For centuries, the optic lens has worked by bending light through translucent, curved material to focus and enhance distant or otherwise difficult-to-view images, but now flat lenses are radically changing how the technology works.
While glass and plastic lenses have improved the ability to view vision impairments, tiny objects, and vast distances, stronger lenses become increasingly bulky, heavy, and unwieldy. Now engineers at Price University, led by Professor Rajesh Menon, are flattening lenses to make stronger optics easier and more affordable to produce, with support from DARPA, the Office of Naval Research, and NASA.
Thinning the Optic Lens
Existing technologies for thinner lenses often come at a premium price, as seen in the additional cost of strong prescription eyeglasses. Menon’s solution is focused on larger-scale lenses used in telescopes and astrophotography, ensuring flat lenses can match the color preservation and light-focusing capabilities of curved ones. By reducing the size and bulk of long-distance lenses, engineers can save valuable space on aircraft, satellites, and space-based telescopes.
With a simple magnifying glass, light bends through the curved lens to enlarge an image. However, achieving stronger magnification requires the lens to be heavier and thicker to bend more light. While standard cameras and backyard telescopes can accommodate this, viewing distant galaxies millions of miles away requires observatories and space telescopes to use curved mirrors to minimize thickness and bulk.
Flattening the Curve
To overcome the limitations of traditional lenses, scientists have been working to design flat lenses that interact with light in fundamentally different ways. Menon is not the first to explore this concept. The Fresnel zone plate (FZP), based on the work of French physicist Augustin-Jean Fresnel, diffracts light through transparent and opaque concentric circles on a disc. However, FZP struggles with color accuracy. Traditional lenses bend all wavelengths of light at the same angle, whereas FZP’s diffraction across multiple ridges bends wavelengths at different angles, resulting in color distortion.
Menon’s team has addressed this issue by developing a lens that retains FZP’s light-bending power without sacrificing accurate color. They achieved this by optimizing the microscopic ridges, carefully adjusting their size and spacing to ensure wavelengths remain close enough to produce sharp images with high color fidelity.
“Our computational techniques suggested we could design multi-level diffractive flat lenses with large apertures that could focus light across the visible spectrum, and we have the resources in the Utah Nanofab to make them,” says Menon.
“Simulating the performance of these lenses over a very large bandwidth, from visible to near-IR, involved solving complex computational problems involving huge datasets,” says Majumder. “Once we optimized the design of the lens’ microstructures, the manufacturing process involved required very stringent process control and environmental stability,” Menon adds.
The Moon in Focus
While Menon’s work has applications across various industries, astronomy remains the primary focus. His team tested their innovation by capturing clear images of the sun and moon using a custom tripod-mounted telescope with the new lens.
The telescope also successfully captured short-range images, such as the Salt Lake City skyline. Post-processing techniques—such as separating, filtering, and combining the red, blue, and green channels before adjusting light curves in Photoshop—further enhanced image accuracy.
“Our demonstration is a stepping stone towards creating very large aperture lightweight flat lenses with the capability of capturing full-color images for use in air-and-space-based telescopes,” says Majumder.
The new paper, “Color Astrophotography with a 100 mm-diameter f/2 Polymer Flat Lens” appeared on February 3, 2025, in Applied Physics Letters.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.