Non-interferometric methods of phase estimation for application in optical tomography

Abstract

We describe here two non-interferometric methods for the estimation of the phase of transmitted wavefronts through refracting objects. T h e phase of the wavefronts obtained is used to reconstruct either the refractive index distribution of the objects or their contours. Refraction corrected reconstructions are obtained by the application of an iterative loop incorporating digital ray tracing for forward propagation and a modified filtered back projection (FBP) for reconstruction. The FBP is modified to take into account non-straight path propagation of light through the object. When the iteration stagnates, the difference between the projection data and an estimate of it obtained by ray tracing through the final reconstruction is reconstructed using a diffraction tomography algorithm. The reconstruction so obtained, viewed as a correction term, is added to the estimate of the object from the loop to obtain an improved final refractive index reconstruction.

Phase retrieval algorithms: a personal tour [Invited]

“…Tomographic imaging can suffer from missing projections [56], or unknown phases in optical refraction tomography [57] and diffraction tomography [58], which iterative algorithms can fill in.…”

Noninterferometric phase retrieval using a fractional Fourier system

“…These methods have been used for a broad range of applications from microscopy [4,5] to astronomy [6], with both fully [7,8] and partially coherent sources [9,10] and wavelengths ranging from the visible to x rays [11]. In a broad sense, all of these methods extract the phase and thereby the complete signal information from single or multiple intensity measurements by using a deterministic algorithm based on the underlying physical model.…”