In order to get the precise measurement results of large-amplitude high-bandwidth non-contact vibration, a new optical model and an algorithm for vibration measurement are put forward. Far-field interference fringe position is related with the phase of two beams of coherent light. The phase difference can be obtained through the position of maximum intensity fringe, which expresses the vibration displacement. Simulation results of cosine signal with the amplitude 10 μm and sound signals with the frequency 44.1 kHz expresses that sub micron vibration and sound vibration can be obtained.