Undersampling homodyne I/Q interferometry for ultra-low-frequency vibration calibration

In order to overcome the limitations associated with existing homodyne laser interferometry for ultra-low-frequency vibration calibration, undersampling homodyne I/Q interferometry is proposed in this letter. Limitation of time-consuming quadrature error compensation algorithm is avoided by using hardware error compensation with a specially designed homodyne interferometry optical configuration, while limitation of high Nyquist frequency is avoided by applying Kalman I/Q signal unwrapping with deeply under-sampled fringe phase signals. The effectiveness of the proposed method is verified through simulation and experiment. Experimental results indicate that sampling frequency can be reduced by 30 times for movement measurement at 1 m/s while quadrature error is compensated in real-time. It can, therefore, be concluded that the proposed method is effective for ultra-low-frequency vibration calibration.