High resolution optical surface testing using transport of intensity equation

Phase distribution may be determined by measuring only the intensity distributions along the optical axis via the Transport of Intensity Equation (TIE). TIE has been a viable alternative to interferometry techniques for experimental conditions where those techniques perform poorly. These conditions are either because of the requirement one applies on the spatial and temporal coherence of the optical source or because of sensitivity and resolution issues. Optical testing is crucial in applications using manufactured optical elements. In this paper, we developed a method and experimental realizations capable to use both Shake-Hartman wavefront sensing (SHWS) and TIE method for testing transparent and reflective optical surfaces. The integration of TIE and SHWS has the advantage for obtaining high spatial resolution and wide dynamic range which cannot be obtained using only one of those methods. We showed that the retrieved phase profile and quantified surface variations of unknown samples from both methods are in very good agreement with each other.