Far-field unlabeled super-resolution imaging with superoscillatory illumination

Abstract

Unlabeled super-resolution is the next grand challenge in imaging. Stimulated emission depletion and single-molecule microscopies have revolutionized the life sciences but are still limited by the need for reporters (labels) embedded within the sample. While the Veselago–Pendry “super-lens,” using a negative-index metamaterial, is a promising idea for imaging beyond the diffraction limit, there are substantial technological challenges to its realization. Another route to far-field subwavelength focusing is using optical superoscillations: engineered interference of multiple coherent waves creating an, in principle, arbitrarily small hotspot. Here, we demonstrate microscopy with superoscillatory illumination of the object and describe its underlying principles. We show that far-field images taken with superoscillatory illumination are themselves superoscillatory and, hence, can reveal fine structural details of the object that are lost in conventional far-field imaging. We show that the resolution of a superoscillatory microscope is determined by the size of the hotspot, rather than the bandwidth of the optical instrument. We demonstrate high-frame-rate polarization-contrast imaging of unmodified living cells with a resolution significantly exceeding that achievable with conventional instruments. This non-algorithmic, low-phototoxicity imaging technology is a powerful tool both for biological research and for super-resolution imaging of samples that do not allow labeling, such as the interior of silicon chips.

High-efficiency broadband achromatic metalens for near-IR biological imaging window

“…The proposed achromatic metalenses with record-high efficiencies and mass-manufacturable fabrication process could be extended to the visible spectrum as well (see Supplementary Fig. 12) and can potentially trigger a revolution in applications of flat optoelectronics 17,[40][41][42][43] . Our work is also expected to accelerate the commercialization and biological applications of metasurfaces in portable devices as well as untethered microrobots.…”

Superoscillatory quartz lens with effective numerical aperture greater than one

“…Binary transmission and phase retardation SOLs [6][7][8] and more sophisticated greyscale metasurfaces SOLs [9] have been developed with an effective numerical aperture for the central hotspot of up to NA=1.52. The superoscillatory focusing can be used in imaging [10] and this technology has been successfully used in confocal microscopes for biological [11,12] and nanotechnology imaging with sub-diffraction resolution [6-8, 13,14], in nanometrology [15] and optical trapping applications [16].…”

Optical superoscillation technologies beyond the diffraction limit

“…83,84 and for details on its implementation, see Ref. 85 . The double SLM technology is robust and apart from imaging applications (see below) it is used for atom trapping in cold atom experiment, see Figure 2S-a,b in Supplementary Materials.…”

“…Let 𝑃 SOL and 𝑃 COL to be the point spread functions of the illuminating superoscillatory lens and conventional objective lens (see Figure 6(d)). The microscope's response is characterised by its point spread function 𝑃 MIC = 𝑃 SOL × 𝑃 COL and it is bandlimited to spatial frequency 𝛷 = 2𝜋 × NA/𝜆, where NA is the average of the numerical apertures of the illuminating lens (SOL) and the imaging lens (COL) 85 . If the object has subwavelength structures and the function 𝑂(𝒓) describing it is not bandlimited to 𝛷, a conventional microscope cannot resolve its fine details beyond 𝜆 2NA…”