His Nanooptics Group advances scattering-type scanning near-field optical microscopy (s-SNOM) and Fourier transform infrared nanospectroscopy (nano-FTIR), applying these techniques across diverse scientific and technological fields. Both methods provide wavelength-independent spatial resolution of 10–20 nm at visible, infrared, and terahertz frequencies—surpassing the diffraction limit by up to three orders of magnitude.