Note: Simultaneous measurement of in-plane and out-of-plane displacement by using orthogonally polarized self-mixing grating interferometer.

In this paper, we present an orthogonally polarized self-mixing grating interferometer (SMGI) for simultaneous measurement of in-plane and out-of-plane displacements. The measurement ranges in both directions are limited only by the length of grating. The orthogonally polarized lights emitted from a birefringent He-Ne laser are separated and enter the grating at ±1st-order Littrow angles. The diffraction beams re-enter the laser cavity and cause self-mixing interference. To differentiate the orthogonally polarized lights and obtain high resolution, phase modulation technique is introduced to extract phases from the orthogonally polarized SMGI signals. The measurement results show that the proposed system can reach a submicron accuracy in the experiment. This work provides a good way to achieve high precision two-dimensional displacement measurement with a robust system configuration.