A heterodyne Nd:YVO4 microchip laser self-mixing interferometry.based on frequency and polarization multiplexing.has been demonstrated. By using two orthogonally.polarized lights to measure the measurement and reference.target, the effect of the acousto-optic crystal thermal creep.and air disturbance in interference light path is eliminated..In addition, the measurement error caused by the difference.between two identical microchip lasers is compensated for.by shifted frequency multiplexing tech
