Near-field thermal imaging by passive millimeter-wave microscopy

Passive millimeter-wave microscopy that enables imaging of the thermal radiation emitted from a sample with a spatial resolution below the diffraction limit is investigated. This technique utilizes a sensitive radiometric receiver in combination with a scanning near-field microscope. Experiments were performed at 50 GHz (λ = 6 mm) with sample temperatures ranging from 320K down to 200 K, and the performance was shown to be superior to that achieved with passive imaging systems in the infrared region.