A Mach-Zehnder interferometer was used, and the given setup was assembled. With the use of a polarizing beam splitter, a laser diode beam was divided into reference and measurement beams. The beams were combined by another beam splitter after travelling through a compensator and a test cell. As these beams were polarized into perpendicular planes, they did not show interference. A quarter-wave plate was put in front of the charge-coupled device (CCD) camera to convert the two linearly polarized beams to right-or left-circularly polarized beams prior to entering the phase splitting 3-CCD camera. The three polarizers were set at the angle of -π/4, 0 and π/4.This led to the generation of three interferograms with phase-shifting of λ/4 with respect to each other.