WHY THIS MATTERS IN BRIEF

3D printing is revolutionising the world of manufacturing, but it’s still slow. This new technique, which prints objects using light, is thousands of times faster.

3D printing, also known as Additive manufacturing, is an amazing technology that’s helping revolutionise a range of industries, from manufacturing and retail to aerospace and healthcare, but after decades of progress there’s no escaping the fact that its layer by layer manufacturing technique is still relatively slow, and that the type and size of products it can be used to manufacture are still limited.

However, that said we’re now entering what I call 3D printings “Jurassic Era,” and I’m seeing a dramatic increase in the range of 3D printer technologies hitting the market, from 3D Bioprinters that print human organs and tissue, and Ultrasonic 3D printers that can print and assemble electronics in the same device to Rapid Liquid printing to name but a few. And that’s not to mention 4D Printing that lets you print a robot, like this self-evolving one, that walks straight out of the printer without you having to lift a finger…

Now though, thanks to researchers at the Lawrence Livermore National Laboratory (LLNL), there’s a new 3D printing technology to add to the mix, Holographic Printing, and unlike its older cousins it can make products in seconds using nothing more than special resins and light.

3D Volumetric Printing, or “Holographic Printing” Explainer

The technique, which was unveiled earlier this week, differs significantly from traditional 3D printing because it uses special resins in vats that solidify when they’re exposed to laser light.

“Most 3D printing techniques build structures layer by layer by depositing either individual dots of material, filaments, or entire layers at once. This means the 3D structures created are actually stacks of 2D layers,” says LLNL engineer Maxim Shusteff, who led the research.

The new technique can also make structures that are impossible for traditional printers to build without support, for example, building from the bottom upwards makes it hard to build sub-structures that hang down from upper layers of an object, so being able to build the entire structure all in one go has the double benefit of removing the limitations of layer by layer approaches and dramatically increasing the speed of manufacture.

“This is the first demonstration of a practical way of making 3D parts in one go, all at once,” says Shusteff, “it’s the next step in the progress of additive manufacturing technology.”

In their paper which was published in the journal Science Advances the researchers explain that it works by splitting a 3D holographic image into three distinct parts. These are then projected into the resin tank by separate laser beams that enter through its front, base, and side, creating what’s known as a 3D “light field” where they overlap.

The resin the researchers used is a Photopolymer that reacts to light by solidifying once a certain energy threshold is reached, and once that threshold is hit the resin solidifies and the researchers can drain the vat and take out their fully formed 3D structure.

The team used the technique to build a variety of millimetre scale shapes such as cubes, pyramids, and lattices, but Shusteff says that with some fine tuning it should be capable of printing products that are just a few micrometers in size. But that said, at the moment the amount of power needed to guarantee the even distribution of light within large vats of resin mean the technique is still some way from being able to make parts that are any larger than 1,000 cm³.

“We haven’t really pushed the boundaries of what this is capable of, so we’re talking in very general terms about application areas at the minute,” he says, “any place where polymer structures are useful it could advance the state of the art.”

Of particular interest to the researchers are biomedical implants, where having a large degree of flexibility in the shapes you can produce, coupled with high resolution, could be very helpful.

“There has been a growing amount of research looking at bioprinting living tissue, which often uses bio-inks made of living cells suspended in biocompatible substances like hydrogels. These materials are often soft and easily deformable, making printing methods involving a lot of movement undesirable,” says Shusteff, so his teams static approach could, one day, become a promising alternative.

“This is an intriguing approach toward advancing the speed of 3D fabrication with photopolymers,” said Joseph DeSimone, a chemistry professor at the University of North Carolina and co-founder of 3D printing company Carbon, who I’ve spoken about before after they penned a contract with none other than Adidas to 3D print sneakers on demand, “they’ll need to have hardware advances coupled with software and resins to pull this together. But it’s exciting.”

Shusteff agrees there’s still considerable work to do, for a start, the material properties of photopolymers are still limited, but he says additive manufacturing is spurring large amounts of research aimed at solving this “materials” problem and the field is growing quickly.

The researchers also think there may be better ways of creating the 3D light fields than holography, but holography requires the use of complicated optical equipment that pushes up costs, and lasers that are prone to “laser speckle,” where the laser light interferes with itself, adding spatial noise to the beam and, in some cases, making the surface of the products rougher.

Fortunately, they say it should be possible to achieve the same effect using LEDs as the light source and amplitude modulation in place of holography.

“We’ve taken a really good first shot at this, but we’ve not yet taken it anywhere near to the limit of its performance, so the space is wide open for us and others to demonstrate what this approach is capable of,” says Shusteff.

As for what’s next for this nascent 3D printing technology, well the team are now experimenting with new resins and a vat that spins on its axis as it’s exposed to an LED light source, something that Shusteff says should give them even more control and flexibility over the finished product.

So I guess holographic 3D printing is a thing now, and if it measures up to its promises then, well, who knows, Adidas and co might be able to print millions of sneakers a day, and that would revolutionise not only manufacturing, but retail as well, among other industries.