We built a scanning force microscope working in ultrahigh vacuum. The lever deflection is measured by a fiber‐optic interferometer. To detect large lever deflections the distance between the fiber end and the cantilever backside is controllable by a piezoelectric device. With this technique force–distance curves can be acquired even over large distances. We implemented a stepper motor with gear reduction system for coarse approach in our microscope. First measurements of thin gold films grown on mica obtainedinsituat 10−8Pa are presented. ©1996 American Institute of Physics.