Glass-based optical lenses are used in multiple applications. From the camera in a cell phone to a sophisticated, professional camera, to microscopes and other imaging devices used in the medical field – glass lenses are the standard. Today’s lenses are bulky and resist miniaturization. Next-generation technologies, in relationship to cameras or microscopes, require lenses made of new materials. Metalens will change lenses for the future.
Lenses for cameras and other applications are based on refractive optics, which involves using curved lenses to bend light rays. The power of a conventional lens is proportional to its thickness. As a result, the refractive lens cannot be very thin. They also have issues with chromatic dispersion, and therefore multiple images are produced over a range of focal lengths. Multiple lenses can cancel out this dispersion, but, this adds further to the weight, thickness and cost of a lens system.
Diffractive lenses offer a route to ultrathin lenses by redirecting light as light waves pass through a series of slits in a thin, opaque material. These lenses can be flat, and therefore much lighter and thinner than refractive optics. However, they suffer from much larger dispersion.
Metasurfaces have facilitated the replacement of conventional optical elements with ultrathin and planar photonic structures. Previous designs of metasurfaces were limited to small deflection angles and small ranges of the angle of incidence.
In a paper published Feb. 9, 2018, in Science Advances, scientists at the University of Washington announced that they have successfully combined two different imaging methods—a type of lens designed for nanoscale interaction with lightwaves, along with robust computational processing—to create full-color images.
The team created an ultra-thin lens which is part of a class of engineered objects known as metasurfaces. Metasurfaces are 2-D analogs of metamaterials – meaning they are materials manufactured with physical and chemical properties not normally found in nature. A metasurface-based lens – or metalens – consist of flat microscopically patterned material surfaces designed to interact with lightwaves.
Images that have been taken with metalenses yield clear images for only small slices of the visual spectrum. However, the UW team’s metalens, in conjunction with computational filtering, is yielding full-color images with very low levels of aberrations across the visual spectrum.
“Our approach combines the best aspects of metalenses with computational imaging—enabling us, for the first time, to produce full-color images with high efficiency,” said senior author Arka Majumdar, a UW assistant professor of physics and electrical engineering.
Instead of being manufactured with glass or silicone, metalenses consist of repeated arrays of nanometer-scale structures, such as columns or fins. When properly laid out on these minuscule scales, these structures can interact with individual lightwaves with the precision not offered by traditional lenses. Since they are so small and thin, they take up much less room that the lenses currently used in cameras and high-resolution microscopes.
Metalens technology is definitely the wave of the future when it comes to imaging, and manufacturing equipment to be lighter and sometimes smaller, as would be the case with a mini-microscope.
At Universe Optics, we pride ourselves on manufacturing the highest quality, precision lenses available. As technology changes, you can be assured that our team of engineers, along with our manufacturing facilities, will deliver exceptional results when it comes to your specifications.