Displacement Measurement of Sub-nanometre Resolution for Positioning System

Abstract

A sub-nanometer resolution displacement measuring method, basing on fringe phase shifting, is developed in this paper. The system mainly consists of a grating interferometer and a phase-shift device. The principle of interfere fringe phase-shifting is to move the photoelectric sensor between the two interference fringes. The method leads to higher resolution in theory than that with laser interferometer. Measuring and positioning experiments to verify the method are made and the’ results indicate that the new displacement measuring method will improve the positioning accuracy about 16%. The displacement measurement resolution with the new method will reach to sub-nanometre in theory.