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Browsing by Author "Yao, Yongwei"

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    Isotropic Two-Dimensional Differentiation Based on Dual Dynamic Volume Holograms
    Wang, Pin; Fan, Houxin; Zhang, Yaping; Yao, Yongwei; Zhang, Bing; Qin, Wenlong; Poon, Ting-Chung (MDPI, 2023-07-17)
    We study the use of two dynamic thick holograms to realize isotropic two-dimensional (2D) differentiation under Bragg diffraction. Acousto-optic modulators (AOMs) are used as dynamic volume holograms. Using a single volume hologram, we can accomplish a first-order derivative operation, corresponding to selective edge extraction of an image. Since the AOM is a 1D spatial light modulator, filtering of the image only occurs along the direction of the sound propagation. To achieve 2D image processing, two AOMs are used within a Mach–Zehnder interferometer (MZI). By aligning one AOM along the x-direction on the upper arm of the interferometer and another AOM along the y-direction on the lower arm, we accomplish the sum of two first-derivative operations, leading to isotropic edge extraction. We have performed both computer simulations and optical experiments to verify the proposed idea. The system provides additional operations in optical computing using AOMs as dynamic holograms.
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    Off-axis optical scanning holography [Invited]
    Zhang, Yaping; Yao, Yongwei; Zhang, Jingyuan; Liu, Jung-Ping; Poon, Ting-Chung (Optical Society of America, 2022-02-01)
    Optical scanning holography (OSH) involves the principles of optical scanning and heterodyning. The use of heterodyning leads to phase-preserving, which is the basic idea of holography. While heterodyning has numerous advantages, it requires complicated and expensive electronic processing. We investigate an off-axis approach to OSH, thereby eliminating the use of heterodyning for phase retrieval.We develop optical scanning theory for holographic imaging and show that by properly designing the scanning beam, we can performcoherent and incoherent holographic recording. Simulation results are provided to verify the proposed idea.