Ultra-Thin Meta-Lens Enables Fully-Focused All-Color Imaging

Due to dispersion effects, scientists have developed a lens that can focus light of different wavelengths to a single spot. It means that different colors are never in focus at the same time: “as a result, an image formed by such a simple lens is inevitably blurred,” they explain.

Conventional imaging systems can solve this problem by stacking multiple lenses and increasing device size, complexity, and weight. According to the team, this raises costs and reduces the potential for integrated dives for various imaging and display purposes.

They developed the first flat lens capable of correctly focusing a wide range of wavelengths with different polarizations to the same focal point without using additional elements. Their revolutionary “flat” lens, only 1m thick, provides performance comparable to top-of-the-line compound lens systems.

The team used their expertise in optical metasurfaces – engineered two-dimensional structures that control light propagation in free space – to create a thinner, lighter, and cheaper lens. The scientists created flat lenses out of pixels or meta-atoms. Each meta-atom is only a fraction of the wavelength of light, so the light passing through it is delayed by a different amount of time.

The researchers achieved the same functionality as a much thicker and heavier conventional lens system by patterning a thin flat layer of nanostructures on a substrate of approximately 100 m thickness.

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