自适应光学系统对实际大气湍流波前的时域校正效果

引入时域校正因子（系统团环校正波前残余误差与系统开环时的湍流波前扰动误差之比）和系统测量信噪比,分析了自适应光学系统对实际大气湍流扰动的时域校正效果与湍流功率指数、湍流功率谱转折频率、系统测量信噪比、系统时间延迟以及系统闭环带宽的关系,并给出了系统的最佳闭环带宽。此外还分析了弱光61单元自适应学系统的时域校正效果。     

应用闭环残余倾斜数据分析自适应光学系统精跟踪回路性能

在自适应光学系统中,目标跟踪误差主要由未完全补偿的大气湍流扰动和望远镜抖动引起的跟踪误差以及系统的倾斜噪声误差两部分组成。提出一种用闭环残余倾斜数据计算倾斜噪声误差、大气湍流扰动和望远镜抖动引起的跟踪误差以及系统跟踪残余误差的新方法,并用此方法分析61单元自适应光学系统中精跟踪回路的性能。     

光学相关论题 自适应光学

O439 2006043796应用闭环残余倾斜数据分析自适应光学系统精跟踪回路性能=Performance analysis for fine tracking loop for a-daptive optical system with closed-loop residual tilt data[刊,中]/吴碧琳(中科院光电技术所.四川,成都(610029)) ,饶长辉…∥光学学报.—2006 ,26(4) .—487-490在自适应光学系统中,目标跟踪误差主要由未完全补偿的大气湍流扰动和望远镜抖放引起的跟踪误差以及系统的倾斜噪声误差两部分组成。提出一种用闭环残余倾斜数据计算倾斜噪声误差、大气湍流扰动和望远镜抖动引起的跟踪误差以及系统跟踪残余误差的新…     

自适应光学闭环系统实时多路自适应控制算法EI北大核心CSCD

分析和介绍了自适应光学闭环系统中一种实用的实时多路自适应控制算法。该多路自适应控制算法综合考虑了大气湍流扰动以及自适应光学系统时间延迟对系统控制效果的影响,其各个控制回路的控制参数能根据外界扰动的变化进行实时的迭代调整,从而使系统始终工作在最优控制状态。利用61单元自适应光学系统上模拟的大气湍流扰动信号,实现了对变形镜各路控制电压进行闭环优化控制的多路自适应控制算法,并对该算法的收敛性、控制效果、控制带宽进行了仿真研究和分析。仿真结果表明,同经典比例积分控制算法相比,多路自适应控制算法具有更强的自适应性,可以更有效地减少外界扰动对自适应光学系统校正效果的影响,提高自适应光学系统的闭环控制带宽,改善控制特性。     

快速响应的硅基纯相位液晶器件对动态大气湍流波前的校正能力研究

液晶相位调制器的响应时间延迟是影响液晶自适应光学系统性能的一个主要因素, 为了提高系统的响应速度, 开发了一种快速响应的向列相液晶材料, 并制成了反射式硅基液晶器件(LCOS). 分析了该LCOS的相位调制特性及其对静态畸变波前和扰动波前的校正能力. 首先, 测量了LCOS的电光响应特性, 得出其780 nm相位调制量的响应时间为2 ms. 其次, 测量了LCOS的相位调制特性, 并对相位调制进行了线性化处理. 再次, 测量了用该LCOS搭建的液晶自适应光学系统的闭环和开环3 dB带宽, 它们分别为16和18 Hz. 最后, 给出了开环液晶自适应光学系统校正大气湍流的数值模拟结果, 结果表明. 系统的Strehl比由校正前的0.025上升到了校正后的0.225. 因此, 该液晶自适应光学系统可以对Greenwood频率为30 Hz以下的大气湍流进行较良好的校正.     

激光大气水平传输湍流畸变波前的功率谱分析I:波前整体倾斜与泰勒频率

利用自适应光学系统的哈特曼 (Hartmann)波前传感器 ,测量了激光实际大气水平传输湍流畸变波前中整体倾斜像差的时间功率谱 ,发现功率谱谱形与科尔莫戈罗夫 (Kolmogorov)湍流理论不完全符合。建立了一种根据实际测量的整体倾斜功率谱估测自适应光学系统倾斜镜需要的控制带宽大小和大气湍流的泰勒 (Tyler)频率指标的方法。     

自适应光学控制系统对Kolmogorov湍流补偿的修正有效带宽

基于时间功率谱反演生成的Kolmogorov湍流时间序列, 模拟分析了自适应光学控制系统跟踪回路与高阶误差校正回路在有限误差-3 dB带宽、 有时间延迟情况下的闭环校正残余误差, 得出了系统的跟踪残余方差、高阶残余方差与误差-3 dB带宽的数值拟合结果, 修正了系统有效带宽的表达式, 使其能更精确地估计校正残余方差. 关键词： Kolmogorov湍流 Tyler频率 Greenwood频率 有效带宽     

自适应光学系统的控制残余方差分析

分析自适应光学系统的控制残余方差与控制带宽的关系.对于存在时间延迟的自适应光学系统,推导了计算大气湍流控制残余方差的近似方式,并给出了有探测噪声情况下确定系统最优控制带宽的公式.以61单元自适应光学系统为例,讨论了实验自适应光学系统中控制带宽的优化选择问题.     

激光大气水平传输湍流畸变波前的功率谱分析I：波前整体倾斜与泰 …

利用自适应光学系统的哈特曼（Ｈａｒｔｍａｎｎ）波前传感器,测量了激光实际大气水平舆湍流畸变波前中整体倾斜像差的时间功率谱,发现功率谱谱形与科尔莫戈罗夫（Ｋｏｌｍｏｇｏｒｏｖ）湍流理论不完全符合,建立了一种根据实际测量的整体倾斜功率谱估测自适应光学系统斜镜需要的控制带宽大小和大气湍流的泰勒（Ｔｙｌｅｒ）频率指标的方法。     

自适应光学系统对大气湍流补偿的有效性分析

从伺服控制系统的角度分析了自适应光学系统的闭环噪声、大气湍流引起的误差以及系统的总体误差，并在此基础上对自适应光学系统的有效性、系统的最佳带宽选取及系统的极限工作能力进行了分析，对已经建立的２．１６米望远镜红外自适应光学系统给出了分析结果曲线。     

Simulation of anisoplanatism of adaptive optical system in inhomogeneous turbulent atmosphere

The goal of this study was to analyse anisoplanatism of adaptive optics under an inhomogeneous turbulent atmosphere over a pupil of finite size. By means of a numerical model with layers of turbulence software was proposed by which point spread function (PSF), optical transfer function (OTF) as well as system isoplanatic angle can be calculated. Atmospheric turbulence was simulated with the aid of a set of moving random phase screens with arbitrary statistics. Both reference and target are assumed to be the point light sources. To simulate atmospheric turbulence we applied the concept of a number of moving random phase screens with Kolmogorov spectrum. In my investigation I used the model of the Shack-Hartmann wave front sensor and the ideal model of a wave front adaptive mirror that is assumed to reproduce a given number of Zernike polynomials without time delays. The designed software allows calculation of instantaneous and average values of phase correction errors at different angles between a reference beacon and target source. Simulations can be made with a broad range of parameters of an adaptive system and atmospheric turbulence. The system of the model allows changing of the control algorithm of phase correction. Both common phase conjugation and weighted phase conjugation algorithm have been tested. This program is capable of calculating the effects of beam diffraction during propagation in the atmosphere.     

Modal prediction for closed-loop adaptive optics

The correction efficiency of adaptive optics is limited mainly by measurement noise and time delay. To overcome this problem, we describe a new modal linear predictive controller whose parameters are optimized by means of a recursive least-squares algorithm to minimize the residual optical phase variance. The method copes with the recursivity of the closed-loop operation. We demonstrate that the optimal rejection transfer function for adaptive optics is proportional to the frequency signal-to-noise ratio. Finally, we present what we believe to be the first experimental results obtained with a predictor used to control the tip-tilt mirror of an adaptive-optics system.     

平行光管气流扰动的液晶自适应光学校正

利用液晶自适应光学技术,建立了一套验证系统.使用哈特曼传感器为波前探测器件,反射式的LCOS液晶器件为波前校正器件,以闭环控制校正方式工作.初步实现了波前PV值从1.02λ下降到0.37λ（λ＝633 nm）的校正准确度,成像质量明显提高.系统的调制传递函数由校正前的不到10 lp/mm提高到了校正后的超过50 lp/mm.     

Experimental validation of closed-loop adaptive optics based on a self-referencing interferometer wavefront sensor and a liquid-crystal spatial light modulator

A closed-loop adaptive optics system based on a self-referencing interferometer wavefront sensor (SRI WFS) using phase-shifting point-diffraction technique and an electrically addressed phase-only liquid-crystal spatial light modulator (LC SLM) is built and validated experimentally. The wavefront aberration of incoming beam is directly measured by analyzing four frames phase-shifted interferograms captured by a single CCD camera in two camera shots, and then by loading the conjugate function onto the SLM the wavefront aberration is corrected. The proposed scheme does not rely on any complicated control algorithm or wavefront-reconstruction algorithm and can achieve high-resolution and high-accuracy correction. Closed-loop correction results of single order Zernike aberrations and a Kolmogorov turbulence phase screen show that considerable improvements in the Strehl ratio (of greater than 0.94) is achieved.     

模式耦合对倾斜校正自适应光学系统的非等晕限制

 分析了当入射信标波前与观测目标不在同一方向且考虑模式之间的耦合时,倾斜校正自适应光学系统的波前残余误差。并引入模式耦合因子变量,分析了模式耦合对倾斜校正自适应光学系统波前校正残余误差的影响。此外还给出了光波水平大气传输时的数值计算结果。     

Performance simulation of an adaptive optics system with liquid crystal corrector under closed-loop and open-loop control

The adaptive optics system (AOS) often operates in a discrete sampling process with finite closed-loop frequency. Reconstruction, detection, and time lag induced errors are the main correction errors of the system. An AOS that is based on a liquid crystal (LC) benefits from the LC’s high correction precision, thus the reconstruction error can be ignored. The primary error will be induced by the time lag from the time of detection to the time of compensation. In this paper, some theoretical simulations are introduced in order to evaluate the correction precision of AOS with an LC corrector. The main purpose is to compare the correction precision between the open-loop and closed-loop control. We attempt to find a method to ascertain the exact precision of the open-loop control and show whether it improves the correction precision. The conclusion is thus reached that the actual error rejection bandwidth for the closed-loop was lower than the −3 dB error rejection bandwidth measured in practice. The increased refresh frequency of the open-loop control can improve the imaging performance to nearly −3 dB bandwidth of the detector measured, which is the maximum possible bandwidth due to the time lag.