  A phase retrieval technique using a spatial light modulator (SLM) and a phase
diffuser for a fast reconstruction of smooth wave fronts is demonstrated
experimentally. Diffuse illumination of a smooth test object with the aid of a
phase diffuser (maximum phase shift, Df = 0.85p) results in a significant
diversity in the intensity measurements which, in turn, is beneficial for a
non-stagnating iterative phase reconstruction. The use of the SLM enables
accurate and fast speckle intensity recording and active correction of
misalignments in the setup. The effectiveness of the technique is demonstrated
in the optical testing of lenses.
