Demonstration of a photonic-lantern focal-plane wavefront sensor using fibre mode conversion and deep learning
Demonstration of a photonic-lantern focal-plane wavefront sensor using fibre mode conversion and deep learning
复制标题
使用光纤模式转换和深度学习演示光子灯笼焦平面波前传感器
DOI：
10.1117/12.2629852
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Vievard, Sébastien
中科院分区：
文献类型：
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作者：
Norris, Barnaby R.;Wei, Jin;Betters, Christopher;Leon-Saval, Sergio;Xin, Yinzi;Lin, Jonathan;Kim, Yoo Jung;Sallum, Steph;Lozi, Julien;Vievard, Sébastien
焦平面波前传感器为自适应光学提供了主要优势，包括去除非共径误差和提供对盲模式（如花瓣）的灵敏度。但是，仅仅使用观测点扩展函数（PSF）是不足以进行波前校正的，因为只测量了强度，而没有测量相位。在这里，我们演示了使用多模光纤模式转换器（光子灯）来直接测量焦平面上的波前相位和振幅。星光在像面上注入多模光纤，光纤内激发的模式组合是入射波前相位和振幅的函数。光纤经历绝热跃迁到一组多个单模输出，使得它们之间的强度分布对入射波前进行编码。PSF中空间模式与输出之间的映射（可能是强非线性的）是稳定的，但必须学习。这是由一个深度神经网络完成的，通过将空间模式的随机组合应用于可变形的镜子来训练。经过训练后，神经网络可以即时预测任意一组输出强度的入射波前。我们利用斯巴鲁望远镜（Subaru Telescope）上的SCExAO观测结果，成功地重建了实验室产生的低风效应波前，并在天空上演示了重建与现有金字塔波前传感器测量结果一致的低阶模式。
A focal plane wavefront sensor offers major advantages to adaptive optics, including removal of non-commonpath error and providing sensitivity to blind modes (such as petalling). But simply using the observed point spread function (PSF) is not sufficient for wavefront correction, as only the intensity, not phase, is measured. Here we demonstrate the use of a multimode fiber mode converter (photonic lantern) to directly measure the wavefront phase and amplitude at the focal plane. Starlight is injected into a multimode fiber at the image plane, with the combination of modes excited within the fiber a function of the phase and amplitude of the incident wavefront. The fiber undergoes an adiabatic transition into a set of multiple, single-mode outputs, such that the distribution of intensities between them encodes the incident wavefront. The mapping (which may be strongly non-linear) between spatial modes in the PSF and the outputs is stable but must be learned. This is done by a deep neural network, trained by applying random combinations of spatial modes to the deformable mirror. Once trained, the neural network can instantaneously predict the incident wavefront for any set of output intensities. We demonstrate the successful reconstruction of wavefronts produced in the laboratory with low-wind-effect, and an on-sky demonstration of reconstruction of low-order modes consistent with those measured by the existing pyramid wavefront sensor, using SCExAO observations at the Subaru Telescope.