Systems and methods for scalable 3D laser processing using a metalens array

Abstract

The present disclosure relates to a system for parallel laser processing. The system has a laser for generating a laser beam, and a light modulator subsystem. The light modulator subsystem may have a modulator component for modulating at least one of a phase or amplitude of light from the laser beam, and a plurality of independently controllable pixels for enabling a phase to amplitude transformation on the light from the laser beam which impinges the light phase modulator component. The light modulator component generates a patterned light beam in accordance with a bit pattern provided by the independently controllable pixels. A non-imaging metalens array patterns the light beam. The metalens array may have a plurality of metalens units which each correspond to a plurality of pixels of the intensity modulator component, for parallel processing a material in at least one of an additive manufacturing printing operation or a material processing operation.

Description

LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POASYSTEMS AND METHODS FOR SCALABLE 3D LASER PROCESSING USING A METALENS ARRAYCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No.63 / 735, 564, filed on December 18, 2024. The entire disclosure of the above application is incorporated herein by reference.FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This invention was made with Government support under Contract No. DE-AC52-07NA27344 awarded by the United States Department of Energy. The Government has certain rights in the invention.FIELD

[0003] The present disclosure relates to laser processing systems used in laser processing applications, and more particularly to large scale and scalable 3D laser processing systems and methods that make use of a focusing component, in some embodiments a metalens array, capable of generating focal spot arrays in arbitrary grayscale or binary patterns, to dramatically increase throughput in laser processing applications, and in some embodiments in two-photon lithography printing operations.BACKGROUND

[0004] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0005] Achieving both high throughput and high resolution in precision manufacturing has long been a challenging goal. At small scales, laser processing stands out as a widely adopted technique for fabricating intricate 3D structures with remarkable precision. Traditional laser processing methods typically involve scanning a single laser focal spot through space to create the desired structures. However, this approach inherently involves a critical trade-off between throughput and resolution, primarily due to the limitations in mechanical scanning speed. To overcome this limitation, various parallel laser exposure techniques have been developed over the past decade, including using holography to generate the exposure geometry, scanning multiple focal spots, and directly projecting of a 2D pattern. Despite their advancements,LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA these methods are often constrained by the field of view (FOV) of the laser focusing unit, such as an objective lens, which restricts the overall size of the printable volume. For structures larger than the FOV, it becomes necessary to print sub-parts consecutively and then stitch them together. This process can introduce stitching errors and mechanical weaknesses at the joining points.

[0006] Accordingly, further advancements in TPL which overcome the limitations on printing throughput associated with the use of objective lenses, and the limitations and drawbacks of needing to stitch together sub-parts of a 3D part being constructed, are needed.SUMMARY

[0007] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0008] In one aspect the present disclosure relates to a system for parallel laser processing. The system may comprise a laser for generating a laser beam and a light modulator subsystem. The light modulator subsystem may have a modulator component for modulating at least one of a phase or amplitude of light from the laser beam, and having a plurality of independently controllable pixels for enabling a phase to amplitude transformation on the light from the laser beam which impinges the light phase modulator component. The light modulator component generates a patterned light beam in accordance with a bit pattern provided by the independently controllable pixels. The system may also comprise a metalens array responsive to the patterned light beam, wherein the metalens array consists of a plurality of metalens units. Each metalens unit corresponds to a plurality of pixels of the intensity modulator component for parallel processing a material in at least one of an additive manufacturing printing operation or a material processing operation.

[0009] In another aspect of the present disclosure the light modulator component comprises a light intensity modulator component, a quarter wave plate and a polarization beam splitter. The light intensity modulator component shapes an intensity distribution of the laser beam to at least one or a flat-top or arbitrary grayscale beam profile, when creating the patterned light beam.

[0010] In another aspect of the present disclosure the light intensity modulator component comprises a spatial light modulator (SLM).LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA

[0011] In another aspect of the present disclosure the light intensity modulator component comprises a digital micromirror device (DMD).

[0012] In another aspect of the present disclosure the light intensity modulator component comprises a grating light valve.

[0013] In another aspect of the present disclosure the laser comprises a femtosecond laser.

[0014] In another aspect of the present disclosure the femtosecond laser comprises a linearly polarized femtosecond laser having a pulse width of less than 200 fs.

[0015] In another aspect of the present disclosure the metalens array comprises a metalens array configured in a grid pattern.

[0016] In another aspect of the present disclosure the system further comprises an electronic controller for controlling at least one of the laser of the light modulator subsystem.

[0017] In another aspect of the present disclosure the system further comprises a telescope optical relay subsystem for receiving the patterned beam and placing a plane of the light intensity modulator component in conjugation with a plane of the metalens array.

[0018] In another aspect of the present disclosure the optical telescope comprises a Keplerian telescope having a first lens and a second lens separated by vacuum cell. The first lens, the second lens and the vacuum cell are aligned such that the patterned beam passes through the first cell, through the vacuum cell, and through the second lens before reaching the metalens array. The vacuum cell contains an intermediate, high-power laser focal spot created by the laser light modulator subsystem to prevent gas-phase ionization of air.

[0019] In another aspect the present disclosure relates to a system for parallel laser processing. The system may comprise an electronic controller, a laser for generating a laser beam, and a system for creating a patterned focal spot array for parallel laser processing. The system for creating a patterned focal spot array may comprise a light modulator subsystem having a plurality of independently controllable pixels and being responsive to the electronic controller, and having a light modulator component having a plurality of independently controllable pixels. The light modulator subsystem may form at least one of a light intensity modulator component for controlling an intensity of light generated by each one of the plurality of independently controllable pixels, or a phase modulator component configured to carry out a phase to amplitudeLLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA transformation on light being emitted from each one of the plurality of independently controllable pixels. The light modulator component generates a patterned light beam in accordance with a bit pattern provided by the independently controllable pixels. A telescopic relay optical system may be included which is comprised of a vacuum chamber that contains the intermediate high-power laser focal spot to prevent gas-phase ionization. The system may also include a metalens array responsive to the patterned light beam, wherein the metalens array consists of a plurality of non-imaging metalens units, and wherein each metalens unit corresponds to one or a plurality of pixels of the intensity modulator system for parallel processing a material in at least one of an additive manufacturing printing operation or a material processing operation.

[0020] In another aspect of the present disclosure the light modulator component comprises a spatial light modulator (SLM).

[0021] In another aspect of the present disclosure the light modulator component comprises a digital micromirror device (DMD).

[0022] In another aspect of the present disclosure the light modulator component comprises a grating light valve.

[0023] In another aspect of the present disclosure the laser comprises a femtosecond laser.

[0024] In another aspect of the present disclosure the femtosecond laser comprises a linearly polarized femtosecond laser having a pulse width of less than 200 fs.

[0025] In another aspect of the present disclosure the metalens array comprises a metalens array with the metalens units arranged in a grid.

[0026] In another aspect the present disclosure relates to a method for performing parallel laser processing. The method may comprise using a laser to generate a laser beam, and using a light modulator subsystem having a light intensity modulator component. The light intensity modulator component has a plurality of independently controllable pixels and patterns the laser beam to produce a patterned light beam in accordance with a bit pattern provided by the independently controllable pixels. The method further involves using a series of calibration procedures to find parameters for the light modulator subsystem to generate uniform or arbitrary programmed patterned light beam. The method further includes using a non-imaging metalens array responsive to the uniform or arbitrary programmed patterned light beam, wherein the metalens array includes a plurality of non-imaging metalens units, and wherein each metalens unit corresponds to one or a plurality of pixels of the light intensity modulator component. TheLLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA metalens unit cells generate focused points of light of uniform or selected intensities. The focused points of light are used to perform parallel processing of a material in at least one of an additive manufacturing printing operation or a material processing operation.

[0027] In another aspect of the present disclosure the processed material is in liquid form or gel form, and is sandwiched between the non-imaging metalens array and a solid substrate. The solid substrate is scanned using a stage system to produce a processed result. When the processed material is solid, the processed material is directly scanned using a stage system to produce the processed result.

[0028] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0030] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.

[0031] Figure 1 is a high level block diagram of one embodiment of a system in accordance with the present disclosure for performing high throughput laser processing in a two-photon lithography operation;

[0032] Figure 2a is a high level block diagram of select components of the system shown in Figure 1 to more fully illustrate how the intensity of the beam is patterned using the SLM;

[0033] Figure 2b is a high level zoomed-in schematic of Figure 2a to illustrate how the beam patterned by the SLM pixels incidents onto the metalens array, where less than one or one or more than one SLM pixels are correspond to and control the beam intensity for each metalens;

[0034] Figure 2c is a graph showing the intensity of the beam incident onto a selected metalens versus the phase value of the SLM pixels corresponding to the selected metalens, with one group of points representing an example set of measurement data, a curve representing interpolation of the measurement data, and another group of points representing the desired SLM pixel phase values that tune the focal spot of theLLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA selected metalens to a certain intensity, which allows the entire focus array to be uniform when it applies to all metalenses;

[0035] Figure 3a is a diagram illustrating a process of finding the processing threshold for each metalens by SLM phase sweeping, and more particularly illustrating a block pattern array to help illustrate how each block may be printed with a different SLM phase that decreases the laser focus intensity along the arrow direction;

[0036] Figure 3b is an optical image of the block arrays that were printed using the SLM phase sweeping of Figure 3a with a 6-by-7 metalens sub-array, with the inset illustration being a block array processed by a single metalens. The images shows that there are 12 blocks printed with this specific metalens, which dictates the threshold SLM phase value for this metalens;

[0037] Figure 4 shows how more than one SLM pixel may be mapped to a single metalens to provide increased bit-depth grayscale tuning for each metalens using multiple SLM pixels; and

[0038] Figure 5a-5e show a gallery of structures printed via two-photon lithography, where the time taken for printing the entire structure is the same as printing a single unit cell of the structure with pre-existing two-photon lithography systems;

[0039] Figure 6 is a high level flowchart showing various operations that may be performed in using the system of Figure 1 to print large array of uniform 3D parts in a two photon lithography printing process; and

[0040] Figure 7 is a high level flowchart showing various operations that may be performed using the SLM in determining a processing threshold for each metalens.DETAILED DESCRIPTION

[0041] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0042] The present disclosure relates to and significantly builds upon U.S. Patent Pub. No. 2022 / 0252761 A1 , assigned to the assignee of the present disclosure and hereby incorporated by reference into the present disclosure. The systems and methods disclosed in that application involve the use of a metalens array to create a focal spot array for two-photon lithography (TPL) was introduced. This significantly enhanced the scalability of 3D nano-printing and enabled an increase in fabrication throughput on the order of thousands of times compared to state-of-the-art TPL techniques. Building on this innovation, the present disclosure goes significantly further in disclosing aLLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA versatile, large-scale laser processing method using a metalens array capable of generating focal spot arrays with uniform intensities, arbitrary grayscale, or binary patterns.

[0043] The present disclosure presents a high-throughput, high-resolution laser processing approach to create large-scale micro- / nanostructures using a metalens array controlled by spatial light modulator(s). Conventional laser processing techniques are constrained by limitations such as slow single-focus scanning, limited working volumes, and significant stitching errors, rendering them unsuitable for the high- throughput fabrication of large structures with tiny features, e.g., a centimeter-scale structure with sub-micrometer resolution. By utilizing a metalens array, a focal spot array span can be generated over the entire wafer. Each focal spot in the array can be dynamically controlled regarding its grayscale and on / off states by one or more pixels of one or more spatial light modulator(s) placed in conjunction to the metalens plane. In some embodiments a large number of focal spots can be generated, and in some embodiments up to 10,000 focal spots can be generated, and in some embodiments greater than 100,000 focal spots can be generated. Laser processing can be performed simultaneously, leading to a massive improvement in the fabrication throughput. The systems and methods described herein can be applied to produce high-density 3D optical memory, architected meta structures, and custom micro-heatsinks for the nextgeneration semiconductor and energy solutions. This enables the writing of wafer-scale 3D structures with sub-micrometer resolution.

[0044] Referring to Figure 1 , one embodiment of a system 10 for TPL micro- / nanoprinting is shown. The system 10 in this example may include an electronic control system or computer 12 (hereinafter simply “ECS” 12) having a memory 14 for storing one or more software modules 16. The memory may be any suitable non-volatile memory such as non-volatile RAM / ROM / DRAM, etc., which may hold one or more algorithms, data tables, look-up tables, materials characteristics tables, performance curves, etc., or any other information / data that would be needed or helpful in printing a 3D part.

[0045] The ECS 12 is in communication with a laser 18. In this example the laser 18 is a femtosecond laser which produces a laser beam 18a. The laser beam 18 is redirected by a first mirror 20 into a beam expander 22. The beam expander expands and collimates the laser beam 18a, after which the laser beam passes through a half wave plate. The laser beam 18a then enters a polarization beam splitter (“PBS”) 26. The PBS 26 directs a portion of the laser beam 18a towards a first quarter wave plate (“QWP”) 28LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA and to an optical modulation component, which in this example is a spatial light modulator (“SLM”) 30. The SLM 30 patterns the light to create a patterned beam 18b which is passed back through the PBS 26 through a second QWP 34. A portion of the laser beam 18a passes through the PBS 26 into a beam dump 32.

[0046] The patterned light beam 18b passes through the second QWP 34 and into a Keplerian telescope formed by a first lens 36, a vacuum cell 38 and a second lens 40. The vacuum cell 38 is optional but preferred as it prevents ionization of air due to the high power, extremely short pulse width of the femtosecond laser 18. The vacuum cell 38 may also be needed with other lasers having a longer pulse width, if the laser power is sufficiently high. The patterned beam 18b is then redirected by a second mirror 42 towards a metalens array 44. The metalens array 44 is positioned closely adjacent to a build stage 46 on which a 3D part is to be constructed from a quantity of photo-resin. The metalens array 44 creates focused points of light representing focal spots 44a, visible in the perspective, highly enlarged rendering portion of Figure 1 , in accordance with the patterned beam 18b. The focal spots 44a, or focused points of light, each have a controlled optical intensity, and cause polymerization of select voxels within the photoresin, which enables 3D parts to be constructed with nano-scale resolution via scanning the build stage 46.

[0047] The system 10 in this example also includes an objective 48, a beam splitter 50, an LED 52 to provide illumination, a lens 54 and a camera 56. The camera 56 in this example is a CMOS device, and will hereinafter be referred to as “CMOS 56”. The CMOS 56 enables visualizing the build process of 3D parts in real time.

[0048] With further reference to Figure 1 , the femtosecond laser 18 in some embodiments is a linearly polarized femtosecond laser with a pulse duration of < 200 fs. The laser beam 18a produced by the femtosecond laser is expanded and collimated by the beam expander 22 or, alternatively, a custom-built magnifying telescope system may be used as a beam expander and collimator. After beam expansion, the size of the laser beam 18a is large enough to fully fill an aperture 30a of the SLM 30. The expanded laser beam 18a then passes through the half-wave plate 24 which rotates its polarization orientation to be reflected by the PBS 26. After that, the laser beam 18a is received by an intensity modulator subsystem comprised of the SLM 30, the first quarter-wave plate QWP 28, and the PBS 26. These components operate to shape the intensity distribution of the laser beam 18a, realizing a flat-top or arbitrary grayscale beam profile, which will be described in detail in Figure 2.LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA

[0049] The intensity-modulated laser beam, which forms the patterned beam 18b, is projected by the Keplerian telescope (components 36, 38 and 40) onto the second mirror 42 which redirects the patterned beam onto the metalens array 44 to form an arbitrary focal spot 44a array. Since the SLM 30 plane is in conjugation with the metalens array 44 by the Keplerian telescope, this effectively allows the SLM grayscale pattern to be accurately projected to the metalens plane without generating diffractive rings.

[0050] As noted above, the vacuum cell 38 is optional, but is preferably inserted into the Keplerian telescope system to prevent the intermediate focal spot from ionizing the air due to the high power from the femtosecond laser 18. The second QWP 34, due to the specific design of the metalens 44 array, only focuses circularly polarized light. It can be removed if the metalens 44 array is polarization independent. One or more other types of spatial light modulators, such as a digital micromirror device (DMD) or a grating light valve (GLV), can also be inserted into the system to provide high-speed dynamic control for the focal spots.

[0051] It will be appreciated that the use of the vacuum cell 38 is especially advantageous because it prevents gas phase ionization when projecting light from the SLM 30 to the metalens array 44, which is important for performing a precise optical relay operation. The configuration does not necessarily have to be as shown in Figure 1 , however. For example, the vacuum cell 38 may be larger to include lenses 36 and / or 40, and potentially other components as well, such as lenses L1 and L2. But the core idea is that the vacuum cell 38 needs to contain the intermediate focal spot in the optical relay system.

[0052] It will also be appreciated that the metalens array 44 is a non-imaging component, in contrast to a conventional objective lens, which actually obtains or passes an image. Those skilled in the art will appreciate that an imaging operation is not possible with the metalens array 44 described herein; rather, the metalens array 44 simply focuses received light into a plurality of focused points of light.

[0053] Referring further to Figure 1 , the CMOS 56, third lens 52, beam splitter 50, LED 52 and the objective 48 can also be viewed as forming a microscope which is built on the opposite side of the metalens 44 to monitor the writing process. During laser processing, the photo-resin is sandwiched between metalens 44 and the printing substrate, and the XYZ build stage 46 is employed to scan the printing substrate in an X / Y / Z space. The stage scanning is done in synchronization with the laser exposure to create 3D structures.LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA

[0054] The intensity modulation for the patterned laser beam 18b is achieved by the setup shown in Figure 2. The polarization orientation of the femtosecond laser 18 is first rotated to the vertical direction by the first HWP 24, which allows the laser beam 18a to be reflected, rather than transmitted, by the PBS 26. Then the reflected laser beam 18a is incident into the intensity modulation system composed of the first QWP 28 with its fast axis at 45 degrees relative to the horizontal direction and the SLM 30 with liquid crystal orientation along the horizontal direction. After the vertically polarized laser beam 18a passes the first QWP 28, a A / 4 phase delay in the horizontal and vertical axis is introduced; and the laser beam 18a becomes circularly polarized. Then, the horizontal polarized part of the laser is modulated by the SLM 30 based on the projected phase pattern, where each SLM pixel is assigned to a designated phase delay value 8, while the vertically polarized part remains unmodulated. As a result, the phase delay between the horizontal and vertical axis now becomes / 4 + 8. The laser then passes through the first QWP 28 again. This phase modulation process can be described in Jones matrix as:After passing through the PBS 28 again, the output field becomes:where fin is a vertically polarized beam with an initial phase of cp0. As a result, the intensity at each pixel is modulated to:

[0055] The curve 100 in Figure 2c is an example of the laser intensity measurements with changing SLM 30 phases. In practice, the laser intensity distribution can be measured and roughly corrected by imaging the focal spot 44a array generated by the metalens 44 via the microscope monitoring system shown in Figure 1 (i.e., collectively components 48, 50, 52, 54 and 56). After acquiring discrete datasets of theLLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA intensities and the SLM 30 phase values, the data is interpolated to map the relationship between the laser intensity profile and the SLM 30 phase pattern, which is then used as a guidance to correct the unevenness of the focal spot 44a array. Among all the focal spots 44a, the one with the lowest intensity is set as the reference for the following uniformity correction. In other words, the intensity of other focal spots 44a are reduced to match with the reference focal spot. The expected SLM 30 phases can be back calculated based on the interpolation parameters and the reference intensity.

[0056] However, using a microscopic imaging system to precisely measure the focus intensities of a large metalens array with high numerical aperture (NA) is challenging. There remains a critical trade-off between the field of view of the imaging system and the measurement precision. A larger field of view may help measure more focal spots within a single image; however, it will lower the NA of the objective lens, leading to mismatched NA of the objective lens and the metalens, and thus reduced measurement precision.

[0057] As such, the methods of the present disclosure in some embodiments first use the imaging results for the rough mapping of the focus spot intensities. After that, a precise correction may be performed by processing a designed pattern array with changing SLM 30 phase value, as depicted in Figure 3a. Each block pattern 200 is printed with a different SLM 30 phase value that decreases the laser focus intensity along the arrow 202 direction. The pattern array can also be designed in other shapes or configurations. Figure 3b shows a highly enlarged optical image of the printed result, which is a zoomed in view of one specific block array 302a printed by a single metalens 44 from a complete collection of block arrays shown in image portion 300. Portion 300 of Figure 3b shows a collection of block arrays printed by an array of metalens 44, with block array 302a being one of the printed collection of blocks. This characterization process serves as a direct measurement for the processing threshold, and it is more reliable than collecting the intensity of the laser focal spot by imaging. In addition, this calibration process only needs to be performed once after building or re-aligning the system 10. Once it is completed, the result can be used to generate the designated focus array pattern for laser processing.

[0058] Depending on the precision requirement for the correction, the increment step of the SLM 30 phase can be custom defined. A regular SLM 30, e.g., a Hamamatsu LCOS-SLM X15213, commercially available from Hamamatsu Corp, of Bridgewater, NJ, only has a modulation bit depth of 8. However, as illustrated in FigureLLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA4, the modulation bit depth can be increased by mapping more than one SLM 30 pixel 30b to the metalens 44. In one embodiment of the present disclosure, the pixel 30b pitch of the SLM 30 is 12.5pm; the size of each metalens 44a of the metalens array 44 is 200 pm; and the magnification ratio from the SLM 30 to the metalens 44a is 1 :1 . Thus, the intensity of each metalens focal spot 44a is controlled by the SLM 30 pixel array, which in this example is a 16-by-16 pixel array, which offers 8-bit (i.e., 0-255) tuning precision. Figure 4 is another example where a single metalens is controlled by a 5-by-5 SLM pixel array. The light gray and dark gray represent two different SLM values that are adjacent to each other, meaning that it is the highest tuning precision that can be achieved by individual SLM pixels. To achieve even higher tuning precision, this SLM pixel array can be further configured as shown in Figure 4, where some pixels are light gray, and some pixels are dark gray. So, the overall tuning result is in between the two adjacent SLM values, realizing high-precision intensity tuning. In practice, one or more metalens can be mapped by one or more SLM pixels. The values of the pixels that map to the same metalens can also be in other configurations. With such high precision grayscale tuning, the process can also be used to tune the size of the voxel in order to be adapted to different printing conditions, for example, to print super high resolution structures or optical grade smooth surfaces.

[0059] Figures 5a-5e show a gallery of structures printed via two-photon lithography, where the time for printing the entire structure is the same as printing a unit cell. Figure 5a is an SEM image 400 of an octet lattice structure, with the red block 402 marks the segment printed with a single metalens. Figure 5b is an optical image 500 of a gradient foam array structure. The enlarged section of Figure 5b is an enlarged section 502 of one gradient foam structure. Figure 5c is a photo 600 of Terahertz metamaterials (a helix array coated with gold), where each helix is printed by a single metalens. Figure 5d is an optical image 600 of the helix array of Figure 5c before gold coating. Figure 5e is a SEM image of a single helix 702 unit. The degree of parallelization, i.e., the throughput, is linearly correlated with the number of the metalens, making the process highly scalable. This high degree of parallelization enables the highly rapid printing of different types of devices. For example, the octet structure in Figure 5a can be easily extended to other lattice structures of architected metamaterials, which open the era of new artificial materials.

[0060] With the above described capability of controlling the intensity of individual focal spots to be uniform, large-scale arrays of 3D structures can be createdLLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA by scanning the stage 46 in combination with the laser 18 firing. This will be explained with brief reference to the flowchart 800 of Figure 6, which describes one specific implementation involving a two-photon lithography printing process. First, an optional calibration process can be executed, if no SLM calibration operation has been performed yet, which is described herein in connection with Figure 7, as indicated at operation 802. Then, the calibration will be applied to the SLM values so that a uniform focal spot array can be achieved, as indicated in operation 804. In the meantime, the unit cell of the 3D structure to be printed is sliced (i.e., sectioned in the X / Y plane) to generate the printing toolpath, where the lateral size (i.e., X and Y axis dimensions) of each unit cell to be printed is equal to the pitch of each metalens 44a of the metalens array, as indicated in operation 806. Next, after setting up the print, the build stage scans the toolpath in synchronization with the laser firing into the photo-resin to print a large array of the unit cell, forming a large 3D structure or repeated 3D unit structures, as indicated by operation 808.

[0061] Referring to Figure 7, a flowchart 900 is shown further illustrating the tuning process described above in connection with Figure 3a. Initially at operation 902 a rough mapping of focus spot intensities is performed, as indicated at operation 902. This is done by collecting the intensities of individual focal spots using a CMOS camera (or other photo detectors) via the monitoring system constructed of 48, 54, and 56. Next, a series of blocks may be printed, each with a different SLM phase value, as indicated at operation 904. The incremental phase value can be custom designed, based on the desired resolution that one needs to have for a given laser processing application. At operation 906 the printing threshold cutoff is determined, which is where no polymerization occurs, and the corresponding SLM phase values that produced it for each metalens are recorded. At operation 908, the SLM phase values corresponding to the printing threshold cutoff is used to correct for higher intensities across the entire metalens array, where the intensity of each metalens focal spot is tuned to be at the same intensity or within a tolerable error. After that, by raising the laser power to pass the printing threshold, the focal spot array generated by the entire metalens array can be used to print uniform 3D structures.

[0062] It will also be appreciated that while the above description has focused on the use of a metalens array, other forms of focusing element could be substituted for a metalens array. For example, a different form of focusing component such as a microlens array, multi-let microlens array, multi-let metalens array and etc. could beLLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA instead. The other focusing component array could be used to perform laser processing at different scales or purposes.

[0063] It will also be appreciated that while the present disclosure has been focused primarily on the use of a single SLM 30, in some embodiments more than one SLMs may be employed. If a plurality of SLMs are employed they may be arranged in series, or in an X / Y grid-like fashion, or even in parallel. In some embodiments, the SLM array may be replaced with, for example and without limitation, one or more LCDs, one or more LCOS units, or one or more DMDs, and such components may be arranged in series, in an X / Y grid-like arrangement, or even in parallel. Accordingly, the present disclosure is not limited to use with only an SLM, and the precise application may dictate that components other than an SLM be used for optimum results and performance.

[0064] It will also be appreciated that while the foregoing discussion has largely focused on applying the laser processing features of the present disclosure with a two photon lithography printing process, that the laser processing teachings described herein may be used in a wide variety of other applications as well. For example, the laser processing systems and methods described herein may also be applied in laser machining (ablation, engraving, patterning, cutting, selective laser etching, laser-induced materials property change, such as writing waveguides), laser-driven direct metal printing, and laser-enabled data storage. The processes that the laser processing teachings described herein can be used in may be any one or more of additive, subtractive, or even property-altering.

[0065] The laser processing methods and systems described herein can also be used for both 2D and 3D patterns. For 3D patterns, laser processing may be in a layer-by-layer fashion to directly scan the build stage 46 in 3D space. Scanning of the build stage 46 in some embodiment can be accomplished by moving the 2D or 3D patterns from location to location while the build stage remains stationary, or in some embodiments the scanning may be accomplished by physical movements of the build stage while the 2D or 3D patterns remain stationary.

[0066] It will also be appreciated that in some implementations the system 10 may instead make use of, without limitation, an electron beam or an ion beam as the beam source instead of a laser beam. In such applications, a suitable focusing component, for example an electrostatic lens array, will be used instead of a SLM and Metalens array. Accordingly, the present disclosure is not limited to only use with a laser beam.LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA

[0067] Combined with the 3D nanofabrication capability of two-photon lithography (TPL), this scalable laser processing method can be used to fabricate large area 3D nanostructures that were not practical to be achieved via conventional TPL techniques. With the high throughput and high processing precision enabled by the systems and methods described herein, one can fabricate interconnects between 3D stacked chiplets with high complexity, which are essential to facilitate high-speed data transfer and reduced signal latency. The systems and methods described herein enable the design and fabrication of customized semiconductor thermal management solutions such as micro heat sinks and thermos vials, which can be tailored to specific chip configurations and requirements. The systems and methods described herein further enable the fabrication of micro- / nanostructured inch-scale mechanical metamaterial that were not found in nature. Via application-targeted structural design, such metamaterials can be applied as gradient impactors, vibration dampers, tunable photonic crystals, etc.

[0068] The teachings disclosed herein can be applied across a wide range of laser processing applications, including additive manufacturing, ablation / machining, and material modification. The proposed method holds significant promise for fabricating micro- / nanoscale 3D interconnects and thermo-structures for semiconductors, architected meta- mate rials for mechanics and photonics, and high-density optical memories.

[0069] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

[0070] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments,LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0071] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0072] When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. As used herein, the term “about”, when used immediately previous to a specific recited value, denotes the specific recited value as well as all values, inclusive, from + / - 10% of the specific recited value.

[0073] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or sectionLLNL Ref. IL-1401 1 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0074] Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Claims

LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POACLAIMSWhat is claimed is:1 . A system for parallel laser processing, comprising: a laser for generating a laser beam; a light modulator subsystem having: a modulator component for modulating at least one of a phase or amplitude of light from the laser beam, and having a plurality of independently controllable pixels for enabling a phase to amplitude transformation on the light from the laser beam which impinges the light phase modulator component; and the light modulator component generating a patterned light beam in accordance with a bit pattern provided by the independently controllable pixels; and a metalens array responsive to the patterned light beam, wherein the metalens array consists of a plurality of metalens units, and wherein each said metalens unit corresponds to a plurality of pixels of the intensity modulator component for parallel processing a material in at least one of an additive manufacturing printing operation or a material processing operation.

2. The system of claim 1 , wherein the light modulator component comprises: a light intensity modulator component; a quarter wave plate; and a polarization beam splitter; and the light intensity modulator component shapes an intensity distribution of the laser beam to at least one or a flat-top or arbitrary grayscale beam profile, when creating the patterned light beam.

3. The system of claim 2, wherein the light intensity modulator component comprises a spatial light modulator (SLM).

4. The system of claim 2, wherein the light intensity modulator component comprises a digital micromirror device (DMD).LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA5. The system of claim 2, wherein the light intensity modulator component comprises a grating light valve.

6. The system of claim 1 , wherein the laser comprises a femtosecond laser.

7. The system of claim 6, wherein the femtosecond laser comprises a linearly polarized femtosecond laser having a pulse width of less than 200 fs.

8. The system of claim 1 , wherein the metalens array comprises a metalens array configured in a grid pattern.

9. The system of claim 1 , further comprises an electronic controller for controlling at least one of the laser of the light modulator subsystem.

10. The system of claim 2, further comprising a telescope optical relay subsystem for receiving the patterned beam and placing a plane of the light intensity modulator component in conjugation with a plane of the metalens array.1 1. The system claim 10, wherein the optical telescope comprises a Keplerian telescope having a first lens and a second lens separated by vacuum cell, wherein the first lens, the second lens and the vacuum cell are aligned such that the patterned beam passes through the first cell, through the vacuum cell, and through the second lens before reaching the metalens array, and wherein the vacuum cell contains an intermediate, high- power laser focal spot created by the laser light modulator subsystem to prevent gasphase ionization of air.

12. A system for parallel laser processing, comprising: an electronic controller; a laser for generating a laser beam; a system for creating patterned focal spot array for parallel laser processing, comprising: a light modulator subsystem having a plurality of independently controllable pixels and responsive to the electronic controller and having:LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA a light modulator component having a plurality of independently controllable pixels and forming at least one of a: light intensity modulator component for controlling an intensity of light generated by each one of the plurality of independently controllable pixels; or a phase modulator component configured to carry out a phase to amplitude transformation on light being emitted from each one of the plurality of independently controllable pixels; the light modulator component generating a patterned light beam in accordance with a bit pattern provided by the independently controllable pixels; a telescopic relay optical system with a vacuum chamber that contains the intermediate high-power laser focal spot to prevent gas-phase ionization; and a non-imaging metalens array responsive to the patterned light beam, wherein the metalens array consists of a plurality of non-imaging metalens units, and wherein each said metalens unit corresponds to one or a plurality of pixels of the intensity modulator system for parallel processing a material in at least one of an additive manufacturing printing operation or a material processing operation.

13. The system of claim 12, wherein the light modulator component comprises a spatial light modulator (SLM).

14. The system of claim 12, wherein the light modulator component comprises a digital micromirror device (DMD).

15. The system of claim 12, wherein the light modulator component comprises a grating light valve.

16. The system of claim 12, wherein the laser comprises a femtosecond laser.

17. The system of claim 16, wherein the femtosecond laser comprises a linearly polarized femtosecond laser having a pulse width of less than 200 fs.LLNL Ref. IL-14011 -03 JT / AJSAttorney Docket No. 16336-000247-WO-POA18. The system of claim 12, wherein the metalens array comprises a metalens array with the metalens units configured in a grid pattern.

19. A method for performing parallel laser processing, comprising: using a laser to generate a laser beam; using a light modulator subsystem having a light intensity modulator component, wherein the light intensity modulator component has a plurality of independently controllable pixels, to pattern the laser beam to produce a patterned light beam in accordance with a bit pattern provided by the independently controllable pixels; and using a series of calibration procedures to find parameters for the light modulator subsystem to generate uniform or arbitrary programmed patterned light beam; and using a non-imaging metalens array responsive to the uniform or arbitrary programmed patterned light beam, wherein the metalens array includes a plurality of metalens units, and wherein each said metalens unit corresponds to one or a plurality of pixels of the light intensity modulator component, to generate focused points of light of uniform or selected intensities, the focused points of light operable to perform parallel processing of a material in at least one of an additive manufacturing printing operation or a material processing operation.

20. The method of claim 19, wherein: when the processed material is in liquid form or gel form, it is sandwiched between the non-imaging metalens array and a solid substrate, where the solid substrate is scanned using a stage system to produce a processed result; when the processed material is solid, the processed material is directly scanned using a stage system to produce the processed result.

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