Far-field nanoscale thermal and structure imaging

The imaging resolution of a conventional optical microscope is limited by diffraction to about half of the illuminating wavelength. A micro/submicron particle induced near-field effect can focus an incident laser beam to a small region of tens of nanometres. Using self-assembled transparent microspheres as far-field superlenses (FSLs), here we report the first experimental demonstration of combined structural, thermal, and stress imaging at a 20 nm resolution (<λ/26, λ=532 nm), even though the laser beam is at μm size. FSLs are integrated into a confocal Raman spectrometer and microscope system to overcome the diffraction limit. Periodical surface structure, thermal and stress information is examined. Furthermore, electromagnetic simulation is conducted to well interpret the experimental results. FSLs provide new opportunities in nanoscale imaging, nanolithography and nanotexturing.