Reconstruction of the complex refractive index in nonlinear phase contrast tomography

A new nonlinear method to reconstruct the complex refractive index distribution with in-line phase tomography measurements is presented. The inverse problem is regularized with the Tikhonov smoothing norm of the index. The original nonlinear iterative approach is based on the Frechet derivative of the intensity recorded at a single propagation distance and on a Simultaneous Algebraic Reconstruction technique. The reconstruction method requires no a priori knowledge about the materials. The algorithm is successfully applied to some simulated data with noise.