Digital holography for three dimensional tomographic and topographic measurements
Tomography is a technique to reconstruct the 3-dimensional (3D) profile of the object. In multi-angle holographic tomography (MAHT), data from different projections with different angles are recorded by an in-line Gabor hologram setup, and the 2-dimensional (2D) shapes of the object for different angles are reconstructed and combined to form a true 3D profile. A one-shot MAHT setup with 3 angles is built and the main issues involved in this technique are discussed. Compressive sensing (CS) is a new alternative to the conventional Fresnel approach for digital holographic reconstruction for sparse objects, and can show a good performance with respect to the depth of focus and working range. The performance of the Fresnel approach, the transfer function approach and the CS approach for holographic reconstruction is compared with respect to the depth of focus, twin-image effect and the computation time, which helps us determine the optimum approach to use in one-shot MAHT.