15 Super-Resolution Imaging and Microscopy by Dielectric …
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Fig. 15.8 SEM image of the Au dimer and bowtie, respectively. The dimer is formed by 120 nm
nanocylinders with 60 nm separation. b, f confocal Images of dimer and bowtie in a, e obtained
through the 5 and 53 μm BTG microsphere, respectively. c, g Calculated images by convolution
method at PSF resolution of λ/7 and λ/5.5, respectively. d, h Comparison of the measured (red
background) and calculated (dashed blue curves) irradiance profles through the cross-section of the
Au dimers (x-axis) (reproduced from [21], with permission from John Wiley and Sons)
in which the integration is performed in the object plane where the coordinates (x o ,
y o ) are linearly related to the image plane via the magnification M as: (x o , y o ) = (x i /M,
y i /M). A Gaussian function for PSF (x o , y o ) with the full width at half maximum
(FWHM) being a fitting parameter. Based on the Houston criterion, fitted values of
FWHM in the object plane were considered as resolution of the system. Based on
this, the image reconstruction with the λ/5.5 PSF resolution allows obtaining a highquality fit to the experimental results, as illustrated in Fig. 15.8g, h. This means that
the resolution for 15 nm gap sample in Fig. 15.8e is λ/5.5, instead of λ/27. Similarly,
it was shown the 60 nm gap sample in Fig. 15.8a is λ/7 (Fig. 15.8c, d).
15.3.2 Scanning Microsphere Super-Resolution Imaging
Microsphere has a viewing window around a quartz size of its diameter. Considering
particles with diameter 1–100 μm, the viewing window is less than 25 μm which
is too small for many practical applications. Controlling the position of the microspheres is required for generating a complete image of sample. Scanning functionalities are, hence, highly sought by the researchers working the field. There are several
proposals existing in the literature, including for example the microsphere-embedded
coverslip, superlensing microscope objective, swimming lens and AFM-style scanning microsphere-lens.
387
Fig. 15.8 SEM image of the Au dimer and bowtie, respectively. The dimer is formed by 120 nm
nanocylinders with 60 nm separation. b, f confocal Images of dimer and bowtie in a, e obtained
through the 5 and 53 μm BTG microsphere, respectively. c, g Calculated images by convolution
method at PSF resolution of λ/7 and λ/5.5, respectively. d, h Comparison of the measured (red
background) and calculated (dashed blue curves) irradiance profles through the cross-section of the
Au dimers (x-axis) (reproduced from [21], with permission from John Wiley and Sons)
in which the integration is performed in the object plane where the coordinates (x o ,
y o ) are linearly related to the image plane via the magnification M as: (x o , y o ) = (x i /M,
y i /M). A Gaussian function for PSF (x o , y o ) with the full width at half maximum
(FWHM) being a fitting parameter. Based on the Houston criterion, fitted values of
FWHM in the object plane were considered as resolution of the system. Based on
this, the image reconstruction with the λ/5.5 PSF resolution allows obtaining a highquality fit to the experimental results, as illustrated in Fig. 15.8g, h. This means that
the resolution for 15 nm gap sample in Fig. 15.8e is λ/5.5, instead of λ/27. Similarly,
it was shown the 60 nm gap sample in Fig. 15.8a is λ/7 (Fig. 15.8c, d).
15.3.2 Scanning Microsphere Super-Resolution Imaging
Microsphere has a viewing window around a quartz size of its diameter. Considering
particles with diameter 1–100 μm, the viewing window is less than 25 μm which
is too small for many practical applications. Controlling the position of the microspheres is required for generating a complete image of sample. Scanning functionalities are, hence, highly sought by the researchers working the field. There are several
proposals existing in the literature, including for example the microsphere-embedded
coverslip, superlensing microscope objective, swimming lens and AFM-style scanning microsphere-lens.