The Gerchberg–Saxton(GS)algorithm is widely used in various disciplines of modern sciences and technologies where phase retrieval is required. However, this legendary algorithm most likely stagnates after a few iterations. Many efforts have been taken to improve this situation.

Recently, researchers at Shanghai Institute of Optics and Fines Mechanics (SIOM) of Chinese Academy of Sciences have generalized the GS algorithm by introducing the strategy of gradient descent in real space, and a weighting mechanics in the Fourier plane.

They propose to introduce the strategy of gradient descent and weighting technique to the GS algorithm, and demonstrate it using two examples: design of a diffractive optical element (DOE) to achieve off-axis illumination in lithographic tools, and design of a computer generated hologram (CGH) for holographic display. Both numerical simulation and optical experiments are carried out for demonstration.Furthermore, the proposed algorithm can be used for various other applications such as phase imaging and optical image encryption.

The study was published in Optics and Lasers in Engineering.

(http://www.sciencedirect.com/science/article/pii/S014381661630032X)

This study was supported by the National Science Foundation of China, the Recruitment Program of Global Youth Experts, and the Shanghai Pujiang Program.

Fig. 1. Block diagram of the proposed phase retrieval algorithm.(Image by Wang Haichao )