A 60 Ghz Scanning Near-Field Microscope With High Spatial Resolution Sub-Surface Imaging

We report a 60 GHz (λ = 5 mm) near-field scanning microscope for surface and sub-surface imaging. The sensing evanescent millimeter-wave probe is made of an alumina microstrip line tapered to 7 μm (~ λ/700) to achieve high spatial resolution. The scanning probe microscopy platform provides amplitude and phase-shift mappings of the reflection coefficient. Our microscope demonstrates the ability to achieve subsurface microscale-resolution images of buried structures.