Nanometer Resolution of Magnetic Levitation Stages for Planar and Linear Scan Application

This article describes the design rules for the magnetic constraints, the sensors, and the controller for planar and linear stages for a scan application with nanometer resolution. For a new planar maglev system, it is shown that very low- and high-resolution optical incremental sensor heads can be used in small gaps inside and below the PCB. The “inside coils sensor” design leads to nonlinearities in the force generation. The article shows that the resulting nonlinearities can be eliminated by a current pre-shaping method. It is also shown that it is possible to use only incremental encoders for linear maglev scan modules as well as for gantry maglev systems, and that this is necessary for low-price area in high-precision automation.