With the help of the kind of light warping that makes “invisibility cloaks” possible, scientists have developed a new kind of 3D printing that is capable of both microscopic detail and high throughput. The researchers suggest their new technique could enable the mass production of complex nanometer-scale structures. The potential applications include drug delivery and nuclear fusion research.
Currently the most precise method for 3D printing complex microscopic features is two-photon lithography. The technique uses liquid resins that solidify only when photosensitive molecules within the resin absorb two photons of light at the same time instead of just one. Two-photon lithography enables the fabrication of items with voxels—the 3D equivalent of pixels—only a few dozen nanometers in size.
However, two-photon lithography has proven too slow for large-scale practical applications. This has largely rendered it a laboratory tool to produce microscopic prototypes.
Until now, two-photon lithography has depended on conventional lenses, which have limitations that slow down the technique. Now, in a new study, Xia and his colleagues have experimented with “metalenses,” which can bend light in unexpected ways.
The scientists experimented with optics made of metastructures—materials whose structures contain repeating patterns at scales that are smaller than the wavelengths of whatever the structures are designed to interact with. Optical metastructures, which include metalenses, can manipulate light in a variety of ways, resulting in devices like invisibility cloaks that can bend light around objects from light.
In the new study, the researchers created metalenses that, when intense laser light shone on them, could each serve as a miniature 3D printer. These flat metalenses could focus this light without the kinds of aberrations that can result from the curves of conventional optics. The resulting lenses can generate high resolution while also avoiding problems that can reduce throughput.
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