Simultaneous measurement of the straightness error and its position using a modified Wollaston-prism-sensing homodyne interferometer

Simultaneous measurement of the straightness error and its position using a modified Wollaston-prism-sensing homodyne interferometer is proposed. In this modified interferometer, we designed a special moving sensor combining a Wollaston prism and a semi-reflective mirror being able to not only avoid the straightness measurement deviation caused by the measured object's rotation but also simultaneously obtain the straightness error's position without adding any measuring beam. Further, phase-modulating homodyne interferometry with phase generation carrier (PGC) demodulation is adopted to reduce the nonlinear error of phase measurement. Benefiting from the modified interferometer, the straightness error and its position can be measured simultaneously, and the measurement accuracy and stability can be improved. The optical configuration and the measurement principle of this method are presented. The influence of rotation angles on the straightness measurement result is also discussed. Finally, three experiments were performed to demonstrate the feasibility and applicability of the proposed method.