Oct. 05, 2018
Webcast

Webcast: Ultra-Thin “Metalens” Technology

Creating the First Flat Lens Capable of Correctly Focusing a Large Range of Colors

  • Top panels: Scanning electron micrographs of sections of broadband meta-lenses. They are composed of silicon nanopillars with various cross-sectional shapes patterned on a glass substrate. Bottom panel: Photo showing two elements of a multi-element meta-lens imaging system.Top panels: Scanning electron micrographs of sections of broadband meta-lenses. They are composed of silicon nanopillars with various cross-sectional shapes patterned on a glass substrate. Bottom panel: Photo showing two elements of a multi-element meta-lens imaging system.

Light of different colors travels at different speeds in different materials and structures. This is why we see white light split into its constituent colors after refracting through a prism, a phenomenon called dispersion. An ordinary lens cannot focus light of different colors to a single spot due to dispersion. This means different colors are never in focus at the same time, and so an image formed by such a simple lens is inevitably blurred. Conventional imaging systems solve this problem by stacking multiple lenses, but this solution comes at the cost of increased complexity and weight.

Columbia Engineering researchers have created the first flat lens capable of correctly focusing a large range of colors of any polarization to the same focal spot without the need for any additional elements. Only a micron thick, their revolutionary "flat" lens is much thinner than a sheet of paper and offers performance comparable to top-of-the-line compound lens systems. The findings of the team, led by Nanfang Yu, associate professor of applied physics, are outlined in a new study, published by Light: Science & Applications.

Original publication:

Sajan Shrestha, Adam C. Overvig, Nanfang Yu, and Ming Lu and Aaron Stein: Broadband Achromatic Dielectric Metalenses, Light: Science & Applications (2018)

Further information:

Columbia University School of Engineering and Applied Science

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