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基于多特征融合的神经网络波前重构方法

Wavefront Reconstruction Method Based on Multi-Feature Fusion in Neural Networks

  • 摘要: SH-WFS (Shack-Hartmann Wavefront Sensor)在自适应光学系统中被广泛使用. 为了充分利用SH-WFS图像中所包含的信息, 一种基于多特征融合的神经网络波前重构方法Moment-U-Net被提出. 该方法在传统波前重构方法使用的质心偏移量的基础上, 额外引入了像斑强度和二阶矩特征, 用来表征像斑的形状信息, 可以对波前进行高精度重建. Moment-U-Net采用U-Net作为主干构架, 通过引入密集连接模块DenseBlock (Dense Convolutional Block)与通道注意力机制SEBlock (Squeeze-and-Excitation Block), 使模型能够在训练过程中有效提取高阶像差特征. 该模型利用仿真生成大规模的大气相位和波前图像数据进行训练, 具有良好的收敛性. 利用仿真生成的不同强度的大气湍流进行验证, Moment-U-Net波前重构均方根误差可达到0.010-0.025 μm. 另外该方法对于暗星也具有较高的重构精度, 在8 mag时重构误差低于0.070 μm. 验证结果表明, Moment-U-Net不仅具有极高的波前重构精度, 还对不同的湍流强度和星等表现出较高的泛化能力, 具备在实际观测中提升自适应光学系统校正能力的潜力.

     

    Abstract: The Shack-Hartmann Wavefront Sensor (SH-WFS) is widely used in adaptive optical systems. To fully utilize the information contained in SH-WFS images, a neural network-based wavefront reconstruction method called Moment-U-Net is proposed. Besides the centroid used in traditional wavefront reconstruction methods, this approach additionally uses spot intensity and second-order moment features to characterize spot shape information, enabling high-precision wavefront reconstruction. Moment-U-Net adopts U-Net as its main architecture and assembles feature extraction modules such as dense connection modules DenseBlock (Dense Convolutional Block) and channel attention mechanisms SEBlock (Squeeze-and-Excitation Block), allowing effective capture of higher-order aberration features during training. The model demonstrates excellent convergence when trained using large-scale simulated atmospheric phase and wavefront image data. Validation tests with simulated atmospheric turbulence of varying intensities show that Moment-U-Net achieves root mean square reconstruction errors ranging from 0.010 μm to 0.025 μm. Additionally, this method has high reconstruction precision for faint stars, achieving errors below 0.070 μm for 8th magnitude stars. Experimental results demonstrate that Moment-U-Net not only has high wavefront reconstruction precision, but also has strong generalization capabilities across different turbulence intensities and stellar magnitudes. This highlights its potential for practical observational applications to enhance the correction capabilities of adaptive optical systems.

     

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