Fig. 1. Schematic diagram of the novel homodyne frequency-shifting interference pattern locking system.

Fig. 2. Detailed scheme of the homodyne redundant phase-measurement interferometer with four interference signals.

Fig. 3. Photograph of experiment setup: (a) optics subsystem and (b) VME-based control subsystem.

Fig. 4. Plots of uncorrected and corrected experiment data sets: (a) Lissajous curve of signals from the HRPMI, (b) value of the HRPMI, (c) discrepancy, and (d) ASD for the data from (c).

Fig. 5. Experiment results: (a) interference pattern drift without locking, (b) residual drift with locking, and (c) ASD (in logarithmic coordinates) for the data from (a) and (b).

Fig. 6. Experiment results: (a) locking result and (b) error.