Fig. 3: Sub-diffraction multicolor 2D imaging.
a Sketch of an SOL-based scanning optical microscope. When the SOL is illuminated by a collimated laser beam, a subwavelength-focused, 10λ-long optical needle is formed at 428 μm away from the SOL output plane. A sample is placed within the needle length and scanned in the x-y plane. The transmitted light is collected by an objective and sent to a CCD camera for recording its image. b SEM micrographs of the resolution testing chart. The practical fabricated CTC distances between the slits in three structures (I-III) are 258 nm, 456 nm, and 677 nm, respectively. c Wide-field, d LSCM and e SOL-based imaging results for the testing chart in b. f–h Line-scanning intensity profiles of the experimental images by addressing the CTC distances from 150 to 350 nm at an interval of 100 nm with three different microscopes under three illumination wavelengths. The resolvable CTC distances are 677 nm for the traditional wide-field microscope, 456 nm for LSCM and 258 nm (0.53λ) for our SOL-based microscope at the incident wavelength of λB = 488 nm.
