基于相位恢复的无调制四棱锥波前传感器

四棱锥波前传感器具有能量利用率高和空间采样率高的优点,已成功应用于天文自适应光学、镜面检测及显微成像等领域。提出一种新的无调制四棱锥波前传感器,根据四棱锥波前传感器的光场传播模型,利用相位恢复算法迭代优化出待测波前。入射光经四棱锥锥尖分光后会聚所得的子光瞳像为相位恢复算法提供了丰富的信息,使其收敛速度加快。数值模拟结果表明,基于相位恢复的四棱锥波前传感器具有精度高、收敛速度快、抗噪性好等特点,并且无需调制便能获得较大的动态范围。     

一种区域波前重构的快速算法

本文提出了一种分块进行波前重构的快速算法。它具有所需存贮量小、噪声传递系数小及数值稳定性好等特点。定性分析与计算机模拟结果表明,由于算法本身带来新的重构误差,它的重构精度与通常算法基本相同。     

基于衍射光栅曲率波前传感器的实时波前重构研究

自适应光学系统要求波前传感器能实现动态实时测量,曲率波前传感技术符合这一发展要求。一种新型的基于扭曲衍射光栅的曲率波前传感器在探测装置的实现方法方面具有较大优势,其波前重构已应用于光学度量。根据衍射光学理论,对其探测信号进行数值模拟,并利用Neumann边界条件的Green函数法对其波前重构进行数值模拟。结果表明：Green函数法归结为2矩阵相乘,计算速度快,达到实时重构要求; Green函数法对阶数不高的Zernike多项式重构效果较好;影响重构误差的主要因素是光强梯度的边界噪声。     

一种基于Zernike多项式的波前探测和重构方法

运用Ｎｏｌｌ建议的Ｚｅｒｎｉｋｅ多项式形式表征大气扰动的波面，求出由两个离焦面上的光强分决定的Ｚｅｒｎｉｋｅ多项式的前ｎ项在特定的探测器上的响应矩阵Ｒ。由Ｒ和输入的随机波面在两个离焦面上的光强分布，可方便地求出其Ｚｅｒｎｉｋｅ多项式的系数，从而实现了波前的探测和重构。采用光线追迹的变方法，用计算机模拟验证了这种方法的原理和可行性。     

基于背景纹影波前传感技术的气动光学波前重构与校正

背景纹影波前传感(backgroud oriented schlieren based wavefront sensing, BOS-WS) 是利用背景纹影技术测量光学波前二维分布的新型实验手段, 可定量测量光线通过干扰场后产生的光学畸变并给出光程差. 为了利用BOS-WS技术获得光线因气动光学效应产生的畸变信息, 并通过已知畸变信息还原原始图像, 进而探索一种新型的超声速成像制导方法, 本文通过理论分析, 验证了利用背景纹影技术测量光学波前的方法, 探索了利用已知波前信息预测畸变位移场以及利用已知位移场进行波前重构的计算方法. 通过数值模拟比较了一阶梯形积分算法和Southwell方法在波前重构上的误差大小和结果合理性, 并通过误差分析证明了Southwell方法更加精确合理. 通过蜡烛火焰上方流场畸变实验和透镜对波前的扰动实验, 创造性地探索了利用已知光学光程差还原畸变位移场及用其校正畸变图像的方法, 并通过验证性实验证明了校正方法的有效性.     

分块式空间望远镜波前传感及控制方法的仿真研究

分块式空间望远镜的波前传感及控制方法是实现高分辨率成像的关键.空间望远镜在轨展开后,由于空间环境及光学系统本身的特点,存在位置和面形误差,波前误差动态范围大、空间频率覆盖宽,需要采用分级校正的方法逐步减小误差.给出了波前校正流程及相应的波前传感及控制方法.利用Zemax软件建立了同轴偏场三反射镜系统仿真模型,并对主镜进行了分块设计.针对该系统模型,建立了分块式空间望远镜系统波前传感及控制集成仿真软件,通过分析分块主镜的波前误差校正过程验证了算法的可行性.     

基于深度学习的自适应光学波前传感技术研究综述

波前传感是自适应光学系统的重要组成部分,在地基大口径望远镜、激光大气传输、无线光通信、激光驱动核聚变等领域发挥了关键作用,同时也常应用于自由曲面的光学测量中。与此同时,深度学习作为一种较为通用的前沿技术,成功在计算机视觉、自然语言处理等众多领域取得了革命性进展。使用深度学习的方法改进自适应光学系统中的波前传感器,以期实现更精准的波前探测,以及适应更复杂的应用场景是自适应光学的发展趋势,也是深度学习应用领域的一个新课题。介绍了深度学习在自适应光学波前传感中的应用现状,主要分析了在相位反演波前传感器和哈特曼波前传感器中的研究特点,并在最后进行了总结和展望。

     

测量噪声对波前重构精度的影响

Hartmann-Shack波前传感器斜率测量误差是自适应光学系统中影响波前重构精度的一个主要误差来源。针对模式法波前重构算法,推导出了普遍适用的模式法波前重构误差传递系数计算公式;利用61单元自适应光学系统中的Hartmann-Shack波前传感器测量的斜率数据,验证了模式法波前重构误差传递系数计算公式的正确性。     

测量噪声对波前重构精度的影响

 Hartmann-Shack波前传感器斜率测量误差是自适应光学系统中影响波前重构精度的一个主要误差来源。针对模式法波前重构算法,推导出了普遍适用的模式法波前重构误差传递系数计算公式;利用61单元自适应光学系统中的Hartmann-Shack波前传感器测量的斜率数据,验证了模式法波前重构误差传递系数计算公式的正确性。     

激光推进应用中的波前重构仿真研究

分析了Hartmann传感器应用于激光推进中波前畸变测量的可行性,介绍了模式法波前重构原理。利用MATLAB7.0对小孔板进行了仿真。并根据几何光线追迹原理,对设定的畸变波前进行了重构。同时比较了选用不同Zernike模式数的波前重构结果以及选用不同采样率小孔板的波前重构结果。仿真结果表明:Hartmann传感器对推进应用中大口径光斑的波阵面测量是可行的。     

高分辨力哈特曼传感器的快速波面重构和拼接

建立哈特曼传感器的模型,证明在高空间分辨力下,可以采用Hudgin模型进行波面重构,避免了采用Fried模型带来的复杂性。对哈特曼子孔径缺失破坏连续性的问题进行了分析,介绍了相应的边缘处理算法。完成了基于离散傅里叶变换的波面重构算法数值模拟,实现了波面的无损重构。针对实际应用中输入波面在被遮挡处不连续的问题,提出了基于最小二乘解的拼接方案,实现了非连续波面拼接。分析了影响波面重构速度的主要因素,提出了提高波面重构性能的方法。     

Adaptive-optics correction of a stellar interferometer with a single pyramid wave-front sensor

We investigate the pyramid wave-front sensor's capability to reconstruct in a closed loop, with only one sensor, the wave fronts on both apertures of a stellar interferometer, including the differential piston: The method consists of placing the principal element of this sensor, namely, a refractive-square-based pyramid, in a combined focal plane of the interferometer instead of using two sensors, one for each individual telescope. We show that the sensor signals allow one to measure the wave-front aberrations on both apertures and the differential piston at the same time. The performance of an adaptive-optics loop is computed numerically for the Large Binocular Telescope in terms of differential-piston rejection under several conditions. The results show that atmospheric correction including differential-piston compensation is possible as long as the corrected Strehl ratio at the wave-front sensing wavelength is greater than 20%.     

Frequency-resolving spatiotemporal wave-front sensor

We report on a high-resolution wave-front sensor that measures the complete spatial profile of any frequency component of a laser field containing multiple frequencies. This probe technique was developed to address the necessity of measuring the spatial overlap of the carrier field with each sideband component of the field exiting the output port of a gravitational-wave interferometer. We present the results of an experimental test of the probe, where we were able to construct the spatial profile of a single radio-frequency sideband at the level of -50 dBc.     

Validity of wave-front reconstruction and propagation of ultrabroadband pulses measured with a Hartmann-Shack sensor

Wave-front reconstruction for ultrabroadband laser pulses is verified by use of a Hartmann-Shack sensor. We estimate the accuracy of numerical wave-front propagation by comparing numerical with experimental results and verify that wave fronts of ultrabroadband laser pulses from a hollow fiber can be propagated correctly by a single polychromatic wave-front measurement to a place where detection is not practicable, e.g., inside a vacuum chamber or laser focus.     

无调制两面锥波前传感器的衍射理论分析和数值仿真

两面锥波前传感器(two-sided pyramid wavefront Sensor,TSPWFS)是一种高空间采样率和高光能利用率的波前传感器.为了深入研究它的波前复原原理,采用波动光学理论详细推导了无调制TSPWFS的衍射理论,给出了无调制TSPWFS波前复原时线性重构矩阵的解析解,并且通过数值仿真确定出最佳的光瞳像中心间距,并对静态像差的波前复原及闭环校正进行数值仿真.分析结果表明,无调制TSPWFS具有波前复原时不需要现场测量响应矩阵,可以校正系统像差,闭环校正结果稳定等优点,可以在实际自适应光学系统中进行波前探测. 关键词： 自适应光学 两面锥波前传感器 波前复原     

Hybrid curvature and gradient wave-front sensor

A new wave-front sensor for adaptive optics that gives signals for the curvature and the two gradient components of the wave front simultaneously is proposed. The sensor uses quad cells placed at the foci of an array of astigmatic lenslets, giving three intensity-normalized differential signals. The parameters of a single subdetector are optimized to maximize the curvature signal. The performance of such a sensor designed for a membrane curvature mirror is analyzed. The good match between sensor and mirror is exhibited by an almost diagonal response matrix between the mirror actuator controls and the curvature signals.     

Measuring wind speeds and turbulence with a wave-front sensor

We analyze wave-front sensor (WFS) measurements taken with the 1.5-m telescope at the Starfire Optical Range in Albuquerque, N.M., of wind speeds in the turbulent atmospheric layers that cause seeing. The frozen-flow hypothesis suggests that atmospheric turbulence is located in thin horizontal layers and that turbulent features do not change over short time scales but are drawn along by the prevailing wind. Exploiting autocorrelation properties of the WFS data that result from these characteristics of atmospheric turbulence, we are able to measure the movements of individual layers. We also test the validity of the frozen-flow hypothesis.     

高质量数字全息波面重建系统研究

基于阿贝成像理论对数字全息波面重建系统进行研究. 结果表明,利用成像系统对物光场进行变换,可以让物光场的高频角谱分量到达电荷耦合器件（CCD）探测器.为研究重建物光场质量,导出了CCD在光学系统后任意位置波面重建的计算公式,研究了物光通过傍轴光学系统到达CCD时波面重建系统的脉冲响应. 理论及实验研究表明,将CCD平面置于物光场像平面附近可以对物光场进行高质量重建. 关键词： 信息光学 数字全息 波面重建     

Improvement of Shack-Hartmann wave-front sensor measurement for extreme adaptive optics

The development of high-performance adaptive optics systems requires the optimization of wave-front sensors (WFSs) working in the high-order correction regime. We propose a new method to improve the wave-front slope estimation of a Shack-Hartmann WFS in such a regime. Based on a detailed analysis of the different errors in the slope estimation with a classical centroid and with the new method, the gain in terms of wave-front-sensing accuracy in both the detector and the photon noise regimes is stressed. This improvement is proposed without major system disruption.     

Iterative image reconstruction algorithms using wave-front intensity and phase variation

Iterative algorithms that reconstruct images from far-field x-ray diffraction data are plagued with convergence difficulties. An iterative image reconstruction algorithm is described that ameliorates these convergence difficulties through the use of diffraction data obtained with illumination modulated in both intensity and phase.