Design and evaluation of a polyimide spring system for the scanning force microscope of the Phoenix Mars Mission 2007

Precise motions in the nanometer and Angstrom range can be achieved by magnetic forces, deflecting a spring mounted platform. Permanent magnets, which are mounted on that platform, are either attracted or repelled by magnetic fields, which are generated in rigidly mounted coils underneath the magnets. These electro-magnetic forces are counter-balanced by mechanical springs, which suspend the platform from the same rigid frame to which the coils are mounted. Rapid actuation may cause mechanical ringing if such a stage is not properly damped. We have evaluated internal friction of the springs as damping mechanism. We found that polyimide springs provide two to three times better damping and moderate temperature dependence compared one made of stainless steel. This allowed us increasing the scan speed of an AFM by a factor of more than two.