Dielectric microscopy with submillimeter resolution

In analogy with optical near-field scanning methods we use tapered dielectric waveguides as probes for a millimeter wave vector network analyzer. By scanning thin samples between two such probes we are able to map the spatially varying dielectric properties of materials with subwavelength resolution. Using a 150GHz probe in transmission mode we see spatial resolution of better than 500μm. Here, we apply the technique to rocks map the mineralogy at the submillimeter scale.