基于二元相位型复用全息元件的模式波前传感器研究

Wavefront sensor (WS) is a key part to comprise adaptive optics (AO) system in an optical-electronic telescope,which directly affects the performance of AO system to correct atmospheric turbulence in real time.Holographic element-based modal wavefront sensor (HMWFS) is a novel wavefront sensing technology proposed in recent years, which is implemented by recording and sensing several aberration modes with a multiplexed holographic element.Its output signals can be related near linearly to the coefficients of tested aberration modes, and readily transformed into the control signals of wavefront correctors without heavy matrix computation.This may help improve the closed-loop bandwidth and compactness of AO systems, and hence make it possible to transform general softwares into computer-free,electronic-only and basic circuitry for AO systems. Also,HMWFS is insensitive to the intensity nonuniformity of optical field, and can be adapted to the circumstances such as high turbulence, strong scintillation. HMWFS has valuable potential applications in terms of airborne high energy lasers,ground-based high quality imaging, and free-space optical communications. We propose an approach of encoding aberration modes with binary phase-only multiplexed holographic element, and carry out extensive investigations on HMWFS in four aspects,respectively, including theoretical analysis,numerical simulation,experimental demonstration and thechnology extensions.

波前传感器是光电望远镜中自适应光学系统的关键组成部分，其直接影响着系统对大气湍流效应的实时校正效果。基于全息元件的模式波前传感器是近年内提出的一种新型波前传感技术，其利用复用全息元件实现对待测像差的存储与探测，输出信号在转化为波前校正器控制信号过程中不需要复杂的矩阵运算，有助于提高自适应光学系统的闭环工作带宽和紧凑性，从而有望将软件驱动的传统自适应光学系统转化为无需计算机控制的纯电子电路系统。该传感器对待测光波的强度非均匀性不敏感，能够适用于强湍流、强闪烁环境，在空基高能激光、地基高清晰成像、自由空间光通信等系统中均有潜在的应用价值。本项目提出利用二元相位型复用全息元件对像差模式进行编码，并分别从理论分析、数值模拟、实验验证和技术扩展四个方面对该波前传感器进行深入研究。

波前传感器是光电望远镜中自适应光学系统的关键组成部分，其直接影响着系统对大气湍流效应的实时校正效果。基于傅里叶光学和标量衍射理论建立了全息模式波前传感器探测畸变波前的解析理论模型。提出了一种分层计算全息模式波前传感器模型，通过对比研究了分层计算全息元件的四种编码设计方案，及其对应远场的衍射光斑强度分布规律、衍射效率，确定了一种能量利用率高、信噪比高的编码设计方案。建立了基于变形镜本征模式的全息自适应光学系统数值模型，通过数值模拟验证了该系统在像差探测和像差闭环校正方面的性能。对比研究了不同载频布局、不同阶数编码模式条件下全息元件远场衍射光强的分布规律，为有效降低全息模式波前传感器中记录模式间串扰效应提供了理论和实践指导。针对空间目标自适应光学图像复原算法存在的不足，提出了一种基于波前传感的自适应光学图像复原算法，为空间目标探测识别和特征提取提供了有效手段。