Optimal quantization method for uneven-phase diffractive optical elements by use of a modified iterative Fourier-transform algorithm.
A method based on an iterative Fourier-transform algorithm (IFTA) with phase optimization for phase-only multilevel diffractive optical elements (DOEs) is presented. Phase optimization by minimizing the mean-squared error composed of an amplitude-weighted probability-density function is performed in the IFTA iterations to ensure that the wavefront difference is minimized and thus to improve the DOEs' performance. Using the proposed method, we obtained a small standard deviation of diffraction efficiency of 20 uneven-phase DOEs, showing that DOEs with high diffraction efficiency did not vary significantly with the initial conditions. The simulation results of even- and uneven-phase four-level DOEs designed by use of direct and stepwise quantization IFTA methods are compared.
Hsu
Wei-Feng
WF
Department of Electro-optical Engineering, National Taipei University of Technology, 1, Section 3, Chung-Hsiao East Road, Taipei 106, Taiwan. whsu@ntut.edu.tw
Lin
Chia-Hsuan
CH