AsianScientist (May 8, 2017) – A team of researchers at the Pohang University of Science and Technology have developed a method to produce a large-scale array of hyperlenses in an attempt to create a flawless lens. Their results have been published in Scientific Reports.
The concept of a perfect lens that can produce immaculate and flawless images has been the Holy Grail of lens makers for centuries. However, a German physicist and optical scientist by the name of Ernst Abbe discovered in 1873 that conventional lenses are fundamentally incapable of capturing all the details of any given image due to the diffraction limit of the lens. Since then, there have been numerous advances in the field to produce images that appear to have higher resolution than allowed by diffraction-limited optics.
In 2000, Professor Sir John B. Pendry of Imperial College London suggested a method of creating a lens with a theoretically perfect focus. Pendry’s theoretic perfect lens would be crafted from metamaterials (materials engineered to have properties not found in nature) to go beyond the diffraction limit of conventional lenses.
Scientists all over the world have since endeavored to achieve super-resolution imaging that capture the finest of details contained in evanescent waves that would otherwise be lost with conventional lenses. Hyperlenses are super-resolution devices that transform scattered evanescent waves into propagating waves to project the image into the far-field.
Recent experiments that focus on a single hyperlens with a hyperbolic dispersion have demonstrated far-field sub-diffraction imaging in real time. However, such devices are limited by an extremely small observation area which consequently require precise positioning of the subject. A hyperlens array has been considered to be a solution, but fabrication of such an array would be extremely difficult and prohibitively expensive with existing nanofabrication technologies.
In collaboration with a team from Korea University, Professor Rho Junsuk has made great contributions to overcoming this obstacle by demonstrating a scalable and reliable fabrication process of a large scale hyperlens device based on direct pattern transfer techniques.
Using nanoimprint lithography, Rho’s team was able to readily fabricate a perfect large-scale hyperlens device on a replicated hexagonal array of hemisphere substrate directly printed and pattern-transferred from the master mold, followed by metal-dielectric multilayer deposition by electron beam evaporation. The resulting hyperlens array was able to resolve sub-diffraction features down to 160 nm under 410 nm wavelength visible light.
Rho anticipates that their cost-effective fabrication method can be used to make practical far-field and real-time super-resolution imaging devices that can be widely used in optics, biology, medical science, nanotechnology and other related interdisciplinary fields.
The article can be found at: Rho et al (2017) Demonstration of Nanoimprinted Hyperlens Array for High-throughput Sub-diffraction Imaging.
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Source: Pohang University of Science and Technology.
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