Laser Self-Mixing Interferometer for Three-Dimensional Dynamic Displacement Sensing

In this letter, we proposed an innovative laser self-mixing interferometer (SMI) with a reflection-type two-dimensional (2D) grating for three-dimensional (3D) dynamic displacement sensing. When the beams emitted by three lasers are incident on a reflective 2D grating with auto-collimation diffraction angles, the diffracted beams will return into the lasers along the original path, thus generating self-mixing interference effect in each laser. In order to obtain higher measurement resolution, phase-modulation technique is applied to the proposed interferometer. The operating principle for the proposed system has been demonstrated in detail. Measurement results show that our method is capable of sensing 3D dynamic displacement with resolution of nanometer level. The SMI presented in this letter has the merits of high resolution, compact system configuration and straightforward operation.