**3.2. Interferograms analysis**

Many algorithms have been developed to extract the phase from the spectral interferograms, including the techniques based on fast Fourier transform (FFT) [26], convolution [27] and Hilbert transform [28]. We developed a FFT-based algorithm for the proposed system because it is effective, accurate and insensitive to intensity noise [5]. The developed algorithm for interpreting the captured interferograms contains five sections, as shown in the flowchart which follows (**Figure 8**).

**Figure 8.** Flowchart of the FFT-based algorithm.
