CN116786846A - Additive manufacturing system with addressable laser array and source real-time feedback control - Google Patents

Abstract

An assembly for combining a set of laser sources into a combined laser beam is provided. Also provided is a blue laser diode array that combines laser beams from components of the blue laser diodes. Laser processing operations and applications are provided using a combined blue laser beam from a laser diode array and module.

Description

Additive manufacturing system with addressable laser array and source real-time feedback control

Description of the divisional application

The application is a divisional application of an application patent application with the application date of 2019, 09, 01 and 201980071257.7 and the name of an additive manufacturing system with an addressable laser array and source real-time feedback control.

The application comprises the following steps: (i) The filing date and priority benefits of U.S. provisional application serial No. 62/726,234 filed on date 1 of 9/9 in 2018, section (e) (1) of U.S. code 35, the entire contents of which are hereby incorporated by reference.

Technical Field

The present application relates to an array assembly for combining laser beams; and in particular, can provide an array assembly for use with high intensity laser beams in systems and applications in the fields of manufacturing, fabrication, entertainment, graphics, imaging, analysis, monitoring, assembly, dentistry and medicine.

Background

Many lasers, particularly semiconductor lasers such as laser diodes, provide a laser beam having a very desirable wavelength and beam quality (including brightness). The wavelengths of these lasers may be in the visible range, the UV range, the IR range, and combinations thereof, as well as higher and lower wavelengths. The technology of semiconductor lasers and other laser sources (e.g. fiber lasers) is rapidly evolving, with new laser sources continually emitting and providing existing and new laser wavelengths. While having a desirable beam quality, many of these lasers have a lower laser power than is desirable or required for a particular application. Thus, these lower powers prevent these laser sources from finding greater utility and commercial application.

Moreover, previous efforts to combine these types of lasers have been largely inadequate, with difficulties in beam alignment, maintaining beam alignment during application, beam quality loss, special placement of the laser source, size considerations, and power management, to name a few.

Infrared (IR) based (e.g., wavelengths greater than 700nm, particularly greater than 1000 nm) additive manufacturing systems using galvanometer scanners suffer from two drawbacks (among others) that limit build volume and build speed. In these IR laser systems, the build volume is limited by the finite size of the scanning system and the spot that can be created for a given focal length collimator and flat field focusing lens (F-theta lens). For example, when using a 140mm focal length collimator and a 500mm F-theta focal length lens, the spot size is about 40 μm for a near diffraction limited single mode laser for a 1 μm laser. This can provide an addressable footprint on the powder bed of approximately 175mm x 175mm, which is a limitation on the size of components that can be built. For IR laser systems, a second limitation on build speed is the absorption of the laser beam by the powder material. Most raw materials have moderate to high reflectivity for wavelengths in the infrared spectrum. As a result, the coupling of infrared laser energy into the powder bed is limited, wherein a significant portion of the energy is reflected off, back or deeper into the powder bed. These limitations are further bundled or linked together in some manner, exacerbating the problems and deficiencies of infrared additive systems. Thus, the limited penetration depth of infrared light determines the optimal layer thickness and thus limits resolution and processing speed. These and other failures of IR-based manufacturing, building systems and processes have not been adequately addressed. Thus, there is a long felt need for improved additive manufacturing systems and processes.

The terms "blue laser beam", "blue laser" and "blue" as used herein, unless explicitly stated otherwise, are to be understood in their broadest sense and generally refer to systems that provide (e.g., transmit) a laser beam or a laser beam providing light having a wavelength from 400nm to 500nm and about 400nm to about 500nm, laser beams, laser sources (e.g., lasers and diode lasers). Blue lasers include wavelengths of 450nm, about 450nm, 460nm, about 460nm. The bandwidth of the blue laser may be from about 10pm to about 10nm, about 5nm, about 10nm, about 20nm, and larger and smaller values.

As used herein, "UV," "ultraviolet spectrum," "ultraviolet portion of the spectrum," and similar terms, unless explicitly stated otherwise, are to be understood in their broadest sense and shall include light having wavelengths from about 10nm to about 400nm and from 10nm to 400 nm.

The terms "visible", "visible spectrum", "visible portion of the spectrum" and similar terms as used herein, unless explicitly stated otherwise, are to be understood in their broadest sense and shall include light having wavelengths from about 380nm to about 750nm and from 400nm to 700 nm.

The terms "green laser beam", "green laser" and "green", as used herein, unless explicitly stated otherwise, are to be understood in their broadest sense and generally refer to systems that provide (e.g., transmit) a laser beam or a laser beam providing light having a wavelength from 500nm to 700nm and about 500nm to about 700nm, laser beams, laser sources (e.g., lasers and diode lasers). The green laser includes wavelengths 515nm, about 515nm, 550nm, about 550nm. The bandwidth of the green laser may be from about 10pm to 10nm, about 5nm, about 10nm, about 20nm, and larger and smaller values.

Generally, the terms "about" and the symbol "-" as used herein, unless otherwise indicated, are meant to encompass a variance or range of ±10%, encompass experimental or instrumental errors associated with obtaining the values, and preferably encompass the larger of them.

As used herein, unless otherwise stated, room temperature is 25 ℃. Moreover, standard ambient temperatures and pressures are 25 ℃ and 1 atmosphere. Unless explicitly stated otherwise, all temperature, pressure or both dependent tests, test results, physical properties and values are provided at standard ambient temperature and pressure, including viscosity.

As used herein, unless otherwise indicated, the recitation of numerical ranges herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each separate value within the scope is incorporated into the specification as if it were individually recited herein.

In general, existing methods employed in additive manufacturing use infrared lasers and galvanometers to scan a laser beam across the surface of a powder bed in a welding process that melts and fuses liquefied powder to an underlying layer or substrate. This method has limitations that determine the speed of the process and has some drawbacks in the process. For example, using a single laser beam to scan a surface, the build rate may be limited by the maximum scan speed of the galvanometer (7 m/sec). Manufacturers are strongly convincing infrared technology, which is generally considered the only wavelength that is feasible, so they have focused (but limited effectiveness) on overcoming this limitation by integrating two or more infrared lasers/galvometers into a system in which they can work together to build a single component, or can work independently to build components in parallel. These efforts aim at increasing the throughput of additive manufacturing systems, but focus on IR alone with limited success, and have not met the long felt need for improved additive manufacturing.

Another example of a limitation in IR processing is the high intensity laser spot that forces the system into a penetrating welding mode that causes spatter and porosity in the part. For example, for diffraction limited infrared lasers, with a 500mm flat field focusing mirror, the IR laser creates a spot size on the order of 40-50 μm. If the laser beam is operated at an optical power of 100 watts, the intensity of the beam is greater than that required to initiate the pass-through welding mode. Penetration welding modes produce a jet of vaporized material that must be removed from the path of the laser beam by the cross jet or the laser beam will be scattered and absorbed by the vaporized metal. In addition, since the welding of the penetration mode relies on the creation of holes on the surface of the liquid metal maintained by the vapor pressure of the vaporized metal, the vaporized metal can be ejected from the penetration holes. This material is known as splatter, resulting in the deposition of molten material elsewhere on the build plane, which can lead to defects in the final part. While manufacturers of additive manufacturing systems have met with limited success in developing rapid prototypes, they have not met with long felt needs and with the requirements required to mass produce commercial or practical parts. Prior to the present invention, the art has not realized a breakthrough in the method of patterning a feature in order to achieve this.

Generally, problems and failures of IR processing and systems are the requirement or need to fuse powders in a pass-through welding mode. This is typically because a single beam is used to process the powder. If the laser beam is operated at an optical power of 100 watts, the intensity of the beam is greater than that required to initiate the pass-through welding mode. Penetration welding modes produce a jet of vaporized material that must be removed from the path of the laser beam by the cross jet or the laser beam will be scattered and absorbed by the vaporized metal. In addition, since welding in the penetrating mode relies on creating holes on the surface of the liquid metal maintained by the vapor pressure of the vaporized metal, materials such as the vaporized metal can be ejected from the penetrating holes. This material is known as splatter, resulting in the deposition of molten material elsewhere on the build plane, which can lead to defects in the final part.

Recent work by the Lawrence Lifromo national laboratory (Lawrence Livermore National Laboratories) using Optically Addressed Light Valves (OALV) has attempted to address these IR limitations. OALV is a high power spatial light modulator for creating light patterns using high power lasers. When the pattern on the OALV is created with a blue LED or laser source from a projector, the output power from the four laser diode arrays will be transmitted through the spatial light modulator and used to heat the image to the melting point and Q-switched IR laser is required to initiate the penetration weld. IR laser is used in the penetrating mode to initiate welding, especially when fusing copper or aluminum materials. Such penetration welding processes can produce spatter, porosity, and high surface roughness on the component, which are often necessary for these materials. Such penetration welding processes typically produce spatter, porosity, and high surface roughness on the component. Thus, the OALV system, like the typical IR system, cannot eliminate the adverse effects of breakthrough initiation in the build process. While it is preferable to avoid the penetration welding step entirely, the prior art fails to overcome this problem and does not provide this solution. The main reason for this failure is that at infrared wavelengths, the absorption characteristics of many metals are so low that a high peak power laser is required to start the process. Since OALV is only transparent in the IR region of the spectrum, it is not feasible to build or use this type of system using a visible laser source as the high energy light source. The cost of the components in the system is very high, particularly the OALV as a custom component.

Existing metal-based additive manufacturing machines are limited in that they are either based on spraying a binder into a powder bed followed by a consolidation step at high temperature or on a high power single mode laser beam that scans the powder bed at high speed by a galvanometer system. Both of these systems have significant drawbacks that cannot be overcome in the art. The first system enables mass production of parts that are loose in tolerance due to shrinkage of the parts during the consolidation process. The build speed of the second process is limited by the galvanometer scan speed, which limits the maximum power level of laser light that can be used and therefore limits the build speed. Manufacturers of scanning-based additive manufacturing systems have struggled to overcome this limitation by building machines with multiple scanning heads and laser systems, which do not provide an adequate solution to these problems. This does indeed increase throughput, but the scale is linear, in other words, a system with two laser scanners produces twice the number of parts as a system with one scanner, or only a single part at twice the speed. Thus, there is a need for a high throughput, laser-based metal additive manufacturing system that is not limited by currently available systems.

The background section of the invention is intended to introduce various aspects of the art that may be associated with embodiments of the present invention. The preceding discussion in this section, therefore, provides a framework for better understanding of the present invention and should not be construed as an admission that the prior art is available.

Disclosure of Invention

There is a long felt unmet need for assemblies and systems that, among other things, combine multiple laser beam sources into a single or several laser beams while maintaining and enhancing desired beam quality, such as brightness and power. The present invention meets these needs, among others, by providing articles of manufacture, apparatus, and processes taught and disclosed herein.

One embodiment of the present invention is an additive manufacturing system based on a one-or two-dimensional array of laser beams that can directly melt powder in a parallel fashion with step and repeat capability using a precision gantry system (fig. 1, 2, 3). The speed can be increased by adding a one-or two-dimensional secondary laser beam for preheating and controlled cooling (fig. 4). The secondary laser may also be an array of addressable laser beams to provide a preheat pattern that is consistent with the pattern being built.

Another element of an embodiment of the present invention is the use of a real-time temperature monitoring camera, such as a thermal imaging camera. The camera may be used to monitor the temperature of the powder layer in real time as it transitions from solid to liquid, and the image on the camera may be correlated to the laser pattern applied, and the power level of the individual laser beams may be adjusted according to predetermined requirements to properly fuse and cool the printed component. Such closed loop control of temperature provides other benefits, such as minimizing porosity of the manufactured part and optimizing surface roughness and minimizing residual stress of the part.

In one embodiment of the invention, an apparatus is included for depositing powder in real time in either direction during printing and compacting the powder bed to minimize the porosity of the powder bed. The primary mechanism for melting and fusing the powder would be conduction mode welding rather than a galvanometer scanning system employing penetration mode welding. This approach minimizes splatter and reduces the need to protect the window and optics of the manufactured part.

In one embodiment, the invention includes a sealed enclosure for forming an oxygen-free environment and a gas recirculation system for continuously cleaning a gas mixture used. Filtration of the gas mixture is necessary because if the airborne powder and welding fumes are not purged from the environment, it can begin to affect the quality of the image and thus the quality of the manufactured part.

In one embodiment, the invention includes a micro-processing system that performs a pre-build analysis, divides a part into multiple pieces, and determines an optimal build strategy. In printing each part of the part pattern, the gantry system can move to the next adjacent part of the pattern, or it can move to an arbitrary position if the build strategy requires that the partial pattern be printed randomly to minimize the residual stress of the part.

In one embodiment, the present invention does not require a weld monitor, except that a simple visual camera is used to view the molten puddle as it expands. Since the penetration type welding mode is not used, the molten pool is very stable even when copper and aluminum are welded, which cannot be achieved using an infrared laser source. Infrared laser sources must rely on weld monitors, such as Optical Coherence Tomography (OCT) scanners, to get an accurate representation of the penetration hole and how the component construction progresses with instability of the penetration pattern. Since the conduction mode of welding the powder to the base material is a very stable welding mode, no spatter occurs, the thickness and shape of the welding powder are very uniform, and since the material does not vaporize during welding, the component density is 100%.

Accordingly, additive manufacturing systems, processes, and laser systems are provided having one or more of the features described above. Laser systems, additive manufacturing systems, processes, and laser systems having one or more of the above features are also provided, in combination with the following laser systems and methods.

Accordingly, there is provided a laser system for performing a laser operation, the system having: a plurality of laser diode assemblies; each laser diode assembly having a plurality of laser diodes capable of producing individual blue laser beams along a laser beam path; means for spatially combining the individual blue laser beams to form a combined laser beam having a single spot in the far field that can be coupled into an optical fiber for delivery to a target material; and means for spatially combining the individual blue laser beams on the laser beam path and optically associated with each laser diode.

Further, methods and systems are provided having one or more of the following features: having at least three laser diode assemblies; and each laser diode assembly has at least one laser diode; wherein the laser diode assembly is capable of transmitting a laser beam having a total power of at least about 2 watts and a beam parameter characteristic of less than 20mm mrad; wherein the beam parameter characteristic is less than 15mm mrad; wherein the beam parameter characteristic is less than 10mm mrad; wherein the means for spatially combining produces a combined laser beam having a power density N times that of the individual laser beams; wherein N is the number of laser diodes in the laser diode assembly; wherein the means for spatially combining increases the power of the laser beam while maintaining the brightness of the combined laser beam; whereby the power of the combined laser beam is at least 50x the power of the individual laser beams and whereby the beam parameter product of the combined laser beams is no more than N times the beam parameter product of the individual laser beams; whereby the beam parameter product of the combined laser beams is not more than 1.5 x n times the beam parameter product of the individual laser beams; whereby the beam parameter product of the combined laser beams is no more than 1*N times the beam parameter product of the individual laser beams; wherein the means for spatially combining increases the power density of the composite laser beam while maintaining the brightness of the individual laser beams; whereby the power density of the combined laser beam is at least 100 times the power of the individual laser beams and whereby the beam parameter product of the combined laser beams is no more than 2*N times the beam parameter product of the individual laser beams; whereby the beam parameter product of the combined laser beams is not more than 1.5 x n times the beam parameter product of the individual laser beams; whereby the beam parameter product of the combined laser beams is no more than 1*N times the beam parameter product of the individual laser beams; wherein the optical fiber is sun-proof; wherein the means for spatially combining has an optical component selected from the group consisting of an aligned face parallel plate and a wedge shape to correct at least one of a position error or a pointing error of the laser diode; wherein the means for spatially combining has a polarizing beam combiner capable of increasing the effective brightness of the combined laser beams over the individual laser beams; wherein the laser diode assembly defines individual laser beam paths with a spacing between each path, whereby the individual laser beams have a spacing between each beam; and wherein the means for spatially combining has a collimator for collimating the individual laser beams on the fast axis of the laser diode, a periodic mirror for combining the collimated laser beams, wherein the periodic mirror is configured to reflect the first laser beam from the first diode in the laser diode assembly and to transmit the second laser beam from the second diode in the laser diode assembly, thereby filling the space between the individual laser beams in the fast direction; wherein the means for spatially combining has a patterned mirror on the glass substrate; wherein the glass substrate has a thickness sufficient to shift the vertical position of the laser beam from the laser diodes to fill the empty space between the laser diodes; and, a stepped heat sink is provided.

There is also provided a laser system for providing a high intensity, high power laser beam, the system having: a plurality of laser diode assemblies; each laser diode assembly has a plurality of laser diodes capable of producing a blue laser beam having an initial brightness; means for spatially combining the blue laser beams to form a combined laser beam having a final brightness and forming a single spot in the far field that can be coupled into an optical fiber; wherein each laser diode is locked to a different wavelength by the external cavity to substantially increase the brightness of the combined laser beam, whereby the final brightness of the combined laser beam is about the same as the initial brightness of the laser beam from the individual laser diode.

Further, methods and systems are provided having one or more of the following features: wherein each laser diode is locked to a single wavelength using a grating-based external cavity and each laser diode assembly is combined into a combined beam using a combining device selected from the group consisting of a narrow-pitch filter and a grating; wherein the raman converter is an optical fiber having a pure fused silica core to produce a higher brightness source and an outer core surrounded by air or a low refractive index polymer to contain blue pump light; in which the Raman converter is used for pumping the Raman converter, e.g. with GeO doped ₂ An optical fiber having an outer core to create a higher brightness source and an outer core that is larger than the central core to contain blue pump light; wherein the Raman converter is doped with P ₂ O ₅ To create a higher brightness source and having an outer core larger than a central core to contain a blue pumpAn optical fiber of Pu Guang; wherein the raman converter is an optical fiber having a graded index core to create a higher brightness source and an outer core that is larger than the central core to contain blue pump light; geO doped with graded refractive index in which the Raman converter ₂ An outer step index core; wherein the raman converter is used to pump a raman converter fiber that is graded index P-doped ₂ O ₅ An outer step index core; wherein the Raman converter is used for pumping the Raman converter optical fiber which is doped with GeO with graded refractive index ₂ Is a fiber core; wherein the Raman converter is graded index doped with P ₂ O ₅ An outer step index core; wherein the raman converter is diamond to produce a higher brightness laser source; wherein the raman converter is KGW to generate a higher brightness laser source; wherein the Raman converter is YVO ₄ To produce a higher brightness laser source; wherein the Raman converter is Ba (NO) ₃ ) ₂ To produce a higher brightness laser source; and wherein the raman converter is a high pressure gas to produce a higher brightness laser source.

There is also provided a laser system for performing a laser operation, the system having: a plurality of laser diode assemblies; each laser diode assembly has a plurality of laser diodes capable of producing a blue laser beam along a laser beam path; means for spatially combining the blue laser beams to form a combined laser beam having a single spot energy in the far field optically coupled to the raman converter to pump the raman converter to increase the brightness of the combined laser beam.

In addition, a method is provided for combining laser beams having an array of raman converted lasers to produce blue laser beams of respective different wavelengths and combining the laser beams to create higher power while preserving the spatial brightness of the original light source.

There is also provided a laser system for performing a laser operation, the system having: a plurality of laser diode assemblies; each laser diode assembly has a plurality of laser diodes capable of producing a blue laser beam along a laser beam path; beam collimation and combining optics along the laser beam path, wherein a combined laser beam can be provided; and an optical fiber for receiving the combined laser beams.

Further, methods and systems are provided having one or more of the following features: wherein the optical fiber is in optical communication with the rare earth doped fiber whereby the combined laser beam is capable of pumping the rare earth doped fiber to create a higher brightness laser source; and wherein the optical fiber is in optical communication with the outer core of the brightness converter, whereby the combined laser beam is capable of pumping the outer core of the brightness converter to create a higher proportion of brightness enhancement.

Also provided is a raman fiber having: a dual core, wherein one of the dual cores is a high brightness central core; and means selected from the group consisting of filters, fiber Bragg gratings to suppress second order Raman signals in the high brightness central core, V-number differences in the first and second order Raman signals, differences in round trip gain of the first and second order Raman signals due to fiber length or cavity mirrors, and microbending loss differences.

In addition, there is provided a second harmonic generation system having: the raman converter is at a first wavelength to generate light at half the first wavelength in the nonlinear crystal; and an external cavity resonant frequency doubling crystal configured to prevent half wavelength light from propagating through the optical fiber.

Further, methods and systems are provided having one or more of the following features: wherein the first wavelength is about 460nm; and the outer cavity resonance frequency doubling crystal is KTP; and wherein the raman converter has a non-circular outer core configured to improve raman conversion efficiency.

Further, there is provided a third harmonic generation system having: the raman converter is at a first wavelength to generate light at a second wavelength lower than the first wavelength; and an external cavity resonant frequency doubling crystal configured to prevent light of a lower wavelength from propagating through the optical fiber.

Further, there is provided a fourth harmonic generation system having: the raman converter is configured to produce 57.5nm light using an external cavity resonant frequency doubling crystal configured to prevent light of 57.5nm wavelength from propagating through the optical fiber.

Further, a second harmonic generation system is provided having a rare earth doped brightness converter with thulium emitting laser light at 473nm when pumped by a blue laser diode array at 450nm to generate light at half wavelength or 236.5nm of the source laser light, using an external cavity resonant frequency doubling crystal but not allowing short wavelength light to propagate through the fiber.

Further, a third harmonic generation system is provided having a rare earth doped brightness converter with thulium emitting laser light at 473nm when pumped by a blue laser diode array at 450nm to generate light at 118.25nm using an external cavity resonant frequency doubling crystal but not allowing short wavelength light to propagate through the fiber.

There is further provided a fourth harmonic generation system having a thulium doped brightness converter with thulium emitting laser light at 473nm when pumped by a blue laser diode array at 450nm to generate light at 59.1nm using an external cavity resonant frequency doubling crystal but not allowing short wavelength light to propagate through the fiber.

Further, there is provided a laser system for performing a laser operation, the system having: at least three laser diode assemblies; at least each of the laser diode assemblies having at least ten laser diodes, wherein each of the at least ten laser diodes is capable of producing a blue laser beam along a laser beam path having a power of at least about 2 watts and a beam parameter product of less than 8mm-mrad, wherein each laser beam path is substantially parallel, thereby defining a space between the laser beams traveling along the laser beam path; means for spatially combining and preserving the brightness of the blue laser beams located on all of the at least thirty laser beam paths, the means for spatially combining and preserving the brightness having a collimating mirror for a first axis of the laser beams, a vertical prism array for a second axis of the laser beams, and a telescope; thus, the means for spatially combining and retaining fills the space between the laser beams with laser energy to provide a combined laser beam having a power of at least about 600 watts and a beam parameter product of less than 44 mm-mrad.

There is also provided an addressable array laser processing system having: at least three laser systems of the type presently described; each of the at least three laser systems is configured to couple each of their combined laser beams into a single optical fiber; whereby each of the at least three combined laser beams is capable of being transmitted along an optical fiber to which it is coupled; at least three optical fibers optically associated with the laser head; a control system; wherein the control system has a program having a predetermined sequence for delivering each of the combined laser beams at predetermined locations on the target material.

Further, methods and systems are provided for an addressable array having one or more of the following features: wherein the predetermined sequence is for turning on and off the laser beams from the laser heads, respectively, to image onto the powder bed to melt and fuse the target material with powder into a part; wherein the fibers in the laser head are configured to be selected from the group consisting of linear, nonlinear, circular, diamond, square, triangular, and hexagonal; wherein the optical fibers in the laser head are configured in a configuration selected from the group consisting of 2x5, 5x2, 4x5, at least 5x at least 5, 10x5, 5x10, and 3x 4; wherein the target material has a powder bed; and, it has: an x-y motion system capable of transporting the laser head across the powder bed to melt and fuse the powder bed; a powder delivery system movable behind the laser source to provide a fresh layer of powder behind the melted layer; the device comprises: a z-motion system capable of transporting the laser head to increase and decrease the height of the laser head above the powder bed surface; the device comprises: a bi-directional powder placement device capable of placing powder directly behind the delivered laser beam while traveling in either the positive x-direction or the negative x-direction; a powder supply system having a plurality of laser beam paths; having a gravity fed powder system; having a powder supply system wherein powder is entrained in an inert gas stream; having a powder supply system transverse to the N laser beams, wherein N.gtoreq.1, and placing the powder by gravity in front of the laser beams; and, a powder supply system transverse to the N laser beams, wherein N.gtoreq.1, and the powder is entrained in an inert gas stream intersecting the laser beams.

Still further, there is provided a method of providing a combined blue laser beam having a high brightness, the method having: operating the plurality of raman converted lasers to provide a plurality of individual blue laser beams and combining the individual blue laser beams to create a higher power source while preserving the spatial brightness of the initial light source; wherein individual ones of the plurality of laser beams have different wavelengths.

Furthermore, a method of laser processing a target material is provided, the method having an addressable array laser processing system having at least three laser systems of the presently described system type to generate three individual combined laser beams into three individual optical fibers; transmitting each combined laser beam along its optical fiber to a laser head; three individual combined laser beams from the laser head are directed to predetermined locations on the target material in a predetermined sequence.

Drawings

Fig. 1 is a perspective view of one embodiment of a fiber array-based three-dimensional printer according to the present invention.

Fig. 2A is a perspective view of one embodiment of a fiber-based printhead according to the present invention.

Fig. 2B is a perspective view of the fiber-based printhead of fig. 2A from another perspective.

Fig. 3 is a schematic graphical depiction of an embodiment of an optical harness and beam path according to the present invention.

FIG. 4A is a perspective view of one embodiment of a one-dimensional harness connector output of an optical fiber bundle of a one-dimensional patterning system according to the present invention.

Fig. 4B is a perspective view of an embodiment of a fiber optic combiner in accordance with the present invention.

FIG. 5A is a schematic diagram of one embodiment of a three-dimensional printer head with a secondary laser heat source and a primary one-dimensional patterning system in accordance with the present invention.

Fig. 5B is a perspective view of one embodiment of a superimposed image of a secondary laser pattern and a multi-spot primary image in accordance with the present invention.

FIG. 6A is a schematic diagram of one embodiment of a three-dimensional printer head with a secondary laser heat source and a primary one-dimensional patterning system in accordance with the present invention.

Fig. 6B is a perspective view of one embodiment of a superimposed image of a secondary laser pattern and a multi-spot primary image in accordance with the present invention.

Fig. 7A is a schematic diagram of an embodiment of a printer head with a one-dimensional primary multi-spot image and a secondary heating image based on a laser diode array for the primary image in accordance with the present invention.

Fig. 7B is a perspective view of one embodiment of a superimposed image of a secondary laser pattern and a multi-spot primary image in accordance with the present invention.

Fig. 8A-8F are plan views of various embodiments of fiber optic bundle image arrangements (e.g., laser beams forming a laser beam pattern, or laser beam patterns) on a powder bed according to the present invention, with arrows showing the direction of movement of the pattern on the powder bed.

Fig. 9A-9F are plan views of various embodiments of a fiber bundle image configuration (e.g., a laser beam forming a laser beam pattern, or a laser pattern) on a powder bed according to the present invention, wherein a primary laser beam image is associated with a secondary laser beam image, the arrows of which represent the directions of movement of the two patterns on the powder bed. (Main image spots are shown as solid spots and sub-image spots are shown as outline spots.)

10A-10F are plan views of various embodiments of a fiber bundle image configuration (e.g., a laser beam forming a laser beam pattern, or a laser pattern) on a powder bed according to the present invention, wherein a primary laser beam image is associated with a secondary laser beam image, and the secondary laser beams have different timing characteristics that produce different shaped secondary images, wherein the arrows show the direction of movement of the two patterns on the powder bed. (Main image spots are shown as solid spots and sub-image spots are shown as outline spots.)

FIG. 11 is a schematic plan view of an image on a powder bed mapped onto a thermal imaging camera according to the present invention.

FIG. 12 is a schematic diagram of an embodiment of a control system and closed loop control process according to the present invention.

Fig. 13 is an image and spectrum of a blue raman converted laser beam according to the present invention.

Detailed Description

The present invention relates to laser processing of materials, in particular laser build materials comprising a laser additive manufacturing process using a laser beam with a wavelength from about 350nm to 700 nm.

1D patterning system

Fig. 1 is a perspective view of a 3D (three-dimensional) additive manufacturing apparatus or printer apparatus 100. The fiber architecture of the printer device 100 is a 1D (one-dimensional) fiber architecture for the printhead. The 1D system may have the incoming fibers arranged in a linear fashion, as shown for example in fig. 2A and 2B, and have the light paths, images, and optics, as shown for example in fig. 3.

Accordingly, fig. 1-3 are examples of 3D printers using a 1D patterning system, where 1D refers to the configuration of a fiber optic bundle that provides and emits laser beams for building a 3D object.

Referring first to fig. 1, but in the context of fig. 2A, 2B, and 3, system 100 generally includes an x-y gantry system 101 that moves printheads 200 in the x and y directions. The gantry system sits on a base 112, which may be made of granite or metal, or preferably other materials that are heavy, stable, and both. The base may use rubber or air supports to isolate vibrations from the rest of the system below to prevent vibrations from passing from the base to powder bed 110 and printer head 200. The entire system 100 may be enclosed in a gas-tight environment (not shown) to provide an inert atmosphere for powder processing. The inert atmosphere may be argon, nitrogen, helium or any other inert gas other than oxygen. The inert atmosphere is under reduced pressure, atmospheric pressure, or elevated pressure, and many flow through (inflow and outflow ports), into (i.e., inflow of make-up gas, but no outflow), or out of (after filling with inert gas, the input and output are closed). Preferred embodiments are argon and argon-CO ₂ The mixture to promote flow of the molten powder by disrupting their surface tension. The gantry carries the printer head 200 and the fiber array bundles are transported to the printer head 200 by QBH type connectors 102. The powder bed 110 is located just below the printer head, with the image transmitted by the fiber optic bundle or array being re-directed on the powder bed 110Imaging 103. The powder is dispersed by a bi-directional powder spreader 108 that moves precisely against a pair of linear rails 109. The powder spreader may be moved by Y-motion of the Y-translation stage 106 of the gantry system 101, or by a separate motor integrated into the powder spreader assembly. At the edge of the base 112 powder is loaded into the powder spreader both at the front and rear and the powder is fed to the powder bed by gravity feed. The powder spreader includes a roller 107 that rotates in a direction opposite to the motion to spread and pressurize the powder bed. By pressurizing the powder bed, the porosity of the final part can be minimized. As the gantry moves in the y-direction, power and sensor readings will be routed through the flexible cable bridge 105 on the side of the gantry.

The gantry system 101 has a Y translation stage 106 for movement of the print head 220 in the Y direction; and has a Z translation stage 111 for movement of the print head 220 in the x-direction. The system 100 has a powder bed elevator 104 (for moving the component downward as the component is built to allow the next layer to be deposited onto the component).

A preferred embodiment of a printer head 200 is shown in fig. 2A and 2B. Fig. 2A and 2B are perspective views of the same embodiment at different viewing angles, it being understood that typically the printhead will be covered, or provided with a front plate, which is not shown in the figures. The optical fiber bundles have 2, 3, 4, 5, 6, 2-10 and combinations of these and larger numbers, arranged in a row, preferably a straight line. The bundle is routed through QBH connector 201. The QBH connector 201 is held in place by a collet 202, which collet 202 is mounted on a housing 203 of the printhead 200. The optical system is mainly composed of a collimator mirror 204 and a focusing mirror 205. Both of these optics may be replaced by a single hypothetical (imaging) optic. The laser beam is emitted from the surface of the fiber 210 and the laser beam travels along the laser beam path to the lens 204, the lens 205, and then exits the window 209 to form the image 103. In addition to the optical system, the printer head 200 may also be equipped with a thermal imaging or pyrometer camera 207 to monitor the temperature of the melt pool on the powder bed via an opening or window 208 for the multi-point image 103.

Referring to fig. 3, a schematic diagram of an embodiment of a 1D optical system 300 and a ray trace of its laser beam path is shown. For example, the 1D optical system may be used in the printhead 200. The fiber bundle 301 has 5 fibers 301a, 301b, 301c, 301d, 301e arranged in a straight line and provides an output laser beam along a beam path having a ray path 305, which output is collimated by a lens 302, which may be a plano-convex lens, a plano-convex aspheric lens, a pair of lenses, a triplet lens or similar type of optical device. The collimated light beam from the array beam having the light path 307 is then focused by a focusing lens 303 to an image 304 having a series of light spots 304a, 304b, 304c, 304d, 304e, which focusing lens 303 may be a plano-convex lens, a plano-convex aspheric lens, a pair of lenses, a triplet lens, or similar type of optical device. The size of the fiber is shown by scale 320 and the size of the image and the spot is shown by scale 321. The curved surfaces of the plano-convex lens and the plano-aspherical lens face each other to minimize the spherical aberration of the system. The ray trace shown in fig. 3 is for two fused silica planar aspherical lenses. The spots are in the focal plane or fourier transform plane and the image will be slightly spread due to small aberrations in the system, resulting in overlapping of the fiber images, i.e. spots 304a, 304b, 304c, 304d, 304e, which constitute image 304. The system may also use a single imaging lens where the emitting face of the fiber source 301 will be placed at least 2f away from the imaging optics and the image plane will be at least 2f away from the same optics. This approach would require a substantially larger lens than the preferred embodiment using a collimating lens and focusing lens to re-image the fiber bundle. For each individual point in the multi-point image, a thermal imaging or pyrometer camera preferably monitors the temperature of the melt pool on the powder bed.

In embodiments of the 1D patterning system, one-dimensional line emitters, e.g., fiber faces, may be 2, 3, 4..n, depending entirely on the physical dimensions of the fibers and QBH connectors. In one embodiment, there is a single fiber. In one embodiment, 2 to 15,2 to 10,5 to 50,2 to 1000,5 to 500, 100 to 2000, 10 more, 20 more, 50 more, and combinations and variations of these, as well as greater and lesser numbers of fibers are placed, for example side-by-side. Thus, fibers having a diameter of, for example, 200 μm (core diameter of, for example, from about 10 to about 185 μm) may be used, as well as their beam and beam pattern re-imaged onto the powder bed to provide energy to fuse the powder into the base material.

Referring to fig. 4A, a perspective view of an embodiment of a QBH-type harness connector output 700 is shown. The connector output 700 has five optical fibers 701 aligned to provide five laser beam emitters and images thereof, such as circular spots. The connector output 700 has a mechanical QBH input 702 that accommodates five fibers. The input 702 may be inserted, for example, into a printer head or a combination, for example, of the type shown in fig. 4B. The connector output 700 has a protective cover 703, which cover 703 covers the optical fibers and has a disconnection sensor.

An example of an implementation of a fiber optic bundle combiner is shown in fig. 4B. In this case, combiner 806 is a free space combiner with input fibers 801, 802, 803, 804, 805 that begin to collimate before being combined and refocused to output fiber bundle 807, which is then transmitted by the fibers to, for example, an output connector, a printer head. The fiber optic bundle receives power from each individual fiber 801, 802, 803, 804, 805 and then re-images onto the powder bed. The power from each fiber may be about 2 watts (W), 10W,100W, about 150W, about 500W, about 1kW, about 2kW, from about 1W to about 2kW, from about 2W to about 150W, from about 250W to about 1kW, or several kW, and combinations and variations of these, depending, for example, on how fast the gantry system can scan and the size of the fiber bundle image.

Examples of various embodiments of one-dimensional laser image patterns (e.g., multi-spot images) that can be generated by one-dimensional fiber bundle construction and printer heads are shown in fig. 8A, 8B, 8C, 8D, 8E, 8F. The direction of movement of the pattern on the powder bed is indicated by the arrow. These laser patterns may be used in any of the embodiments of additive manufacturing systems, printer heads, and methods according to the present invention.

The spots in a multi-spot image may be circular, elliptical, square, rectangular, and other shapes; they may be contiguous, adjacent, overlapping, partially overlapping; they may be linear, rectilinear, curvilinear, staggered, shaped into a pattern of larger areas (e.g., square or rectangular); and combinations and variations of these and other constructions and arrangements. These laser patterns may be used in any of the embodiments of additive manufacturing systems, printer heads, and methods according to the present invention.

The part is printed out by scanning a one-dimensional image of the fiber bundle over the powder bed. The one-dimensional image of the high power fiber output is scanned in the y-axis through the gantry system and stepped across in the x-axis to repeat the pattern. The stepping across the printer may be right adjacent to the track, or may be randomly varied depending on the stress pattern desired in the final part. After printing, a powder bed elevator located below the powder bed lowers the powder bed by a predetermined amount (e.g., about 40 μm, about 50 μm, about 60 μm, from about 35 μm to about 65 μm, and combinations and greater and lesser distances of these), the powder spreader spreads a uniform layer of powdered metal, and the rollers compress the powder bed to reduce the porosity of the powder. After the powder bed is prepared for the next layer, the next layer is printed and an image of the one-dimensional fiber bundle is scanned over its entire surface.

The fiber optic system may also be replaced by a separate laser diode, but this is not a preferred embodiment due to the size of the print head and the complex electronics required to drive the separate laser diode. The individual laser diodes may be part of an addressable laser diode array stripe, in which case the individual laser diodes are all part of a continuous stripe assembly with individual current drive capabilities. This is a good choice for fiber optic methods where the power per transmitter is limited.

1D patterning system with secondary laser

In one embodiment, an additional laser beam or a second laser beam is added to the printhead to provide means for preheating, controlling cooling, and controlling the temperature of the printed image. The secondary laser beam may also be referred to as a heating beam; while the primary laser beam used to melt and fuse the powder to form the object may be referred to as the build laser and build laser beam.

An embodiment of a printhead having a primary laser beam and a secondary laser beam is shown in fig. 5A. The fiber bundle that provides the primary laser beam and creates the primary image 409 (which may be a multi-spot image) on the powder bed is transported by the QBH connector 401 and mounted on the printhead 400 by the collet 402. The optical system for beam path and beam delivery of the primary image 409 mainly includes a lens 405 to collimate the output of the fiber optic bundle. The collimated output is then focused by a focusing lens 406 onto a powder bed as a master 409. The optical system is similar to the previous description, wherein the lens may be a plano-convex lens, a plano-convex aspherical lens, a pair of lenses or a triplet lens. The second laser beam is introduced into the printhead 400 through an optical fiber delivered by a QBH connector 403, which QBH connector 403 is mounted on the printhead by a chuck 404. The lens 407 is used to collimate the output of the fiber. The lens 407 may be a plano-convex lens, plano-convex aspheric lens, a pair of lenses, or a triplet lens. At high power levels, the pair or triplet lenses must be air-spaced because most cements cannot withstand high power levels. The collimated beam is then transformed and focused onto a powder bed by a lens or microlens system 408, which shapes the beam into a secondary image and redirects it to overlap with the primary image 409. Fig. 5B shows one embodiment of these overlapping images. The overlay image 450 may be a main multi-spot image 451 with main spots 411, 412, 413, 414, 415 propagating from the main fibers in the main fiber bundle. The primary spot is combined with the transformed secondary image 410 of the secondary laser beam. Preferably, the secondary image heats a volume of powder 420. In this embodiment, the secondary laser beam is positioned to deposit a substantial portion of its energy just in front of the one-dimensional pattern 451 that translates in the "y" direction as indicated by arrow 416. Both the primary pattern 451 and the secondary pattern 410 move at the same rate and in the same direction 416. The secondary beam pattern preheats the powder, helps the image of the fiber bundle to melt the powder and fuse it to the substrate, and provides some heat after fusing to anneal the material, thereby reducing internal stresses in the part being printed. The remaining functions of the system are as described in the previous section, wherein a thermal imaging camera or pyrometer array is integrated into the system to provide feedback to the laser system to maintain the powder just in front of the main fiber optic bundle image 451 at a predetermined temperature, preferably just below the melting point of the powder. During fusion, feedback signals from the thermal imaging camera or pyrometer array are used to control the power of the secondary laser, the power of the individual lasers in the fiber bundle creating image 451, and both to create a predetermined powder temperature in the image of the fiber bundle. The predetermined powder temperature used in the system will first be determined empirically by the system and used as a criterion for all build to minimize surface roughness, part porosity and part size. The secondary laser sources may be 50W,100W,150W,500W,1000W, from about 50W to about 2kW, from about 250W to about 1kW, and a few kW, and all values in these ranges, for example, depending on the scan speed of the printhead and the area of the fiber array pattern in use.

Referring to fig. 6A and 6B, there is shown a perspective view of a laser head 500, the laser head 500 providing a combined image 509 of a secondary image 552 and a primary image 551, wherein both secondary fiber-bundle laser sources provide an addressable thermal pattern on a powder bed. Fig. 6 illustrates the use of a secondary fiber optic bundle, where the fiber optic bundle is attached by a connector 503, and the connector 503 is attached to the printer head 500 by a collet 504. The main fiber bundle is attached to the printer head 500 by connector 501 and collet 502 and has collimating lens 505 and fourier transform focusing lens 506. The lens 507 collimates the fiber bundle and the beam conversion system 508 creates n images of the secondary fiber bundle that can be individually controlled to form an image 552, the image 552 having images 516, 517, 518, 519, 520 corresponding to a volume of powder in the heated powder bed in this embodiment. By controlling the time each secondary laser source is turned on and off, the preheat and cool down characteristics of each respective volume can be changed to images 516-520. In the embodiment of fig. 5B, the two outer fibers providing the outer secondary images 516, 520 are turned on and off simultaneously to preheat the outer edges of the pattern. The two inner fibers immediately following the provision of images 517, 519 are then opened to allow heat from the outer fibers to collect into the inner region because less energy is required for the inner region due to the heat of the two outer fibers. The central secondary fiber image 518 requires even less energy, so the light source is later turned on at a lower power level and turned off later to provide heat to anneal one region corresponding to the laser spot 513 or the entire region corresponding to the laser spots 511-515 (forming the primary multi-spot image 551), depending on the thermal conductivity of the material and the design of the components. Each secondary fiber may carry 30 watts, 100 watts, 150 watts, from about 50 watts to about 2kW, from about 250 watts to about 1kW, and thousands of watts of power, and all values within these ranges, depending, for example, on the scan speed of the printhead and the size of the heating pattern.

Referring to fig. 7A and 7B, there is shown a perspective view of a laser printhead 600, the laser printhead 600 providing a primary multi-spot laser beam image 608 and a secondary laser beam image 609, the primary multi-spot laser beam image 608 having spots 610, 611, 612, 613, 614, the secondary laser beam image 609 overlapping the image 608 and heating a volume 651 of powder. The primary laser source is a diode array 601 (which can provide a one-dimensional pattern or a two-dimensional pattern) and the primary laser beam path exits the array 601 and enters first beam conversion optics 604 and then enters second beam conversion optics 605 to form an image 608 (which is a one-dimensional pattern) on the surface of the powder bed. The secondary laser has an optical fiber or bundle of optical fibers connected to the printer head 600 through a connector 603 and a collet 603. The secondary laser beam path travels from the fiber or fiber bundle to a collimating lens 606 and then to beam conversion optics 607 to shape and overlap secondary laser beam image 609 with primary laser beam image 608. Arrow 615 shows the direction of travel of the laser beams and their respective images relative to the powder bed.

In the embodiment of fig. 7A and 7B, an addressable laser diode array source produces an addressable thermal pattern on a powder bed. Each emitter of the addressable laser diode array source 601 may be 3 watts, 10 watts, or higher, subject to the limitations of diode array technology. The individual power levels of the laser diode are not sufficient by themselves to melt many metallic materials, so any design using an addressable laser diode requires a secondary heat source or laser source provided by the optical fiber or optical fiber bundle in the connector 602. A heated powder bed or secondary laser source may be used. Here, a secondary laser source is used to provide an image 609 to preheat the powder of the volume 651 to just below the melting point, and an image of the laser diode array 608 is used to melt and fuse the powder to the material below it. The secondary laser source may be a single fiber, a bundle of fibers, connected to the printer head 600 by a connector 602 and a collet 603, or the secondary laser source may be another array of laser diodes that are collimated and re-imaged to form a single image 609 or a series of images, such as shown in the embodiment of fig. 6A. The preferred embodiment of the laser diode array is a blue laser diode source because absorption is enhanced over an infrared laser diode source. The 1D pattern that can be used in a direct laser diode array source is most likely the embodiment of fig. 8B and 8D, where the spacing between the diodes must be considered in any design, however, optics that transform the image can be used to create any of the images of the embodiments of fig. 8A-8A.

One or more or all of the primary laser beams forming the primary laser beam pattern may be entirely in the region of the secondary laser pattern, partially in the region of the secondary laser pattern, entirely outside the region of the secondary laser beam pattern, and combinations and variations of these. In embodiments, the movement of the primary and secondary laser beam patterns may be at the same speed in the same direction, at different speeds in the same direction (e.g., faster primary or secondary laser beam patterns), and at the same or different speeds in different directions, as well as combinations and variations of these. The primary and secondary laser beams may also be moved in separate predetermined patterns to build a particular type of article or to provide a particular type of feature to build an article.

The primary laser beam pattern may have one, two, three, four, or more, and tens or more laser beams. The secondary laser beam pattern may be a single beam, may be a plurality of laser beams, or may be a plurality of overlapping laser beams, as well as combinations and variations of these.

The cross-section of the primary laser beam may be circular, elliptical or square or other shape. The primary laser beam pattern may be arranged linearly, in a square configuration, in a rectangular configuration, in a circular configuration, in an elliptical configuration, in a parabolic configuration (convex or concave with respect to the movement of the pattern), in an arcuate configuration (convex or concave with respect to the movement of the pattern), in an arrow or "V" configuration, in a diamond configuration, as well as other geometric patterns and configurations, as well as combinations and variations of these.

In one embodiment, the secondary pattern may be from high intensity visible light imaged by a spatial light modulator, a UV or IR lamp, or from a high power laser imaged by a spatial light modulator or a laser array ranging from 1 to N light sources arranged in a one-or two-dimensional pattern. The secondary laser array may be a laser diode array or an array of optical fibers connected to a separate laser system.

2D patterning system

One preferred embodiment is to use a two-dimensional (2D) fiber optic bundle or laser array as a heat or energy source when printing metal parts. Examples of some 2D fiber bundles are shown in the embodiments of fig. 8D-8F, along with the laser patterns or multi-spot images they generate. Fig. 8F is an image of square spots formed by an array of square or rectangular fibers or other optics that shape the beams to provide these spots. In one embodiment, the change from one-dimensional patterning system to two-dimensional patterning system embodiments is the addition of more rows of fibers in the printer head (compare FIG. 8C with FIG. 8E) and the ability to print faster due to larger addressable areas. These 2D sources may have individual laser power levels of 3 watts, 10 watts, 20 watts, 100 watts, 150 watts, from about 50 watts to about 2kW, from about 250 watts to about 1kW, and several kW, depending on the scan speed of the printer system and the size of the pattern being printed.

The 2D patterning system may also be combined with a single secondary laser source, an array of secondary laser sources, or a cluster of secondary laser sources, as well as combinations and variations of these, to provide energy to preheat or control the cooling of the pattern being printed. In an embodiment, the high power image on the powder bed may be covered by a single secondary laser. Referring to fig. 9A to 9F, plan views of embodiments of composite images of a main image and a sub image are shown. The direction of movement of both the primary and secondary beam patterns is shown by the arrows in each figure.

Fig. 9A shows an embodiment where the straight line 1D multi-spot primary image is at an angle to the direction of motion and is entirely in a circular secondary image.

Fig. 9B shows an embodiment in which the primary image is a tilted-array one-dimensional image in which the dead space between each spot is compensated by the tilt angle of the spot, and the single secondary image is provided by a secondary laser source for preheating the powder prior to fusion. In this embodiment, the secondary image is adjacent to but does not overlap the primary beam pattern.

FIG. 9C illustrates an embodiment where a simple linear array primary image is overlaid with a rectangular secondary laser image to provide pre-heating and post-fusion energy for temperature control throughout the build sequence.

Fig. 9D shows an embodiment where the spaced 2D array patterns are again overlapped by a single elliptical secondary laser spot to provide the energy required for a given scan speed to bring the temperature of the powder just below the melting temperature and to provide a means for annealing the material after welding.

Fig. 9E is an embodiment where the 2D primary image from the dense fiber array again has a single pre-heat beam image from the secondary laser source adjacent to and preceding the primary image.

Fig. 9F illustrates one embodiment of a 2D primary image from a dense array of adjacent square fibers. In one embodiment, the squares are overlapped to minimize process gaps. This dense array pattern is overlapped by the secondary laser source intended to preheat the powder, providing additional energy during the fusion and bonding process, and eventually providing some temperature control after the fusion and fusion steps.

The secondary laser sources of the secondary image patterns of the embodiments of fig. 9A-9F, and in other embodiments of the secondary laser patterns and images, may be about 2 watts, about 3 watts, about 10 watts, about 20 watts, about 50 watts, about 100 watts, about 150 watts, from about 50 watts to about 2kW, from about 10 watts to about 200W, from about 50 watts to about 500W, from about 250 watts to about 1kW, and several kW, depending, for example, on the scan speed of the printhead, the power of the primary laser beam, and the size of the heated area.

Combining a primary optical fiber bundle-like light source with a secondary optical fiber bundle-like light source makes it possible to vary the preheating and cooling temperature cycles during the construction of the object. Thus, the preheating and cooling process cycles can be varied, for example to accommodate the conditions of the build article as it is being built. In this way, information about the properties of the build article, such as temperature, roughness, density, spectrum of emitted or reflected light, is used to change and adjust the properties of the secondary fiber laser beam, such as on-time and power, to adjust the secondary image relative to the primary image, the build of the article, and both "fly". Fig. 10A-10F illustrate different configurations and timing effects that are possible when overlapping an addressable laser image pattern with an addressable secondary preheat pattern. Another advantage of laser preheating is the elimination of the inconvenience of consuming a large amount of energy to heat the entire bed or chamber.

Temperature control system

Prior to the present invention, existing additive manufacturing systems were operated in an open loop manner, such that print quality could not be precisely controlled. This is a significant drawback of these prior systems, which is addressed and improved by embodiments of the present invention. In an embodiment of the present invention, a feedback loop is used to precisely control the temperature in each of the 1D or 2D patterns as well as the secondary laser patterns and the powder bed that delivers these patterns. Such a feedback loop has many advantages, including, for example, lower porosity, lower defects, and better surface roughness of the part being constructed than can be achieved with an open loop system. Since the gantry system travels at a relatively low speed compared to the galvanometer-based system, it is possible to measure the powder bed temperature at each point in the print pattern and alter the power setting of that region of the laser-addressed print pattern in real time to a more optimal setting, during printing, e.g. "fly-in", the printing process being adjusted based on the temperature profile of the article during its construction. In one embodiment, the temperature profile of the powder bed is monitored and controlled on a laser spot by laser spot basis, and then the power, timing, and both of the laser spots are adjusted to control the build process of the article. Fig. 11 shows how an image 1101 of a fiber bundle can be re-imaged 1103 onto a camera sensor array 1102. The software for reading the sensor array can then identify the heated zones and provide an average temperature for each zone. If the laser sources all have the same power, the central pixel will read much higher than the output pixel temperature and the power to the internal source can be reduced until a uniform temperature profile is obtained. This keeps the melting and fusing of the powder within an optimal temperature range. This applies not only to two-dimensional fiber bundle images, but also to one-dimensional fiber bundle images. Once the temperature of the zones is measured, as shown in fig. 12, a sequence of command signals is calculated 1204-1210, increasing or decreasing the power to each zone until a uniform or predetermined optimal temperature profile is obtained. Thus, an image 1201 of an array or fiber bundle on a powder bed is imaged onto a device to receive an analysis image, e.g., a sensor, a camera such as a FLIR camera. This provides a matrix 1202 of temperature profiles on a pixel by pixel basis. A processor (e.g., computer, microprocessor) inserts and converts the temperature profile from matrix 1202 relative to the build program by sending control signals 1204-1210 to the lasers associated with the individual fibers or the images produced by these lasers and adjusts the laser power to meet the build strategy. In this way, the flight adjustment and build profile of the laser beam is provided spot by spot. Moreover, by providing a real-time feedback signal to the laser source, it is possible to increase the power to the area to increase the likelihood of proper melting thereof in the event that the powder does not properly melt. This will occur in areas where the powder diameter varies greatly, large diameter powders requiring more energy to melt than small diameter powders. It is also important to prevent the vaporization of small diameter powder so that real time feedback of temperature to the laser source can be used to dial in an average zone temperature sufficient to melt large powder particles but insufficient to vaporize small powder particles.

Table I lists examples of systems, processes, configurations, and methods of embodiments of the present systems and methods.

TABLE I

Furthermore, and in general embodiments of the invention, it relates to combinations of laser beams, systems for performing these combinations, and processes utilizing the combined beams. In particular, the present invention relates to arrays, assemblies and devices for combining laser beams from multiple laser beam sources into one or more combined laser beams. These combined laser beams preferably have various aspects and characteristics of the remaining, enhanced, and both of the laser beams from the various sources.

Embodiments of the present array assembly and the combined laser beams they provide find wide applicability. Embodiments of the present array assembly are compact and durable. Embodiments of the present array assembly have applicability in the following: welding, additive manufacturing (including 3D printing); additive manufacturing-grinding systems, such as additive manufacturing and subtractive manufacturing; astronomy; meteorology; imaging; projection, including entertainment; and medicines, including dentistry, to name a few.

While this description focuses on blue laser diode arrays, it should be understood that this embodiment is merely illustrative of the type of array assembly, system, process, and combined laser beam contemplated by the present invention. Accordingly, embodiments of the present invention include array assemblies for combining laser beams from various laser beam sources, such as solid state lasers, fiber lasers, semiconductor lasers, and other types of lasers, as well as combinations and variations thereof. Embodiments of the present invention include combinations of laser beams of all wavelengths, such as laser beams having wavelengths from about 380nm to 800nm (e.g., visible light), from about 400nm to about 880nm, from about 100nm to about 400nm, from 700nm to 1mm, and combinations of specific wavelengths within these various ranges. Embodiments of the present array may also find application in microwave coherent radiation (e.g., wavelengths greater than about 1 mm). Embodiments of the present array may combine beams from one, two, three, tens or hundreds of laser sources. These laser beams may range from a few milliwatts to a few watts to a few kilowatts.

Embodiments of the present invention generally include an array of blue laser diodes that are combined in a configuration to preferably produce a high brightness laser source. The high brightness laser source can be directly used for processing materials, namely marking, cutting, welding, brazing, heat treatment and annealing. The material to be processed (e.g., starting material or target material) may comprise any material or component or composition, and may include, for example, semiconductor components such as, but not limited to, TFTs (thin film transistors), 3D printing starting materials, metals including gold, silver, platinum, aluminum and copper, plastics, tissues and semiconductor wafers, to name a few. Direct processing may include, for example, ablating gold from electronic devices, projection displays, and laser shows, to name a few.

Embodiments of the high brightness laser source of the present invention may also be used to pump raman lasers or anti-stokes lasers. The raman medium may be an optical fiber, or a crystal, such as diamond, KGW (gadolinium potassium tungstate, KGd (WO) ₄ ) ₂ )，YVO ₄ And Ba (NO) ₃ ) ₂ . In one embodiment, the high brightness laser source is a blue laser diode source, which is a semiconductor device operating in the wavelength range of 400nm to 500 nm. The raman medium is a brightness converter that can increase the brightness of the blue laser diode light source. The brightness enhancement can be extended until a single-mode diffraction-limited light source is created, i.e., the laser beam quality factor (M ² ) For about 1 and 1.5, the beam parameter product is less than 1, less than 0.7, less than 0.5, less than 0.2 and 0.13mm-mrad, depending on wavelength.

In one embodiment, an "N" or "N" (e.g., two, three, four, etc., tens, hundreds, or more) laser diode sources may be configured in the fiber optic harness that enable an addressable light source that may be used for marking, melting, welding, ablating, annealing, heat treating, cutting materials, and combinations and variations of these, just to name a few laser operations and procedures.

Embodiments of a laser system having an addressable laser delivery architecture. The system has an addressable laser diode system. The system provides independently addressable laser beams to a plurality of optical fibers (greater and lesser numbers of optical fibers and laser beams are contemplated). The optical fibers are combined into an optical fiber bundle and are accommodated in a protective tube or a protective cover. The optical fibers in the fiber optic bundle are fused together to form a printhead that includes an optical assembly that focuses and directs a laser beam along a beam path to a target material. The printhead and the powder hopper move together as the printhead moves in the forward direction. Additional material may be placed on top of the molten material each time the printhead or hopper passes. The print head is bi-directional and fuses material in both directions as the print head moves, so the powder hopper operates behind the print head to provide build material to fuse on the next pass of the laser print head.

By "addressable array" is meant one or more of the following: a power; a transmission duration; a transmission sequence; a launch position; beam power; the shape of the beam spot, and, thus, the focal length (e.g., depth of penetration in the z-direction) can be independently varied, controlled and predetermined, or each laser beam in each fiber to provide an accurate and predetermined delivery pattern created from the target material highly accurate end product (e.g., build material). Embodiments of the addressable array can also have separate beams and laser stations created by these beams, capable of performing various predetermined, precise laser operations, such as annealing, ablation, and melting.

The following examples are provided to illustrate various embodiments of the laser arrays, systems, devices and methods of the present invention. These examples are for illustrative purposes only and should not be considered as, and in other ways should not limit, the scope of the present invention.

Example 1

An array of blue laser diodes, spatially combined to form a single spot in the far field, may be coupled into a insolation-resistant fiber for delivery to a workpiece.

Example 2

The array of blue laser diodes as described in example 1, combined into a polarized beam to increase the effective brightness of the laser beam.

Example 3

An array of blue laser diodes, with a space between each collimated beam on the fast axis of the laser diodes, is then combined with a periodic plate that reflects the first laser diode and transmits the second laser diode to fill the space between the laser diodes in the fast direction of the first array.

Example 4

Patterned mirrors on glass substrates were used to complete the space filling of example 3.

Example 5

The mirror was patterned on one side of the glass substrate to complete the space filling of example 3, and the thickness of the glass substrate was sufficient to shift the vertical position of each laser diode to fill the empty space between the individual laser diodes.

Example 6

The stepped heat sink completes the space filling of example 3 and is the patterned mirror described in example 4.

Example 7

The array of blue laser diodes as described in example 1 wherein each individual laser is locked to a different wavelength by the external cavity to increase the brightness of the array substantially to the equivalent brightness of a single laser diode light source.

Example 8

The array of blue laser diodes as described in example 1, wherein a single laser diode array is locked to a single wavelength using a grating-based external cavity, and each laser diode array is combined into a single beam using a narrow pitch optical filter or grating.

Example 9

An array of blue laser diodes as described in example 1 for pumping raman converters, such as optical fibers with pure fused silica cores to create a higher brightness source and a fluorinated outer core to accommodate blue pump light.

Example 10

The array of blue laser diodes as described in example 1 for pumping raman converters, such as optical fibers, with GeO doped ₂ With an outer core to create a higher brightness source and an outer core larger than the central core to accommodate the blue pump light.

Example 11

Blue laser two as described in example 1An array of polar tubes for pumping raman converters, such as optical fibers, with doped P ₂ O ₅ To create a higher brightness source and the outer core is larger than the central core to accommodate the blue pump light.

Example 12

The array of blue laser diodes as described in example 1 for pumping raman converters, such as optical fibers, has a graded index core to create a higher brightness source and an outer core that is larger than a central core to accommodate blue pump light.

Example 13

The array of blue laser diodes as described in example 1 for pumping a raman converter fiber that is graded index GeO-doped ₂ And an outer step index core.

Example 14

The array of blue laser diodes as described in example 1 for pumping a raman converter fiber that is graded index P-doped ₂ O ₅ And an outer step index core.

Example 15

The array of blue laser diodes as described in example 1 for pumping a raman converter fiber that is graded index GeO-doped ₂ Is provided.

Example 16

The array of blue laser diodes as described in example 1 for pumping a raman converter fiber that is graded index P-doped ₂ O ₅ And an outer step index core.

Example 17

Other implementations and variations of the example 1 embodiment may be considered. The blue laser diode array as described in example 1 was used to pump a raman converter (e.g., diamond) to create a higher brightness laser source. Fig. 13 shows an image 1301 and spectrum 1302 of a Lan Sela man converted laser beam from a diamond chip and wavelength shifts from 450nm to 478 nm. The blue laser diode array as described in example 1 for pumping a raman converter (e.g., KGW) to create higher brightnessIs provided. The blue laser diode array as described in example 1 for pumping a raman converter (e.g. YVO ₄ ) To create a higher brightness laser source. The blue laser diode array as described in example 1, used for pumping a raman converter (e.g., ba (NO ₃ ) ₂ ) To create a higher brightness laser source. The blue laser diode array as described in example 1 was used to pump a raman converter as a high pressure gas to create a higher brightness laser source. The blue laser diode array as described in example 1 was used to pump rare earth doped crystals to create a higher brightness laser source. The blue laser diode array as described in example 1 was used to pump rare earth doped fibers to create a higher brightness laser source. The blue laser diode array as described in example 1 was used to pump the outer core of the brightness converter to create a higher proportion of brightness enhancement.

Example 18

An array of raman converted lasers can be operated at individual wavelengths and combined to create a higher power source while preserving the spatial brightness of the original light source.

Example 19

Raman fibers having dual cores and a mechanism using filters, fiber bragg gratings to suppress the second order raman signal in the high brightness central core, the V-number discrimination or microbending loss discrimination of the first and second order raman signals.

Example 20

N laser diodes, where N.gtoreq.1, can be individually turned on and off and can be imaged onto a powder bed to melt and fuse the powder into unique parts.

Example 21

The N laser diode arrays of example 1, where n+.1, the output can be fiber coupled and each fiber can be arranged in a linear or nonlinear fashion to create an addressable array of high power laser beams that can be imaged or focused onto the powder to melt and fuse the powder layer by layer into unique shapes.

Example 22

The outputs of one or more laser diode arrays combined by means of raman converters may be fiber-coupled and each fiber may be arranged in a linear or non-linear fashion to create an addressable array of N (where N is ≡1) high power laser beams that can be imaged or focused onto the powder to melt and fuse the powder layer by layer into unique shapes.

Example 23

An x-y motion system capable of delivering N (where N.gtoreq.1) blue laser sources to the entire powder bed while melting and fusing the powder bed, the powder delivery system being located behind the laser sources to provide a fresh layer of powder after fusing the layer.

Example 24

The z-axis motion system was able to increase/decrease the height of the component/powder bed of example 20 after placement of a new powder layer.

Example 25

The z-axis motion system was able to increase/decrease the height of the part/powder of example 20 after the powder layer was melted by the laser source.

Example 26

The bi-directional powder placement function of example 20, wherein the powder is placed directly behind the laser spot while traveling in either the positive or negative x-direction.

Example 27

The bi-directional powder placement function of example 20, wherein the powder is placed directly behind the laser spot while traveling in either the positive y-direction or the negative y-direction.

Example 28

The powder supply system is coaxial with the N laser beams, wherein N is greater than or equal to 1.

Example 29

A powder feed system wherein the powder is fed by gravity.

Example 30

A powder supply system wherein the powder is entrained in an inert gas stream.

Example 31

A powder supply system transverse to the N laser beams, wherein N.gtoreq.1, and the powder is placed by gravity just before the laser beams.

Example 32

A powder supply system transverse to the N laser beams, wherein N.gtoreq.1, and the powder is entrained in an inert gas stream intersecting the laser beams.

Example 33

A second harmonic generation system that uses the output of a raman converter at, for example, 460nm to generate light at half the wavelength of the source laser or 230nm, which consists of an external cavity resonant frequency doubling crystal such as KTP but does not allow short wavelength light to propagate through the fiber.

Example 34

A third harmonic generation system that uses the output of a raman converter at, for example, 460nm to generate 115nm light uses an external cavity resonant frequency doubling crystal but does not allow short wavelength light to propagate through the fiber.

Example 35

A fourth harmonic generation system that uses the output of a raman converter at, for example, 460nm to generate 57.5nm light uses an external cavity resonant frequency doubling crystal but does not allow short wavelength light to propagate through the fiber.

Example 36

The second harmonic generation system uses the output of a rare earth doped brightness converter (e.g., thulium) that emits laser light at 450nm at 473nm when pumped by a blue laser diode array to generate light at half the wavelength of the source laser light or 236.5nm, uses an external cavity resonant frequency doubling crystal but does not allow short wavelength light to propagate through the fiber.

Example 37

A second harmonic generation system uses the output of a rare earth doped brightness converter (e.g., thulium) emitting laser light at 450nm at 473nm when pumped by a blue laser diode array to generate light at wavelength 118.25nm, using an external cavity resonant frequency doubling crystal but not allowing short wavelength light to propagate through the fiber.

Example 38

A second harmonic generation system uses the output of a rare earth doped brightness converter (e.g., thulium) emitting laser light at 450nm at 473nm when pumped by a blue laser diode array to generate light at a wavelength of 59.1nm, uses an external cavity resonant frequency doubling crystal but does not allow short wavelength light to propagate through the fiber.

Example 39

All other rare earth element doped fibers and crystals that can be pumped by a high power 450nm source to produce visible or near visible light output can be used in examples 34-38.

Example 40

High power visible light is emitted into the non-circular outer core or cladding to pump the raman or inner core of the rare earth doped core fiber.

Example 41

Polarization maintaining fibers are used to increase the gain of the raman fiber by aligning the polarization of the pump with the polarization of the raman oscillator.

Example 42

An array of blue laser diodes as described in example 1 for pumping a raman converter, such as an optical fiber, configured to produce a higher brightness source of a particular polarization.

Example 43

An array of blue laser diodes as described in example 1 for pumping raman converters, such as optical fibers, configured to produce higher brightness sources of a particular polarization and to maintain the polarization state of the pump sources.

Example 44

The array of blue laser diodes as described in example 1 for pumping raman converters such as optical fibers to create a higher brightness source with a non-circular outer core configured to improve raman conversion efficiency.

Example 45

Embodiments of examples 1 through 44 may further include one or more of the following members or assemblies: means for leveling the powder before the laser sweeps through the powder bed at the completion of each pass; means for generating a higher power output beam by scaling the output power of the laser by combining a plurality of low power laser modules by means of a fiber combiner; means for generating a higher power output beam by scaling the output power of the blue laser module by free space combining a plurality of low power laser modules; an apparatus that combines multiple laser modules on a single substrate with embedded cooling.

It is noted that there is no requirement to provide or address theory underlying the novel and innovative processes, materials, properties or other beneficial features and characteristics that are the subject of the present invention or are associated with the embodiments of the present invention. However, various theories are provided in this specification to further advance the art in this important field, particularly laser, laser processing, and laser application. The theory presented in the specification, unless explicitly stated otherwise, in no way limits, limits or narrows the scope of the claimed invention. These theories are not needed or practiced with the present invention. It is also to be understood that the present invention may be directed to new, heretofore unknown theories to explain the operation, function, and characteristics of embodiments of the methods, articles of manufacture, materials, devices, and systems of the present invention. And such later developed theory should not limit the scope of the protection afforded by the present invention.

It should be understood that headings are used in this specification for clarity and not for limitation in any way. Accordingly, the processes and disclosures described under the heading should be read in the context of the entire specification, including various embodiments. The use of headings in this specification should not be construed as limiting the scope of the invention.

The various embodiments of lasers, diodes, arrays, modules, components, activities and operations set forth in this specification can be used in the fields identified above and in various other fields. Embodiments of the present invention may use methods, apparatus, and systems of patent application publication nos. WO 2014/179345, 2016/0067780, 2016/0067827, 2016/032777, 2017/0343729, 2017/0341180, and 2017/0341144, the entire disclosures of each of which are incorporated herein by reference, among others. In addition, these embodiments may be used, for example, with the following devices: existing lasers, additive manufacturing systems, operations and activities, and other existing equipment; future laser, additive manufacturing system operations and activities; and to such items as may be (partially) modified in accordance with the teachings of this specification. Furthermore, the various embodiments set forth in this specification may be used differently and in various combinations with one another. Thus, for example, the configurations provided in the various embodiments of the present specification may be used with each other. For example, components having embodiments of A, A' and B and components having embodiments of a ", C and D may be used with each other in various combinations, e.g., A, C, D, and A, A", C and D, etc., in accordance with the teachings of the present specification. Therefore, the scope of protection provided by the present invention should not be limited to the particular embodiments, configurations or arrangements set forth in one particular example, illustration, or implementation in a particular drawing.

The present invention may be embodied in other forms than those specifically disclosed without departing from the spirit or essential characteristics thereof, and is therefore to be considered in all respects as illustrative and not restrictive.

Claims (38)

1. An additive manufacturing system configured to provide a multi-spot image on a metal powder bed, the system comprising:

a. a light source for providing a laser beam, the light source in optical communication with the re-imaging optics;

wherein the re-imaging optics are configured to re-image the multi-spot image on the metal powder bed; and whereby said multi-spot image has a power density sufficient to fuse and build a part from metal powdered in said metal powder bed;

b. the multi-spot image comprises a plurality of laser beam spots on the metal powder bed; and

c. a control system comprising a program having a predetermined sequence for delivering the plurality of laser beam spots at predetermined locations on the metal powder bed.

2. The additive manufacturing system of claim 1, wherein the light source comprises an array of fiber raman lasers.

3. The additive manufacturing system of claim 2, wherein the laser beam has a wavelength in the range of 400nm to 500 nm.

4. The additive manufacturing system of claim 1, wherein the light source comprises an array of laser diodes.

5. The additive manufacturing system of claim 4, wherein the laser beam has a wavelength in a range of about 400nm to about 500 nm.

6. The additive manufacturing system of claim 1, wherein the light source comprises a plurality of optical fibers coupled to a laser diode operating in a wavelength range of about 400nm to about 500 nm.

7. The additive manufacturing system of claim 6, wherein the optical fiber has a diameter in the range of 10 μιη to 50 μιη.

8. The additive manufacturing system of claim 6, wherein the optical fiber has a diameter in the range of 50 μιη to 100 μιη.

9. The additive manufacturing system of claim 6, wherein the optical fiber has a diameter in the range of 100 μιη to 500 μιη.

10. Additive manufacturing system according to any one of claims 6 to 9, wherein the optical fibers are mounted independently.

11. The additive manufacturing system of any one of claims 1 to 9, wherein the power of the re-imaging optics is in the range of 1:0.5 to 1:10.

12. The additive manufacturing system of any one of claims 1 to 9, wherein each of the laser beam spots has a power density sufficient to fuse and build a part from the metal powder.

13. The additive manufacturing system of any one of claims 1 to 9, wherein each of the laser beam spots has a power density sufficient to fuse and build a part from the metal powder; and wherein one or more of the plurality of laser beam spots overlap.

14. The additive manufacturing system of any one of claims 1 to 9, wherein each of the laser beam spots has a power density sufficient to fuse and build a part from the metal powder; and wherein one or more of the plurality of laser beam spots are arranged in a linear fashion.

15. The additive manufacturing system of any one of claims 1 to 9, wherein each of the laser beam spots has a power density sufficient to fuse and build a part from the metal powder; and wherein one or more of the plurality of laser beam spots are arranged in a plurality of lines.

16. The additive manufacturing system of any one of claims 1 to 9, wherein each of the laser beam spots has a power density sufficient to fuse and build a part from the metal powder; and wherein one or more of the plurality of laser beam spots are not adjacent to other laser beam spots such that there is space between the laser beam spots.

17. The additive manufacturing system of any one of claims 1 to 9, wherein each of the laser beam spots has a power density sufficient to fuse and build a part from the metal powder; and wherein one or more of the plurality of laser beam spots are adjacent, wherein the spots are adjacent but not overlapping.

18. An additive manufacturing system configured to provide an image on a metal powder bed, the system comprising:

a. a first light source for providing a laser beam, the first light source in optical communication with the re-imaging optics; wherein the re-imaging optics are configured to re-image a first image on the metal powder bed; and whereby said first image has a power density sufficient to fuse and build a part from metal powdered in said metal powder bed;

b. the first image includes a first plurality of laser beam spots on the metal powder bed,

wherein one or more laser beam spots of the first plurality of laser beam spots have a power density sufficient to fuse and build a part from the metal powder;

c. means for monitoring and controlling the temperature of the metal powder in said metal powder bed;

d. A control system comprising a program having a predetermined sequence for delivering the first plurality of laser beam spots at predetermined locations on the metal powder bed; and

e. the control system is configured to control the means for monitoring and controlling the temperature of the metal powder.

19. The additive manufacturing system of claim 18, wherein the means for monitoring and controlling the temperature of the metal powder is a closed loop system.

20. The additive manufacturing system of claim 18, wherein the system is configured to provide spot-by-spot component build quality.

21. The additive manufacturing system of claim 18, wherein the means for monitoring and controlling the temperature of the metal powder comprises a high resolution thermal imaging camera for directly monitoring the temperature of each spot of the first image and providing a feedback signal to the controller during operation.

22. The additive manufacturing system of claim 21, wherein the system is configured to provide part build quality on a spot-by-spot basis.

23. The additive manufacturing system of claim 18, wherein the means for monitoring and controlling the temperature of the metal powder comprises a pyrometer array for directly monitoring the temperature of each spot of the first image and providing a feedback signal to the controller during operation.

24. The additive manufacturing system of claim 23, wherein the system is configured to provide spot-by-spot component build quality.

25. The additive manufacturing system of any one of claims 18 to 24, wherein the light source comprises an array of fiber raman lasers.

26. The additive manufacturing system of any one of claims 18 to 24, wherein the wavelength of the light beam is in the range of 400nm to 500 nm.

27. The additive manufacturing system of any one of claims 18 to 24, wherein the light source comprises an array of laser diodes.

28. The additive manufacturing system of any one of claims 18 to 24, wherein the light source comprises an array of laser diodes; and wherein the wavelength of the laser beam is in the range of about 400nm to about 500 nm.

29. The additive manufacturing system of any one of claims 18 to 24, wherein the light source comprises a plurality of optical fibers coupled to a laser diode operating within a wavelength range of about 400nm to about 500 nm.

30. The additive manufacturing system of any one of claims 18-24, wherein the light source comprises a plurality of optical fibers coupled to a laser diode; and wherein the diameter of the optical fiber is in the range of 10 μm to 50 μm.

31. The additive manufacturing system of any one of claims 18 to 24, wherein the diameter of the optical fiber is in the range of 50 μιη to 100 μιη.

32. The additive manufacturing system of any one of claims 18 to 24, wherein the re-imaging optics have a power in the range of 1:0.5 to 1:10.

33. The additive manufacturing system of any one of claims 18 to 24, wherein the means for monitoring and controlling the temperature of the metal powder comprises a second light source for providing a laser beam in a second image on the metal powder bed.

34. The additive manufacturing system of any one of claims 18 to 24, wherein the means for monitoring and controlling the temperature of the metal powder comprises a second light source for providing a laser beam in a second image on the metal powder bed; and wherein one or more of the first plurality of laser beam spots overlap.

35. The additive manufacturing system of any one of claims 18 to 24, wherein the means for monitoring and controlling the temperature of the metal powder comprises a second light source for providing a laser beam in a second image on the metal powder bed; and wherein one or more of the plurality of laser beam spots are arranged in a linear fashion.

36. The additive manufacturing system of any one of claims 18 to 24, wherein the means for monitoring and controlling the temperature of the metal powder comprises a secondary light source for providing a laser beam in a second image on the metal powder bed; and wherein one or more of the plurality of laser beam spots are arranged in a plurality of lines.

37. The additive manufacturing system of any one of claims 18 to 24, wherein the means for monitoring and controlling the temperature of the metal powder comprises a second light source for providing a laser beam in a second image on the metal powder bed; and wherein the first image and the second image overlap.

38. The additive manufacturing system of any one of claims 18 to 24, wherein the means for monitoring and controlling the temperature of the metal powder is configured to provide real-time control signals to the controller; wherein the additive manufacturing system is configured to optimize one or more of surface roughness, porosity, and stress in the component.