Objective
The goal of hyperlens is to magnify the sub-diffraction-limited objects and project the magnified images to the far field.
Background
The diffraction limit in far-field optical imaging was considered to be a fundamental barrier. Since high spatial frequency information carried by evanescent waves only exists in the near field of an object, only the propagating light reaches the far-field image plane and the resolution of the conventional microscope is limited to half of the wavelength. The hyperlens breaks the diffraction limit by magnifying the sub-diffraction-limited objects and projecting the magnified images to the far field. The hyperlens is composed of a curved periodic stack of Ag (35 nm) and Al2O3 (35 nm) deposited on a half-cylindrical cavity fabricated on a quartz substrate. This anisotropic metamaterial has electric permittivities in opposite signs in two orthogonal directions, which not only enables waves with large tangential wave vectors to propagate in the medium but also achieves an image magnification.
Results
Our experimental results demonstrated far-field imaging with resolution down to 125nm at 365nm working wavelength.
Fig. 1 Magnifying optical hyperlens. (a) Schematic of hyperlens and numerical simulation of imaging of sub-diffraction-limited objects. (b) Left: SEM image of tilted line pair object with indicated gap sizes. Middle: Image captured by optical microscope through hyperlensing. Right: Intensity profiles of the three indicated cross sections showing resolved 125nm gap (top).
[1] Zhaowei Liu, Hyesog Lee, Yi Xiong, Cheng Sun and Xiang Zhang, "Far-Field Optical Hyperlens Magnifying Sub-Diffraction-Limited Objects", Science, 315, 1686, 2007 view pdf
[2] Hyesog Lee, Zhaowei Liu, Yi Xiong, Cheng Sun and Xiang Zhang, "Development of optical hyperlens for imaging below the diffraction limit", Optics Express, 15, 15886, 2007 view pdf
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