Researchers from the École Polytechnique Fédérale de Lausanne (EPFL) have introduced a compact, high-efficiency holographic tomographic volumetric additive manufacturing (HT-VAM) system that leverages a MEMS-based phase-only light modulator. This development marks a significant advancement in addressing the light delivery limitations associated with volumetric 3D printing.Their work, detailed in a preprint on arXiv (June 2025) demonstrates how phase modulation can revolutionize light-based fabrication, enabling faster, higher-resolution prints with unprecedented energy efficiency.
Holography meets volumetric manufacturing
Volumetric Additive Manufacturing (VAM) is a layerless 3D printing technique that cures entire objects simultaneously by projecting light patterns into a rotating vial of photoresin. Unlike layer-by-layer methods, VAM eliminates stair-stepping artifacts and enables support-free fabrication of complex geometries. EPFL’s approach, Tomographic VAM (TVAM), adapts computed tomography principles to generate dynamic light fields that polymerize resin volumetrically.
Traditional TVAM systems often rely on Digital Micromirror Devices (DMDs), binary amplitude modulators with limited light efficiency, typically below 10%. The EPFL team replaces these with a phase-only Phase Light Modulator (PLM), which enables precise wavefront control. This change results in a measured light efficiency of 23.78%, representing a 70× improvement over DMDs, while also reducing imaging artifacts like speckle noise.
Phase Modulation: A Game Changer
Until recently, Liquid Crystal on Silicon (LCOS) Spatial Light Modulators (SLMs) were the standard for phase modulation. However, LCOS suffers from limitations including slow response times (60–120 Hz), ultraviolet (UV) degradation, and polarization sensitivity.
In contrast, EPFL’s MEMS-based PLM, developed by Texas Instruments, uses piston-motion micromirrors to encode phase directly. It features a 4-bit resolution (16 phase levels) for precise wavefront shaping, high speed (1,440 Hz frame rate) for rapid patterning and polarization insensitivity and UV stability, critical for photopolymerization.
This architecture enables the use of low-power, single-mode 405 nm lasers, lowering both cost and system complexity while achieving near-theoretical diffraction efficiency.
Speckle Reduction and Print Quality
A key innovation lies in the system’s speckle-reduction pipeline. Speckle, caused by interference in coherent light, was mitigated through time-multiplexed projection of nine laterally shifted holograms per angle. Combined with Bessel beam axicon phases, this reduced speckle contrast by 50% (from 0.45 to 0.33) and extended the system’s depth of focus, ensuring uniform resolution throughout the print volume.
Rapid, high-fidelity printing
The system demonstrated rapid printing of complex models, such as a 4 mm fusilli pasta structure in 32 seconds (18 mW laser power), a Stanford Bunny (8 mm tall) in 61 seconds (50 mW) and DNA helices with smooth surfaces at micrometer scales. Potential applications span bioprinting, micro-optics, and aerospace, where speed, resolution, and material efficiency are critical.
Volumetric printing matures with innovations in light control and biomedical applications
Volumetric additive manufacturing has gained momentum as a promising alternative to traditional layer-by-layer 3D printing, offering the ability to fabricate entire objects simultaneously with fewer constraints on geometry and speed. Recent advances include automated exposure control systems for more precise light dosing during tomographic projection, and the use of light-converting nanoparticles to enable deeper and more controlled polymerization. Swiss firm Readily3D, a spin-off from EPFL, has also advanced volumetric bioprinting through its collaborations with BIO INX, aiming to simplify the fabrication of complex biological models.
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Featured image shows surface quality improvement comparison. Image via Laboratory of Applied Photonics Devices (LAPD), EPFL.
