CONVERGENCE OF ALGORITHMS FOR PHASE RETRIEVAL FROM TWO INTENSITY DISTRIBUTIONS.

Iterative techniques of reconstructing the phase of an image from modulus data measured in two defocused planes are examined with an emphasis on their practical use in image and wavefront reconstruction. The Misell algorithm is seen to be the most efficient in the cases where it does converge, but convergence seems highly dependent on the image characteristics and the amount of defocus. Some modification of this method can be used to help convergence when the amount of defocus is small. The gradient search techniques have little problem in reconstructing the phase where the amplitude is large, but become considerably slower in finding the phase in areas of low intensity.