Super Resolution Imaging of Material Properties Using MEMS Near-Field Microwave Spatial Modulator Arrays

Near-field microwave probes were developed and used to image electromagnetic properties of materials with spatial resolutions only limited by the probe aperture size, signal-to-noise ratio and not by the Abbe barrier. The price of this "super" resolution is point-by-point scanning of the sample that makes it slow and requires additional mechanisms to control the probe-to-sample distance during the scan. Here we discuss a new technique that combines aspects of the "free-space" imaging with the super resolution of near-field scanning probes by using an array of local scatterers near the sample. Upon illumination with microwaves, the array of local scatterers generates near-fields near the sample. The near-fields interact with the nearby sample and modulate the reflection coefficient of the scatterers in the array. Vibrating or rotating different scatters at different base frequency, the reflected microwaves are multiplexed by the array and then de-multiplexed at the receiver to reveal the 2-D spatial field. We implemented applications of this technique in imaging a non-homogenous dielectric sample at 10 GHz using an array of micromotors as scatterers. We also imaged carbon nanotubes using an atomic force microscope tip as the local scatterer with an unprecedented resolution of 5 nm at 100 GHz