Yu Zeqing, Zhang Qiangbo, Tao Xiao, Li Yong, Tao Chenning, Wu Fei, Wang Chang, Zheng Zhenrong
Opt Express. 2022 Oct 24;30(22):40871-40883. doi: 10.1364/OE.470419.
Metasurface has drawn extensive attention due to its capability of modulating light with a high degree of freedom through ultrathin and sub-wavelength optical elements, and metalens, as one of its important applications, promises to replace the bulky refractive optics, facilitating the imaging system light-weight and compact characteristics. Besides, computer-generated holography (CGH) is of substantial interest for three-dimensional (3D) imaging technology by virtue of its ability of restoring the whole optical wave field and re-constructing the true 3D scene. Consequently, the combination of metalens and CGH holds transformative potential in enabling the miniaturization of 3D imaging systems. However, its imaging performance is subject to the aberrations and speckle noises originating from the metalens and CGH. Inspired by recent progress that computational imaging can be applied to close the gap, a novel full-color imaging system, adopting end-to-end joint optimization of metalens and CGH for high imaging quality, is proposed in this paper. The U-net based network as the pre-processing adjusts weights to make the holographic reconstruction offset imaging defects, incorporating the imaging processing into the step of generating hologram. Optimized by deep learning, the proposed imaging system is capable of full-color imaging with high fidelity in a compact form factor, envisioned to take an essential step towards the high-performance miniaturized imaging system.
超表面因其能够通过超薄和亚波长光学元件以高度的自由度调制光而受到广泛关注，而超透镜作为其重要应用之一，有望取代笨重的折射光学器件，实现成像系统的轻量化和紧凑化。此外，计算机生成全息术（CGH）凭借其恢复整个光波场和重建真实三维场景的能力，在三维（3D）成像技术中备受关注。因此，超透镜与CGH的结合在实现3D成像系统的小型化方面具有变革潜力。然而，其成像性能受到来自超透镜和CGH的像差和散斑噪声的影响。受计算成像可用于缩小差距这一最新进展的启发，本文提出了一种新颖的全彩色成像系统，该系统采用超透镜和CGH的端到端联合优化以实现高成像质量。基于U-net的网络作为预处理调整权重，使全息重建抵消成像缺陷，将成像处理纳入生成全息图的步骤。通过深度学习优化，所提出的成像系统能够以紧凑的外形实现高保真全彩色成像，有望朝着高性能小型化成像系统迈出重要一步。
