Thanks to advances in 3D printing, tiny, powerful lenses can be made quickly and even be used with an iPhone camera.
Our ability to observe anything at the microscopic level is about to get more open source, thanks to a team from Northwestern University in the US. The researchers revealed a new breakthrough in 3D printing that can let anyone with the right materials and machine put together a powerful lens in a matter of hours.
In a paper published to Advanced Materials, the team said it had spent the past two years developing a method that allows for the printing of a customisable lens, 5mm in height and 5mm in width, in as little as four hours.
Unlike the older process that relied on the time-consuming and costly process of polishing lenses, the 3D-printing method is much more efficient – but was not without its initial drawbacks.
Similar to other 3D-printed objects, each layer of the lens needed to be placed on top of the other, but this led to a noticeable stepping effect in the curved layers, which distorted the image.
“We realised that the layers on top of each other created surface roughness,” said Cheng Sun, whose lab developed the process.
“The layer thickness is typically five microns, while the wavelength of visible light is around 0.5 microns. This creates an optically rough surface. That was the bottleneck. The roughness made the lens incapable of clear optics.”
‘We are very excited about this lens’
To get around this bottleneck without slowing the manufacturing down, the team developed a two-step process of layering and polishing.
Starting with greyscale images to create more transitions between steps, Sun and the team then coated the surface with the same photo-curable resin, forming a meniscus that further smooths the surface.
The concept improves upon a similar design developed by a German company that produced a high-precision femtosecond 3D printer with 150-nanometre precision. This older design builds the lens in a point-by-point fashion, which is more time-consuming than layering.
Xiangfan Chen, who was also involved in the research, said succinctly: “If you want to make a lens, do you want to make it in two hours or two weeks? We are very excited about this lens.”
Aside from offering the potential to quickly create customisable contact lenses for correcting distorted vision, the team also demonstrated that it could be used with an iPhone, having taken high-quality detailed images of a sunset moth’s wing using it.