Researchers are making microscopic 3D printing stronger and faster by combining two-photon lithography with advanced optics called metalenses, tells IEEE Spectrum. Two-photon lithography is a technique where a liquid resin solidifies only where it absorbs two photons of light at the same time. That lets printers build tiny structures with details on the scale of tens of nanometers because polymerization happens only at the focal point of the laser beam. This gives resolution far beyond standard 3D printing methods.
The problem until now has been throughput and scale. Two-photon lithography is precise but slow and limited to small areas, which has kept it mostly in research labs for prototypes rather than large-scale manufacturing. Conventional lenses used to focus the laser introduce optical aberrations that limit both printing speed and precision.
The new approach uses metalenses, flat optical elements engineered from tiny, repeating structures that bend and focus light without the distortions that plague normal lenses. By integrating arrays of these metalenses with two-photon lithography systems, researchers can create far more focal points at once and maintain high-resolution focus across a larger area. In one demonstration, arrays of more than 120,000 metalenses worked together to print arrays of microscopic chessboard pieces just 100 micrometers wide with feature sizes around 113 nanometers. The system printed at rates up to 120 million voxels per second, roughly 1,000 times faster than typical two-photon lithography setups, and could cover areas up to 12 square centimeters without stitching multiple prints together.
Metalenses operate by manipulating light with sub-wavelength surface structures, giving engineers control over focus and wavefront shaping that traditional optics can’t match. Faster, high-resolution, and larger-area printing brings applications such as drug delivery devices, microoptics, and fusion research targets closer to reality because manufacturing no longer has to choose between detail and speed.