Metalenses are typically made using electron beam lithography, in which a focused beam of electrons is scanned onto a piece of glass or other transparent substrate to create antenna-like patterns point by point. However, the scanning process of the electron beam limits the size of the lens that can be created, as scanning each point is time-consuming and has low throughput.
As the size of the metalens increased, the digital files required to process the patterns became significantly larger, which would take a long time for the DUV lithography machine to process. To overcome this issue, the researchers compressed the files using data approximations and by referencing nonunique data.“We utilized every possible method to reduce the file size,” Ni said. “We identified identical data points and referenced existing ones, gradually reducing the data until we had a usable file to send to the machine for creating the metalens.”Using the new fabrication method, the researchers developed a single-lens telescope and captured clear images of the lunar surface — achieving greater resolution of objects and much farther imaging distance than previous metalenses. Before the technology can be applied to modern cameras, researchers must address the issue of chromatic aberration, the Penn State team members said. The researchers are exploring designs in the visible range, Ni said, and will compensate for various optical aberrations, including chromatic aberration.The research was published in Nano Letters (www.doi.org/10.1021/acs.nanolett.2c03561).