Quan Jiale, Yan Binbin, Sang Xinzhu, Zhong Chongli, Li Hui, Qin Xiujuan, Xiao Rui, Sun Zhi, Dong Yu, Zhang Huming
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China.
Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing 100084, China.
Micromachines (Basel). 2023 Mar 6;14(3):605. doi: 10.3390/mi14030605.
In this paper, we propose a method to generate multi-depth phase-only holograms using stochastic gradient descent (SGD) algorithm with weighted complex loss function and masked multi-layer diffraction. The 3D scene can be represented by a combination of layers in different depths. In the wave propagation procedure of multiple layers in different depths, the complex amplitude of layers in different depths will gradually diffuse and produce occlusion at another layer. To solve this occlusion problem, a mask is used in the process of layers diffracting. Whether it is forward wave propagation or backward wave propagation of layers, the mask can reduce the occlusion problem between different layers. Otherwise, weighted complex loss function is implemented in the gradient descent optimization process, which analyzes the real part, the imaginary part, and the amplitude part of the focus region between the reconstructed images of the hologram and the target images. The weight parameter is used to adjust the ratio of the amplitude loss of the focus region in the whole loss function. The weight amplitude loss part in weighted complex loss function can decrease the interference of the focus region from the defocus region. The simulations and experiments have validated the effectiveness of the proposed method.
在本文中，我们提出了一种使用带有加权复数损失函数的随机梯度下降（SGD）算法和掩膜多层衍射来生成多深度纯相位全息图的方法。三维场景可以由不同深度的层组合来表示。在不同深度的多层波传播过程中，不同深度层的复振幅会逐渐扩散并在另一层产生遮挡。为了解决这个遮挡问题，在层衍射过程中使用了一个掩膜。无论是层的向前波传播还是向后波传播，该掩膜都可以减少不同层之间的遮挡问题。否则，在梯度下降优化过程中实现加权复数损失函数，它分析全息图重建图像与目标图像之间聚焦区域的实部、虚部和振幅部分。权重参数用于调整整个损失函数中聚焦区域的振幅损失比例。加权复数损失函数中的权重振幅损失部分可以减少聚焦区域来自离焦区域的干扰。仿真和实验验证了所提方法的有效性。
