Single-View Holographic Volumetric 3D Printing with Coupled Differentiable Wave-Optical and Photochemical Optimization

TL;DR

SHVAM addresses the challenge of fast micro-scale volumetric printing by using a single-view, phase-only holographic approach to fabricate 3D objects in a static setup. The authors develop SHVAM, integrating a differentiable wave-optical forward model with a simplified photochemical model that includes inhibitor diffusion to pre-compensate blur. Optimizing a time-multiplexed sequence of phase-only holograms yields prints with features down to about 10 μm in 0.8×0.8×3 mm volumes within seconds. The work highlights diffusion as a key fidelity-limiting factor and points to diffusion-engineered resins and higher-NA optics as paths to further improvements, with applicability beyond SHVAM to other VAM modalities.

Abstract

Volumetric additive manufacturing promises near-instantaneous fabrication of 3D objects, yet achieving high fidelity at the micro-scale remains challenging due to the complex interplay between optical diffraction and chemical effects. We present \emph{Single-View Holographic Volumetric Additive Manufacturing} (SHVAM), a mechanically static system that shapes volumetric dose distributions using time-multiplexed, phase-only holograms projected from a single optical axis. To achieve high resolution with SHVAM, we formulate hologram synthesis as a coupled inverse problem, integrating a differentiable wave-optical forward model with a simplified photochemical model that explicitly captures inhibitor diffusion and non-linear dose response. Optimizing hologram sequences under these coupled constraints allows us to pre-compensate for chemical blur, yielding higher print fidelity than optical-only optimization. We demonstrate the efficacy of SHVAM by fabricating simple 2D and 3D structures with lateral feature sizes of approximately \SI{10}{\micro\meter} within a $\SI{0.8}{\milli\meter} \times \SI{0.8}{\milli\meter} \times \SI{3}{\milli\meter}$ volume in seconds.

Figures (14)

• Figure 1: Schematic of the SHVAM printer. A coherent beam is phase-modulated by a spatial light modulator (SLM) and Fourier-transformed by a lens. The strong zero-order (unmodulated) component arising from the pixelated SLM is suppressed using an off-axis spatial filter. A relay imaging system (tube lens and microscope objective) then re-images the filtered field into the resin at the printing plane ($z=0$), from which the 3D field distribution is computed via angular-spectrum wave propagation.
• Figure 2: Visual description of the optimization process. A fixed number of phase patterns is projected into the resin which results in the intensity summation of those patterns. Their sum results in a time integrated intensity. After applying the chemical model we obtain a binary solidified print. Evaluating this print and the chemical concentrations with our loss function allows to update the phase patterns via gradient-descent based optimization.
• Figure 3: Impact of oxygen diffusion on inverse-designed dose patterns. We compare holograms optimized without diffusion (top row) and with diffusion-aware optimization (bottom row), using $D_{\ce{O2}}=200µm\squared\per s$. a,f) projected intensity (slice), b,g) oxygen concentration after exposure, c,h) accumulated polymerization field, d,i) thresholded print prediction, and e,j) histograms of oxygen (pink) and polymerization values for object (blue) and void (orange) voxels. Neglecting diffusion depletes oxygen throughout the volume and reduces class separation, leading to unintended curing in void regions; diffusion-aware optimization preserves inhibitor in voids and yields a cleaner thresholded reconstruction.
• Figure 4: Experimental calibration of the oxygen diffusion coefficient. First row) Example optimized projected intensity for a candidate diffusion coefficient. Second row) Corresponding simulated print outcome. Third row) Experimental print imaged from above in a widefield configuration.
• Figure 5: Lateral resolution test comparing different inhibitor configurations: a) oxygen only (with diffusion correction), b) oxygen and TEMPO (without TEMPO diffusion modeling), and c) oxygen and TEMPO (with optimized diffusion coefficients). Each row displays: 1) projected light intensity, 2) final inhibitor concentration, 3) simulated print outcome, and 4) experimental result.