Optical-heterodyne displacement measurement using a frequency-ramped laser diode

Abstract We propose a new technique for measuring displacement of an object based on dynamic, optical-heterodyne interferometry using a frequency-modulated laser diode. Vibration amplitudes ranging from 0.26 nm to 5.2 nm at 1 kHz of oscillation frequency are determined with high accuracy. Theoretical treatments explain the principles, and the experiments verify the feasibility of this technique. The available performance of the newly developed system is also discussed in some detail.