Saturated Optical Radiation Emission and Ultrahigh Resolution Microscopy
Their method makes possible the optical imaging of nanostructures less than 1/8 the wavelength of the light used!
A joint group of researchers led by Katsumasa FUJITA and Satoshi KAWATA (Department of Applied Physics, Osaka University) and Shi-Wei CHU (Department of Physics/Molecular Imaging Center, National Taiwan University) succeeded in developing a totally new method for greatly enhancing the resolution capacity of conventional optical microscopy.
Whereas various new methods of overcoming the diffraction limit of conventional optical microscopes have been demonstrated, those methods all made use of switching or saturation of fluorescence, methods which did not permit repeated imaging of samples without loss of scattering intensity. This joint group, however, succeeded in developing a totally new method that makes use of intense scattering of a SPR (surface plasmon resonance) structure, in this case, a gold nanoparticle. To quote their research report, "…the saturation is governed by SPR. By extracting the saturated part, sub-70-nm full width at half maximum (FWHM) is achieved, demonstrating the first superresolution far-field imaging based on scattering. There is no bleaching of the scattering after prolonged observation and the reversibility of saturable scattering is demonstrated. We thus expand the horizon of superresolution imaging from fluorescence to scattering."
Abstract
"We show that scattering from a single gold nanoparticle is saturable for the first time. Wavelength- dependent study reveals that the saturation behavior is governed by depletion of surface plasmon reso- nance, not the thermal effect. We observed interesting flattening of the point spread function of scattering from a single nanoparticle due to saturation. By extracting the saturated part of scattering via temporal modulation, we achieve λ=8 point spread function in far-field imaging with unambiguous separation of adjacent particles."
To learn more about this research, please read the full research report entitled " Measurement of a Saturated Emission of Optical Radiation from Gold Nanoparticles: Application to an Ultrahigh Resolution Microscope " at this page of the Physical Review Letters website.
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