Features of D-PSI interferometer

The existing Piezo-type interferometers interpret the interferogram by using PZT to make a phase shift.
During the phase shift, there occurs an error in interpreting the interferogram due to a noise arising from changes in the external environment (e.g., vibration, temperature, air flow).
The D-PSI interferometer allows a single camera to simultaneously get four pieces of interferograms with different phases, so it stand strong against noise.