In case you're unfamiliar with the diffraction limit, for telescopes it says that the ultimate limit for angular resolution is a function of the used wavelength and diameter of the used focusing element. For a microscope their resolution is a function of the wavelength and the index of refraction. That's why astronomical telescopes tend to be huge and microfabrication uses shorter wavelengths.
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"The seemingly infinite enhancement offered by SPADE does not imply unlimited resolution for finite photon numbers. Provided that enough photons can be collected, however, the giant improvements over direct imaging should still be useful."
Far-field linear optical super-resolution via heterodyne detection in a higher-order local oscillator mode
"If our technique is used with state-of-the art microscopes, precision on nanometer scales can be expected."
Achieving the ultimate optical resolution
"Our results stress that diffraction resolution limits are not a fundamental constraint but, instead, the consequence of traditional imaging techniques discarding the phase information."