposite to, including, consisting essentially of, or consisting of a lens. The first optical element may be disposed optically upstream of the second optical element. The first optical element may be disposed 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 manipulation system may be configured to position the first optical element and / or the second optical element laterally off-center within the path of the radiation beam. The first optical element may comprise, consist essentially of, or consist of fused silica and / or zinc sulfide. The second optical element may comprise, consist essentially of, or consist of fused silica and / or zinc sulfide.

  The beam source includes: a beam emitter that emits a plurality of discrete beams; a focusing optics for focusing the plurality of beams on the dispersive element; and receiving the focused beam and dispersing the received focused beam A dispersive element and a dispersive beam are positioned to transmit a portion of the dispersive beam as a radiation beam therethrough and reflect a second portion of the dispersive beam toward the dispersive element. May comprise or consist essentially of a partially reflective output coupler. The radiation beam may consist of multiple wavelength radiation. The focusing optics may comprise 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 comprise or consist essentially of a diffraction grating (eg, a transmission diffraction grating or a reflection diffraction grating).

  These and other objects, along with the advantages and features of the invention disclosed herein, will become more apparent through reference to the following description, the accompanying drawings, and the claims. Further, it should be understood that the features of the various embodiments described herein are not mutually exclusive and may exist in various combinations and permutations. As used herein, the term “substantially” means ± 10%, and in some embodiments ± 5%. The term “consisting essentially of” is meant to exclude other materials that contribute to function unless otherwise defined herein. Nevertheless, such other materials can be present in trace amounts, either collectively or individually. In this specification, the terms "radiation" and "light" are used interchangeably unless otherwise indicated. As used herein, “downstream” or “optically downstream” is used to indicate the relative location of the second element where the light beam strikes the first element after impact, The element is “upstream” or “optically upstream” of the second element. As used herein, the “optical distance” between two components is the distance between the two components actually traveled by the light beam, and the optical distance is the physical distance between the two components. For example, but not necessarily due to reflections from the mirror or other changes in the propagation direction that are experienced by light traveling from one of the components to the other.

  In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead being placed upon illustrating generally the principles of the invention. In the following description, various embodiments of the present invention will be described with reference to the following drawings.

FIG. 1 illustrates a conventional method of cutting a curve from a material using the polarization of a fixed cutting beam. FIG. 2A illustrates an exemplary adjustment of polarization according to a cutting path in a material, according to various embodiments of the invention. FIG. 2B illustrates exemplary adjustment of polarization according to material thickness, according to various embodiments of the invention. FIG. 2C illustrates an exemplary adjustment of polarization from linear to radial polarization according to various embodiments of the invention. 3A-3G illustrate an exemplary system for varying beam polarization based at least in part on the processing direction or material thickness, according to various embodiments of the invention. 3A-3G illustrate an exemplary system for varying beam polarization based at least in part on the processing direction or material thickness, according to various embodiments of the invention. 3A-3G illustrate an exemplary system for varying beam polarization based at least in part on the processing direction or material thickness, according to various embodiments of the invention. 3A-3G illustrate an exemplary system for varying beam polarization based at least in part on the processing direction or material thickness, according to various embodiments of the invention. 3A-3G illustrate an exemplary system for varying beam polarization based at least in part on the processing direction or material thickness, according to various embodiments of the invention. 3A-3G illustrate an exemplary system for varying beam polarization based at least in part on the processing direction or material thickness, according to various embodiments of the invention. 3A-3G illustrate an exemplary system for varying beam polarization based at least in part on the processing direction or material thickness, according to various embodiments of the invention. FIG. 4A illustrates a method for cutting or welding material using a self-adjusting polarized beam, according to various embodiments of the invention. 4B-4D are graphs of cutting speed as a function of workpiece thickness comparing laser beams using controlled polarization and conventional unpolarized beams according to various embodiments of the present invention. 4B-4D are graphs of cutting speed as a function of workpiece thickness comparing laser beams using controlled polarization and conventional unpolarized beams according to various embodiments of the present invention. 4B-4D are graphs of cutting speed as a function of workpiece thickness comparing laser beams using controlled polarization and conventional unpolarized beams according to various embodiments of the present invention. FIG. 5 is a schematic diagram of a laser beam delivery system according to various embodiments of the invention. FIG. 6 is a schematic illustration of a flat top conical optical element, according to various embodiments of the present invention. FIG. 7A is a graph of BPP variation as a function of distance of a fused silica flat top conical optical element from a beam source, according to various embodiments of the invention. FIG. 7B is a graph of BPP variation as a function of the distance of the zinc sulfide flat top conical optical element from the beam source, according to various embodiments of the present invention. FIG. 8A is a schematic illustration of a laser delivery system having off-center optical elements in accordance with various embodiments of the invention. 8B-8D depict the beam profile as a function of off-center distance produced by the laser delivery system of FIG. 8A. FIG. 9 is a schematic illustration of a flat top spherical optical element, according to various embodiments of the present invention. FIG. 10A is a graph of BPP variation as a function of distance of a fused silica flat top spherical optical element from a beam source, according to various embodiments of the invention. FIG. 10B is a graph of BPP variation as a function of the distance of the zinc sulfide flat top spherical optical element from the beam source, according to various embodiments of the invention. 11A-11C depict a beam profile as a function of off-center distance produced by a laser delivery system incorporating the optical element of FIG. 9, according to various embodiments of the invention. FIG. 11D is a graph of irradiance as a function of position for the two-peak beam profile depicted in FIG. 11C. FIG. 12A is a schematic illustration of a portion of a laser delivery system having two axicon lens optical elements, according to various embodiments of the invention. FIGS. 12B and 12C depict axicon lens geometric design parameters, according to various embodiments of the present invention. FIGS. 12B and 12C depict axicon lens geometric design parameters, according to various embodiments of the present invention. FIG. 13 is a graph of BPP variation as a function of gap distance between positive and negative axicon lenses according to various embodiments of the present invention. FIG. 14 depicts beam profiles at different gap distances between positive and negative axicon lenses according to various embodiments of the invention. FIG. 15 depicts beam profiles at different gap distances between positive and negative axicon lenses laterally off-center in the beam path, according to various embodiments of the invention. FIG. 16A is a schematic illustration of a portion of a laser delivery system having a pair of phase plate lenses, according to various embodiments of the present invention. FIGS. 16B and 16C depict the geometric design parameters of a phase plate lens, according to various embodiments of the present invention. FIG. 16D is a graph of BPP as a function of the inner diameter of a pair of phase plates, according to various embodiments of the invention. FIG. 16E is a graph of the optimized inner diameter of a pair of phase plates as a function of separation from the input fiber end cap, according to various embodiments of the present invention. FIG. 16F is a graph of BPP variation as a function of gap distance between a pair of phase plate lenses, according to various embodiments of the invention. FIG. 16G depicts beam profiles at different gap distances between a pair of phase plate lenses, according to various embodiments of the invention. FIG. 17A is a schematic illustration of a meniscus lens optical element, according to various embodiments of the invention. FIG. 17B is a graph of BPP variation as a function of distance of a fused silica meniscus lens optical element from a beam source, according to various embodiments of the invention. FIG. 18A is a schematic diagram of a partial laser beam delivery system incorporating a triple collimator for increased beam divergence, according to various embodiments of the invention. FIG. 18B is a graph of BPP variation as a function of the distance of the flat top spherical optical element from the beam source in the laser delivery system of FIG. 18A, according to various embodiments of the invention. 18C is a graph of BPP variation as a function of distance of the meniscus lens optical element from the beam source in the laser delivery system of FIG. 18A, according to various embodiments of the invention. FIG. 18D is a schematic diagram of a partial laser beam delivery system that incorporates a triple collimator for increased beam divergence and a pair of phase plate optical elements, according to various embodiments of the present invention. FIG. 18E is a graph of BPP variation as a function of gap distance between paired phase plate lenses in the laser beam delivery system of FIG. 18D, according to various embodiments of the invention. FIG. 19 is a schematic diagram of a wavelength beam combination laser system that can be utilized to provide an input beam for a laser beam delivery system, according to various embodiments of the invention. FIG. 20 is a schematic diagram of a laser system according to various embodiments of the invention. FIG. 21 is a series of images depicting exemplary beam shapes utilized in accordance with various embodiments of the present invention. Figures 22A and 22B are schematic views of a workpiece being processed using laser beams having different shapes, according to various embodiments of the present invention. 23A-23D are a series of schematic views of a welding process utilizing laser beams having a plurality of different beam shapes, according to various embodiments of the present invention.

  The aspects and embodiments generally adjust the polarization and / or shape of the laser beam used in manufacturing to produce better manufacturing results, including little debris and clean cut surfaces and welds. Related to the field. In various embodiments, the present invention therefore relates to optimizing the polarization and / or shape of the laser beam for the material being processed. More specifically, systems and methods for adjusting polarization selectively select the polarization based on, for example, the geometry, material, and thickness of the material being processed, and the instantaneous orientation of the beam relative thereto. To vary the orientation of the wave plate through which the beam passes. The approaches and embodiments described herein may be applied to single and dual beam output systems that use polarization maintaining optical fibers and deliver the output beam from the laser system to the laser head. In some cases, these laser systems may be wavelength beam combination systems that produce multi-wavelength output beams.

  Thus, embodiments of the present invention establish an optimal polarization direction for a given material and maintain this direction relative to the processing direction as processing proceeds. This is in contrast to the behavior of the prior art system as illustrated in FIG. 1, which does not alter the polarization direction. In FIG. 1, a sheet of material 100 is processed with a linearly polarized beam that follows a desired cutting path 102, which may be curved. The linear polarization shown at 104 maintains a fixed orientation regardless of the varying orientation of the beam relative to the material 100. In many systems, the optimal beam polarization is parallel to the direction of processing. In FIG. 1, this occurs only once, in fact, in most places the polarization is disadvantageously perpendicular to the processing direction. This can delay processing, produce debris, cause incomplete cutting, and the like.

  One optimal behavior for the exemplary system is illustrated in FIG. 2A. The polarization orientation 204 of the processing beam remains parallel to the processing direction throughout the processing path 102. Another optimal behavior for the exemplary system is illustrated in FIG. 2B. The polarization state 210 of the processing beam changes from linear polarization to elliptical polarization to circular polarization as the thickness of the material 100 increases. In yet another embodiment, illustrated in FIG. 2C, the polarization state 210 of the processing beam changes from linear to radial polarization along the processing path 102. Although the processing path in FIGS. 2B and 2C is substantially linear, in embodiments of the invention, the processing path may include one or more directional changes, as shown in FIG. 2B. In general, the processing path may be curved or linear, and a “linear” processing path may be characterized by one or more directional changes, ie, linear processing paths are not necessarily parallel to each other. It may consist of two or more substantially straight sections.

  An exemplary system for performing polarization fluctuations according to embodiments of the invention is shown in FIGS. 3A-3C. Referring to FIG. 3A, system 300 includes a laser (or other beam emitter such as a polarizing fiber) 305 and a controller 310. The controller 310 controls the operation of the laser 305 (ie, activates the laser 305 and controls beam parameters such as intensity during processing as needed). The controller also operates a conventional positioning system 315 and polarization controller 320. The positioning system 315 may be any controllable optical system, mechanical system, or optomechanical system for directing the beam through the processing path along a two or three dimensional workpiece. During processing, the controller 310 may operate the positioning system 315 and the laser 305 so that the laser beam traverses the processing path along the workpiece. The processing path may be provided by the user and stored in on-board or remote memory 325, which also relates to parameters related to the type of processing (cutting, welding, etc.) and necessary to perform the processing. Beam parameters may be stored. In this regard, the local or remote database 330 may maintain a library of materials and thicknesses that the system 300 will process, depending on the user selection of material parameters (material type, thickness, etc.) The controller 310 queries the database 330 and obtains the corresponding parameter value. The stored value may include a polarization orientation and / or state suitable for the material.

  As is well understood in plotting and scanning techniques, the relative motion required between the beam and the workpiece is determined by the optical deflection of the beam using a movable mirror, a gantry, a lead screw, or a laser using other arrangements. Instead of (or in addition to) physical movement and / or beams, it may be produced by a mechanical arrangement for moving the workpiece. The controller 310, in some embodiments, may receive feedback from the feedback unit 335 regarding the position of the beam relative to the workpiece and / or processing effectiveness, which will be connected to a suitable monitoring sensor. . In response to the signal from feedback unit 335, controller 310 modifies the path, composition, and / or polarization of the beam.

  In one embodiment shown in FIGS. 3B and 3C, polarization adjustment is performed in the laser head component 350, which is typically the last optomechanical part of the laser system that emits the beam used in manufacturing. is there. Laser head 350 includes a collimating lens 355, a conditioning / rotating wave plate 360, and a focusing lens 365 for directing beam 370 onto the surface of the workpiece. The wave plate 360 may be a quarter wave plate, a half wave plate, or other wave plate for rotating the polarization of the beam 370. With reference to FIGS. 3A-3C, the conventional electromechanical rotation device 375 rotates the wave plate 360 as the beam travels through the processing path 102 under the control of the controller 310, and thus the beam 370 relative to the path 102. Results in a consistent polarization direction. In other configurations, multiple wave plates may be employed and rotated separately by individual rotating devices 375. The use of multiple wave plates can improve response time. The polarization of beam 370 is shown in a first orientation 380a prior to encountering wave plate 360 and a second orientation 380b after passing through wave plate 360.

  In one embodiment shown in FIGS. 3D and 3E, polarization adjustment is also performed within the laser head component 350. Laser head 350 includes a collimating lens 355 and a focusing lens 365 for directing beam 370 onto the surface of the workpiece, similar to laser head 350 depicted in FIG. 3B. In the embodiment of FIG. 3D, the laser head 350 includes a Babenet-Soleil compensator 385 between the collimating lens 355 and the focusing lens 365. As is known in the art, the Babenet-Soleil compensator 385 is a continuously variable optical retarder that can change the polarization of light traveling therethrough from linear to circular and any elliptical polarization state therebetween. . In various embodiments, the Babenet-Soleil compensator 385 includes, consists essentially of, or consists of a compensator plate 386, a fixed birefringent wedge 387, and a movable birefringent wedge 388. The major axis of the compensator plate 386 is typically perpendicular to the major axis of the wedges 387,388. Movement of wedge 388 relative to plate 386 and wedge 377 alters the polarization state of beam 370 to any elliptical state between linear and circular. Referring to FIGS. 3A, 3D, and 3E, a conventional electromechanical translation device 389 is under control of the controller 310 as the beam moves through the processing path 102 (eg, as the thickness of the workpiece changes). , The movable wedge 388 of the Babenet-Soleil compensator 385 is translated, thereby changing the polarization state along the path 102 as a function of the workpiece thickness. For example, the circularity of the polarization state of beam 370 (ie, the transition from linear to elliptical or circular) can be increased as the thickness of the workpiece increases. The polarization of beam 370 is shown in a first state 390a prior to encountering the Babenet-Soleil compensator 385 and in a second state 390b after passing through the Babenet-Soleil compensator 385.

  In another embodiment shown in FIGS. 3F and 3G, polarization adjustment is also performed within the laser head component 350. The laser head 350 includes a collimating lens 355 and a focusing lens 365 for directing the beam 370 onto the surface of the workpiece, similar to the laser head 350 depicted in FIGS. 3B and 3D. In the embodiment of FIG. 3F, the laser head 350 includes a radial polarization converter 391 between the collimating lens 355 and the focusing lens 365. As is known in the art, the radial polarization converter 391 may comprise, consist essentially of, or consist of a glass wave plate that converts linearly polarized light into radial or azimuthal polarization. For example, the radial polarization converter 391 may be a half wave plate with a continuously varying slow axis or spatially deformed quarter wave plate having radial symmetry. The radial polarization converter 391 is a nanostructured grating, such as the S-wave plate radial polarization converter available from UAB Altechna (Vilnus, Lithuania) or Edmund Optics Inc. It may comprise, consist essentially of, or consist of a glass plate having thereon one of the radial polarization converters available from (Barrington, New Jersey). In other embodiments, the radial polarization converter 391 is an Arcopix radius available from liquid crystals, eg, Arcopix (Neuchatel, Switzerland), in which the liquid crystal molecules are specifically matched to produce the desired radial or azimuthal polarization. It may comprise, consist essentially of, or consist of a directional polarization converter. Movement of the radial polarization converter 391 in the path of the beam 370 changes the polarization state of the beam 370 from linear to radial or azimuth or vice versa. In various embodiments, the radially polarized beam 370 can be focused to a spot size smaller than beam 370 having linear polarization. Referring to FIGS. 3A, 3F, and 3G, a conventional electromechanical translation device 389 translates the radial polarization converter 391 as the beam travels through the processing path 102 under the control of the controller 310, thereby , Changing the polarization state along the path 102. The polarization of beam 370 includes a first state 392a (ie, linear polarization) prior to encountering radial polarization converter 391 and a second state 392b (ie, radial polarization) after passing through radial polarization converter 391. ).

  FIG. 4A illustrates an exemplary method 400 for operating the system 300 and performing a cutting operation. In a first step 410, the user pre-programs the desired path into the system 300 using any suitable input device or using file transfer. In step 420, the controller 310 analyzes the path curve, features (eg, thickness), and cutting direction, queries the database 330, and determines the speed at which the cutting can be performed, if necessary, and the cutting direction. Determine the optimal polarization direction and / or state of the laser beam relative to. During the operation shown in step 430, the controller 330 operates the laser 305 and subsystems 315, 320 to cut along the pre-programmed path and maintain the proper polarization. If the composition and / or thickness of the material being processed changes, the location and nature of the change may be programmed, and the controller 310 may optionally include laser beam parameters (including polarization and / or beam shape). Can be adjusted. Optimal cutting, welding, or manufacturing solutions are still not necessarily the cleanest cut surfaces or welds because additional steps in the process (eg, deburring, grinding, and / or polishing) may be required. Note that there may be cases. Thus, global optimization can be based on the desired output, and the method and system are configured to produce their desired results, whatever they may be. As described above, cutting is only one example of laser processing that can benefit from the approach of embodiments of the present invention.

  Controller 310 may be provided as either software, hardware, or some combination thereof. For example, the system is a Pentium® or Celeron family processor manufactured by Intel Corporation (Santa Clara, Calif.), A 680x0 and POWER PC family processor manufactured by Motorola Corporation (Schaumburg, Ill.), And / Or Advanced Micro Devices, Inc. (Sunnyvale, Calif.) 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 an ATHLON line processor manufactured by Sunnyvale, Calif. The processor may also include a main memory unit for storing programs and / or data associated with the methods described above. The memory may be one or more application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), electrically erasable programmable read only memories (EEPROMs), programmable read only memories (PROMs), programmable logic devices ( It may include random access memory (RAM), read only memory (ROM), and / or flash memory that resides on commonly available hardware such as a PLD) or read only memory device (ROM). In some embodiments, the program may be provided using external RAM and / or ROM such as optical disks, magnetic disks, and other commonly used storage devices. For embodiments in which the functionality is provided as one or more software programs, the program can be any number such as FORTRAN, PASCAL, JAVA, C, C ++, C #, BASIC, various scripting languages, and / or HTML. May be written in any of these high level languages. In addition, the software may be implemented in assembly language directed to a microprocessor residing on the target computer. For example, if the software is configured to run on an IBM PC or PC clone, it may be implemented in Intel 80x86 assembly language. The software is embodied on an article of manufacture, including but not limited to a floppy disk, jump drive, hard disk, optical disk, magnetic tape, PROM, EPROM, EEPROM, field programmable gate array, or CD-ROM. May be.

  Although the methods described herein for improving processing work well for linearly polarized beams (delivered via free space lasers or polarization maintaining fibers), the technique also Also works well with elliptically polarized beams (biased with one polarization). For example, a beam from a standard multimode fiber is likely to be elliptically polarized and may benefit from the approaches described herein.

  Embodiments of the present invention may advantageously be utilized for more efficient cutting of various materials, such as metallic materials. FIG. 4B is a graph of achievable cutting speed as a function of workpiece thickness for a workpiece made of 304 stainless steel under nitrogen gas flow. Four different laser systems were utilized for cutting. Initially, a laser system according to an embodiment of the present invention that utilizes a 58 μm polarization maintaining optical output fiber to operate at a power of 1 kW and produce a linearly polarized laser output beam comprises a workpiece with a polarization direction. Used to cut in parallel and vertical directions. Trend line 440 depicts the cutting speed achievable for beams polarized parallel to the cutting direction, and trend line 445 depicts the cutting speed achievable for beams polarized perpendicular to the cutting direction. As shown, the parallel polarized beam allows a significantly higher cutting speed than the vertically polarized beam, especially for thinner workpieces. Trend lines 450 and 455 depict data for two different commercially available 1 kW laser systems with an unpolarized output beam (ie, utilizing an output fiber optic cable, not a polarization maintaining fiber). As shown, the unpolarized beam allows faster cutting compared to the vertically polarized beam at trend line 445, but is slower than the parallel polarized beam at trend line 440. Trend line 460 depicts data for a 2 kW laser that has a 100 μm output fiber but also produces an unpolarized beam. As would be expected, this more powerful laser system allows a faster cutting speed than a lower power laser system, but the parallel polarized beam of trend line 440 has a lower power and more The advantage of cutting at a higher speed despite operating with a smaller output fiber is reduced and even disappears for thinner workpieces.

  FIG. 4C is a graph of the achievable cutting speed as a function of workpiece thickness for a workpiece made of 3003 aluminum under a nitrogen gas flow. The laser system utilized is the same as described above with respect to FIG. 4B. As shown, the parallel polarized beam represented by the trend line 440 exhibits the best cutting performance, and the performance of the parallel polarized beam is that of the 2 kW, 100 μm unpolarized beam of the trend line 460, especially for thinner workpiece thicknesses. Even better than the ones. As in FIG. 4B, the vertically polarized beam of trend line 445 depicts the worst performance and highlights the advantageous effects of embodiments of the present invention where the polarization direction is maintained parallel to the cutting direction.

  FIG. 4D is a graph of the cutting rate achievable as a function of workpiece thickness for a workpiece made of brass under nitrogen gas flow. The laser system utilized is the same as described above with respect to FIG. 4B. As shown, the parallel polarized beam represented by trend line 440 exhibits fast cutting performance, especially for thinner workpiece thicknesses. The parallel polarized beam represented by trend line 440 also exhibits a much faster cutting speed than the comparable 1 kW unpolarized beam represented by trend line 450. As in FIGS. 4B and 4C, the vertically polarized beam of trend line 445 depicts the worst performance and, in fact, is not capable of cutting speed to be evaluated for a workpiece having a thickness of 3 mm.

  Embodiments of the present invention combine techniques for beam polarization adjustment in response to workpiece material and / or physical properties using techniques for shaping the beam and / or adjusting the BPP of the beam, or Replace. FIG. 5 depicts a schematic diagram of a laser beam delivery system 500 that incorporates beam manipulation optics according to an embodiment of the present invention. In various embodiments, the laser beam delivery system 500 may be disposed, for example, in a laser-based cutting head or welding head (eg, the cutting head 350) and utilized to adjust the polarization of the output beam. You may combine with the various components (for example, an optical element, a controller, etc.) in it. The beam delivery system 500 includes a beam delivery fiber terminating in a fiber end cap 505, a collimating lens 510, connected to the rest of the laser generation system (eg, a WBC laser system not shown in FIG. 5). It may feature a focusing lens 515 and an optical element 520 positioned between the end cap 505 and the collimating lens 510. In various embodiments of the invention featuring combined functionality for beam shaping and polarization adjustment, elements such as collimating lens 510 and focusing lens 515 may be shared between their functionality. That is, the laser beam delivery system may have various optical elements that, in various embodiments, facilitate both beam shaping and polarization adjustment. In various embodiments, the optical element 520 is positioned proximate to the fiber end cap 505 to minimize the size of the beam striking the optical element 520. Refraction of the smaller beam may be performed using optics having a smaller geometric dimension of the optics, and higher sensitivity may be used to vary the output profile. FIG. 5 also depicts an optional second optical element 525 positioned between the focusing lens 515 and the workpiece 530. Workpiece 530 may include or consist essentially of one or more parts (eg, metal parts) that are welded, drilled, and / or cut, for example, by a beam focused by focusing lens 515. . In various embodiments, the first optical element 520 is disposed between the focusing lens 515 and the workpiece 530, and the second optical element 525 is omitted. Each of the optical elements 520, 525 may comprise or consist essentially of, for example, a phase plate.

  The position of the first optical element 520 and / or the second optical element 525 includes, or includes, one or more mechanical or motor driven translation stages 535 that are movable along, for example, two or three axes. It can be translated into the beam profile through the use of a lens manipulation system, which can be inherent. The lens manipulation system may be responsive to the controller 540. The controller 540 may provide a BPP or other measurement of the desired target radiant power distribution and / or beam quality (eg, by and to the workpiece, distance to the workpiece, workpiece composition, workpiece topography, workpiece thickness). In response to an input based on one or more properties of the workpiece to be processed, etc.), positioning optical element 520 and / or optical element 525 and operating beam 545 using target radiation power distribution or beam quality The workpiece 530 may be hit. The controller 540 may be programmed to achieve a desired power distribution and / or output BPP and / or beam quality via specific optical element positioning, as detailed herein. The controller 540 may be provided as either software, hardware, or some combination thereof. For example, the system may be a Pentium® from Intel Corporation (Santa Clara, Calif.), Or a Celeron family processor, a Motorola Corporation (Schaumburg, Ill.) 680x0 and POWER PC family processor, and / or an AdvancedDev. , Inc. (Sunnyvale, Calif.) May be implemented on one or more conventional server class computers, such as a PC having a CPU board containing one or more processors, such as an ATHLON line processor. The processor may also include a main memory unit for storing programs and / or data associated with the methods described herein. The memory may be one or more application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), electrically erasable programmable read only memories (EEPROMs), programmable read only memories (PROMs), programmable logic devices ( It may include random access memory (RAM), read only memory (ROM), and / or flash memory resident on commonly available hardware such as PLDs) or read only memory devices (ROM). In some embodiments, the program may be provided using external RAM and / or ROM such as optical disks, magnetic disks, and other commonly used storage devices. For embodiments in which the functionality is provided as one or more software programs, the program can be any number such as FORTRAN, PASCAL, JAVA, C, C ++, C #, BASIC, various scripting languages, and / or HTML. May be written in any of these high-level languages. In addition, the software may be implemented in a microprocessor-oriented assembly language that resides on the target computer, eg, if the software is configured to run on an IBM PC or PC clone, an Intel 80x86 assembly. May be implemented in a language. The software is embedded on the manufactured product, including but not limited to floppy disk, jump drive, hard disk, optical disk, magnetic tape, PROM, EPROM, EEPROM, field programmable gate array, or CD-ROM. May be.

  FIG. 6 is a schematic diagram of an optical element 600 having a frustoconical shape (flat upper cone shape or tapered cylindrical shape), according to an embodiment of the present invention. For example, optical element 600 may be utilized as optical element 520 and / or optical element 525 within delivery system 500. Parameters D, d, θ, and H are slopes that define an outer diameter, an inner diameter (which may correspond to the beam size of the beam when striking the optical element), and a maximum arrow (or “droop”, h), respectively. Geometric design parameters relating to angle, separation of the outer ring of the beam from the center of the beam spot, and the thickness of the optical element 600. Geometric optical ray tracing may be used to design optical elements according to embodiments of the present invention based on energy conservation, optical path length constancy, and Snell's law. The lens design and its surface profile can, for example, transform the beam profile from a Gaussian with a desired intensity distribution to a Bessel laser beam.

Table 1 includes, consists of, consists essentially of, or consists of two different materials, namely fused silica and zinc sulfide (eg, ZnS MultiSpectral available from II-VI Inc. (Saxonburg, PA)). Example design values for the optical element 600 are provided.

  7A and 7B are graphs of BPP at different distances from the fiber end cap 505 to the exemplary fused silica (FIG. 7A) and zinc sulfide (FIG. 7B) optical elements 600 having the design parameters provided in Table 1. It is. In the plot, the initial position of the optical element 600 is assumed to be 25 mm from the end cap 505. As shown, in both cases, the BPP of the beam can be increased from about 4 to about 12 via a displacement of the optical element 600 of only about 30 mm. The slope of this change in BPP as a function of displacement may be modified through changes in the numerical aperture of the fiber output at end cap 505. The beam profile at a distance of 50 mm from the optical element 600 to the fiber end cap 505 is also shown in FIGS. 7A and 7B.

  An adjusted beam profile with two peaks on one axis causes the optical element 600 (or other optical element detailed herein) to move laterally within the beam path, as shown in FIG. 8A. Can be obtained by positioning it off-center (ie, partially introducing it into the input laser beam). Depending on the degree of introduction, the beam profile of the output laser beam can be optimally adapted for various laser applications. In FIGS. 8B-8D, beam profiles at different off-center distances (0 mm, 2 mm, and 4 mm) for optical element 600 at a distance of 40 mm to end cap 505 are shown. FIG. 8E is a graph of irradiance as a function of position for the beam profile depicted in FIG. 8D, clearly showing the two-peak nature of the beam profile. In various embodiments, the variation in BPP at different off-center positions of the optical element 600 is approximately zero while the irradiance changes as a function of position across the beam profile.

  Optical elements according to embodiments of the present invention may also have a truncated spherical (ie, flat top spherical) configuration and may be used to produce a Bessel beam profile. A geometric design for an optical element 900 according to such an embodiment is schematically depicted in FIG. Optical element 900 may be utilized as optical element 520 and / or optical element 525 within delivery system 500. The design parameters are the same as those detailed above for the flat top cone optical element 600, except for the radius of curvature R, which also results in the maximum droop of the resulting annular beam ring from the beam spot center ( h) and defining separation.

Table 2 provides exemplary design values for an exemplary optical element 900 comprising, consisting essentially of, or consisting of two different materials: fused silica and zinc sulfide.

  10A and 10B are graphs of BPP at different distances from the fiber end cap 505 to the exemplary fused silica (FIG. 10A) and zinc sulfide (FIG. 10B) optical elements 900 having the design parameters provided in Table 2. It is. In the plot, the initial position of the optical element 900 is assumed to be 25 mm from the end cap 505. As shown, in both cases, the BPP of the beam can be increased to about 4 to about 12 via displacement of the optical element 900 by about 30 mm (eg, about 28 mm to about 32 mm). The slope of this change in BPP as a function of displacement may be modified through changes in the numerical aperture of the fiber output at end cap 505. The beam profile at a distance of 50 mm from the optical element 900 to the fiber end cap 505 is also shown in FIGS. 10A and 10B as a graph of its irradiance as a function of position for the 50 mm spacing between the optical element 900 and the end cap 505. Shown in

  11A-11C, as shown for optical element 600 in FIG. 6A at different off-center distances (0 mm, 2 mm, and 4 mm) for optical element 900 at a distance of 40 mm of end cap 505. The beam profile is shown. FIG. 11D is a graph of irradiance as a function of position for the beam profile depicted in FIG. 11C, clearly showing the two-peak nature of the intensity of the beam profile. In various embodiments, the variation in BPP at different off-center positions of the optical element 900 is approximately zero, even while the irradiance changes as a function of position across the beam profile.

  Embodiments of the present invention utilize optical elements to produce an annular beam shape. Embodiments of the invention feature one or more optical elements that comprise, consist essentially of, or consist of an axicon lens. As is known in the art, an axicon lens is a lens having at least one conical surface for imaging a point source into a line segment along the optical axis. It may be used. The rotationally moving conical surface can hybridize light from a point source located on the rotational motion axis by reflection and / or refraction. Embodiments of the present invention, as shown in FIG. 12A, include a double positive (ie, double convex) axicon lens 1200 and double negative (ie, double convex) between the fiber end cap 505 and the collimating lens 510. , Double concave) using a combination of axicon lenses 1210, the beam size at the workpiece can be varied using the present lens system. As shown, the lenses 1200, 1210 are separated in the beam path by a gap distance 1220. θ1 and θ2 are the slope variables of the conical surface that define the maximum droop (h1 and h2) and separation of the annular beam ring from the center of the beam spot, as schematically depicted in FIGS. 12B and 12C. In various embodiments of the present invention, one or both conical surfaces of lenses 1200, 1210 have a smooth edge and a radius of curvature of less than about 5 μm.

  FIG. 13 is a graph depicting the BPP control of a laser delivery system as a function of the gap distance 1220 between two axicon lenses 1200, 1210. As shown in FIG. 13, a variation of approximately 7 mm in the gap distance 1220 results in a 4-12 BPP increase, demonstrating the wide range of BPP control enabled by such embodiments of the present invention. The beam profile as a function of the gap distance 1220 between the lenses 1200, 1210 is shown in FIG. 14 and the gap distance is listed in millimeters. As shown, adjustment of the gap distance 1220 may transform a beam profile having a single peak into one having two, three, or more peaks. FIG. 15 depicts a similar beam profile when two axicon lenses 1200, 1210 are laterally offset from the center by 4 mm in the beam path and separated by the listed gap distance 1220 (gap distance is Enumerated in millimeters).

  Embodiments of the present invention include one or more curved surfaces comprising, consisting essentially of, or consisting of a phase plate, having one planar surface and its opposing surface, at least partially curved convex or concave Features an optical element. FIG. 16A depicts a partial beam delivery system featuring two such plates 1600, 1610 separated by a gap Z. FIG. As shown, the plate 1600 is separated from the fiber end cap 505 by a distance S. 16B and 16C depict plates 1600, 1610 in more detail. As shown, the plates 1600, 1610 have an outer diameter D and the convex / concave portion of the surface has an inner diameter d that defines a maximum droop h (in conjunction with R detailed below). . The thickness of the plate at its outer perimeter (ie, the thickness between the planar portions of its opposing surface) is represented by H, and the radius of curvature of the convex / concave portion is represented by R. As depicted in FIGS. 16B and 16C, plates 1600, 1610 have substantially the same H, D, d, and R, but various embodiments of the present invention may employ one or more of these parameters. Characterized by paired plates (ie, one having a partially concave surface and one having a partially convex surface).

Table 3 provides exemplary design values for exemplary optical elements 1200, 1210 comprising, consisting essentially of, or consisting of two different materials, fused silica and zinc sulfide.

  16D and 16E are optimized so that the inner diameter d of the plates 1600, 1610 maximizes the output BPP of the laser delivery system as a function of the distance S from the fiber end cap 505, according to embodiments of the present invention. Describe what can be done. FIG. 16D is a graph of BPP as a function of inner diameter d for plates 1600, 1610 having a distance S 40 mm, a gap distance Z 10 mm, and a radius of curvature R 500. As shown, the resulting BPP is maximized at an inner diameter d of about 5 mm. The BPP is substantially independent of changes in the gap distance Z and the radius of curvature R. FIG. 16E is a graph of the optimized inner diameter d (ie, the inner diameter d that maximizes the output BPP) as a function of the distance S between the end cap 505 and the plate 1600. As shown, the optimized inner diameter d may be selected to maximize the output beam BPP as a function of the distance S.

  FIG. 16F is a graph of BPP at different gap distances Z between the plates 1600, 1610 having the design parameters provided in Table 3 (using the design parameters in Table 3, fused silica and zinc sulfide plates 1600, 1610 Both provide the same result). In the plot, the distance S to the end cap 505 is assumed to be 40 mm. As shown, the BPP of the beam can be increased from about 4 to about 12 through modification of the gap Z between the plates 1600, 1610 by only about 9 mm. Various beam profiles of the output beam as a function of gap Z (in mm) are illustrated in FIG. 16G as a graph of its irradiance as a function of position. As shown, as the beam BPP increases, the beam shape changes from having a single peak to having a broader multi-peak irradiance profile.

  Optical elements according to embodiments of the present invention may also include, consist essentially of, or consist of a meniscus lens. A geometric design for an optical element 1700 according to such an embodiment is schematically depicted in FIG. 17A. As shown, in various embodiments, one surface of optical element 1700 is curved convexly over substantially the entire surface, while the opposing surface is curved concavely over a portion of the surface to have an inner diameter d. Define. Optical element 1700 may be utilized as optical element 520 and / or optical element 525 within delivery system 500. As shown, optical element 1700 has an outer diameter D, an inner diameter d, a thickness H, a maximum sagging h1 of a convex curved surface, and a maximum sagging h2 of a partially concave curved surface. May be. The radius of curvature R, which may be substantially the same for both surfaces of the optical element 1700, defines the maximum droop h1 and h2 and the resulting annular beam ring separation from the beam spot center.

Table 4 provides exemplary design values for an exemplary optical element 1700 comprising, consisting essentially of, or consisting of two different materials, fused silica and zinc sulfide.

  FIG. 17B is a graph of BPP at different distances from the fiber end cap 505 to the exemplary fused silica optical element 1700 with the design parameters provided in Table 4. In the plot, the initial position of the optical element 1700 is assumed to be 25 mm from the end cap 505. As shown, the BPP of the beam can be increased from about 4 to about 12 via displacement of the optical element 1700 by about 24 mm. The beam profile at a distance of 46 mm from optical element 1700 to fiber end cap 505 is also shown in FIG. 17B as a graph of irradiance as a function of position for the 46 mm spacing between optical element 1700 and end cap 505. Indicated.

  Laser beam delivery systems according to embodiments of the present invention may also utilize various lens arrangements to form a larger and more dispersed input beam for BPP variation as a function of optical element movement. FIG. 18A depicts a portion of a laser delivery system 1800 that incorporates a movable optical element 1805 for BPP variation and a triple collimator to increase the divergence of the laser beam. As shown, the triple collimator increases the beam divergence from angle α to angle β. In various embodiments, the ratio of β to α is about 2 to about 1.5, for example about 1.74. As will be described in more detail below, this increased divergence allows for better control of the BPP with less movement of the optical element 1805. In various embodiments, optical element 1805 includes any one or more of optical element 600, optical element 900, optical element 1700, phase plate 1600/1610, or axicon lenses 1200, 1210, and Consists essentially of or consists of.

  A triple collimator for increasing beam divergence according to embodiments of the invention may consist of various combinations of lenses. FIG. 18A depicts one such embodiment that includes a plano-concave lens 1810, a meniscus lens 1815 (eg, a positive meniscus lens), and a plano-convex lens 1820. In various embodiments of the invention, the optical element 1805 is disposed in the beam path between the plano-concave lens 1810 and the meniscus lens 1815. In other embodiments, the optical element 1805 may be disposed in the beam path between the meniscus lens 1815 and the plano-convex lens 1820 or further optically downstream of the plano-convex lens 1820.

  FIG. 18B illustrates an exemplary design parameter provided in Table 1 from a fiber end cap 505 when utilized in a laser beam delivery system 1800 in conjunction with a triple collimator for increased beam divergence. 4 is a graph of BPP at different distances to a fused silica optical element 600. FIG. In the plot, the initial position of the optical element 600 is assumed to be 25 mm from the end cap 505. As shown, the BPP of the beam is a displacement of the optical element 600 of only about 16 mm, i.e., less than about 2 times the displacement (i.e., better than the beam delivery system lacking the triple collimator of FIG. 18A). Can be increased from about 4 to about 12 (see FIG. 7A). The beam profile at a distance of 21 mm from the optical element 600 to the fiber end cap 505 is also shown in FIG. 18B.

  FIG. 18C illustrates an exemplary design parameter provided in Table 4 from a fiber end cap 505 when utilized in a laser beam delivery system 1800 in conjunction with a triple collimator for increased beam divergence. 4 is a graph of BPP at different distances to a fused silica optical element 1700. In the plot, the initial position of the optical element 1700 is assumed to be 25 mm from the end cap 505. As shown, the BPP of the beam has a displacement of the optical element 600 of only about 12 mm, ie, less than about twice as much displacement (ie, better than the beam delivery system lacking the triple collimator of FIG. 18A). Can be increased from about 4 to about 12 (see FIG. 17B). The beam profile at a distance of 17.5 mm from the optical element 1700 to the fiber end cap 505 is also shown in FIG. 18C.

  18D is a schematic of a partial laser beam delivery system 1800 that incorporates the aforementioned pair of phase plate optical elements 1600, 1610 separated in the beam path by a gap distance Z. FIG. FIG. 18E illustrates exemplary fused silica optical elements 1600, 1610 having the design parameters provided in Table 3 when utilized in a laser beam delivery system 1800 in conjunction with a triple collimator for increased beam divergence. It is a graph of BPP regarding different gap interval Z. In the plot, the position of the optical element 1600 is assumed to be 25 mm from the end cap 505. As shown, the BPP of the beam increases the gap distance Z between the optical elements 1600, 1610 by only about 3 mm, ie, about 3 as compared to the beam delivery system lacking the triple collimator of FIG. 18A. It can be increased from about 4 to about 12 through less than twice the displacement (ie, better control) (see FIG. 16F). The beam profile at a 3 mm gap distance between the optical elements 1600, 1610 is also shown in FIG. 18C.

  Laser systems and laser delivery systems, as detailed herein, according to embodiments of the present invention may be utilized within and / or with a WBC laser system. Specifically, in various embodiments of the present invention, the multi-wavelength output beam of the WBC laser system is subject to BPP, beam shape, and / or polarization variations, as detailed herein. It may be utilized as an input beam for a laser beam delivery system. FIG. 19 depicts an exemplary WBC laser system 1900 that utilizes one or more lasers 1905. In the example of FIG. 19, the laser 1905 features a diode bar with four beam emitters that emit a beam 1910 (see enlarged input FIG. 1915), but embodiments of the present invention can be applied to any number of individual A diode bar or a two-dimensional array or stack of diodes or diode bars emitting a plurality of beams may be utilized. In FIG. 1915, each beam 1910 is represented by a line, where the length or longer dimension of the line represents the slow divergence dimension of the beam, and the height or shorter dimension represents the fast divergence dimension. Collimating optics 1920 may be used to collimate each beam 1910 along the fast dimension. Deformation optics 1925, including or consisting essentially of one or more cylindrical or spherical lenses and / or mirrors, are used to combine each beam 1910 along the WBC direction 1930. The deformable optics 1925 then comprises or essentially consists of a dispersive element 1935 (eg, a reflective or transmissive diffraction grating, a dispersive prism, a grism (prism / grating), a transmission grating, or an echelle grating). The overlapping and combined beams are then transmitted on the output combiner 1940 as a single output profile. The output combiner 1940 then transmits the combined beam 1945 on the output front view 1950 as shown. The output coupler 1940 is typically partially reflective and acts as a common front facet for all laser elements in the external cavity system 1900. The external cavity is a lasing system and the secondary mirror is displaced by a distance so that it separates from the emission aperture or facet of each laser emitter. In some embodiments, additional optics is placed between the emission aperture or facet and the output coupler or partially reflective surface. The output beam 1945 is thus a multi-wavelength beam (combining the wavelengths of the individual beams 1910) and may be utilized as an input beam in the laser beam delivery system detailed herein, and / or It may be coupled into an optical fiber.

  FIG. 20 depicts a laser system 2000 having a variable shape output beam that is utilized in accordance with various embodiments of the invention. As shown, laser system 2000 may include a laser source 2010 (eg, WBC laser system 1900 forms an output beam of multiple wavelengths) coupled to optical fiber 2020. At the distal end of the optical fiber 2020 is a processing head or laser beam delivery system 2030. The processing head 2030 may include, consist essentially of, or consist of, for example, all or part of the components of the laser beam delivery system 500 described above. For example, the processing head 2030 may incorporate and / or respond to a controller (eg, controller 540) that controls the output beam shape at the focal point 2040 at or near the surface of the workpiece. In various embodiments, as detailed herein, the processing heads 2030 are shaped and / or movable relative to each other to form an output laser beam having a variable output beam shape. It may include or consist essentially of various optical elements. FIG. 21 depicts a series of different output beam shapes that can be formed by laser system 2000, according to an embodiment of the invention. As shown, the output beam shape is highly focused in response to a control voltage applied within the processing head 2030 (eg, via a controller for controlling the position of one or more optical elements therein). From the spot beam, it extends to the diffuse, defocused larger spot, the annular beam. Also, as shown in FIG. 21, the BPP of the beam can also change as the beam shape changes.

  In various embodiments, laser system 2000 includes a controller (eg, controller 540 as described above) and / or a positioning system (eg, positioning system 315). The controller controls the operation of the laser system (ie, activates the laser and controls beam parameters such as intensity and / or output beam shape as needed during processing). The controller may also operate the positioning system. The positioning system may be any controllable optical system, mechanical system, or optomechanical system for directing the beam through the processing path along the two-dimensional or three-dimensional workpiece. During processing, the controller may cause the laser beam to traverse the processing path along the workpiece and / or a particular point on the workpiece where the laser output beam is to be processed (eg, position for welding). The positioning system and laser system 2000 may be operated so that The processing path and / or one or more processing points may be provided by the user and stored in on-board or remote memory, which also includes parameters related to the type of processing (cutting, welding, etc.) You may memorize | store the beam parameter (for example, output beam shape) required in order to perform the process. In this regard, the local or remote database may maintain a library of materials and thicknesses that the laser system will process, depending on user selection of material parameters (material type, thickness, etc.) May query the database to obtain the corresponding parameter value.

  As is well understood in plotting and scanning techniques, the relative motion required between the output beam and the workpiece used optical deflection of the beam using a movable mirror, gantry, lead screw, or other arrangement. It may be produced by physical movement of the laser and / or mechanical arrangement for moving the workpiece rather than (or in addition to) the beam. The controller, in some embodiments, may receive feedback from the feedback unit regarding beam position and / or beam processing effectiveness relative to the workpiece, which will be connected to a suitable monitoring sensor. In response to the signal from the feedback unit, the controller modifies the beam path, position, BPP, and / or shape.

  In addition, the laser system may incorporate one or more systems for detecting the thickness of the workpiece and / or the height of the features thereon. For example, as detailed in US patent application Ser. No. 14 / 676,070, filed Apr. 1, 2015, the entire disclosure of which is incorporated herein by reference, A system (or component thereof) for workpiece interference depth measurement may be incorporated. Such depth or thickness information is controlled by the controller, for example, according to the records in the database corresponding to the type of material being processed, and the workpiece processing (eg, cutting or welding). It may be used to optimize.

  22A and 22B depict an exemplary cutting scenario according to an embodiment of the present invention. In various embodiments of the present invention, the laser system 2000 may make different depth and / or different size cuts into the workpiece 2200 and / or make consistent size cuts into the workpiece 2200 having variable thickness. Used for As shown, the output beam shape has a highly focused spot due to shallow cutting and is forced by a thicker area on the workpiece 2200 and / or a change in angle between the processing head 2030 and the workpiece 2200. May be gradually or substantially abruptly varied to have a defocused spot and / or an annular shape (and / or a spot with two or more distinctly different intensity peaks) for a deeper cut to be made Good. For example, as shown in FIG. 22A, the output beam may strike workpiece 2200 at a substantially normal angle to the surface of workpiece 2200, and the output beam can be all or part of the thickness of workpiece 2200. In order to make a relatively shallow cut through, it may have the shape of a highly focused spot. Also, as shown in FIG. 22A, the shape of the beam can be increased to make a larger width cut into the workpiece 2200 and / or the distance through the workpiece 2200 along the output beam direction. As such, when the angle between the output beam and the workpiece surface 2200 is modified (eg, reduced), it may be modified to a defocused spot or an annular shape.

  In various embodiments, as shown in FIG. 22B, the angle of the processing head 2030 (and thus the output beam) can vary during the relative movement between the beam and the workpiece 2200 during the topology, thickness of the workpiece 2200. , And / or as the surface angle varies, the controller may be kept constant (eg, substantially vertical), and the controller may be presented to the processing head 2030 at various processing points or across the processing path to the effective thickness of the workpiece 2200. The beam shape is controlled according to (ie, the depth of cut required to cut through the workpiece 2200 or to a defined distance therein). For example, the thickness of the workpiece 2200 presented to the processing head 2030 on the left side of FIG. 22B is larger than that on the right side of FIG. 22B due to, for example, the surface topology, and the beam shape is adjusted accordingly. . Such an arrangement eliminates the need for the processing head 2030 and / or the output beam to be repositioned to present a consistent angle between the beam and the workpiece surface. Thus, complex robots and / or other equipment and associated costs and complexity for angular repositioning of the processing head can be avoided.

  In various embodiments of the present invention, a laser system is utilized to weld one or more workpieces while minimizing or substantially eliminating the need to scan the output beam across the surface of the workpiece. The 23A-23D depict an exemplary welding sequence according to an embodiment of the present invention. As shown, the output beam shape 2300 provides a larger area during spot welding to weld the two workpieces 2310, 2320 together without the need for relative movement between the output beam and the workpiece. From an annular shape (FIG. 23A), it is varied to a smaller annulus (FIG. 23B), a large focused spot (FIG. 23C), and a smaller focused spot (FIG. 23D). Thus, a uniform weld that is larger than spot size 2300 in FIG. 23D (and / or at least as large as the outer boundary of spot size 2300 in FIG. 23A), the two workpieces are scanned without the beam being scanned along its surface. Formed between pieces 2310, 2320. In various embodiments, the controller may vary the output power and / or BPP of the beam during the welding process in addition to variations in 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 power of a more defocused and / or annular beam, which can facilitate the formation of a spatially uniform weld. In this way, a large uniform single weld is produced on the workpiece, simply by modifying the beam shape (and in some embodiments, the beam power), multiple smaller over the same area. The need to form spot welds (as well as the need to move the workpiece relative to the beam with each weld) can be eliminated. Although FIGS. 23A-23D depict an exemplary spot welding process, embodiments of the present invention include other processing techniques and types of welding, such as lap welding and spot welding. In addition, the various welding steps using the different beam shapes depicted in FIGS. 23A-23D may be performed in any order in accordance with embodiments of the present invention. Although FIGS. 23A-23D depict a series of four different beam shapes utilized for welding, embodiments of the present invention are more than two, three, or four when welding workpieces Different beam shapes may be utilized.

  The terms and expressions employed herein are used for the purpose of description, not limitation, and the use of such terms and expressions excludes any equivalents of the features illustrated and described or portions thereof. It will be appreciated that various modifications are possible within the scope of the claimed invention.

Claims (46)

A method of processing a workpiece, the method comprising:
Creating a relative motion between a laser output beam and the surface of the workpiece and defining a processing path, wherein the thickness of the workpiece along a direction parallel to the laser output beam is Fluctuating along a processing path, and the laser output beam physically alters the surface of the workpiece along at least a portion of the processing path;
Meanwhile, altering the shape of the laser output beam based at least in part on the thickness of the workpiece.   The method of claim 1, wherein the shape of the laser output beam is varied between a focused spot and an annulus as the thickness of the workpiece increases.   The thickness of the workpiece along a direction parallel to the laser output beam varies at least in part due to a change in angle between the laser output beam and the surface of the workpiece. The method according to 1.   The method of claim 1, wherein the shape of the laser output beam is modified while maintaining a substantially constant angle between the laser output beam and the surface of the workpiece.   The method of claim 1, further comprising measuring the thickness of the workpiece during relative movement between the laser output beam and the surface of the workpiece.   The method of claim 1, wherein a shape of the laser output beam is modified based on a composition of the workpiece.   The method of claim 1, wherein the laser output beam comprises a plurality of wavelengths. A system for processing a workpiece, the system comprising:
A beam emitter for emitting a laser output beam;
A positioning device for varying the position of the laser output beam relative to the workpiece;
Means for modifying the shape of the laser output beam;
A controller coupled to the positioning device and the shape modifying means, wherein the controller (i) operates the beam emitter to route the laser output beam across at least a portion of the workpiece; A controller that traverses and physically modifies the surface; (ii) modifies the shape of the laser output beam based at least in part on the thickness of the workpiece along the path; system.   The beam emitter comprises a processing head from which the laser output beam is emitted, the shape modifying means comprising: (i) one or more optical elements in the processing head; and (ii) in the processing head. 9. A system according to claim 8, comprising a second controller for modifying the position of at least one of the optical elements.   The system of claim 8, wherein the controller is configured to vary the output power of the beam emitter along the path.   The system of claim 8, wherein the controller is configured to vary the shape of the laser output beam based on the composition of the workpiece.   The system of claim 8, further comprising a database including a plurality of records, each of the plurality of records associating a laser output beam shape with a workpiece parameter.   The system of claim 12, wherein the workpiece parameter comprises at least one of a workpiece thickness and a workpiece composition. The beam emitter is
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 the focused beam and dispersing the received focused beam;
A partially reflected output combiner, wherein the partially reflected output combiner receives the dispersed beam and transmits a portion of the dispersed beam therethrough as the laser output beam; 9. The system of claim 8, comprising: a partially reflective output coupler positioned to reflect a second portion of the laser beam toward the dispersive element, wherein the laser output beam comprises a plurality of wavelengths. A method of joining first and second workpieces at a processing point, wherein the first and second workpieces overlap and / or approach each other at the processing point, the method comprising:
A laser output beam is focused in proximity to the processing point to melt a portion of at least one of the first or second workpieces, thereby joining the first and second workpieces together. Combining
Meanwhile, changing the shape of the laser output beam without causing relative movement between the laser output beam and the first and second workpieces.   The method of claim 15, wherein the shape of the laser output beam is varied between a focused spot and an annulus.   The method of claim 15, wherein the laser output beam comprises a plurality of wavelengths. A method of splicing first and second workpieces using a laser output beam that can be focused to a minimum spot size and using a weld having a spatial range greater than the minimum spot size, the method comprising: ,
Focusing the laser output beam onto at least one of the first or second workpiece and causing its melting;
Varying the shape of the laser output beam and increasing the size of the weld without causing relative movement between the laser output beam and the first and second workpieces. .   The method of claim 18, wherein the shape of the laser output beam is varied between a focused spot and an annulus.   The method of claim 18, wherein the laser output beam comprises a plurality of wavelengths. A system for processing a workpiece, the system comprising:
A beam emitter;
A positioning device for varying the beam position of the beam emitter relative to the workpiece;
A variable polarizer for varying the polarization of the beam;
A beam shaper for changing the shape of the beam;
A controller coupled to the positioning device, the polarizer, and the beam shaper, wherein the controller operates the beam emitter for processing the workpiece and causes the beam to move at least on the workpiece; A controller that traverses a path across a portion and varies the polarization and / or shape of the beam along the path based at least in part on one or more properties of the workpiece; A system that provides.   The system of claim 21, wherein the controller is configured to maintain a linear polarization of the beam having a polarization direction substantially parallel to the path as the beam traverses the path.   The system of claim 21, wherein the controller is configured to vary an eccentricity of polarization of the beam based at least in part on the thickness of the workpiece.   The system of claim 21, wherein the controller is configured to vary the polarization of the beam between a linear polarization state and a radial polarization state.   The system of claim 21, wherein the variable polarizer comprises a wave plate and a rotating element, the rotating element being operated by the controller.   26. The system of claim 25, wherein the wave plate comprises at least one of a half wave plate or a quarter wave plate.   26. The system of claim 25, wherein the beam is linearly polarized and the controller operates the rotating element to maintain a polarization direction parallel to the path.   The variable polarizer comprises a compensator plate, a fixed birefringent wedge disposed across the compensator plate, a movable birefringent wedge disposed across the fixed birefringent wedge, and a translation element. The system of claim 21, wherein an element is operated by the controller.   The system of claim 21, wherein the variable polarizer comprises a radial polarization converter. A memory accessible to the controller, the memory storing data corresponding to the path;
A database for storing polarization data for a plurality of materials, wherein the controller queries the database to obtain the polarization data for the material of the workpiece and based at least in part on the polarization data The system of claim 21, wherein the system is configured to vary the polarization of the beam.   The system of claim 21, wherein the path includes at least one directivity change. The beam emitter is
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 the focused beam and dispersing the received focused beam;
A partially reflective output combiner, wherein the partially reflective output combiner receives the dispersed beam and transmits a portion of the dispersed beam therethrough as a beam of the beam emitter; The system of claim 21, comprising: a partially reflective output coupler positioned to reflect a second portion of a beam toward the dispersive element, wherein the beam of the beam emitter comprises a plurality of wavelengths. The beam shaper is
A collimating lens for collimating the beam received from the beam emitter;
A focusing lens for receiving the collimated beam and focusing the beam toward the workpiece;
An optical element disposed between the beam source and the collimating lens, the optical element receiving the beam and altering its shape;
A lens manipulation system for changing a position of the optical element in the path of the beam, and wherein the controller is configured to control the lens manipulation system and vary the shape of the beam. The system according to 21.   The optical element comprises a lens having (i) a first surface having a frustoconical shape and (ii) a substantially planar second surface opposite the first surface. 34. The system according to 33.   The optical element comprises a lens having (i) a first surface having a truncated spherical shape and (ii) a substantially planar second surface opposite the first surface. 34. The system according to 33.   34. The system of claim 33, wherein the optical element comprises a meniscus lens.   34. The system of claim 33, wherein the lens manipulation system is configured to position the optical element laterally off-center within the beam path.   And further comprising a second optical element disposed between the focusing lens and the workpiece, wherein the lens manipulation system is configured to change the position of the second optical element in the path of the beam. 34. The system of claim 33.   The second optical element comprises a lens having (i) a first surface having a frustoconical shape and (ii) a substantially planar second surface opposite the first surface. 40. The system of claim 38.   The second optical element comprises a lens having (i) a first surface having a truncated spherical shape and (ii) a substantially planar second surface opposite the first surface. 40. The system of claim 38.   40. The system of claim 38, wherein the second optical element comprises a meniscus lens. The beam shaper is
A collimating lens for collimating the beam received from the beam emitter;
A focusing lens for receiving the collimated beam and focusing the beam toward the workpiece;
First and second optical elements disposed between the beam source and the collimating lens, wherein the first and second optical elements receive the beam and modify its shape; A first and second optical element;
(I) the position of the first optical element in the path of the beam; (ii) the position of the second optical element in the path of the beam; or (iii) between the first and second optical elements. 23. A lens manipulation system for changing at least one of the distances, wherein the controller is configured to control the lens manipulation system and vary the shape of the beam. System.   43. The system of 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.   43. The system of claim 42, wherein the lens manipulation system is configured to vary a distance between the first and second optical elements within a range of about 0 mm to about 20 mm. The first optical element has (i) a substantially planar first surface, (ii) (a) a convex curved first portion, and (b) a substantially planar second portion. A lens having a second surface opposite to the surface of
The second optical element has (i) a substantially planar first surface, (ii) (a) a concave curved first part, and (b) a substantially planar second part. 43. The system of claim 42, comprising a lens having a second surface opposite the first surface.   43. The lens manipulation system is configured to position at least one of the first optical element or the second optical element laterally off-center within the path of the beam. The described system.