OPTICAL MEASUREMENT OF SPINDLE RADIAL MOTION BY MOIRE TECHNIQUE OF CONCENTRIC-CIRCLE GRATINGS

Abstract

This paper describes an optical moire method intended for the testing of the radial motion of a rotating spindle. Two concentric-circle gratings of fine pitches were configured for the radial motion to be directly detected by analyzing the interferometric fringes generated by the gratings. This method was immune to mechanical and electrical disturbances since neither master cylinder nor electrical gap gage was needed. Test results demonstrated that a measuring accuracy of less than 0.01 mum can practically be achieved using the method.