This paper describes the development of a novel mechanically scanned and non-contacting surface profiling technique in which measurements of electrical capacitance are used to maintain a small separation between the tip of a fine wire probe and the surface of the sample under examination as the probe is scanned over the surface. The principle of operation of the technique is described and examples of results obtained are shown. A prototype instrument has achieved a height resolution of approximately 5 nm and a lateral resolution of better than 500 nm, though these are by no means ultimate resolutions. This instrument also demonstrated the capability of the technique to measure surface profiles over both insulating and conducting surfaces. A commercial implementation of the technique offering 0.1 micron height resolution has recently become available and is described. Applications of this instrument and of the technique in general are discussed.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.