Apertureless scanning near-field microscopy at terahertz frequencies: development and applications

We discuss the development of an apertureless near-field scanning microscope capable of nano-scale imaging and spectroscopy measurements in the terahertz frequency range. We describe potential applications of this instrument at both elevated and cryogenic temperatures; such as imaging the metal-insulator transition in vanadium dioxide (VO$_{2}$) thin films,\footnote{Qazilbash et. al., \textbf{Science} 318, 1750 (2007)} and spectroscopy measurements of high-temperature cuprate superconductors.\footnote{Stinson et. al., \textbf{Phys. Rev. B} 90, 014502 (2014)}