A HAMMER-ACTION MICROPOSITIONER FOR SCANNING PROBE MICROSCOPES

The hammer-action effect produced by the closing of a miniature electr omechanical relay was used to propel a rod along a track by the stick- slip inertial slider effect, with step sizes in the range of 30-500 nm and at frequencies up to 75 Hz. The rod was held tightly against the track by spring loaded balls so that the device worked well in any ori entation, including vertical motion against gravity. The device was te sted as the coarse approach mechanism in a scanning tunneling microsco pe, at room temperature and liquid nitrogen temperature. The voltage s ensitivity actually increased as the temperature was lowered, which is a vast improvement over the piezoelectrically driven micropositioners previously reported in the literature. Further advantages over the pi ezotranslators are the simple square pulse driving voltage, the much r educed sensitivity to slider surface contaminations, and the improved rigidity. Motion in two- or three-dimensions would be possible by usin g two or three such translators mounted orthogonally. (C) 1997 America n Institute of Physics.