Research Papers
A curated list of key publications on Computed Axial Lithography (CAL) and volumetric additive manufacturing (VAM). The two most important papers, the original CAL paper and the first OpenCAL paper, are highlighted first.
Foundational Papers
⭐ The Original CAL Paper — Science, 2019
Volumetric additive manufacturing via tomographic reconstruction
Brett E. Kelly, Indrasen Bhattacharya, Hossein Heidari, Maxim Shusteff, Christopher M. Spadaccini, Hayden K. Taylor — University of California, Berkeley & Lawrence Livermore National Laboratory (LLNL).
The paper that introduced Computed Axial Lithography. It showed that an entire 3D object can be formed all at once by illuminating a rotating volume of photosensitive resin with a dynamically evolving light pattern: no layers, no support structures, and the ability to print around pre-existing objects, with print times of 30–120 seconds. This is the foundation that every CAL system, including OpenCAL, is built on.
⭐ The First OpenCAL Paper — arXiv, 2025
An Open-Sourced, Community-Driven Volumetric Additive Manufacturing Printer and Post-Processor
Taylor Waddell, Erik Broude, Tristan Bourgade, Natalia Fabiana De La Torre, Erfan Kohyarnejadfard, Tavleen Kaur, Scarlett Hao, Dylan Motley, Daniel Oslund, Evan Percival, Rajdeep Summan, Connor Vidmar, Hayden K. Taylor — University of California, Berkeley.
The paper that introduces OpenCAL itself, a low-cost, open-source CAL printer and post-processor designed to put volumetric additive manufacturing in the hands of researchers, educators, and makers. It documents the hardware, software, and resin so the system can be reproduced and built upon by the wider community. Start here to understand the project this site supports.
Additional Reading
Reconstruction & algorithms
Deconvolution volumetric additive manufacturing — Antony Orth, Daniel Webber, Yujie Zhang, Kathleen L. Sampson, Hendrick W. de Haan, Taylor Waddell, Hayden K. Taylor, et al. (Nature Communications, 2023). National Research Council Canada & UC Berkeley. Shows that light-dose spread from chemical diffusion and optical blur becomes significant for features below ~0.5 mm, then introduces a deconvolution method to correct for it and sharpen fine features. View paper
OSMO — Object-Space Optimization of Tomographic Reconstructions for Additive Manufacturing — Charles M. Rackson, Kyle M. Champley, Joseph T. Toombs, Erika J. Fong, Vishal Bansal, Hayden K. Taylor, Maxim Shusteff, Robert R. McLeod (Additive Manufacturing, 2021). University of Colorado Boulder, UC Berkeley & LLNL. Rather than optimizing the projected images, OSMO iteratively optimizes the digital model itself by forward/back-projecting the part, finding regions of excess or missing dose, and adjusting the model accordingly. Simple to implement and improves accuracy of complex parts even with imperfect optics and materials. View paper
BCLP — Tomographic projection optimization with general band-constraint Lp-norm minimization — Chi Chung Li, Joseph Toombs, Hayden K. Taylor, Thomas J. Wallin (Additive Manufacturing, 2024). UC Berkeley. Optimizes the computed light patterns using a band-constrained Lp-norm minimization, producing sharper dose contrast between the part and surrounding resin and improving resolution and fidelity. View paper
Process monitoring & control
Automatic Exposure Volumetric Additive Manufacturing — Antony Orth, et al. (Advanced Materials Technologies, 2025). National Research Council Canada. Introduces automatic exposure control for VAM: instead of guessing the dose and time, the system uses real-time optical feedback to determine the correct light dose and stop the print at the optimal moment, improving consistency and removing trial-and-error. View paper
On-the-fly 3D metrology of volumetric additive manufacturing — Antony Orth, Kathleen L. Sampson, Yujie Zhang, Kayley Ting, Derek Aranguren van Egmond, Kurtis Laqua, Thomas Lacelle, Daniel Webber, Dorothy Fathi, Jonathan Boisvert, Chantal Paquet (arXiv, 2022). National Research Council Canada. Demonstrates in-situ optical monitoring of a part as it forms during printing, measuring the emerging geometry in real time to enable closed-loop feedback rather than after-the-fact evaluation. View paper
Materials & chemistry
Advancing Tomographic Volumetric Printing via Oxygen Inhibition Control — Yujie Zhang, Katherine Houlahan, Daniel Webber, Nicolas Milliken, Kathleen L. Sampson, Hendrick W. de Haan, Hao Li, Robynne Vlaming, Liliana Gaburici, Antony Orth, Chantal Paquet (Advanced Materials, 2025). National Research Council Canada. Turns oxygen inhibition into a tool rather than a nuisance: using N-methyldiethanolamine (MDEA), the same additive in the OpenCAL resin, to regenerate radicals, the authors achieve high-resolution, large-volume prints (up to 60 mm, a 16× increase in print volume). View paper
A review of materials used in tomographic volumetric additive manufacturing — Jorge Madrid-Wolff, Joseph Toombs, … Christophe Moser (19 authors) (MRS Communications, 2023). EPFL, with UC Berkeley, Harvard, Utrecht, LLNL, CU Boulder, Freiburg, ETH Zürich and others. A broad survey of the photopolymer resins and material systems used across VAM, summarizing their properties, trade-offs, and current limitations, a good orientation to the materials side of the field. View paper
In-space manufacturing
Demonstration and Analysis of Volumetric Additive Manufacturing via Sub-Orbital Spaceflight Testing — UC Berkeley SpaceCAL team (Acta Astronautica, 2026). University of California, Berkeley. Reports SpaceCAL Mission 3, which autonomously manufactured and post-processed four parts during ~140 seconds of microgravity on a suborbital flight, the first integrated CAL workflow demonstrated in space, with analysis of the distortions encountered. View paper