Iterative Fourier transform algorithm: comparison of various approaches

In this paper, a convergence of various approaches within the iterative Fourier transform algorithm (IFTA) is analysed for the case of phase-only diffractive optical elements with quantized phase levels (either binary or multilevel structures). Firstly, the general scheme of the IFTA iterative approach with partial quantization is briefly presented and discussed. Then, the special assortment of the general IFTA scheme is given with respect to quantization constraint strategies. Based on such a special classification, the three practically interesting approaches are chosen, further analysed and compared with each other. The performance of these algorithms is compared in detail in terms of the development of the signal-to-noise ratio characteristic with respect to the number of iterations, for various input diffusive-type objects chosen. Also, the performance of the complex spectra developments is documented for typical computer reconstruction results. The advantages and drawbacks of all approaches are discussed, and a brief guide on the choice of a particular approach for typical design tasks is given. Finally, two ways of amplitude elimination within the design procedure are considered, namely direct elimination and partial elimination of the amplitude of the complex hologram function.