In a new study, physicists at the University of Toronto have invented a simple structure called a meta-screen, designed to focus light into tiny spots smaller than the wavelength of the photons in use.
These sub-wavelength spots overcome the diffraction limit, thus allowing even the smallest details of an object to be visualized.
Researchers developed a meta-screen composed of slots cut into a metallic screen, each narrowly spaced (less than half a wavelength apart) and of a precise length. They found that screen was able to effectively increase the range of sub-wavelength spots, enabling greater image resolution.
The meta-screen is the first sub-wavelength focusing technique capable of being scaled to any arbitrary wavelength, thereby offering unprecedented levels of resolution and flexibility for imaging and sensing apparatuses involving electromagnetic waves, such as radio waves for medical diagnostics or light for optical microscopy.
- Loïc Markley, Alex M. H. Wong, Yan Wang, and George V. Eleftheriades. Spatially Shifted Beam Approach to Subwavelength Focusing. Physical Review Letters, 2008; 101 (11): 113901 DOI: 10.1103/PhysRevLett.101.113901
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