A special imaging mode of the scanning tunneling microscope (STM) based on charge trapping was used to probe the uniformity of lubricant distribution on magnetic thin film rigid disks at resolutions of better than 35 nm. Electron beam deposited STM tips were used to achieve this resolution. Coupons from untested rigid disks and those subjected to wear in dry helium and humid air were examined. We also examined coupons of an untested disk on which a scratch mark was made with a ferrite pin. It was found that the lubricant layer was nonuniform in the scratched region. © 1991 by ASME.