AI 中文总结
针对低通量下金字塔波前传感器（PyWFS）的噪声问题，提出结合FFT加速分组与3D小波滤波的全帧去噪策略，经VLT规模SCAO系统模拟验证，可提升斯特列尔比、极限星等及PSF质量，扩展其对暗导星的适用范围。
AI 中文摘要
在低通量条件下工作的自适应光学系统面临重大挑战，尤其是光子和探测器噪声会劣化波前测量结果，最终限制校正性能。尽管金字塔波前传感器（PyWFS）在许多工作模式下比夏克-哈特曼传感器等传统波前传感器具有更高的灵敏度，但在光子匮乏条件下获取准确的波前估计仍是一项关键挑战。我们提出一种针对PyWFS的全帧图像去噪策略，该策略利用波前传感器图像块的非局部自相似性，通过FFT加速的图像块分组和全局协同3D小波滤波实现，在斜率计算前直接应用于原始PyWFS强度帧。具体而言，该方法在抑制噪声的同时保留了准确波前重建所需的结构特征。我们使用VLT规模的SCAO系统进行端到端模拟对该方法进行评估，结果显示在低信噪比条件下性能得到提升，典型的斯特列尔比增益最高达12%，在中等视宁度条件下极限星等提升约0.5。模态分析表明，多数受控模态的方差降低。改进的点扩散函数（PSF）质量可使半高全宽（FWHM）减小，对比度增强。这些结果表明，图像域去噪可提高基于PyWFS的自适应光学（AO）系统的鲁棒性，并将其工作范围扩展至更暗的导星。
英文摘要
Adaptive optics systems operating under low-flux conditions face significant challenges, as photon and detector noise in particular degrade wavefront measurements and ultimately limit correction performance. While pyramid wavefront sensors (PyWFSs) offer greater sensitivity than conventional wavefront sensors such as the Shack-Hartmann sensor in many operating regimes, obtaining accurate wavefront estimates under photon-starved conditions remains a key challenge. We present a full-frame image denoising strategy for the PyWFS that exploits the nonlocal self-similarity of wavefront sensor image patches through FFT-accelerated patch grouping and global collaborative 3D wavelet filtering, applied directly to the raw PyWFS intensity frame prior to slope computation. Specifically, the method suppresses noise while preserving structural features required for accurate wavefront reconstruction. The approach is evaluated using end-to-end simulations of a VLT-scale SCAO system. The results show improved performance in low signal-to-noise regimes, with typical Strehl ratio gains of up to 12% and an increase in limiting magnitude of approximately 0.5 in median seeing conditions. Modal analysis indicates reduced variance across most controlled modes. The improved PSF quality enables a reduction in the FWHM and an enhanced contrast. These results demonstrate that image-domain denoising can improve the robustness of PyWFS-based AO systems and extend their operational range toward fainter guide stars.
CommentsSPIE Astronomical Telescopes + Instrumentation 2026
