Abstract: An apparatus and method for positioning a wafer holding platform by moving it along a first set of axes concurrently through a path measured along a second set of axes. An apparatus of the present invention comprises a motor system to move the wafer holding stage and a motion control system to control the path of the wafer holding stage. The motor system constrains the wafer holding stage to a first two axes of movement, and the motion control system controls the path along a second two axes of movement. The first two axes and second two axes are located at angles from one another. The distance a wafer on the wafer holding stage is to be moved is measured along the second two axes. A method comprises constraining the movement of a wafer holding stage to a first and a second movement axes and controlling a path of the wafer holding stage along a third and a fourth movement axis. The present invention increases the speed of the wafer holding platform, thereby decreasing the time needed to test a wafer.

Abstract: Movable (a head) and stationary (a stator) members are disposed in contiguous relationship. First magnetizable and non-magnetizable zones are alternately disposed on the stator in a particular direction. Second magnetizable and non-magnetizable zones are alternately disposed on the head in the particular direction. The zones on the head and the stator face each other and have substantially equal spacings. First means are associated with the head for producing magnetic fluxes in the magnetizable zones in the head and stator in a particular pattern to obtain incremental relative movements between the head and the stator on a vectorial basis in the particular direction. Second means are associated with the head for compensating for hysteresis effects in the magnetizable zones in the head and stator. The second means may produce magnetic flux of alternating polarity and decaying amplitude near the end of each incremental movement of the head relative to the stator.