Advancing Nanoscale Imaging: A 100-GHz Ultramicroscopy System Based on Nonfocusing Zero-Intermediate Frequency Radar Technology

A scattering-scanning near-field microscope, integrated with a 100-GHz zero-intermediate frequency (zero-IF) radar system, is proposed and demonstrated. Near-field imaging with a resolution of 140 nm is achieved through the utilization of a fundamental mixer. The nonfocusing structure simplifies the original focusing optical path and, combined with single-source zero-IF radar technology, streamlines the overall system structure while ensuring data collection efficiency. This facilitates subsequent system integration. The impacts on the actual excitation and collection of near-field signals were compared between the focusing mode and the nonfocusing mode. Subsequently, near-field imaging in the nonfocusing mode was successfully accomplished. A signal-to-noise ratio (SNR) of 35 dB in near-field amplitude images is attained by using commercial probes. This indicates that the unique system structure can provide a new solution for low-terahertz bans scanning near-field microscopes.