An ultrathin and flat "metalens" could someday replace curved (convex) lenses typically used in microscopes, telescopes, cameras, smartphones and other devices.
Developed by engineers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), planar or flat lenses are highly efficient compared to conventional ones. We list down several advantages of replacing traditional glass lenses with these novel materials.
Advantages Of Planar MetaLens Over Curved Lens
1. Less bulky than conventional lens
Planar lenses feature layers of titanium dioxide at about 600 nanometers in length, which focus on intended light based on patterns, allowing a uniform-thickness component. These towers of titanium dioxide bend light toward the focal point.
SEAS engineers report that although the metalens appears smaller, it reaches the same magnification and resolution as a traditional glass lens, which is typically 5 to 6 centimeters (1.97 to 2.36 inches) in length. It achieves the same performance while being less bulky.
2. Practical and cheaper to manufacture
Professor Federico Capasso, an Applied Engineering and Physics expert at Harvard, says the fabrication of the planar lenses could actually become more cost-effective. This is thanks in part to the technology's compatibility with microprocessor chip and memory foundries, where it could potentially be mass-produced.
Capasso says planar lenses could be produced similarly to integrated circuits. Unlike conventional glass optics, these planar lenses do not require complicated post-processing steps or polishing. This makes it very practical and inexpensive to manufacture.
3. Produces aberration-free and sub-wavelength resolution images
Planar lenses are only about 2 millimeters (0.078 inches) across and finer than a hair strand. This tiny device can enlarge nanoscale objects and offer sharper focus than high-end microscope lenses.
It works in the visible spectrum and is capable of covering all colors, separating distances smaller than the wavelength of light. The lens uses an array of waveguides called "metasurfaces" that can bend light as it passes through, just like curved lenses.
Researchers report that when compared to the focal point of top-end lenses in microscopes, those of planar lenses were 30 percent sharper. This would allow for finer details and much higher resolution.
Capasso, whose contributions to physics include the quantum cascade laser, believes that planar lenses could revolutionize material science.
"In my opinion, this technology will be game-changing," he adds.