Optical Tomography Of Phase Objects With Phase-Shifting Interferometry And Stepping Wise Shifted Ronchi Ruling

摘要

An experimental setup for tomographic inspection of phase objects is presented. The system is based on an interferometer which uses two windows in the input plane and a translating grating as its pupil. In the output, interference of the fields associated with replicated windows can be achieved by a proper choice of the spacing between windows with respect to the grating period. Placing a rotating object in one window and with a reference crossing through the second one, the phase of projections results encoded in a composite interference pattern over the plane of the traditional sinogram. Phase stepping of such composite interferograms can be achieved by lateral translation of the grating to obtain the unwrapped phase distribution as the corresponding sinogram of the object slide under inspection. The sinogram allows tomographic reconstruction of slices by standard procedures. Composite interferograms and preliminary reconstructions for some transparent samples are shown.