Phys.org October 18, 2023
Imaging with resolutions much below the wavelength λ remains challenging at lower frequencies, where exponentially decaying evanescent waves are generally measured using a tip or antenna close to an object. Such approaches are often problematic because probes can perturb the near-field itself. Researchers in Australia have demonstrated that information encoded in evanescent waves can be probed further than previously thought, by reconstructing truthful images of the near-field through selective amplification of evanescent waves like a virtual superlens that images the near field without perturbing it. They quantified trade-offs between noise and measurement distance, experimentally demonstrated reconstruction of complex images with subwavelength features down to a resolution of λ/7 and amplitude signal-to-noise ratios < 25dB between 0.18–1.5 THz. According to the researchers their procedure can be implemented with any near-field probe, it greatly relaxes experimental requirements for subwavelength imaging at sub-optical frequencies and opens the door to non-invasive near-field scanning… read more. Open Access TECHNICAL ARTICLEÂ
Concept schematic of virtual superlens. Credit: Nature Communications volume 14, Article number: 6393 (2023)