  Phase retrieval and imaging phase measurements are fields of intense
research. It has recently been shown that phase retrieval from self-referencing
interferograms (SRI) can be reformulated leading to a stable, linear equation
provided the amplitude of the field is known from prior measurement steps
(HOLOCAM). Consequently, the numerical solution thereof is straightforward.
This is a big achievement since convergence is otherwise not always guaranteed.
Applications are expected in X-ray microscopy, general phase retrieval,
holography, tomography and optical imaging.
