Fig. 5: Optical nanoscale imaging using DSPP.

a SEM image of the measured sample, which consists of two opposing triangles and a narrow slit between them. The black dashed rectangular box indicates the measurement region for DSPP. b AFM characterization image of the sample. c Optical morphology test results of the sample obtained using DSPP. d Measurement results of the blue line in b as a function of position, with the measured slit width being 28.2 nm. The black dots represent experimental measurement results, and the blue solid line represents the results obtained using Gaussian fitting, where FWHM denotes full width at half maximum. e Near-field intensity of the red line in c as a function of position, with FWHM being 28.6 nm. f Optical measurement results of the sample using confocal microscopy. g Comparison of slit size measurements obtained using AFM, confocal microscopy, and DSPP. The blue dashed line represents the measurement results of the blue line marked in (b), the red solid line represents the near-field intensity results of the red line marked in (c), and the green solid line represents the measurement results of the green line marked in (f)