Can holograms improve the additive manufacturing process? This is the subject of a study by a team of scientists from EPFL and the University of Southern Denmark. They sought to understand how to perfect tomographic volumetric additive manufacturing (TVAM). Instead of depositing material layer by layer, laser beams are projected onto the rotating resin tray. While this method saves considerable time, it is also more inefficient and energy-consuming. But the team of scientists seems to have found a solution by projecting a hologram directly onto the moving resin tray. What impact could this method have on the additive manufacturing market?
We’ve been hearing about volumetric 3D printing, also known as tomographic 3D printing, for some years now. It involves repeatedly projecting a pattern into a vat filled with transparent liquid resin, from different angles. Unlike additive manufacturing, it is possible to create a shape in a single operation, as layers are not superimposed, but a defined volume of material is “frozen.” In addition to the speed of the process, the user is also freed from the need for printing supports, since the resin acts as such, in the same way as the powder tray in SLS.
However, this process has certain limitations. Only one percent of the coded light actually hits the resin to create the desired part, requiring a lot of light to guarantee a minimum of results. To overcome this challenge, the researchers projected a hologram directly onto the rotating resin tray. They found that this not only reduced the amount of energy required but also significantly increased resolution. Christophe Moser leads the research team and explains:
All pixel inputs are contributing to the holographic image in all planes, which gives us more light efficiency as well as better spatial resolution in the final 3D object, as the projected patterns can be controlled in the projection depth.
The team relies on HoloTile to generate the holograms, a method that enables them to reproduce 3D parts even more faithfully. So far, it has 3D printed various parts such as a benchy, cylinders and spheres, all in less than 60 seconds and using 25 times less optical power than other volumetric printing methods.
The process still needs to be further optimized. Indeed, the researchers explain that they would like to eliminate the need to rotate the resin tank to simplify the process and further reduce energy consumption. Finally, in terms of applications, the team notes an interesting potential for biomedical applications. Maria Isabel Alvarez-Castaño, EPFL student and lead author, concludes: “We are interested in using our approach to build 3D complex shapes of biological structures, allowing us to bio-print, for example, life-scale models of tissues or organs,” Click HERE to find out more.
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*All Image Credits: LAPD EPFL