Velocity measurement of MEMS with temporal heterodyne microscopic speckle interferometry

With the rapid development of micro electro mechanical systems (MEMS), the high-precision measurement technology applied to MEMS devices becomes increasingly important. Traditional micro scale measurement techniques such as scanning electron microscope (SEM), atomic force microscope (AFM), and scanning tunnelling microscope (STM) are widely used in measuring the surface topography and local deformation of MEMS. However, these scanning-based measurement technologies are difficult to achieve full-field and dynamic detection, and they are easy to cause damages to the measured object. In this paper, the microscopic speckle interferometry and heterodyne technology are combined to realize the measurement of constant velocity of MEMS. We presented the experimental principle of temporal heterodyne microscopic speckle interferometry, and measured the real-time motion of MEMS, which verified the feasibility of this method. The experimental results prove that our method has the advantages of real-time, full-field, good noise immunity and low-cost.