The determination of differential phase introduced bydisplacement with interferometric technique is widelyemployed, for example, in the production control [1] orlever deflection of atomic force microscope [2] where thenon-contact and high resolution with nanometric scale isrequired. These measurements also require many aspectsof design, instrumentation and analysis techniques. Amongvarious interferometric interrogation methods for measuring the displacement in real time, quadrature detectionassociates with homodyne [3] or heterodyne [4] interferometry is attractive. This is because the quadrature detectionpermits wide dynamic range on phase measurement due