Application of incremental polymeric scales for high precision piezoelectric angular positioning system

A high precision piezoelectric rotational stage with low-cost incremental polymeric scales is proposed and investigated in this work. For avoiding datum plane surface errors caused by application of additional bearings to support the rotational part, the latter one contacts with a stationary piezoelectric disc, which oscillates in travelling wave mode, at three specific points via contacting ring. The resolution of rotation is determined only by geometrical errors of external surface of the piezoelectric disc and can be easily achieved to be in the range of 1 mu m. Low-cost polymeric scales are applied to measure angular displacement by means of moire fringes. Peculiarities of scales fabrication are defined taking into consideration the final accuracy of the device.