Self-mixing Grating Interferometer with Dual Laser Diodes for Sensing of Two-dimensional Dynamic Displacement
In this paper, a novel self-mixing grating interferometer (SMGI) with dual laser diodes (LDs) is proposed for two-dimensional (2D) dynamic displacement measurement. The light beams emitted from the LDs are incident onto a reflection grating with ±1st order auto-collimation diffraction angles and then diffracted back into the lasers respectively, which can cause self-mixing interference effect in each LD. Theoretical analysis on the SMGI signals corresponding to 2D displacement is presented and verified with the experimental observations. Measurement results of 2D dynamic displacement demonstrate that the proposed system can achieve the measurement resolution better than 10nm. The proposed SMGI sensing system has the advantages of high stability, compact mechanical structure and relatively straightforward operation.