It might be small, but it’s a big feat. A lens has been built that is thinner than the waves of light it focuses. Such lenses, made from light-warping metamaterials, might someday replace the heavier glass lenses used in everything from microscopes to phone cameras.
Ref: Metalenses at visible wavelengths: Diffraction-limited focusing and subwavelength resolution imaging. Science (3 June 2016) | DOI: 10.1126/science.aaf6644
ABSTRACT
Subwavelength resolution imaging requires high numerical aperture (NA) lenses, which are bulky and expensive. Metasurfaces allow the miniaturization of conventional refractive optics into planar structures. We show that high-aspect-ratio titanium dioxide metasurfaces can be fabricated and designed as metalenses with NA = 0.8. Diffraction-limited focusing is demonstrated at wavelengths of 405, 532, and 660 nm with corresponding efficiencies of 86, 73, and 66%. The metalenses can resolve nanoscale features separated by subwavelength distances and provide magnification as high as 170×, with image qualities comparable to a state-of-the-art commercial objective. Our results firmly establish that metalenses can have widespread applications in laser-based microscopy, imaging, and spectroscopy.