Laser Self-Mixing Grating Interferometer for MEMS Accelerometer Testing

A simple and robust testing system based on a laser self-mixing grating interferometer (SMGI) is proposed to determine the sensitivity of accelerometers. Self-mixing grating interference occurs when the light emitted from a laser diode is incident onto a reflective grating at a fixed angle and the first-order diffracted light returns back into the laser cavity. Frequency ratio method and minimum point method that are officially used to calibrate accelerometers are modified to make it suitable to an SMGI testing system. In order to evaluate the performance of the proposed method, the sensitivity of a commercial microelectromechanical system accelerometer was tested at different vibration frequency. The obtained results show good agreement with the sensitivity given by the manufacturer's specification. Given its stability, simplicity, and efficiency, the proposed system has the potential to be adopted as an alternative method to test accelerometers for industrial applications.