Linear encoders can position linear motors with repeatabilities
ranging from several microns to a few nanometers. In addition to
providing positioning data, most linear encoders also provide
velocity data that the drive uses in commutating the motor. With
the increasing use of linear motors, competition is heating up
among the various encoder technologies. Over the next few years,
engineers can expect to see many refinements to the repeatable
accuracies of measuring linear motion.  The accuracy of linear
encoders is a function of the scale graduation, the scanning
method, the system mounting, and the signal processing
electronics. At all mounted lengths, thermal factors affect the
accuracy. In addition, deviations in the signal during a signal
period also affect the position accuracy. Deviations in any of
these areas ultimately affect the speed stability of the linear
motor, even at low traversing speeds.  No vibrations, please
How and where an engineer mounts the encoder affects overall
system accuracy. The