Magnetostrictive force actuators for superprecise positioning

Magnetostrictive actuators for superprecision positioning in steps of 10/sup -2/ nm over a range of displacements up to 1 m have been developed and investigated. The actuators generate forces up to 10/sup 4/ N and are suitable as force actuators in steps of 10 nm. Exact displacement is achieved by an active element made from Terfenol D alloy based on rare-earth metals with a giant magnetostriction. The actuators can be controlled manually without any additional power source or by using a computer. For manual control the minimum linear-displacement step does not exceed 3 nm, and when the device is used on a turntable the minimum angular displacement step is 15-10/sup -3/ angular seconds, while for computer control these quantities are 10/sup -2/ nm and 4/spl times/10/sup -5/ angular seconds respectively.