Digital holographic imaging technique with twin image elimination

A digital holographic imaging method, comprising the following steps:

• (a) obtaining a single hologram by holography, said hologram being representative of a spatial intensity distribution, in a hologram plane at a hologram coordinate of an imaged object, of interference caused by interactions between an illumination beam and the imaged object placed at an object coordinate on an imaging axis,
• (b) implementing a plurality of iterations, each comprising the following steps:
• (i) by back-propagation to the object coordinate of a hologram field comprising a spatial amplitude distribution corresponding to the spatial intensity distribution of the hologram and a spatial phase distribution, determining an object field containing a spatial absorption distribution and a spatial phase-shift distribution of the imaged object,
• (ii) thresholding values of the spatial absorption distribution and of the spatial phase-shift distribution of the imaged object by decreasing the values of the spatial absorption distribution below an absorption threshold and by decreasing the values of the spatial phase-shift distribution below a phase-shift threshold, the absorption threshold and the phase-shift threshold decreasing with each iteration,
• (iii) by re-propagation of the object field to the hologram coordinate, determining a modified hologram field comprising a modified spatial amplitude distribution and a modified spatial phase distribution,
• (iv) replacing the spatial phase distribution of the hologram field with the modified spatial phase distribution, the spatial amplitude distribution of the hologram field being retained,
• (c) determining the spatial phase-shift distribution and the spatial absorption distribution of the imaged object as being those of the object field of a last iteration.