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From Beam Shaping to Area Beam Patterning: Which Path to Scaling Metal Additive Manufacturing?

Updated: May 2

Authored by Seurat's Electro-Optics Director, Selim Elhadj.

Seurat’s Alpha System Printer. Approximately 8m L x 2.3m W x 2.6m H
Fig. 1 Archimedes’ mirror burning Roman military ships. Painted in 1600 by Gieulio Parigi (Uffizi Gallery, Stanzino delle Matematiche, Florence, Italy)

Beam Shaping: From Destruction to Creation

Prometheus was perhaps the first to harness the power of focused light, using shaped optics to convert the sun's energy into an earthly burn (Fig. 1).  While that stellar shaped light was used for destruction, other forms of light can be used for creation and  transformation. Man-made light sources, especially high-power lasers, are increasingly deployed in industrial manufacturing for cutting, welding, marking, ablating, lithographing, cleaning, shock peening, and surface processing (micro processing) [REF1].  An emerging industry in manufacturing that uses lasers is additive manufacturing, aka laser 3D printing. Laser powder bed fusion (LPBF) is commonly used to produce near-net shape parts where a thin layer of metal powder feedstock is spread on a bed, and the laser spot is raster scanned on the bed to locally melt a slice of a part. Complete parts are “additively“ built-up one layer at a time.


Challenges

One of the biggest challenges in metal additive manufacturing is precisely controlling the process of melting tiny grains of metal powder together—roughly 10s of microns in size—using laser or electron beams around 100 microns wide. The extreme heat required to melt the metal introduces complexities, such as rapid heating and cooling, along with unpredictable powder behavior, which can lead to defects such as pores, cracks, and spatter. These flaws can compromise surface finish, mechanical properties, and dimensional accuracy, making process control a critical factor in ensuring reliable, high-performance parts.

 

Optimizing laser parameters for metal additive manufacturing can take weeks or even months to validate and optimize a part for production. Fine-tuning the process involves adjusting key factors: laser power, beam size, wavelength, raster pattern (e.g., hatching), scanning order, and scan speed. Despite all this tuning, the core challenge for LPBF remains: increasing print speed to boost productivity requires a proportional increase in laser power. At higher irradiance levels, controlling the melt pool becomes significantly more difficult, as excessive heat can lead to metal evaporation and instability in the process. As a result, build defects invariably increase as the speed of LPBF printing increases.



The core challenge for LPBF remains:

Increasing print speed to boost productivity



The Rise of Beam Shaping

In recent years, laser beam shaping strategies have been introduced to improve control over melt pool dynamics and reduce particle spatter during printing. These approaches utilize passive shaping methods such as beam transformers, diffractive optics, and homogenizers [REF2].  In a typical LBPF process the ubiquitous Gaussian beam shape (Fig. 2) is used as-is when spontaneously formed within a laser cavity. This beam shape concentrates peak laser intensity at its center, causing localized overheating that exceeds the metal’s melting point. The resulting recoil pressure from evaporated metal can destabilize the melt pool, leading to defects like "keyholing." (pores or weak spots).   To address this, flat-top beams—characterized by a more uniform energy distribution—have shown limited improvements in melt pool dynamics, along with improved parts quality produced at speed [REF3].  Use of more complex shapes, such as Bessel beams [REF4] and annular beams [REF5], have also emerged to improve the uniformity of the laser-induced heating to minimize the dynamic interactions with the molten metal. (Fig. 3) illustrates how carefully selected beam shapes can improve surface finish by redistributing the laser energy more evenly to reduce excessive heating, and control temperature gradients and melt pool depth.

Seurat’s fully swappable print cartridges reduce printer downtime to minutes.
Fig. 2 A Gaussian beam (left) can be converted to a flat “top-hat" profile (right) to deliver energy more efficiently to the bed surface for processing of a workpiece (https://www.sciencedirect.com/science/article/pii/S2238785421015209)

Fig. 3  Sa is a measure of surface flatness. Shaped beams top hat, Bessel, or annular can be leveraged to improve surface finish and materials processing.
Fig. 3  Sa is a measure of surface flatness. Shaped beams top hat, Bessel, or annular can be leveraged to improve surface finish and materials processing.

Critically, these improvements in controlled laser interactions have enabled increased laser speed processing, while lowering the number of defects—and opening the door for significant productivity improvements [REF6].  Therefore, industrial laser users are starting to adopt dynamic beam shaping to further optimize the beam size and shape based on local features and printing conditions.  This dynamic approach, particularly when combined with multi-kilowatt lasers, introduces a fourth dimension—time control—allowing greater beam shape and size management to further boost LPBF productivity [REF8]. 


Beam Shaping Limitations

Despite significant advances in beam shaping, LPBF remains fundamentally too slow for true mass serial production. At its core, the process still relies on a single-point beam, much like painting with a brush or writing with a pen, where only a small line is added at a time. Even with beam shaping improvements, the small spot size (no larger than several human hairs) is a barrier to industrial-scale serial manufacturing.


Attempts to accelerate LPBF by adding more lasers—sometimes up to 64— introduce extreme system complexity, driving up capital costs and integration challenges. Worse still, multiple beams operating simultaneously create potential interference effects, as neighboring beams interact with nearby plumes of metal vapor, further disrupting the process. Even with beam shaping enhancements, these fundamental limitations prevent LPBF from reaching the throughput necessary for true serial production.


The Area Printing Breakthrough

To break through this bottleneck and achieve the productivity levels of metal casting, forging, or machining, a fundamentally new approach is required. The next revolution in manufacturing will leverage highly parallelized laser metal processing from a single large, patterned beam—dynamically controlled at a pixel level.  Instead of relying on individual laser spots, this approach allows each pixel to be precisely addressed with programmable laser pulses in both space and time.


Seurat’s Area Printing® technology [REF9] achieves this by combining tiled patterned laser pulses with extreme laser power ~10’s of kW that scale the energy needed for large area 3D printing. This unique pattern printing technology drastically speeds up the additive build process [REF10].  Unlike conventional multi-beam LPBF, which operates with ~100 micron-sized laser spots, this technology scales up the addressable powder bed area by orders of magnitude. Today, Seurat’s Area Printing technology is capable of processing sections up to 10 × 10 mm² in a single pulse. (Fig. 4). This represents a dramatic leap in throughput—enabling the system to print up to 10,000 times more area per unit time compared to traditional laser powder bed fusion (LPBF) methods.



Fig. 4 Beam Shaping vs. Area Printing pulse size coverage comparison Seurat's technology enables high-rate printing without loss of resolution.

Crucially, Area Printing boosts throughput without sacrificing resolution. The final printed surfaces maintain edge precision as fine as the patterned tiles—less than 50 µm. This breakthrough paves the way for additive manufacturing at true industrial production scales, unlocking new possibilities for the industry.


Seurat’s printing tile is patterned using a unique technology adapted from beam blockers found in a laser system for nuclear fusion tests at the National Ignition Facility at Lawrence Livermore National Laboratory, a US Department of Energy facility [REF11].  Seurat’s innovation to adapt the beam blocker for 3D printing is a high peak and average power-capable optically addressed spatial light modulator, also known as a “light valve”. This enables Area Printing of over 2.3 million pixels in a precisely defined patterned tile with a single laser pulse. In contrast, a single beam—even when shaped—only offers surface resolution based on the beam size, resulting in a final part with only rough features. If high-resolution features are desired, then LPBF-produced parts often require extensive, time-consuming, and costly post-processing.


Fig. 5  Area Printing provides the speed and fidelity to scale additive manufacturing for industrial serial production (316 stainless steel parts shown).
Fig. 5  Area Printing provides the speed and fidelity to scale additive manufacturing for industrial serial production (316 stainless steel parts shown).

Unlike beam shaping, which can only enhance control over the melt pool, Area Printing decouples printing speed from spatial resolution, unlocking scalable capacity for industrial serial production and enabling companies to break free from the constraints of traditional methods like machining, forging, and casting. With its modular, high-performance architecture and patterned beams, Seurat's Area Printing offers unprecedented manufacturing agility and capacity. Best of all, Area Printing is about more than the plans you have now—it’s about using additive in ways you never imagined possible.


Fig. 6  Seurat's exclusive Light Valve technology makes Area Printing possible.
Fig. 6  Seurat's exclusive Light Valve technology makes Area Printing possible.

References

3. Jiang Bi, Liukun Wu, Shide Li, Zhuoyun Yang, Xiangdong Jia, Mikhail Dmitrievich Starostenkov, Guojiang Dong, Beam shaping technology and its application in metal laser additive manufacturing: A review,Journal of Materials Research and Technology, Volume 26, 2023, Pages 4606-4628, ISSN 2238-7854, https://doi.org/10.1016/j.jmrt.2023.08.037.

4. Tumkur TU, Voisin T, Shi R, Depond PJ, Roehling TT, Wu S, et al. Nondiffractive beam shaping for enhanced optothermal control in metal additive manufacturing. Sci Adv 2021;7:eabg9358. https://doi.org/10.1126/

7. The Laser User Issue 113, Summer 2024



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