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Researchers from Beihang University and The Hong Kong Polytechnic University have introduced a new 3D printing technique that significantly reduces the time and number of light projections needed to manufacture complex objects.
Led by Dr. Huiyuan Wang, the team developed a method known as sparse-view irradiation processing volumetric additive manufacturing (SVIP-VAM). In many cases, this approach reduces the number of required projections from more than a thousand to just 15. Published in the International Journal of Extreme Manufacturing, the study also saw contributions from Xidian University and Changshu Institute of Technology.
According to the researchers, volumetric additive manufacturing (VAM) enables faster and support-free printing by curing the structure in one go. However, traditional VAM requires hundreds or even thousands of light projections and significant computation time to prepare them. These steps slow the process and limit how widely the technology can be used.
Reducing projections without sacrificing detail
To overcome this, the researchers looked to medical imaging for inspiration. Techniques like sparse-view computed tomography use fewer projections without sacrificing quality. Applying a similar principle, they discovered that the outer shape of an object could be reconstructed using as few as eight projections. For more detailed models, only 15 were needed to complete the structure with high accuracy.
A key part of the breakthrough was a new projection strategy called odd-even (OE) irradiation. Traditional methods use evenly spaced projections, which often collect overlapping information. In contrast, the OE method adjusts the angles to reduce duplication, making each projection more meaningful. Simulations showed that this not only improved print accuracy but also made the process more efficient, particularly when fewer projections were used.
To test the system, the team printed a variety of shapes. Cubes were printed with just four projections, while cylinders and spheres needed eight. More detailed models, including a human figure known as the Thinker, were completed with 12 or 15 projections and closely resembled those made with 360. The results were evaluated using standard image comparison tools, and in all cases, prints using 15 projections scored above 0.9 for both structural similarity and image quality.
Along with reducing projection count, the method brought a major drop in computation time. Generating the necessary light patterns for 1,440 projections took over an hour. With SVIP-VAM, the same process using just 15 projections took about seven minutes i.e., nearly ten times faster. The efficiency of each individual projection also increased more than 60-fold. For simpler prints, the gain was even higher, reaching up to 125 times.
The researchers built a custom setup to carry out the experiments. It included a 405-nm LED light source, a digital micromirror device, a set of lenses, and a resin vat suspended in a refractive index-matching liquid. A camera monitored the printing in real time, and two different types of resin were tested to verify the system’s flexibility.
Once printing was complete, the objects were cleaned in isopropyl alcohol using ultrasonic treatment and then cured under violet light. The final prints showed strong structural integrity and fine details. Among them, the vase cover model stood out for its precision, with wall thicknesses as thin as 130 µm.
The study confirms that SVIP-VAM reduces both light projection count and computation time in volumetric 3D printing without compromising quality, potentially broadening its use in fields like medical devices, tissue engineering, and aerospace, where speed is essential.
Research into scaling volumetric 3D printing
Away from Beihang university, efforts have been made to improve exposure control and light delivery in volumetric 3D printing targeting different bottlenecks in speed, resolution, and automation.
Two months ago, National Research Council Canada and the University of Victoria researchers developed AE-VAM, a fully automatic exposure control system for tomographic volumetric 3D printing. By tracking light scattering in real time, the system precisely ends UV exposure without the need for manual adjustments, improving consistency and repeatability.
In tests with the 3DBenchy model, AE-VAM achieved fine feature reproduction and an average RMS surface deviation of 0.100 mm, matching or outperforming commercial SLA and DLP printers. It also printed up to ten times faster and supported resin reuse, offering a practical path toward scalable, hands-free volumetric printing.
Additionally, researchers at École Polytechnique Fédérale de Lausanne (EPFL) have developed a compact, high-efficiency holographic tomographic volumetric additive manufacturing (HT-VAM) system that uses a MEMS-based phase-only light modulator. By replacing older micromirror technology, they achieved over 70 times better light efficiency and reduced image noise that often affects print quality.
The system projects multiple shifted holograms to minimize artifacts and preserve sharp details throughout the print volume. Using low-power UV lasers, it quickly printed complex parts like a 4 mm fusilli in 32 seconds and an 8 mm Stanford Bunny in just over a minute, showing strong potential for precise, high-speed printing in advanced fields.
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Featured image shows the SVIP-VAM system. Image via Beihang University.
