Engineers create first lightweight flat telescope lens that can capture color

For centuries, telescopes have relied on curved lenses and mirrors to capture images of the cosmos. While effective, these traditional optical elements are heavy and bulky. Large observatories and space-based telescopes require massive, curved mirrors to bend light efficiently.

However, mirrors can introduce distortions and imperfections, affecting image clarity. Now, researchers have developed an innovative flat lens that promises to revolutionize telescope design by reducing weight and improving image quality.

Lenses have always worked by bending light to focus images, but as they become more powerful, they also become heavier and bulkier. This limitation presents a significant challenge for large-scale telescopes that need to gather light from distant celestial objects. While mirrors offer an alternative, they can still distort images and are not always the ideal solution.

Scientists have explored lightweight alternatives such as diffractive lenses, which manipulate light through structured patterns rather than curved surfaces.

One type, the Fresnel zone plate (FZP), uses concentric ridges to focus light, making it much thinner and lighter than traditional lenses. However, FZPs suffer from chromatic aberration, which results in color distortions. These limitations have hindered their widespread adoption in astronomical imaging.

A research team from the University of Utah, led by engineering professor Rajesh Menon, has developed a large-aperture flat lens that overcomes these challenges. Their work, published in Applied Physics Letters, demonstrates how this new lens design can achieve high-resolution imaging without the bulk of traditional optics.

Using a novel computational design method and advanced lithography techniques, the team created a 100-millimeter-wide diffractive lens capable of focusing light across a broad range of wavelengths, from 400 to 800 nanometers.

Unlike previous diffractive lenses, this new flat lens maintains accurate color representation while achieving sharp image resolution.

"We demonstrated that computational methods could achieve similar results with significant reductions in weight and footprint," Menon explained.

The lens consists of microscopically small concentric rings etched onto a substrate. Unlike the ridges found in FZPs, these rings are designed to minimize chromatic aberration, allowing all visible wavelengths of light to focus correctly. This results in a full-color, in-focus image—an essential requirement for astronomy and Earth observation.

To evaluate their design, the researchers built a custom optical system and adapted the lens for use in a telescope. They tested it by capturing images of the sun and moon, demonstrating its ability to resolve fine details such as sunspots and lunar craters.

"Our demonstration is a stepping stone towards creating very large aperture lightweight flat lenses capable of capturing full-color images for use in air-and-space-based telescopes," said Apratim Majumder, a research assistant professor at the University of Utah and lead author of the study.

Simulating and optimizing the lens' performance required solving complex computational problems involving massive datasets. The fabrication process also demanded extreme precision, as even minor imperfections in the lens' microstructures could degrade image quality.

"Once we optimized the design of the lens’ microstructures, the manufacturing process required very stringent process control and environmental stability," Majumder noted.

This breakthrough has significant implications beyond astrophotography. The ability to produce large, lightweight lenses could lead to simpler and more affordable airborne and space-based imaging systems.

"If successful, these flat lenses could lead to simpler, cheaper airborne and space-based imaging systems for astronomy and Earth observation," Menon stated. "Lighter, cheaper ground-based telescopes would also have many applications, including use by hobbyists."

The aerospace industry could also benefit from this technology, as compact, high-performance lenses are essential for satellites, drones, and reconnaissance equipment. Moreover, industries requiring high-resolution imaging, such as medical diagnostics and environmental monitoring, could see advancements based on this research.

By combining computational techniques with precise manufacturing, Menon's team has created a lens that maintains optical performance while shedding the weight and limitations of traditional designs.

Their work marks a crucial step toward the future of lightweight, high-quality optical systems that could transform how telescopes, satellites, and other imaging devices capture the world and the universe beyond.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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