Light of different wavelengths travels at different speeds in different materials and structures. But an ordinary lens cannot focus light of different wavelengths to a single spot due to dispersion effects. This, say a team of researchers at the University of Columbia’s Engineering Department, NY, means different colors are never in focus at the same time: “so an image formed by such a simple lens is inevitably blurred”.
Conventional imaging systems can solve this problem by stacking multiple lenses, but this approach has the disadvantages of increased device size, complexity and weight. This increases costs and reduces the potential for integrated dives for various imaging and display purposes, say the team.
The Columbia Engineering researchers have created the first flat lens capable of correctly focusing a large range of wavelengths of any polarization to the same focal point without the need for any additional elements. At just 1µm thick, their revolutionary “flat” lens 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 in Light: Science & Applications.