Self-mixing Interferometer for Contactless Vibration Measurements

Self-mixing interferometer is a suitable tool for implementing industrial sensors, with the advantages of optical techniques, such as high accuracy and contactless operation, but at potential very-low cost. This paper describes some techniques recently developed for realizing vibration measurements, based on different signal elaborations and with different performances and applications. Particular attention is devoted to a novel digital-feedback vibrometer, realized through a feedback loop on the pump current.