Phase retrieval with the transport of intensity equation. Part III. Implementation with explicit separation of boundary signal

Using the transport of intensity equation (TIE), we implement a rapid method of non interferometric phase retrieval. Our algorithm retrieves the phase of a paraxial wave uniformly illuminating a circular aperture, using a matrix approach based on an expansion of the aberrated wavefront into a weighted sum of Zernike circle polynomials. Our method incorporates an explicit and robust separation of the boundary signal from the longitudinal intensity derivative of the field. We also present a condition which the distance between the intensity images must satisfy in order to yield an accurate estimate for the intensity derivative, together with an estimate for the optimal value of this defocus distance. (authors). 8 refs., 1 tab., 4 figs