Study Of Phase Retrieval Method From Intensities Of Coherent Light

Among the noninterferometric measurements, the iterative method, transport of intensity equation (TIE) method and phase space algorithm are discussed respectively as for the developing progress, basic theory and models, while iterative method and TIE method are especially focused on. The author classifies the TIE method into simple TIE (STIE) and pseudo-exact TIE (PTIE) according to the approximation calculation level of the measured intensity. The former is simple and fast while the latter is slightly slower but more accurate.The iterative algorithm possesses simple theory and good anti-noise performance with the error keeping decreasing. Unfortunately the iterative process takes time and convergence speed often depends on the initial value selection, which sometimes gets extremely slow. The TIE method goes much faster due to its non-iterative calculation process but possesses lower accuracy. Therefore the author attempted to combine these two methods in a certain extent (GS-TIE method), i.e. take the result from TIE calculation as the initial value for the GS (Gerchberg-Saxton algorithm) iterative algorithm. Experiment show that the GS-TIE method possesses higher accuracy.Multiple phase retrieval algorithms are simulated and analyzed mainly utilizing MATLAB as platform. Near-field and far-field Fresnel diffraction during MATLAB simulation are discussed respectively. The classical GS method, TIE method and GS-TIE method are simulated while result shows convergence speed of GS-TIE is much faster. As for the experiment and test part, we took coin and lens respectively as reflective object and transparent object, and obtained relatively good result.Generally speaking the optical detectors, based on photoelectric effect, only record the intensity, not the phase of optical field. So phase retrieval from only intensity measurements has always been an important issue for modern optics. This article focused on the noninterferometric determination of the phase of coherent light field, which is the basic problem of phase retrieval. The GS-TIE method proposed in this article has potential theoretical and practical value.