Scanning microwave microscopy of active superconducting microwave devices

We have developed a scanning microwave microscope which can image features with 20 /spl mu/m spatial resolution. The microscope consists of a section of open-ended coaxial cable which is scanned over the surface of a planar sample. Images can be made in either passive mode, in which the reflectivity of the probe tip is measured as a function of position, or in active mode, in which stray fields from the sample are picked up by the scanning probe and measured with a vector demodulation circuit. We have imaged reflectivity variations of metallic and superconducting samples in passive mode to determine the spatial resolution of the technique. Images are also presented in active mode of a superconducting microwave device taken at liquid nitrogen temperature.