Phase management in interferometric diffraction tomography with Incoherent illumination

The reconstruction of amplitude objects based on the method of grating interferometric tomography1 requires the measurement of both the contrast and phase of fringes formed in many different planes. For a relative high spatial frequency (~200-lines/mm) grating interferometric system, it appears very difficult to measure the phase difference between different fringe patterns (which in fact are the Fourier components of the object) directly. An axicon lens system has been developed to correct the random error generated by the CCD camera carrying slide that transports the camera to different planes. Also, the real phase of the Fourier component must be calculated from the measured phase of the corresponding fringe plane. The measurement error of a random nature degrades the reconstruction; the linear phase error or obliquity of the alignment process generates a permutation of the reconstruction. In addition, the window size, both for the object and the fringe pattern, must be set properly to retrieve the right phases.