Signal processing method of phase correction for laser heterodyne interferometry

• A novel signal processing method of movement direction identification and phase correction is presented for laser heterodyne interferometry.
• The real-time movement direction identification is realized.
• The phase correction approach is proposed in detail to solve the fraction phase compensation when the initial phase difference is not equal to the zero phase difference.
• Bi-directional movement displacement experiments were performed to verify the feasibility of the presented signal processing method.

A novel signal processing method of movement direction identification and phase correction is presented for laser heterodyne interferometry. Based on the reference signal, four intervals with phase difference of 90° each other are set up. The real-time movement direction identification and the integer fringe counting are realized by detecting the times that the rising-edge of the measurement signal crosses the intervals. The phase correction approach is proposed in detail to solve the fraction phase compensation when the initial phase difference is not equal to the zero phase difference. Three experiments of the stability test, the nanometer and micrometer displacement tests on bi-directional movement were performed to demonstrate the usefulness and feasibility of the presented signal processing method.