What impacts repeatability in linear motor stages?

Uni-directional repeatability is primarily impacted by the mechanical noise of the bearings and drift related to thermal expansion and to a lesser extent encoder related errors. Bi-directional repeatability is mainly linked to these errors in combination with angular hysteresis of the carriage. The XMS Series for example, uses non-recirculating cross roller bearings which have very little mechanical noise. Utilizing a stage design that minimizes carriage distortion, XM stages offer outstanding guaranteed bi-directional repeatability of ± 40 nm.

How does a linear motor work and what types are used in Newport Stages?

Linear Motors are typically integrated in motion systems that require the best dynamic response and performance while providing the advantage of no inherent drive wear. The fundamental working principle behind linear motors is based on the Lorentz Force, which describes the force on moving charged particles in the presence of electric and magnetic fields. The Lorentz Force experienced by individual charged particles can be taken collectively to describe the macroscopic force on a current carrying wire. A linear motor consists of rare earth element magnets that create the static field. These magnets are laid out in a sequence of alternating polarities mounted on an iron plate. A “forcer” element is made with current carrying windings, which is subject to the Lorentz Force and provides motion along the magnetic track when the windings are energized.