Grayscale region printing for additive manufacturing

Abstract

An additive manufacturing system includes one or more light sources and one or more light valves, which may be written with a two-dimensional grayscale pattern, which light valves apply the two-dimensional grayscale pattern on a beam from the one or more light sources to obtain one or more patterned beams. The one or more patterned beams are diverted to each of a plurality of regions on the powder layer. A two-dimensional grayscale pattern is selected to achieve desired material characteristics at each pixel location of the patterned beam incident on the powder layer. The light valve may modulate one or more of amplitude, phase, or coherence. The material characteristics may include one or more of Young's modulus, porosity, grain size, and crystalline microstructure.

Description

Cross-references to related patent applications

[0001] This application is a continuation-in-part of U.S. Patent Application No. 17 / 091,915 filed on November 6, 2020, which is a continuation-in-part of U.S. Patent Application No. 15 / 337,507 filed on October 28, 2016, which claims the benefit of the following provisional applications: U.S. Patent Application No. 62 / 248,758, filed October 30, 2015, U.S. Patent Application No. 62 / 248,765, filed October 30, 2015, U.S. Patent Application No. 62 / 248,770, filed October 30, 2015, U.S. Patent Application No. 62 / 248,776, filed October 30, 2015, U.S. Patent Application No. 62 / 248,783, filed October 30, 2015, U.S. Patent Application No. 62 / 248,791, filed October 30, 2015, U.S. Patent Application No. 62 / 248,799, filed October 30, 2015, U.S. Patent Application No. 62 / 248,966, filed October 30, 2015, U.S. Patent Application No. 62 / 248,968, filed October 30, 2015, U.S. Patent Application No. 62 / 248,969, filed October 30, 2015, U.S. Patent Application No. 62 / 248,980, filed October 30, 2015, U.S. Patent Application No. 62 / 248,989, filed October 30, 2015, U.S. Patent Application No. 62 / 248,780, filed October 30, 2015, U.S. Patent Application No. 62 / 248,787, filed October 30, 2015, U.S. Patent Application No. 62 / 248,795, filed October 30, 2015, U.S. Patent Application No. 62 / 248,821, filed October 30, 2015, U.S. Patent Application No. 62 / 248,829, filed October 30, 2015, U.S. Patent Application No. 62 / 248,833, filed October 30, 2015, U.S. Patent Application No. 62 / 248,835, filed October 30, 2015, U.S. Patent Application No. 62 / 248,839, filed October 30, 2015, U.S. Patent Application No. 62 / 248,841, filed October 30, 2015, U.S. Patent Application No. 62 / 248,847, filed October 30, 2015 and U.S. Patent Application No. 62 / 248,848, filed on October 30, 2015.

[0002] This application is a continuation-in-part of U.S. patent application No. 15 / 977,476 filed on May 11, 2018, which claims the benefit of U.S. provisional patent application No. 62 / 504,853 filed on May 11, 2017.

[0003] This application is a continuation-in-part of U.S. patent application No. 17 / 506,349 filed on October 20, 2021, which claims the benefit of U.S. Provisional Patent Application No. 63 / 105,066 filed on October 23, 2020.

[0004] This application is a continuation-in-part of U.S. patent application No. 17 / 513,005 filed on October 28, 2021, which claims the benefit of U.S. Provisional Patent Application No. 63 / 107,077 filed on October 29, 2020.

[0005] This application is a continuation-in-part of U.S. patent application No. 17 / 513,402 filed on October 28, 2021, which claims the benefit of U.S. provisional patent application No. 63 / 107,303 filed on October 29, 2020.

[0006] This application is a continuation-in-part of U.S. patent application No. 17 / 513,230 filed on October 28, 2021, which claims the benefit of U.S. Provisional Patent Application No. 63 / 107,310 filed on October 29, 2020.

[0007] This application is a continuation-in-part of U.S. Patent Application No. 17 / 670,149, filed on February 11, 2022, which claims the benefit of U.S. Provisional Patent Application No. 63 / 148,788, filed on February 12, 2021. All of the foregoing are hereby incorporated herein by reference. Technical Field

[0008] The present disclosure relates generally to optical devices for additive manufacturing, and more particularly to additive manufacturing involving melting powder with a laser. background

[0009] Current energy deposition print bed fusion additive manufacturing (ED-PBF-AM) uses a single point of energy to melt powder (metal, ceramic, glass or glass-like material) to form / print 3D parts. This enables rapid manufacturing of parts and the manufacture of parts that cannot be made with conventional machining techniques. Parts made using this technology can be used for prototyping and can have sufficient strength and precision for production parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Non-limiting and non-exhaustive embodiments of the present disclosure are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various figures unless otherwise specified.

[0011] Figure 1A An additive manufacturing system is shown; Figure 1B is a top view of a structure formed on an additive manufacturing system; Figure 2 An additive manufacturing method is shown; Figure 3A is an animated diagram illustrating an additive manufacturing system including a laser; Figure 3B yes Figure 3A A detailed description of the light patterning unit shown; Figure 3C is an embodiment of an additive manufacturing system having a "switchyard" for directing and re-patterning light using multiple image repeaters; Figure 3D A switchyard system supporting reuse of patterned two-dimensional energy is shown; Figure 3E Mirrored image pixel remapping is shown; Figure 3F A series of image transformation image relays for pixel remapping are shown; Figure 4A is a layout diagram of an energy patterning binary tree system for laser recycling in an additive manufacturing process according to an embodiment of the present disclosure; Figure 4B is a diagram showing pattern recycling from one input to multiple outputs; Figure 4C is a diagram showing pattern recovery from multiple inputs to one output; Figure 4Dis a schematic example of an implementation of a switch station concept supporting two light valve patterning steps and beam redirection, wherein switches may be used for at least some of the energy steering units; Figure 4E is a schematic example of the implementation of a switch station concept supporting two light valve patterning steps and beam redirection, where switches are available for all energy steering units; Figure 5A is an animated diagram illustrating area printing of multiple tiles using a solid-state system having a print bar; Figure 5B is an animated diagram illustrating area printing of multiple tiles using a solid state system having a matrix sized to be coextensive with a powder bed; Figure 5C is an animated diagram illustrating regional printing of multiple tiles using a solid-state system having a matrix having separate steering units and sized to be coextensive with a powder bed; Fig. 6A is a diagram showing control of Young's modulus of a printed component using a two-dimensional grayscale pattern; Figure 6B is a diagram showing the crystallography of controlling macroscopic arrangement using two-dimensional grayscale patterns; Figure 6C Shows the temporal structuring of printing using two-dimensional grayscale patterns to control material properties; Figure 7 is a schematic diagram of a component manufactured with a support member according to an embodiment of the present invention; Figure 8 is a schematic diagram showing printed pixels and non-printed pixels; Fig. 9 is a schematic diagram showing the volume of a pixel. DETAILED DESCRIPTION

[0012] In the following description, reference is made to the accompanying drawings, which form a part of the description and in which are shown by way of illustration specific exemplary embodiments with which the present disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the concepts disclosed herein, and it should be understood that the various disclosed embodiments may be modified and other embodiments may be utilized without departing from the scope of the present disclosure. Therefore, the following detailed description should not be construed as limiting.

[0013] The present disclosure proposes an optical system suitable for reducing wasted light in an additive manufacturing system, which is caused by rejecting unwanted light due to a pattern to be printed. The proposed optical system can be used, for example but not limited to, in laser-based additive manufacturing techniques in which a mask is applied to the light. Advantageously, in various embodiments according to the present disclosure, the discarded energy can be recovered in a homogenized form or as patterned light and used to maintain high productivity. In addition, the discarded energy can be recovered and reused to increase the intensity and print more difficult materials.

[0014] By recycling and reusing the rejected light, the system strength can be increased in proportion to the fraction of light that is rejected. This allows all energy to be used to maintain high print rates. In addition, light recycling may enable "bar" printing, where a single bar sweeps across the build platform. Alternatively, pattern recycling may allow the creation of a solid matrix that is coextensive with the build platform, printing all areas of the build platform without the need for movement.

[0015] An additive manufacturing system having one or more energy sources is disclosed. In one embodiment, the one or more energy sources include one or more laser beams or electron beams, and the one or more energy sources are positioned to emit one or more energy beams. A beam shaping optical device can receive one or more energy beams from the energy source and form a single beam. An energy patterning unit receives or generates a single beam and transfers a two-dimensional pattern to the beam, and can reject unused energy that is not in the pattern. An image relay receives the two-dimensional patterned beam and focuses it as a two-dimensional image to a desired location on a highly fixed or movable building platform (such as a powder bed). In some embodiments, some or all of any rejected energy from the energy patterning unit is reused.

[0016] In various examples, multiple beams from a laser array are combined using a beam homogenizer. The combined beam can be directed to an energy patterning unit that includes a transmissive or reflective pixel addressable light valve. In one embodiment, the pixel addressable light valve includes a liquid crystal module with a polarizing element and a light projection unit that provides a two-dimensional input pattern. The two-dimensional image focused by the image relay can be sequentially directed to multiple locations on the powder bed to build a 3D structure.

[0017] The additive manufacturing system can utilize grayscale patterns to control material properties corresponding to each pixel position of the pattern. Material properties can include Young's modulus, porosity, grain size, and crystallite structure. The grayscale pattern can be imposed on the beam by modulating a light valve in one or more of amplitude, phase, and coherence.

[0018] As shown in FIG. 1 , the additive manufacturing system 100 has an energy patterning system 110 having an energy source 112 that can direct one or more continuous or intermittent energy beams toward a beam shaping optical device 114. After shaping, the beam is patterned by an energy patterning unit 116, if necessary, and typically some of the energy is directed to a rejected energy processing unit 118. The patterned energy is relayed by an image relay 120 toward an article processing unit 140, typically as a two-dimensional image 122 focused near a bed 146. The bed 146 (with optional walls 148) can form a chamber that contains a material 144 dispensed by a material dispenser 142. The patterned energy directed by the image relay 120 can melt, fuse, sinter, amalgamate, change the crystal structure, affect the stress pattern, or otherwise chemically or physically change the dispensed material 144 to form a structure with desired properties.

[0019] Energy source 112 generates photons (light), electrons, ions or other suitable energy beams or fluxes that can be guided, shaped and patterned. A variety of energy sources can be used in combination. Energy source 112 may include a laser, an incandescent lamp, concentrated solar energy, other light sources, an electron beam or an ion beam. Possible laser types include, but are not limited to: gas lasers, chemical lasers, dye lasers, metal vapor lasers, solid-state lasers (e.g., optical fibers), semiconductor (e.g., diode) lasers, free electron lasers, pneumatic lasers, "nickel-like" samarium lasers, Raman lasers, or nuclear pumped lasers.

[0020] The gas laser may include a laser such as a helium-neon laser, an argon laser, a krypton laser, a xenon ion laser, a nitrogen laser, a carbon dioxide laser, a carbon monoxide laser, or an excimer laser.

[0021] Chemical lasers may include lasers such as a hydrogen fluoride laser, a deuterium fluoride laser, a COIL (chemical oxygen iodine laser), or an Agil (all gas phase iodine laser).

[0022] The metal vapor laser may include a laser such as a helium-cadmium (HeCd) metal vapor laser, a helium-mercury (HeHg) metal vapor laser, a helium-selenium (HeSe) metal vapor laser, a helium-silver (HeAg) metal vapor laser, a strontium vapor laser, a neon-copper (NeCu) metal vapor laser, a copper vapor laser, a gold vapor laser, or a manganese (Mn / MnCl2) vapor laser.

[0023] Solid-state lasers may include lasers such as: ruby ​​lasers, Nd:YAG lasers, NdCrYAG lasers, Er:YAG lasers, neodymium YLF (Nd:YLF) solid-state lasers, neodymium-doped yttrium vanadate (Nd:YVO4) lasers, neodymium-doped yttrium calcium oxyborate Nd:YCa4O(BO3) solid-state lasers 3 Or simply referred to as Nd:YCOB, neodymium glass (Nd: glass) laser, titanium sapphire (Ti: sapphire) laser, thulium YAG (Tm: YAG) laser, ytterbium YAG (Yb: YAG) laser, ytterbium: 2O3 (glass or ceramic) laser, ytterbium-doped glass laser (rods, plates / sheets and fibers), holmium YAG (Ho: YAG) laser, chromium ZnSe (Cr: ZnSe) laser, cerium-doped lithium strontium (or calcium) aluminum fluoride (Ce: LiSAF, Ce: LiCAF), promethium-doped 147 phosphate glass (147Pm +3 :glass) solid-state lasers, chromium-doped chrysoberyl (alexandrite) lasers, erbium-doped and erbium-ytterbium co-doped glass lasers, trivalent uranium-doped calcium fluoride (U:CaF2) solid-state lasers, divalent samarium-doped calcium fluoride (Sm:CaF2) lasers, or F-center lasers.

[0024] The semiconductor laser may include laser media types such as GaN, InGaN, AlGaInP, AlGaAs, InGaAsP, GaInP, InGaAs, InGaAsO, GaInAsSb, lead salts, vertical cavity surface emitting lasers (VCSELs), quantum cascade lasers, hybrid silicon lasers, or combinations thereof.

[0025] For example, in one embodiment, a single Nd:YAG q-switched laser can be used in combination with multiple semiconductor lasers. In another embodiment, an electron beam can be used in combination with an array of ultraviolet semiconductor lasers. In other embodiments, a two-dimensional array of lasers can be used. Pre-patterning of the energy beam can be accomplished by selectively activating and deactivating the energy source.

[0026] The beam shaping unit 114 may include a variety of imaging optical devices to combine, focus, diverge, reflect, refract, homogenize, adjust the intensity, adjust the frequency, or otherwise shape and direct one or more energy beams received from the energy source 112 to the energy patterning unit 116. In one embodiment, wavelength selective mirrors (e.g., dichroic mirrors) or diffractive elements may be used to combine multiple light beams, each with a different wavelength of light. In other embodiments, multi-faceted mirrors, microlenses, and refractive or diffractive optical elements may be used to homogenize or combine multiple beams.

[0027] The energy patterning unit 116 may include static or dynamic energy patterning elements. For example, a photon, electron or ion beam may be blocked by a mask having fixed or movable elements. In order to increase the flexibility and simplicity of image patterning, pixel addressable masking, image generation or transmission may be used. In some embodiments, the energy patterning unit includes an addressable light valve that provides patterning alone or in combination with other patterning mechanisms. The light valve may be transmissive, reflective, or use a combination of transmissive and reflective elements. Electrical addressing or optical addressing may be used to dynamically change the pattern. In one embodiment, a transmissive light addressing light valve is used to rotate the polarization of light passing through the valve, wherein the optically addressed pixels form a pattern defined by a light projection source. In another embodiment, a reflective light addressing light valve includes a write beam for changing the polarization of a read beam. In yet another embodiment, the electronic patterning device receives an address pattern from an electrical or photon stimulation source and generates a patterned emission of electrons.

[0028] The rejected energy processing unit 118 is used to disperse, redirect or utilize energy that is not patterned and passes through the energy pattern image repeater 120. In one embodiment, the rejected energy processing unit 118 may include a passive or active cooling element that removes heat from the energy patterning unit 116. In other embodiments, the rejected energy processing unit may include a "beam dump" to absorb any beam energy that is not used when defining the energy pattern and convert it into heat. In still other embodiments, the rejected beam energy can be recovered using the beam shaping optical device 114. Alternatively or additionally, the rejected beam energy can be directed to the item processing unit 140 for heating or further patterning. In certain embodiments, the rejected beam energy can be directed to an additional energy patterning system or item processing unit. Any of the above techniques can be used in combination in the rejected energy processing unit 118 to disperse, redirect or utilize energy that is not patterned and passes through the energy pattern image repeater 120.

[0029] The image relay 120 receives the patterned image (typically two-dimensional) from the energy patterning unit 116 and directs it toward the item processing unit 140. In a manner similar to the beam shaping optics 114, the image relay 120 may include optics for combining, focusing, diverging, reflecting, refracting, modulating intensity, modulating frequency, or otherwise shaping and directing the patterned image.

[0030] The article handling unit 140 may include a chamber 148 with a wall and a bed 144, and a material dispenser 142 for distributing materials. The material dispenser 142 can distribute, remove, mix, provide gradations or changes in material type or particle size, or adjust the layer thickness of the material. The material may include metals, ceramics, glasses, polymer powders, other meltable materials that can undergo a thermally induced phase change from solid to liquid and back to solid, or a combination thereof. The material may also include a composite material of a meltable material and an infusible material, one or both of which may be selectively targeted by an imaging relay system to melt the meltable component while retaining or subjecting the infusible material to evaporation / destruction / combustion or other destruction processes along with the infusible material. For example, a slurry, spray, coating, line, strip or sheet of material may be used. Unwanted material may be removed for disposal or recycling by using a blower, a vacuum system, sweeping, vibrating, shaking, tipping or inverting the bed 146.

[0031] In addition to material handling components, the article handling unit 140 may include components for holding and supporting 3D structures, mechanisms for heating or cooling the chamber, auxiliary optics or support optics, and sensors and controls for monitoring or adjusting material or environmental conditions. The article handling unit may support a vacuum or inert gas atmosphere in whole or in part to reduce unwanted chemical interactions and mitigate the risk of fire or explosion (particularly for reactive metals).

[0032] The control processor 150 may be connected to control any component of the additive manufacturing system 100. The control processor 150 may be connected to various sensors, actuators, heating or cooling systems, monitors, and controllers to coordinate operations. A wide range of sensors, including imagers, light intensity monitors, thermal sensors, pressure sensors, or gas sensors, may be used to provide information used in control or monitoring. The control processor may be a single central controller, or alternatively, may include one or more independent control systems. The control processor 150 is provided with an interface that allows manufacturing instructions to be input. The use of a wide range of sensors allows various feedback control mechanisms to improve quality, manufacturing output, and energy efficiency.

[0033] Figure 1B1 is an animated diagram showing a bed 146 of support material 144. A structure 149 is additively manufactured using a series of sequentially applied two-dimensional patterned energy beam images (squares in dashed outline 124). As will be appreciated, image patterns with non-square boundaries may be used, overlapping images or interpenetrating images may be used, and images may be provided by two or more energy patterning systems. In other embodiments, the images may be formed in conjunction with a directed electron beam or ion beam, or in conjunction with a printing system or a selective spraying system.

[0034] Figure 2 202 is a flow chart illustrating one embodiment of an additive manufacturing process supported by the described optical and mechanical components. In step 202, a material is positioned in a bed, chamber, or other suitable support. The material may be a powder that can be melted, fused, sintered, induced to change crystal structure, have an affected stress pattern, or otherwise chemically or physically modified to form a structure having desired properties.

[0035] In step 204, unpatterned energy is emitted by one or more energy emitters, including but not limited to solid-state or semiconductor lasers, or power supplies that cause electrons to flow along wires. In step 206, the unpatterned energy is shaped and changed (e.g., intensity modulated or focused). In step 208, the unpatterned energy is patterned, wherein the energy that does not form part of the pattern is processed in step 210 (this may include conversion into waste heat, or recycling as patterned or unpatterned energy). In step 212, the patterned energy now forms a two-dimensional image, which relays the patterned energy toward the material. In step 214, the image is applied to the material to build a portion of the 3D structure. These steps can be repeated (loop 218) until the image (or a different subsequent image) has been applied to all necessary areas of the top layer of the material. When the energy application to the top layer of the material is completed, a new layer can be applied (loop 216) to continue to build the 3D structure. These process cycles continue until the 3D structure is completed, at which time the remaining excess material can be removed or recycled.

[0036] Figure 3Ais an embodiment of an additive manufacturing system 300 using multiple semiconductor lasers as part of an energy patterning system 310. A control processor 350 may be connected to various sensors, actuators, heating or cooling systems, monitors, and controllers to coordinate the operation of multiple lasers 312, light patterning unit 316, and image relay 320, as well as any other components of system 300. These connections are generally indicated by dashed outlines 351 surrounding components of system 300. As will be appreciated, the connections may be wired or wireless, continuous or intermittent, and include capabilities for feedback (e.g., heating may be adjusted in response to sensed temperature). Multiple lasers 312 may emit, for example, 90 mm wide by 20 mm high, 1000 nm wavelength beams 301. The beams 301 are sized by imaging optics 370 to produce beams 303. In one example, beam 303 is 6 mm wide by 6 mm high, and beam 3 is incident on a light homogenizer 372, which mixes the light together to produce a mixed beam 305. Then, beam 305 is incident on imaging assembly 374, which reshapes the light into beam 307, which is then incident on hot cold mirror 376. Mirror 376 can allow light of a first wavelength to pass but reflect a second wavelength, for example, the mirror can allow light of 1000nm to pass but reflect light of 450nm. A light projector 378 capable of projecting low-power light at, for example, 1080p pixel resolution and 450nm emits beam 309, which is then incident on hot cold mirror 376. Beam 309 can be a two-dimensional pattern (e.g., an image), in which each pixel of the pattern is independently controllable. The intensity of each pixel can be independently set to a range of possible values, so that the two-dimensional pattern is a grayscale pattern. As used herein, "grayscale" should be understood to mean at least three levels, including zero intensity, maximum intensity, and one or more intensities between zero intensity and maximum intensity. For example, the number of levels can be at least 8, at least 16, at least 32, at least 64, at least 128, or any value greater than or equal to 2^N, where N is greater than 1. The grayscale pattern or image as used herein need not include each of the multiple levels, but rather includes at least three levels that are not equal to each other, and each level can be selected from a range of available levels. Beam 307 and beam 309 overlap in beam 311, and both are imaged onto the optically addressed light valve 380, for example, as an image 20 mm wide and 20 mm high. The image formed from the homogenizer 372 and the projector 378 is recreated and overlaid on the light valve 380.

[0037] The optically addressed light valve 380 is stimulated by light (in an example, the wavelength of the light may be in the range of 400nm-500nm) and imprints a polarization rotation pattern in the transmitted beam 313, which is incident on a polarizer 382. The polarizer 382 splits the two polarization states, transmitting the p-polarization into the beam 317 and reflecting the s-polarization into the beam 315, which is then sent to a beam dump 318 that processes the rejected energy. As will be appreciated, in other embodiments, the polarization may be reversed, with the s-polarization formed into the beam 317 and the p-polarization reflected into the beam 315. The beam 317 enters the final imaging assembly 320, which includes an optical device 384 that adjusts the size of the patterned light. The beam is reflected from the movable mirror 386 as a beam 319, which terminates in a focused image of the material bed 344 in the article processing unit 340. The depth of field in the image is selected to span multiple layers, providing optimal focus within the error or offset of several layers.

[0038] The optically addressed light valve 380 can be implemented as a variety of optical devices that affect other characteristics of the beam 307 output by the laser 312 in response to the patterned beam 309, which can be a grayscale patterned beam. The frequency used for the patterned beam 309 corresponds to the frequency required to apply the pattern to the various optical devices used in the following examples.

[0039] In a first alternative example, the polarizer 382 is omitted and the light valve 380 is implemented as the light valve described in 17 / 506,349. In such an embodiment, the light valve 380 may include a photoconductor layer and an electro-optical layer between the transparent conductive oxide layer. The patterned beam 309 illuminates the photoconductive layer as a scanned beam, thereby producing a two-dimensional grayscale pattern or a two-dimensional image defining the two-dimensional grayscale pattern. In either case, the intensity and / or wavelength at each position in the two-dimensional pattern is independently controllable to apply the two-dimensional grayscale pattern to the photoconductive layer. The two-dimensional grayscale pattern applied to the photoconductive layer causes a corresponding two-dimensional grayscale pattern to be applied to the beam 307 incident on the light valve 380, resulting in an output beam 313 leaving the light valve 380 having a corresponding grayscale pattern. The output beam 313 can then be input to the final imaging optical device 320 without first passing through the polarizer 382.

[0040] In a second alternative example, light valve 380 applies a patterned phase change on beam 307, and polarizer 382 is implemented as a pattern separator with phase-dependent transmittance as disclosed in 17 / 513,005. Light valve 380 may include a phase change material (e.g., crystalline, amorphous, liquid crystal, glass, ceramic, polymer, quantum dot, artificial dielectric, plasma, or metamaterial). In other examples, a pixel strained phase change light valve is used. The phase change light valve is written by a two-dimensionally patterned writing beam, which may be a grayscale pattern. While passing through the phase change light valve, beam 307 undergoes a two-dimensional pattern of local phase changes to obtain a beam 313 having a two-dimensional phase pattern applied thereto. Beam 313 then passes through a pattern separator with phase-dependent transmittance, producing a beam 317 having a two-dimensional amplitude pattern corresponding to the two-dimensional grayscale pattern.

[0041] In a third alternative example, polarizer 382 is omitted and light valve 380 is a quantum dot resonance based light valve (QDRLV) or a quantum dot resonance controlled diffraction light valve as described in 17 / 513,402, which is illuminated by patterned beam 309 including a two-dimensional grayscale pattern. Beam 307 is incident on light valve 380, and beam 313 exiting light valve 380 has a two-dimensional amplitude pattern corresponding to the two-dimensional grayscale pattern. Beam 313 can then be incident on final imaging optics 320.

[0042] In a fourth alternative example, polarizer 382 is omitted and light valve 380 is a holographic light valve as disclosed in 17 / 670,149. Holographic light valve 380 may include a photoconductive layer illuminated by a two-dimensional grayscale write pattern in beam 309. Beam 309 has a first frequency and causes the photoconductive layer to apply a corresponding two-dimensional patterned field to be applied to multiple transparent conductive oxide (TCO) layers. When passing through the TCO layers, the TCO layers apply a corresponding two-dimensional phase pattern on beam 307. A lambda magic mirror (LMM) is illuminated by a second two-dimensional grayscale write pattern at a second frequency, which is different from the first frequency. The LMM applies a grayscale amplitude pattern to the phase patterned beam output by the TCO layer, so that beam 313 output from light valve 380 is a phase and amplitude patterned high fluence beam. Beam 313 can then be incident on the final imaging optical device 320.

[0043] In a fifth alternative example, the light valve is an LMM as described in 17 / 513,402. The LMM is illuminated by a two-dimensional grayscale write pattern from projector 378, so that when beam 307 is incident on the LMM, the coherence is locally changed on the LMM, so that a portion of beam 307 is diverted according to the coherence change, resulting in beam 313 having a two-dimensional amplitude pattern corresponding to the two-dimensional grayscale write pattern.

[0044] In a sixth example, light valve 380 is replaced with a high-speed electron beam addressed reflective light valve (EBA-RLV) described in 17 / 091,915, 17 / 513,230. Beam 307 is incident on the EBA-RLV. Projector 378 and polarizer 382 can be emitted and replaced with an electron beam scanner. The electron beam is scanned onto the EBA-RLV to apply a two-dimensional grayscale pattern on the EBA-RLV. When the electron beam is scanned on the EBA-RLV, the voltage of the electron beam can be modulated to apply a two-dimensional grayscale pattern to the EBA-RLV. Beam 307 is incident on the EBA-RLV, and the reflected portion having a two-dimensional amplitude pattern corresponding to the two-dimensional grayscale pattern is used as beam 313. Beam 313 can then be incident on the final imaging optical device 320.

[0045] The bed 390 can be raised or lowered (vertically indexed) within the chamber wall 388 that contains the material 344 dispensed by the material dispenser 342. In some embodiments, the bed 390 can remain stationary and the optics of the final imaging assembly 320 can be raised or lowered vertically. Material distribution is provided by a sweeper mechanism 392, which can evenly spread the powder held in the hopper 394, capable of providing new layers of material as needed. For example, an image of 6 mm wide by 6 mm high can be sequentially directed by the movable mirror 386 at different locations on the bed.

[0046] When using powdered ceramic or metal materials in the additive manufacturing system 300, the powder can be spread on top of the bottom substrate (and subsequent layers) in a thin layer of about 1-3 particles thick when building the part. When the powder is melted, sintered or fused by the patterned beam 319, it is bonded to the layer below, producing a solid structure. The patterned beam 319 can be operated in a pulsed manner, for example at a frequency of 40 Hz, moving to subsequent image positions (e.g., 6 mm×6 mm) at intervals ranging from 10 ms to 0.5 ms (in various examples, the interval range is 3 ms to 0.1 ms) until the selected patterned area of ​​the powder has melted. The bed 390 then lowers itself by the thickness corresponding to one layer, and the sweeper mechanism 392 spreads a new layer of powdered material. The process is repeated until the 2D layer has established the desired 3D structure. In some embodiments, the item handling unit 340 may have a controlled atmosphere. This allows reactive materials to be manufactured in an inert gas or vacuum environment without the risk of oxidation or chemical reactions or fire or explosion (if reactive metals are used).

[0047] Figure 3B Shown in more detail Figure 3A The operation of the light patterning unit 316 is as follows. Figure 3B As shown, a representative input pattern 333 (here considered as the number "9") is defined in an 8×12 array of light pixels projected toward mirror 376 as beam 309. Each gray pixel represents a pixel filled with light, while white pixels are not lit. In practice, each pixel can have different levels of light, including no light, partial light intensity, or maximum light intensity. The unpatterned light 331 that forms beam 307 is guided and passes through the hot / cold mirror 376, where the unpatterned light 331 is combined with the patterned beam 309. The patterned beam 309 is generated by a light projector 378, which is controlled by a computer X3 through a cable wiring X5. After reflection from the hot / cold mirror 376, the patterned beam 311 is formed by the superposition of beams 307 and beams 309 in beam 311, and both beams 307 and beams 309 are imaged onto an optically addressed light valve 380. The polarization state of the unpatterned light 331 is rotated by the optically addressed light valve 380, which is stimulated by the patterned light beams 309 / 311 and the electrical signal from the computer X3 through the cabling X4 to selectively not rotate the polarization state of the polarized light 307 / 311 in the pattern of the number "9" into the beam 313. The unrotated light in the beam 313 representing the pattern 333 is then allowed to pass through the polarizer mirror 382, ​​thereby producing the beam 317 and the pattern 335. The polarized light in the second rotation state is rejected by the polarizer mirror 382, ​​forming the beam 315 carrying the negative pixel pattern 337 consisting of the unlit number "9".

[0048] Other types of light valves may be used in place of or in combination with the light valves described. Reflective light valves or light valves based on selective diffraction or refraction may also be used. In some embodiments, non-light addressable light valves may be used. These may include, but are not limited to, electrically addressable pixel elements, movable mirrors or micro-mirror systems, piezoelectric or micro-actuated optical systems, fixed or movable masks or shields, or any other conventional system capable of providing high intensity light patterning. For electron beam patterning, these valves can selectively emit electrons based on address location, thereby injecting a pattern on the electron beam leaving the valve.

[0049] Figure 3C The details and operation of the energy switching unit X0 are shown. Figure 3C As shown, a light beam 311 carrying a representative input pattern 376 (here viewed as the number "9" in an 8×12 pixel array) in an s-polarization state is incident on a single pixel liquid crystal (LC) cell 380. The LC cell 380 rotates the polarization state of the beam 311 (if necessary), and the LC cell 380 is electrically stimulated by the computer X3 via the cabling X4 to selectively rotate the polarization state of the polarized light 311 to the p-polarization state in the beam 313, which then causes the entire beam to pass through the polarizer element 382 to form the beam 317 carrying the image information 335. Alternatively, the LC cell 380 can be directed by the computer X3 via the cabling X4 to not rotate the polarization state of the beam 311, thereby maintaining the polarization state of the s-polarization in the beam 313, which results in the reflection of the beam 315 carrying the image information 337. The polarizer element 382 can also be used to receive light from the source beam X1 carrying the image information X2. The routing of beam X1 is completely passive based on its polarization state, if X1 is s-polarized it will be reflected into beam 317, or alternatively if it is p-polarized it will be transmitted into beam 315 (or vice versa).

[0050] Other types of energy switching devices may be used in place of or in combination with the described LC cells. Reflective LC cells, or energy switching devices based on mechanical motion (such as movable mirrors) or selective refraction, piezoelectric or microactuated optical systems, fixed or movable masks or shields, or any other conventional system capable of providing high intensity energy switching may also be used. For electron beams, these switching mechanisms may consist of large arrays of EM fields that direct the beam into different channels or paths.

[0051] Figure 3D is an embodiment of an additive manufacturing system including a switch station system that supports repeated use of patterned two-dimensional energy. Figure 1AIn the embodiment discussed, the additive manufacturing system 220 has an energy patterning system having an energy source 112 that directs one or more continuous or intermittent energy beams to a beam shaping optical device 114. After shaping, the beam is patterned in two dimensions by an energy patterning unit 230, where generally, some of the energy is directed to a rejected energy processing unit 222. The patterned energy is relayed by one of a plurality of image relays 232 toward one or more item processing units 234A, 234B, 234C, or 234D, typically as a two-dimensional image focused near a movable or fixed height bed. The bed (with optional walls) can form a chamber that holds the material dispensed by the material dispenser. The patterned energy directed by the image relay 232 can melt, fuse, sinter, merge, change the crystal structure, affect the stress pattern, or otherwise chemically or physically change the dispensed material to form a structure with desired properties.

[0052] In this embodiment, the rejected energy processing unit has multiple components to allow the rejected patterned energy to be reused. Repeaters 228A, 228B, and 228C can transfer energy to generator 224, heating / cooling thermal management system 225, or energy dump 226, respectively. Optionally, repeater 228C can direct the patterned energy to image repeater 232 for further processing. In other embodiments, the patterned energy can be directed by repeater 228C to repeaters 228B and 228A for insertion into the energy beam provided by energy source 112. Image repeater 232 can also be used to reuse patterned images. Images can be redirected, inverted, mirrored, sub-patterned, or otherwise transformed to be distributed to one or more item processing units 234A-234D. Advantageously, the reuse of patterned light can improve the energy efficiency of the additive manufacturing process, and in some cases improve the energy intensity directed to the bed, or reduce manufacturing time.

[0053] Figure 3D is an animated diagram 235 showing a simple geometric transformation of a rejected energy beam for reuse. An input pattern 236 is directed into an image relay 237 which provides a mirrored image pixel pattern 238. As will be appreciated, more complex pixel transformations are possible, including geometric transformations or pattern remapping of individual pixels and groups of pixels. Rather than being wasted in a beam dump, this remapped pattern can be directed to an article processing unit to improve manufacturing yield or beam intensity.

[0054] Figure 3Eis an animated diagram 235 showing multiple transformations of the rejected energy beam for repeated use. An input pattern 236 is directed into a series of image relays 237B-237E which provide a pixel pattern 238.

[0055] In another embodiment that supports light recycling and reuse, multiplexing of multiple light beams from one or more light sources is provided. Multiple light beams can be reshaped and mixed to provide a first light beam. A spatial polarization pattern can be applied to the first light beam to provide a second light beam. The polarization state of the second light beam can be split to reflect a third light beam, and the third light beam can be reshaped into a fourth light beam. The fourth light beam can be introduced as one of the multiple light beams to produce a fifth light beam. In fact, this system or similar systems can reduce the energy costs associated with additive manufacturing systems. By collecting, beam combining, homogenizing and reintroducing unwanted light rejected by a spatial polarization valve or light valve operating in a polarization modification mode, the total transmitted light power can potentially be unaffected by the pattern applied by the light valve. This advantageously results in the light passing through the light valve being effectively redistributed into a desired pattern, thereby increasing the light intensity in proportion to the amount of patterned area.

[0056] Combining beams from multiple lasers into a single beam is one way to increase beam intensity. In one embodiment, wavelength selective mirrors or diffraction elements can be used to combine multiple beams, each with a different wavelength of light. In some embodiments, reflective optical elements that are insensitive to wavelength-dependent refractive effects can be used to direct multi-wavelength beams.

[0057] The patterned light can be directed using a movable mirror, prism, diffractive optical element, or solid-state optical system that does not require substantial physical movement. In one embodiment, a magnification ratio and image distance associated with the intensity and pixel size of incident light at a location on the top surface of a powder bed can be determined for a three-dimensional (3D) printing job for additive manufacturing. One of a plurality of lens assemblies can be configured to provide incident light with a magnification ratio, wherein the lens assembly has both a first group of optical lenses and a second group of optical lenses, and the second group of optical lenses can be exchanged from the lens assembly. Rotation of one or more groups of mirrors mounted on a compensation gantry and a final mirror mounted on a build platform gantry can be used to direct incident light from a precursor mirror to a location on the top surface of the powder bed. The translational movement of the compensation gantry and the build platform gantry can also ensure that the distance of the incident light from the precursor mirror to the location on the top surface of the powder bed is substantially equal to the image distance. In practice, this enables the beam delivery size and intensity to be quickly varied at the location of the build area for different powdered materials while ensuring high availability of the system.

[0058] Multiple build chambers may optionally be used, each having a build platform for holding a powder bed, the build chambers may be used in conjunction with multiple optomechanical assemblies arranged to receive one or more incident energy beams and direct them into the build chamber. Multiple chambers allow one or more print jobs to be printed simultaneously in one or more build chambers. Removable chamber sidewalls may simplify removal of printed objects from the build chamber, allowing rapid exchange of powdered materials. The chamber may also be equipped with an adjustable process temperature controller.

[0059] As described above, one or more build chambers can have a build chamber that is maintained at a fixed height while the optics are vertically movable. The distance between the final optics of the lens assembly and the top surface of the powder bed can be managed to be substantially constant by indexing the final optics upward a distance equivalent to the thickness of the powder layer while maintaining the build platform at a fixed height. Advantageously, large and heavy objects can be more easily manufactured than with a vertically moving build platform because precise micron-scale movement of the ever-changing mass of the build platform is not required. Typically, build chambers intended for metal powders with volumes greater than about 0.1-0.2 cubic meters (i.e., greater than 100-200 liters or weighing more than 500-1,000 kg) will benefit most from maintaining the build platform at a fixed height.

[0060] Optionally, a portion of the powder bed may be selectively melted or fused to form one or more temporary walls from the fused portion of the powder bed to accommodate another portion of the powder bed on the build platform. Fluid channels may be formed in one or more first walls to achieve improved thermal management.

[0061] Improved powder handling can be another aspect of the improved additive manufacturing system. The build platform supporting the powder bed can be tilted, inverted, and shaken to substantially separate the powder bed from the build platform in a hopper. The powdered material forming the powder bed can be collected in the hopper for reuse in subsequent printing jobs. The powder collection process can be automated, and a vacuum system or gas injection system can also be used to assist in powder removal and removal.

[0062] Some embodiments of the disclosed additive manufacturing system can be configured to easily process parts that are longer than the available room. Continuous (long) parts can be sequentially advanced from a first area to a second area in a longitudinal direction. In the first area, selected particles of granular material can be merged. In the second area, unmerged particles of granular material can be removed. A first portion of the continuous part can advance from the second area to a third area, while the last portion of the continuous part is formed within the first area, and the first portion remains in the same position in the lateral direction and the transverse direction as the first portion occupied in the first area and the second area. In fact, additive manufacturing and cleaning (e.g., separation and / or reuse of unused or unmerged granular material) can be performed in parallel (i.e., simultaneously) at different locations or areas on the part conveyor without stopping to remove granular material and / or parts.

[0063] Optionally, additive manufacturing capabilities may be enhanced by using an enclosure that limits gaseous material exchange between the interior of the enclosure and the exterior of the enclosure. An airlock provides an interface between the interior and the exterior; wherein the interior has multiple additive manufacturing chambers, including a chamber that supports powder bed fusion. A gas management system maintains gaseous oxygen within the interior at or below a limiting oxygen concentration, thereby increasing the flexibility of powder types and processes that can be used in the system.

[0064] Capacity can be increased by including a 3D printer within the enclosure that is capable of creating parts weighing greater than or equal to 2000 kg. A gas management system can maintain gaseous oxygen within the enclosure at a concentration below atmospheric levels. In some embodiments, a wheeled vehicle can transport parts from inside the enclosure through an airlock, as the airlock serves to buffer between the gaseous environment inside the enclosure and the gaseous environment outside the enclosure, and to a location outside both the enclosure and the airlock.

[0065] Optionally, collected powder samples can be collected in real time in a powder bed fusion additive manufacturing system. The acquisition system is used for in-process collection and characterization of powder samples. Collection can be performed periodically, and the results of the characterization lead to adjustments to the powder bed fusion process. The acquisition system can optionally be used for one or more of auditing, process adjustment, or actions (such as modifying printer parameters or verifying the correct use of licensed powder materials).

[0066] Yet another improvement to the additive manufacturing process is described, which may be provided by the use of a manipulator device, such as a crane, lifting gantry, robotic arm, or similar device, which allows manipulation of parts that are difficult or impossible for a person to move. The manipulator device can grasp various permanent or temporary additive manufacturing manipulation points on the part to enable the part to be repositioned or manipulated.

[0067] According to the present disclosure, an optical system capable of recycling rejected, unwanted light and / or unused light is provided. Recycling and reusing unwanted light can increase the intensity of laser emission light provided to a build platform. In addition, recycling and reusing unwanted light can reduce energy costs associated with the system. By collecting, beam combining, homogenizing, and reintroducing unwanted light that is rejected by a spatial polarization valve or light valve operating in a polarization modification mode, the total transmitted light power can potentially be unaffected by the pattern applied by the light valve. This advantageously results in the light passing through the light valve being effectively redistributed into a desired pattern, thereby increasing the light intensity in proportion to the amount of patterned area. This is useful for advanced additive manufacturing methods using powder bed fusion techniques, such as those described herein with respect to Figures 1A to 3B Those described above are particularly useful, and are particularly useful for laser additive manufacturing, because the increased intensity can allow shorter dwell times and faster print rates to increase material conversion rates while maintaining efficiency.

[0068] Spatial patterns of light can be imprinted on a beam of light through light valves or light modulators. When light intensity is a concern or quality factor for an optical system, conservation of system power is a priority. Liquid crystal-based devices are able to pattern a polarized beam by selectively rotating "pixels" in the polarized beam and then passing the beam through a polarizer to separate rotated pixels from non-rotated pixels. Instead of discarding rejected polarization states, photons can be combined with the original input beam and homogenized to the light valve. The light path can be divided into three segments, including: 1) the optical transmission fraction between the light source and the light valve (denoted as "f1" in this article), 2) the optical transmission fraction between the light valve and the light source, such as considering the return loop (denoted as "f2" in this article), and the fraction of the light valve that is patterned to the desired transmission state (denoted as "f2" in this article). p ”). The final optical power can be expressed as follows using Equation 1:

[0069] Equation 1: .

[0070] Therefore, according to Equation 1, when the transmission fraction f 1 and f 2 Increasing to a full value of 1, the final power is equal to the initial power, regardless of the fraction of the beam being patterned. The final intensity increases relative to the initial intensity in proportion to the amount of patterned area. This increased intensity requires compensation of the dwell time, which is however known a priori.

[0071] One example implementation of this concept is in the field of additive manufacturing, which uses lasers to melt powder layers of material. Without beam recycling, as the fill factor of the patterned area decreases, the material print rate also decreases, thereby reducing the overall mass production rate of the printer. Compensation for the dwell time due to light recycling causes the dwell time to decrease in a non-linear manner for higher intensities. Shorter dwell times tend to result in even faster print rates and faster overall mass conversion rates. This ability to increase the material print rate of low fill factor print areas allows the additive manufacturing machine to maintain a high level of powder to engineered shape conversion rate, therefore producing a higher performance product.

[0072] Another example implementation of the concept is when using a light bar that sweeps across the build platform and is modulated on and off while sweeping to produce a two-dimensional (2D) solid layer from a powder substrate. The use of recycled light in conjunction with this example is novel. The use of a bar that sweeps across the entire build platform requires that it needs to be able to always print at a 100% fill factor. However, typically only 10%-33% of the build platform is used. This low fill factor means that, on average, the size of the capital equipment in the laser power is 3 to 10 times oversized for the system. However, if the light can be recycled and the bar sweep speed is adjusted to match the required dwell time proportional to the fill factor, the printing speed can be increased so that it is closer to the optimal fill factor efficiency. In this case, capital equipment can be fully utilized. The ability to print with a sweeping light bar enables unidirectional printing, thereby simplifying the gantry system required to move the light around. This capability also allows for easy integration of powder sweeping mechanisms.

[0073] Another example implementation of the print bar concept includes a powder dispensing system that follows the bar, which puts down the next layer of powder while the previous layer is being printed. Advantageously, this can minimize system downtime.

[0074] Another example implementation of light recycling is to share light with one or more other print rooms. This example effectively makes available laser light appear as an on-demand resource, much like electricity available at a wall socket.

[0075] As previously mentioned Figure 2 As noted in the related description, recycling light need not be limited to reusing a uniform, unpatterned beam. Patterned images can also be reused, where the rejected light pattern can be inverted, mirrored, sub-patterned, or otherwise transformed for distribution to one or more item handling units. Figure 4A An embodiment for recycling light is shown in FIG. 4, which shows that it is possible to recover light from an input 401 and (2 n -1) Patterning levels 402a-402d generate 2n The energy patterning binary tree system 400 for each image can be created. At each level, a "positive" light pattern and a "negative" or rejected light pattern counterpart can be created and directed to additional patterning units or as patterned output 408. Each light pattern can be further modified by multiple level transformations 404, which can modify the pattern, reduce the intensity in selected pattern areas, or otherwise change the light characteristics.

[0076] Figure 4B 4 is an animated diagram 410 showing pattern recycling from one input 411 to multiple outputs 414 by using a combined light patterning and steering mechanism 412. In this example, four output paths are provided, with a first possible output path having no patterned light, a second output path having a reduced light intensity pattern that is mirrored but otherwise identical to the input pattern 411, a third output path having a new pattern created by light pixel redirection, and a fourth output path having a significantly smaller but higher intensity pattern. As will be appreciated, these patterns are merely examples, and various output patterns that are smaller, larger, differently shaped, or have lower / higher light intensity patterns may be formed by appropriate adjustments. In some embodiments, the output pattern may be modified by optical reflection, inversion, etc. of the entire input image, while in other embodiments, pixel block or individual pixel level adjustments are possible.

[0077] Figure 4C is an animated diagram 420 showing pattern recycling from multiple inputs 421 to output 424 by using a combined light patterning and steering mechanism 422. In this example, four patterned inputs are combined into a higher intensity output 424 by rotating or flipping light input patterns 2, 3, and 4 to match and combine with input pattern 1. Similar to the animation Figure 4B It should be understood that these patterns are examples only and that modifications of the pattern and light intensity can be made at the level of the entire image, pixel blocks or individual pixels.

[0078] Figure 4D is a schematic example of an implementation of a switchyard concept for additive manufacturing, detailing two light valve patterning steps and beam redirection, where each image can only access half of the energy steering elements. In this example, one image can only access beam steering elements 471, 462, 472, and 466, while the second image can access 470, 473, 455, and 474. In operation, an unpatterned infrared beam 430 in an s-polarization state is incident on an energy patterning element 432 (e.g., similar to Figure 3BEnergy patterning unit 432 is addressed by a patterned UV image 433 (here a representation of the number "9" in an 8×12 pixel format) from a projector via beam 434. The polarization state of beam 431 containing image information 433 is maintained regardless of where the UV light is incident on the energy patterning unit. Upon incident on an internal polarizer element at 430, energy patterning unit 432 then splits the beam, directing image 446 in the p-polarization state along beam 435 to energy switching unit 447 (e.g., via Figure 3C 43). The image 437 in the s-polarization state is then sent along beam 436 to a second energy patterning unit 438, which is addressed by a UV beam 440 containing image information 439. The energy patterning unit 438 sends the image 442 in the p-polarization state along beam 441 to an energy switching unit 449. The image 444 in the s-polarization state from the energy patterning unit 438 is sent along beam 443 to a beam dump 445, where the image 444 is rejected or otherwise utilized.

[0079] The first image, denoted as 446, is incident on an energy switching unit 447, which receives beam 435 containing image information 446 in a p-polarization state and, in this example, passes beam 435 unchanged as beam 457, which still contains image information 446 and maintains p-polarization, and beam 457 is then incident on an energy switching unit 458. Energy switching unit 458 receives beam 457 containing image information 446 and, in this example, passes beam 457 as beam 463 converted to an s-polarization state and still containing image information 446, and beam 463 is then incident on an energy switching unit 464. Energy switching unit 464 receives beam 463 containing image information 446 and, in this example, passes beam 463 as beam 465, which maintains s-polarization state and still contains image information 446, and beam 465 is then incident on an energy steering unit 466. The energy steering unit 466, which may be a mechanical (rotating) galvanometer or other solid-state or rotating device, then directs the beam 465 within its range of motion to the desired tile location on the print bed.

[0080] The second image, denoted as 442, is incident on an energy switching unit 449, which receives beam 441 containing image information 442 in a p-polarization state and, in this example, passes beam 441 unchanged as beam 450 still containing image information 442 and maintaining p-polarization, and beam 450 is then incident on energy switching unit 451. Energy switching unit 451 receives beam 450 containing image information 442 and, in this example, passes beam 450 as beam 467 maintaining p-polarization and still containing image information 442, and beam 467 is then incident on energy switching unit 468. Energy switching unit 468 receives beam 467 containing image information 442 and, in this example, passes beam 467 as beam 469 maintaining p-polarization and still containing image information 442, and beam 469 is then incident on energy steering unit 470. The energy steering unit 470 can be a mechanical (rotating) galvanometer or other solid-state or rotating device, which then directs the beam 469 to the desired tile location on the print bed within its range of motion. Figure 3D and Figure 5A-Figure 5C The image relay in question occurs between beam 435 / 441 and the energy steering unit. Figure 4D Lenses, mirrors and other pre-, post- or intermediate optical devices are not shown, but may be used as desired.

[0081] Figure 4E is a schematic example of an implementation of the switch station concept, detailing two light valve patterning steps and beam redirection, where switching is demonstrated to reach all energy steering units. In this example, an image can now reach beam steering units 471, 462, 472, 466, 470, 473, 455, and 474. An unpatterned infrared beam 430 in the s-polarization state is incident on energy patterning unit 432 (e.g., via Figure 3B 316 in the figure), the energy patterning unit 432 is addressed by a patterned UV image 433 (here a representation of the number "9" in an 8×12 pixel format) from a projector via beam 434. The polarization state of beam 431 containing image information 430 is maintained regardless of where the UV light is incident on the energy patterning unit. When 430 is incident on the internal polarizer element, the energy patterning unit 432 then splits the beam, directing the image 446 in the p-polarization state along beam 435 to the energy switching unit 447 (as by Figure 3C43). The image 437 in the s-polarization state is then sent along beam 436 to a second energy patterning unit 438, which is addressed by a UV beam 440 containing image information 439. The energy patterning unit 438 sends the image 442 in the p-polarization state along beam 441 to an energy switching unit 449. The image 444 in the s-polarization state from the energy patterning unit 438 is sent along beam 443 to a beam dump 445, where the image 444 is rejected or otherwise utilized.

[0082] The first image 446 is incident on an energy switching unit 447, which receives the beam 435 containing the image information 446 in the p-polarization state and, in this example, modifies the polarization state to s-polarization so as to switch to a beam 448 that still contains the image information 446, which is then incident on an energy switching unit 449. The energy switching unit 449 receives the beam 448 containing the image information 446 and, in this example, transfers the beam 448 to a beam 450 that keeps the s-polarization state unchanged and still contains the image information 446, which is then incident on an energy switching unit 451 (this process is performed by Figure 3C The beam X1 in the image information 446 interacts with the polarizer 382 to form the beam 317 (described in detail). The energy switching unit 451 receives the beam 450 containing the image information 446, and in this example, transmits the beam 450 to the beam 452 which maintains the s-polarization state and still contains the image information 446, and then the beam 452 is incident on the energy switching unit 453. The energy switching unit 453 receives the beam 452 containing the image information 446, and in this example, transmits the beam 452 to the beam 454 to maintain the p-polarization state and still contain the image information 446, and then the beam 454 is incident on the energy steering unit 455. The energy steering unit 455 can be a mechanical (rotating) galvanometer or other solid-state or rotating device, and then the energy steering unit 455 guides the beam 454 to the desired tile position on the print bed within its range of motion.

[0083] The second image, denoted as 442, is incident on an energy switching unit 449, which receives beam 441 containing image information 442 in a p-polarization state and, in this example, modifies the polarization state to s-polarization so as to switch to beam 456 still containing image information 442, which is then incident on an energy switching unit 447. Energy switching unit 447 receives beam 456 containing image information 442 and, in this example, transfers beam 456 to beam 457 which retains the s-polarization state unchanged and still contains image information 442, which is then incident on an energy switching unit 458 (this process is performed by Figure 3CThe beam X1 in the image information 442 interacts with the polarizer 382 to form the beam 317 (described in detail). The energy switching unit 458 receives the beam 457 containing the image information 442, and in this example, transmits the beam 457 to the beam 459 that modifies the beam to the p-polarization state and still contains the image information 442, and then the beam 459 is incident on the energy switching unit 460. The energy switching unit 460 receives the beam 459 containing the image information 442, and in this example, transmits the beam 459 to the beam 461 that modifies the beam to the s-polarization state and still contains the image information 446, and then the beam 461 is incident on the energy steering unit 462. The energy steering unit 462 can be a mechanical (rotating) galvanometer or other solid-state or rotating device, and then the energy steering unit 462 guides the beam 461 to the desired tile position on the print bed within its range of motion. In this example, such as at least the present disclosure with respect to Figure 3D and Figure 5A-Figure 5C The image relay in question occurs between beam 435 / 441 and the energy steering unit. Figure 4E Lenses, mirrors and other pre-, post- or intermediate optical devices are not shown, but may be used as desired.

[0084] Figure 5A is an animated diagram 500 illustrating area printing of multiple tiles using the print bar concept. The print bar 506 can include a galvanometer mirror array or a solid-state system that does not necessarily require a movable mirror. Multiple input patterns 503 are redirected by multiple image relays 504 into the print bar 506, which includes a solid-state array of image pipes and optics. As shown, the print bar 506 can be moved across the powder bed 510 along a single axis, selectively irradiating one or more tiles 512. In other embodiments with larger powder beds, the print bar can be moved along the X-axis and Y-axis to cover the powder bed 510. In one embodiment, the optics associated with the print bar can be fixed to support a single tile size, while in other embodiments, movable optics can be used to increase or decrease the tile size, or compensate for any Z-axis movement of the print bar. In another embodiment, the recycled light pattern can be used to create a patterned image, including but not limited to, such as about Figure 4A Energy patterning binary tree system discussed. In some embodiments, multiple tiles can be printed simultaneously in a given time period. Alternatively, if the available patterning energy, thermal issues or other print bar configuration issues do not allow full utilization, subsets of tiles can be printed at different times.

[0085] Figure 5Bis an animated diagram 501 showing area printing of multiple tiles using an overhead fixed array system consisting of multiple beam steering units. The beam steering units, which are delineated unit cells in 508, can be composed of movable mirrors (galvanometers) or an alternative solid state beam steering system. Multiple input patterns 503 are redirected by multiple image relays 504 into a matrix 508 containing an array of optics. The dimensions of the matrix 508 are designed to be coextensive with the powder, and the matrix 508 does not need to be moved across the powder bed 510. This greatly reduces the errors associated with moving the print bar and can simplify the assembly and operation of the system. In one embodiment, the optics associated with the matrix can be fixed to support a single tile size, while in other embodiments, movable optics can be used to increase or decrease the tile size, or to compensate for any Z-axis movement of the matrix 508. Similar to the description of Figure 5A The embodiments discussed can use the recycled light patterns to create patterned images, including but not limited to, Figure 4A , Figure 4D or Figure 4E Energy patterning binary tree system discussed. In some embodiments, multiple tiles can be printed simultaneously in a given time period. Alternatively, if the available patterning energy, thermal issues or other matrix configuration issues do not allow full utilization, subsets of tiles can be printed at different times.

[0086] Figure 5C is an animated diagram 502 showing area printing of multiple tiles using an alternative layering system. Multiple input patterns 503 are redirected by multiple image relays 504 into separate beam steering units 510, which in turn direct the patterned images into a matrix 508 containing multiple optical devices and beam steering units. The dimensions of the matrix 508 are designed to be coextensive with the powder, and the matrix 508 does not need to be moved across the powder bed 510. Similar to the Figure 5A The embodiments discussed can use the recycled light patterns to create patterned images, including but not limited to, Figure 4A Energy patterning binary tree system discussed. In some embodiments, multiple tiles can be printed simultaneously in a given time period. Alternatively, if the available patterning energy, thermal issues or other matrix configuration issues do not allow full utilization, subsets of tiles can be printed at different times.

[0087] refer to FIG. 6A to FIG. 6D In the above method, a high fluence energy beam (e.g., beam 307) is image patterned with a two-dimensional pattern and then the patterned beam is transferred to a powder bed, where the pattern is transferred to a molten metal pool on the powder bed with direct spatial correlation to the two-dimensional pattern. As described above, the two-dimensional pattern can be a grayscale pattern. FIG. 6A to FIG. 6CThe described method utilizes 2D grayscale patterns to achieve desired material properties beyond simply selecting regions of the powder bed to be melted. In particular, spatial temperature gradients and local control of heat flow can be controlled by the selection of 2D grayscale patterns. FIG. 6A to FIG. 6C The described method can also be implemented using binary intensity levels (eg, 0% intensity and 100% intensity), where the duty cycle (duration of the on and off periods) of each pixel of the two-dimensional pattern is adjusted.

[0088] Fig. 6A A method 600a for performing grayscale area printing for additive manufacturing (AM) is shown. In a first example 602, an amplitude-based method can be used to perform area printing in AM. In a second example, a phase-based method 604 can be used to perform area printing in AM. Figure 3A Examples of amplitude-based printing and phase-based printing using two-dimensional grayscale patterns are described.

[0089] In both the amplitude-based and phase-based methods, an unpatterned high-fluence light (HFL) (e.g., laser) beam 606 is generated. The HFL beam 606 may be composed of light from multiple different sources that are mixed and combined to form a single beam. The HFL beam 606 enters a patterning device 608 that modifies a certain optical property of the HFL and leaves a desired two-dimensional grayscale image on the property to be printed at the powder bed. In some embodiments, the patterning device 608 may include another optical element that separates the desired pattern from the undesired waste (beam) and sends the desired pattern to the bed, while the undesired pattern enters a switchyard system for recycling or enters a beam collector.

[0090] The patterning device 608 may include one or more optically addressed light valves (OALVs). For example, the patterning device 608 may include one or more OALVs, each OALV being configured to implement the above-described Figure 3A The OALV can be used to print an image ("tile") of the light valve onto a layer of metal powder at the powder bed. The fluence of the HFL beam 606 on the OALV is limited by the laser induced damage threshold (LiDT) of the OALV. In other embodiments, as described above with respect to Figure 3B As described above, the patterning device 608 performs patterning by electron beam.

[0091] In a first example, a patterning device 608 includes a first OALV 610 and a second OALV 612, the first OALV 610 being illuminated by the HFL beam 606 and the second OALV 612 being illuminated by a DL beam 614 from one or more diode lasers (DL). The DL beam 614 and the HFL beam 606 may have different wavelengths, for example, the DL beam may have a longer wavelength than the HFL beam 606. The HFL beam 606 may also have a pulse duration that is much shorter than the pulse length of the DL beam 614, because the high peak fluence of the HFL beam 606 may damage the OALV 610. The OALV 610 and the OALV 612 apply patterns to the HFL beam 606 and the DL beam, respectively, to obtain a patterned HFL beam 616a and a patterned DL beam 616b. The patterned beams 616a and 616b are directed to a printing plane 618. The patterns applied to the beams 606 and 614 may be the same or different.

[0092] At the print plane 618, the patterned DL beam 616a raises the metal powder temperature to just below the melting point, and the shorter pulses of the patterned HFL beam 616b melt the powder areas ("tiles") in the pattern applied by the OALV 610 valve to the HFL beam 606. The maximum size of the printed tile depends on the laser fluence that the OALV can retain without laser damage. The overlap of the light in the patterned beams 616a, 616b raises the fluence above the threshold for powder melting.

[0093] The patterned beams 616a, 616b may be directed to a print plane 618 with the aid of one or more galvo / steering mirrors 620, which selectively direct the patterned beams 616a, 616b to different areas of the print plane 618 where the beams 616a, 616b melt the powder and generate a print pattern 622 corresponding to the pattern of the patterned beams 616a, 616b. The beams 616a, 616b may pass through one or more optical components before being incident on the one or more galvo / steering mirrors 620. Other beam steering modalities, such as liquid crystals, may also be used.

[0094] In a second example 624, phase-based grayscale generation is performed using multiple beams that have a degree of coherence across the tile dimensions in the print plane 618. The coherence can be used to generate a two-dimensional pattern, so that in some embodiments, the HFL beam has a degree of coherence at the print plane 618. In contrast, the DL beam heats but does not melt the powder and can be unpatterned and incoherent at the print plane 618.

[0095] In phase-based grayscale, a high fluence beam 606 enters a patterning unit 608 that generates a patterned beam 616a, which is then split into several beamlets 626 that travel on different paths. Phase patterning may be applied to the high fluence beam 606 before splitting, or each beamlet 626 may be individually applied by a separate OALV or a different region of the same OALV. In some embodiments, better coherence and improved modulation are obtained if patterning is applied to the high fluence beam 616 before splitting. Optics may be used to arrange the beamlets 626 to ultimately combine at the print plane 618. The optics may include a path for each beamlet 616, and may include compensation optics to adjust the phase delay of each path, thereby improving the phase dynamic range achieved on the print bed. The beamlets 626 may then be reflected off the galvanometer / folding mirror 620 before combining and overlapping 628 at the print plane 618. Interference between beamlets 626 produces a two-dimensional intensity pattern that melts the two-dimensional print pattern 622 on the build plane.

[0096] The patterning unit 608 may be implemented as a phase interferometer device for applying grayscale patterns as described in US Application Serial No. 17 / 670,149.

[0097] Figure 6B An example 600b of using grayscale printing to control the Young's modulus of a printed part is shown. In these examples, the print plane 618 contains an example layer 630 under printing, which contains a volume 632 that is shown as being separated from the layer 630. The volume 632 is composed of the current printing layer 630a and one or more previously printed layers 630b, 630c. The volume 632 contains a structured material that is printed using grayscale printing to build its lattice structure and modify the grain features within the lattice structure.

[0098] Using the area printing method described in this article, each printed tile can be composed of millions of pixels. In this article, "pixel" is used to describe a single controlled area of ​​the melt pool associated with a specific two-dimensional pattern of the incident HFL beam, rather than an element of a two-dimensional image. The fluence intensity observed by each pixel can be controlled within a grayscale dynamic range using any of the above methods. For example, adjacent pixels can have different grayscale values. In examples where different pixels have different grayscale values, the melt pool sees multiple different fluence levels. This results in a temperature gradient from pixels with more fluence (more delivered energy is equivalent to higher temperature) to pixels with lower fluence (the opposite).

[0099] The global on-time of the HFL pulses of the HFL beam and the heating pulses of the DL beam allows the heat flow to be stabilized in the direction from high fluence to low fluence. The grain structure that begins to form after the end of the HFL pulse is in the same direction, so the grain structure follows the heat flow from high fluence pixels to low fluence pixels. For example, the grain structure can be affected by both the temperature to which the metal structure is heated and the cooling time. In various examples, the grain size will increase with increasing temperature. In other examples, the grain structure will increase with increasing cooling time. Therefore, the grain structure will be affected by the temperature to which the molten pool is heated and / or the cooling cycle. The temperature distribution applied to each pixel of the molten pool also affects the microstructure of the grain itself. For example, the type of crystal within each grain or a mixture of multiple types and different crystal types within each grain. For example, in the case of steel, crystals grow in the form of martensite dendrites and austenite. Therefore, the temperature distribution can control the formation of martensite and austenite within each grain.

[0100] The relationship between grain size and grain microstructure with respect to the temperature distribution controlled at each pixel level can be obtained using the method described in the following reference, which is incorporated herein by reference in its entirety: Ryan R, Dehoff, “Electron Beam Melting Technology Improvements,” Oak Ridge National Laboratory (January 2019); Jorge Mireles et al., “Closed Loop Automatic Feedback Control in Electron Beam Melting,” Int. J. Adv. Manuf. Technol. 78:1193-1199 (2015); Timothy Horn, “Material Development for Electron Beam Melting,” Center for Additive Manufacturing and Logistics, NC State University (2015); T. Mahale et al., “Advances in Electron Beam Melting of Aluminum Alloys,” 2007 International Solid Freeform Fabrication Symposium; Tomas Kellner, “This Electron Gun Builds Jet Engines,” General Electric, (August 18, 2014); Sciaky Inc., “Sciaky to Deliver Industry-Leading ElectronBeam Additive Manufacturing System to EWI,” Sciaky Inc. (July 20, 2016).

[0101] Material properties, such as stiffness, have a direct correlation to this grain growth and the resulting microstructure. Stiffness can be controlled by controlling the thermal gradient in order to control the direction in which the grains are allowed to grow and / or the local chemistry of each grain, such as solute elements at the walls of each grain that can affect the Young's modulus. For example, stiffness can increase with increasing grain size. Thus, in regions where the grain size is above average, the stiffness can be above average, while in regions where the grain size is below average, the stiffness can be below average. Thus, the stiffness of an object created using an additive manufacturing process as described above can be controlled on a per pixel basis according to the amount of fluence each pixel receives and therefore the temperature to which each pixel is heated.

[0102] In another example, the lattice structure and grain size of the material being cooled can be controlled based on the thermal gradient. For example, by controlling the thermal gradient of adjacent or nearby pixels and / or the cooling of the pixels, the level of epitaxial growth can be controlled and the overall structure of the material can be affected.

[0103] The grain structure between layers can be controlled by grayscale printing in synergy with time fluence control of the beam, so cooling can occur from bottom to top, with columnar grain growth following the cooling rate. Grain growth in this direction can be coupled with feature size. For example, acoustic resonances can be generated in the plane of layer 630, allowing acoustic resonances in all three dimensions. Acoustic resonances in the interlayer direction can be different from acoustic resonances in the plane of printed layer 630, due to better control in the latter.

[0104] In the example, one or more cold pixels still above the sintering point will have a first stiffness, one or more moderately heated pixels above the melting point will have a second stiffness, and one or more pixels with the highest temperature will have a third stiffness. For those areas within the tile that exhibit a thermal gradient (according to the above-mentioned fluence differences), the modulus will vary from one level to another. It should be noted that while the modulus is described as having "levels", this does not necessarily describe discrete changes, and the change can be continuous.

[0105] Both the grain structure and the lattice structure can affect the thermal and acoustic properties of the cooled finished part. Depending on the structures created and whether these structures resonate with the acoustic field, the thermal and acoustic properties can be adjusted at least partially independently. As shown in the view 634 of the volume 632 in the normal direction 636 relative to the printing plane 618, the volume 632 can be composed of one or more types of lattices, for example, two or more types of lattices with a first periodicity 638 and a second periodicity 640 extending orthogonally to each other can be observed. The width of each lattice feature in two mutually perpendicular dimensions (e.g., dimension 'X', dimension 'Y') of the printing plane 618 can resonate at a specific acoustic frequency.

[0106] Acoustic properties can be formed based on grayscale, for example, grayscale along "X" and across "Y" can have a periodicity corresponding to the desired lattice spacing 638, lattice spacing 640. The spacing in the lattice openings can also resonate at the same or different frequencies. In an embodiment, the acoustic resonance is a macroscopic result of the variation of Young's modulus within and between tiles as shown in view 634. When viewed parallel to the plane along direction 642, the print volume 632 can show that the direction of grain growth applied between layers as shown in view 644 shows two or more lattice types with a second periodicity (e.g., in the X direction or the Y direction) and a third periodicity 646 (e.g., in the Z direction).

[0107] In another embodiment, by controlling the Young's modulus and large-scale cross-sectional area of ​​a desired path, heat can be conducted in a specific manner to adjust thermal control. By increasing the density of a part from one layer to another or from within any lateral volume to any lateral volume, thermal paths can be established within the part, allowing a user to design and build thermal loops for enhanced cooling in the finished part. For example, referring to a normal (e.g., top-down) view of the printed layers 630, the first layer 630b can have a first density and the second layer 630c can have a second density. For example, the first layer 630b can have a lower density while the second layer 630c can have a higher density, or vice versa. Although in Figure 1BIn the examples shown, the density increase is depicted as a density increase between layers, but in other example embodiments, the density increase can be connected in a plane or in any desired volume shape. The grayscale printing techniques described herein can enable the creation of thermal paths within a tile, within a plane, or across layers to generate these volumes. The density can be further controlled to adjust the porosity so that heat pipes can be formed within the material along the X, Y, or Z directions or in non-perpendicular or curved paths relative to these directions.

[0108] Figure 6C An example 600c of crystallography of a macroscopic arrangement using grayscale printing is shown. Build plane 618 holds a print volume 640 including volume 642, which is Figure 6C 642. Volume 642 may represent one or more tile locations or a portion of a tile location in a plane parallel to build plane 618. Each tile may consist of millions of image pixels. Each image pixel has an independent fluence value within the range of fluence values ​​applied by OALV of any of the modalities listed above.

[0109] The top surface of the volume 640 currently being printed is located above the previously printed layers. Most of these layers are composed of crystal structures 644 of the same orientation, while other portions exhibit different crystal structures 646, 648, such as polycrystallographic structures. Structures 644, 646, 648 can span multiple layers of volume 640 and can have the same shape in each layer, or vary in shape from layer to layer to form structures 644, 646, 648 with curved or otherwise shaped contours whose boundaries are not perpendicular relative to build plane 618.

[0110] The crystal structures 644, 646, 648 can be formed layer by layer by using grayscale printing on one or more tiles forming the structures 644, 646, 648. Each grayscale level in the printed image represents a different fluence of powder / melt pool that hits that pixel, and in turn represents a different temperature that the melt pool will reach. If there are different grayscale levels across the tiles in the image, there can be a temperature gradient (representing a gradient from higher temperature to lower temperature) from a higher fluence melt pool to a lower fluence melt pool. As the HFL fluence decreases, these melt pools will begin to crystallize according to the time pulse function of the HFL coupled with the thermal gradient and the polycrystalline formation of the material. Depending on these factors (HFL beam characteristics, gradients, and crystal orientation), short grains or long grain structures are formed along these gradients. Various material properties are derived from crystal orientation and grain type (short or long and orientation), including yield strength, ductility, creep, fatigue, elongation, thermal and acoustic conduction, acoustic response and acoustic resonance, glass response (ability to self-heal or crack arrest), and fracture strength.

[0111] In addition to having structures 644, 646, 648 that span multiple layers, one or more layers 652 can be constructed within the volume 640 that have a different crystal structure than the layer 650 above or below the one or more layers 652. This may be useful for volume stress relief, planned delamination, volume crack arrest, or ensuring consistently sharp edges or similar controlled surfaces when micro-flaking. Additionally, these built-in features / defects can be used to incorporate desired thermal paths or other controlled phononic features into the volume 640.

[0112] These features / defects can be phononic resonators, which will allow local or global acoustic and thermionic resonances to be enhanced, controlled or dissipated for better operational performance, and can allow new mechanical capabilities to emerge. There is a large body of knowledge using "phononic crystals" and these techniques can be used to create, manipulate, control, enhance or dissipate phonons of varying frequencies and spatiotemporal bandwidth products, allowing existing and new applications to be incorporated into AM parts. For example, if an appropriate part is constructed with a variety of phononic resonators dispersed (by design) in a volume, then an external stimulus applied at a specific point on the outer surface of the finished part can induce a range of acoustic resonances. Changing the location and nature of the stimulus can induce other resonances, leading to other desired behaviors.

[0113] Fig.6D An example 600d of temporal structuring of grayscale printing in control of material properties is shown. A build plane 618 holds a print volume 660 being printed, with a current print layer 662 of the print volume 660 being shown as being printed. The current layer 662 is shown in detail as a shape 664 formed by a matrix of tiles 666, each of which includes an array of print pixels. Each tile 668 in the tiles 666 is shown as an array of individual pixels 670. The fluence size (grayscale value) and duration can be controlled for each pixel 670 of each tile 668. The fluence size and duration can then be selected to control the properties at each pixel location corresponding to each pixel 670 within each layer as each pixel 670 is printed as the current layer 662. The number of pixels shown is exemplary, and more or fewer pixels can be used depending on the resolution of the optical components used.

[0114] like Fig.6D As shown, tile 668 may include regions of pixels 670 having different material properties (shown by gray and white portions). Pixel matrix 672 shows exemplary timings 674 for each pixel 670 of a portion of tile 668. For each pixel 670, a timing having a value t is shown. nThe timing 674 of n = 0, 1, 2 or 3 (or any other number), depending on which region the pixel occupies. The time variable t n Some or all of the pulse duration, interval between pulses, and pulse pattern may be defined for each pixel 670. Some or all of the pulse duration, interval between pulses, and pulse pattern may be defined for one or both of the HFL beam and the DL beam.

[0115] For example, Fig.6D A timing diagram 674 of a pulse pattern for a pixel 670 is shown, where the horizontal axis is time and the vertical axis is the intensity or amplitude of the fluence. The higher (higher intensity) bars may correspond to the fluence of the HFL beam, and the lower (lower intensity) bars may correspond to the DL beam. In a first pattern 676, the DL beam has a single pulse with a first pulse duration, and the HFL beam has a plurality of second pulses with a second duration, all of which occur during the first duration of the HFL beam. The second pulses may be separated by a zero fluence period. The second pulses may have equal or unequal durations, and the zero fluence periods between the second pulses may have equal or unequal durations. As shown, the first pulse may start before the first of the second pulses and may continue after the last of the second pulses of the pattern 676. The duration of the first pulse before the first of the second pulses and the duration of the first pulse after the last of the second pulses may be equal or unequal.

[0116] In one example, pattern 676 represents a baseline pattern corresponding to t0. Patterns corresponding to t1, t2, t3 or other timing values ​​can be composed in various ways. In a first example, the patterns corresponding to t1, t2, t3 each have a corresponding number of repetitions of pattern 676. For example, pattern 678 includes pulses 680, 682, 684, each of which can represent a second pulse of the HFL beam or an instance of pattern 676. In either case, pulses 680, 682, 684 can appear within the duration of a single first pulse of the DL beam. In one example, pulse 680 corresponds to t1, pulse 682 corresponds to t2, and pulse 684 corresponds to t3.

[0117] In a second example, the duration of zero HFL beam intensity before and / or after pattern 676 is different for each pattern t1, t2, t3. In a third example, the pattern corresponding to t1, t2, t3 includes a second pulse having an intensity and / or duration different from the intensity and / or duration of the second pulse of the baseline pattern 676. The variables of pulse duration, pulse intensity, zero intensity duration between pulses, zero intensity duration before and after the second pulse define a design space from which a pattern can be defined to achieve the desired material properties for a given pixel. In particular, the duration of zero HFL intensity can allow cooling during or after execution of pattern 676. Although the first pulse is shown as constant intensity, it can have a time-varying intensity across pattern 676, which is achieved using the grayscale patterned beam generation techniques described herein.

[0118] In the example shown, the timing sequence t0, t1, t2, t3 of the matrix 672 results in different pixel regions 686a-686d within the tile 668, each region resulting in different material properties at the corresponding pixel location in the current print layer 662. For example, the first region 686a that receives the fluence pattern t0, the region 686b that receives the fluence pattern t1, the region 686c that receives the fluence pattern t3, and the region 686d that receives the fluence pattern t0. In the regions 686a, 686d, the material properties may correspond to the grayscale intensity level of the second pulse, which has a relatively small change due to the control of the cooling rate. In contrast, the regions 686b, 686c may have different material properties due to different patterns that provide a modification of the cooling rate indicated by the second pulse and the period of zero HFL beam fluence in which cooling occurs.

[0119] The duration of the first pulse, the second pulse, and the zero intensity period between the pulses may have a minimum duration determined by the switching period of the OALV used to pattern the HFL beam and the DL beam. Likewise, the increment by which the duration of the pulses may be varied may be a function of the switching period of the OALV used. For example, the OALV may have a switching period from 10 ms to 50 ms.

[0120] Figure 7An example application of grayscale AM ​​described herein is shown. Component 700 may include a protrusion 702 having a distal end 704, which is closer to the printing plane 618 than the attachment point of the proximal end 706 of the protrusion 702 to the rest of the component 700. The distal end 704 is printed before the proximal end 706 because the layer closer to the printing plane 618 will be printed before the layer farther away from the printing plane 618. Therefore, a support 708 can be printed and spanned between the printing plane 618 and the distal end 704 to keep the distal end 704 in place when printing subsequent layers. The support 708 is not part of the component 700 and must therefore be removed. In some embodiments, grayscale printing is used so that the support 708 has different material properties from the component 700. For example, the support 708 can be made more brittle, softer and / or more porous than the material forming the component 700.

[0121] Figure 8 Another example application of the grayscale AM ​​described herein is shown. Figure 8 A portion of the pixels of a component in a plane parallel to the print plane 618 or perpendicular to the print plane 618 is shown. Blank pixels represent non-printing pixels so that when printing, the powder area located within the projected tile will remain unmelted. Pixels marked "A" correspond to the edge of the printed component at the boundary between non-printing pixels and printing pixels. Pixels marked "B" correspond to the interior of the component that is not restricted by non-printing pixels. The heat flow rate flowing out of the A pixel is different from the heat flow rate flowing out of the B pixel because the non-printing pixel is not melted. Using the grayscale pattern, the intensity and / or duration of the fluence applied to the powder at each pixel position of the tile can be adjusted to take this into account. For example, the A pixel can receive a higher intensity fluence and / or a higher duration fluence from the HFL beam than the B pixel. In addition, the non-printing pixel can still be irradiated by the DL beam to slow down the heat flow from the A pixel. The pixels shown can represent pixels in a plane parallel to the print plane 618 or perpendicular to the print plane 618.

[0122] refer to Fig. 9, in a more general case, each pixel 900 can be understood as the central pixel in a 3×3×3 array 902, which includes the pixel 900 and all surrounding pixels. Testing, modeling, or a combination of both can be performed for a wide range of arrangements of the 3×3×3 pixel array 902. Specifically, modeling and / or testing can be performed for different arrangements of printed pixels and non-printed pixels, different values ​​of various material properties (Young's modulus, porosity, hardness, strength, grain size, microcrystalline structure, etc.) for each pixel, and different gradients in which the material properties vary across the 3×3×3 pixel array 902. Modeling and / or testing can be performed to determine the two-dimensional grayscale pattern and / or timing pattern that can be applied to each layer of the 3×3×3 pixel array 902 to achieve any of the above arrangements. Since all pixels except the center pixel 900 will be adjacent to other pixels, the modeling and testing can determine the grayscale intensity value and / or timing pattern of the pixel 900 given the characteristics of the pixel 900 and the surrounding pixels defined by the arrangement. Other array sizes may be modeled and / or tested, such as 5×5×5, 7×7×7, or N×M×P, where N, M, and P are integers greater than 3 and may or may not be equal.

[0123] Then, for a given component and the desired properties for each pixel of the component, a grayscale fluence value and / or timing pattern for each pixel can be selected based on the desired material properties (printed / unprinted, Young's modulus, porosity, hardness, strength, grain size, microstructure, etc.) and the desired material properties of neighboring pixels. In particular, a matching array 902 can be identified, and a grayscale fluence value and / or timing pattern can be selected for each pixel of the component based on the grayscale fluence and / or timing pattern of the center pixel 900 of the matching array 902.

[0124] In some cases, there may not be an array that matches exactly. To accommodate this, various techniques may be used, such as rotating the matrix 902 to conform to the contours and / or gradients of the component. In some embodiments, curve fitting, machine learning, or other techniques may be used to associate the material properties of the matrix 902 with the grayscale fluence value and / or timing pattern of the center pixel 900. In the case of using machine learning, a neural network, a convolutional neural network (CNN), a deep neural network (DNN), or other types of machine learning models may be trained using training data entries, each of which includes a matrix 902 of one or more material properties (printed / non-printed, Young's modulus, porosity, hardness, strength, grain size, etc.) for each pixel of the three-dimensional array, and the grayscale fluence value and / or timing pattern of the center pixel 900 (or other pixel position) of the three-dimensional array as the desired output. Each training data entry may be processed using a machine learning model to obtain an estimate. The estimate may be compared to the desired output of the training data entry. The parameters of the machine learning model may be adjusted according to a loss function corresponding to the difference between the estimate and the desired output. The machine learning model can then be utilized by inputting the three-dimensional array of desired properties to obtain the grayscale fluence value and / or timing pattern of one or more pixels (eg, the center pixel) of the three-dimensional array.

[0125] Many modifications and other embodiments of the present invention will occur to those skilled in the art having benefit of the teachings given in the foregoing description and the associated drawings. Therefore, it should be understood that the present invention is not limited to the specific embodiments disclosed, and modifications and embodiments are intended to be included within the scope of the appended claims. It should also be understood that other embodiments of the present invention can be practiced without elements / steps not specifically disclosed herein.

Claims

1. A method comprising: Depositing a powder layer on a print surface; writing a two-dimensional grayscale pattern into a light valve; emitting an original light beam from a light source onto the light valve to obtain a patterned beam having a two-dimensional fluence pattern corresponding to the two-dimensional grayscale pattern; and The patterned beam is directed onto an area of ​​the powder layer to obtain a molten portion having a two-dimensionally varying material property corresponding to the two-dimensional grayscale pattern.

2. The method according to claim 1, wherein: The two-dimensional grayscale pattern has at least three intensity levels.

3. The method according to claim 1, wherein: The two-dimensional grayscale pattern has at least three intensity levels selected from a range of at least 128 levels.

4. The method according to claim 1, wherein: The light valve modulates the amplitude of the original light beam to obtain the patterned beam.

5. The method according to claim 1, wherein: The light valve modulates the phase of the original light beam to obtain the patterned beam.

6. The method according to claim 1, wherein: The light valve modulates the coherence of the original light beam to obtain the patterned beam.

7. The method according to claim 1, wherein: The light source is a first light source, the light valve is a first light valve, the two-dimensional grayscale pattern is a first two-dimensional grayscale pattern, and the patterned beam is a first patterned beam, and the method further comprises: writing a second two-dimensional grayscale pattern into a second light valve; emitting a low fluence beam onto the second light valve to obtain a low fluence patterned beam, the low fluence beam being insufficient to melt the powder layer and having a lower fluence than the first patterned beam; and The low fluence patterned beam is directed onto the area simultaneously with the first patterned beam being directed onto the area.

8. The method according to claim 7, wherein: The first patterned beam includes one or more first pulses, and the low-fluence beam includes one or more second pulses, the one or more second pulses being longer than the one or more first pulses.

9. The method according to claim 1, wherein: The material properties include Young's modulus.

10. The method according to claim 1, wherein: The material properties include porosity.

11. The method according to claim 1, wherein: The material properties include grain size.

12. The method according to claim 1, wherein: The material properties include crystalline microstructure.

13. A system comprising: a powder delivery system configured to deposit a layer of powder onto a build plane; Light valve; a patterning unit configured to write a series of two-dimensional grayscale patterns into the light valve; a light source configured to emit an original light beam onto the light valve so that the light valve outputs a patterned beam corresponding to each two-dimensional grayscale pattern in the series of two-dimensional grayscale patterns; a beam redirector configured to redirect the patterned beam to a plurality of regions of the build plane to selectively melt portions of the powder layer according to the series of two-dimensional grayscale patterns; and A controller is coupled to the light source, the patterning unit and the beam redirector and is configured to generate the series of two-dimensional grayscale patterns to achieve two-dimensionally varying material properties within the portion.

14. The system according to claim 13, wherein: The controller is further configured to generate the series of two-dimensional grayscale patterns so as to apply a pulse pattern to each of the plurality of regions.

15. The system of claim 14, wherein: The series of two-dimensional grayscale patterns defines an array of pixel locations, and the controller is programmed to independently control the pulse pattern for each pixel location in the array of pixel locations.

16. The system of claim 13, wherein: The light source is a first light source, the light valve is a first light valve, the original light beam is a first original light beam, the patterned beam is a first patterned beam, and the series of two-dimensional grayscale patterns is a series of first two-dimensional grayscale patterns; Wherein, the system further comprises: - a second light valve; and - a second light source configured to emit a second original light beam onto the second light valve, the second light source having a smaller fluence than the first light source that is insufficient to melt the powder layer; wherein the patterning unit is configured to write a series of second two-dimensional grayscale patterns to the second light valve, so that the second light valve outputs a second patterned beam corresponding to each second two-dimensional grayscale pattern in the series of second two-dimensional grayscale patterns; and wherein the series of first two-dimensional grayscale patterns and the series of first two-dimensional grayscale patterns define a pixel position array, and the controller is programmed to independently control a first mode of a first pulse in the first patterned beam for each pixel position in the pixel position array, and to independently control a second mode of a second pulse in the second patterned beam for each pixel position in the pixel position array.

17. The system of claim 16, wherein: The first light source is a high fluence laser and the second light source is a diode laser.

18. The system of claim 13, wherein: The controller is configured to cause at least one pattern in the series of two-dimensional grayscale patterns to include at least three intensity levels selected from a range of at least 128 levels.

19. The system of claim 13, wherein: The light valve is configured to perform one of the following modulations: modulating the amplitude of the original light beam to obtain the patterned beam; modulating the phase of the original light beam to obtain the patterned beam; or The coherence of the original light beam is modulated to obtain the patterned beam.

20. The system of claim 13, wherein: The material properties include one or more of Young's modulus, porosity, grain size, and crystalline microstructure.

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