3D printers are useful devices for all kinds of reasons, but most have a critical weakness: they simply take a long time to do something . Indeed, additive manufacturing usually works by depositing an object on one microscopic layer at a time. But a new holographic printing technique makes it possible to create everything in one go – in as little as a second or two.
Light-based 3D printing techniques typically use lasers to cure a resin layer, but like extrusion printers, they must do so layer by layer. If the laser shone all the way through the liquid resin, it would cause the healing of a big line.
But what would happen if you shone a few weaker lasers through the resin, none of which were powerful enough to heal it except when they all crossed? This is the technique developed by a team led by researchers at the Lawrence Livermore National Laboratory.
This basic idea has been applied in several other areas: by carefully superimposing weak beams of light, sound or radiation, you can expose a selected volume to a critical volume while leaving the other parts untouched .
In this case, the three beams of light must be carefully modeled so that they intersect only one another and produce this constructive interference in the exact points that must solidify. And once this pattern is set, it only takes a handful of seconds to complete the process of curing the resin – flush it out and your object is ready for use. Some other techniques have tried something like this, but have not been able to create complete 3D shapes like this one.
This figure of the article shows the installation of lenses and holographic as well as several examples of forms printed using the technique.
The advantages are many: you can, for example, produce structures with other structures moving freely inside them, like gears in a gearbox. There is no need for support structures under the overhangs, so some shapes that were impractical or impossible when printing from bottom to top or top to bottom are simple to create this way. You can also print multiple structures quickly – a bunch of dice, for example.
It's still a bit rude compared to what comes out of most commercial 3D printers, but that's to be expected – it's really only a proof of concept in a laboratory.
"With this work, we made a first attempt to demonstrate and prove that one-off 3D fabrication is possible," senior researcher Maxim Shusteff told TechCrunch in an email. "So we have not pushed the boundaries of the construction performance metrics yet (speed, build size, resolution, complexity)."
Ultimately, the "resolution" will probably be determined by the smallest piece of resin that can be solidified reliably, which has to do with a number of chemical and optical factors. It would be premature to speculate on what this resolution might be, but from the results already obtained, it seems clear that it will certainly work for the levels of complexity for which 3D printers are already in use.
Shusteff and his colleagues at LLNL, MIT, Berkeley, and the University of Rochester aim to continue developing this very promising technique. Commercial applications are still far away, but it's not hard to imagine parties that would be interested in a 3D printer that creates things in seconds rather than, at a minimum, several minutes, and more often, hours.
Featured image: LLNL / Maxim Shusteff