Microsphere-Coupled Scanning Laser Confocal Nanoscope for Sub-Diffraction-Limited Imaging at 25 nm Lateral Resolution in the Visible Spectrum

Abstract

We report a direct optical super-resolution imaging approach with 25 nm (∼ λ/17) lateral resolution under 408 nm wavelength illumination by combining fused silica and polystyrene microspheres with a conventional scanning laser confocal microscope (SLCM). The microsphere deposited on the target surface generates a nanoscale central lobe illuminating a sub-diffraction-limited cross-section located on the target surface. The SLCM confocal pinhole isolates the reflected light from the near-field subdiffractive cross-section and suppresses the noises from the side lobe and the far-field paraxial focal point. The structural detail of the subdiffractive cross-section is therefore captured, and the 2D target surface near the bottom of microspheres can be imaged by intensity-based point scanning.

Multimodal Nonlinear Optical Imaging of Live Cells Using Plasmon-Coupled DNA-Mediated Gold Nanoprism Assembly

“…Since the two-photon optical properties is directly proportional to the fourth power of the fundamental field amplitude, an enhancement of 10 1 of the local field at the fundamental frequency for assembly structure will lead to an increase of up to 10 4 of the two-photon NLO properties. Our experimental findings are supported by finite difference time domain (FDTD) simulation 40–42 investigation, where we have included the multipolar and finite size effects in our calculation.…”

“…Experimental details has been reported before 3,10,14,40 . For TPS and TPF intensity measurement, the fundamental 1100 and 1300 nm excitation light was generated using optical parametric amplifier (OPO), pumped by 100 fs pulse width and 80 MHz repetition rate Ti:sapphire laser ( Coherent, USA).…”

“…For electromagnetic wave calculations, we used FDTD simulation software package, as previously reported by us and other groups 10,40–42 . Frequency dependent dielectric function of gold was used for the gold nano-antenna made from gold nanoprism assembly.…”

Nano-jet related to Bessel beams and to super-resolutions in microsphere optical experiments

“…Also as the microsphere is composed of dielectric materials there are not any nonlinear effects in this system. High resolutions were obtained in microsphere optical experiments (up to 50 nm in [7][8][9] and 25 nm in [10]). Such high resolutions might have an impact in the fields of integrated optics, microchips, photo lithography plus plasma etching, photo resists etc., in which very high resolutions are needed.…”

Characterization of photonic nanojets in dielectric microdisks

“…The microspheres have been proved the facility to discern the shape of pattern with a minimum feature size of 25 nm. This super-resolution imaging technique can find many applications in micro-fluidic system, biomedical microscopy and nano-photonics circuit [20][21][22]. However, the detailed imaging mechanism of photonic nanojets in a dielectric microdisk should be studied further.…”