Scanning near-field infrared microscopy based on tapered silver–halide probes

We report on developments in scanning near-field infrared microscopy where the scanning elements are silver–halide tapered fiber probes. These probes showed good transmission efficiency and a transparency over a very wide spectral range (0.6–10 μm), which may prove useful in high-resolution spectroscopy. We performed spatial characterization of the radiation distribution emitted from these probes, using the knife-edge technique. The obtained profiles, measured both for midinfrared and for visible radiation, were consistent with theoretical predictions. Images of subwavelength features, acquired with these probes, validated their potential for super-resolution microscopy, spectroscopy, and radiometry in the midinfrared.