共查询到20条相似文献,搜索用时 234 毫秒
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自适应光学系统的数值模拟:噪音和探测误差的效应 总被引:1,自引:1,他引:0
噪音和探测误差是影响自适应光学系统性能的三个主要因素之一。噪音和探测误差使哈特曼-夏克(Hartmann-Shack)波前传感器所测得的华斜量产生误差,进而影响整个自适应光学系统的性能,建立了对噪声和探测误差对哈特曼-夏克波前传感器的影响进行数值模拟的理论模型,编制了计算程序,与已有的激光大气传输与自适应光学系统的计算程序相衔接,进行了模拟计算,对有限的离散采样,读出噪音和光子噪音的效应作了数值模拟研究,获得了一些对于实际的自适应光学系统的最佳设计有价值的结果。 相似文献
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在基于哈特曼-夏克波前传感器(SH-WFS)的自适应光学系统中,通常采用质心算法探测点源信标的子孔径光斑偏移量.然而质心算法探测精度受到诸如减阈值等因素的影响,在低信噪比(SNR )时不能准确估计光斑质心位置,而相关哈特曼算法不需要减阈值,具有更好的鲁棒性.本文在介绍相关SH-WFS基本原理的基础上,通过建立基于点源信标探测的相关SH-WFS算法的随机噪声模型,推导了光斑偏移测量误差表达式,系统分析了光子噪声、CCD读出噪声、背景光子噪声等因素对相关SH-WFS测量误差的影响.并进行了数值仿真及实验,仿真
关键词:
相关哈特曼-夏克波前传感器
相关哈特曼算法
质心算法
测量误差 相似文献
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哈特曼波前探测及波前校正的仿真与误差分析 总被引:3,自引:1,他引:2
报道了以37单元自适应光学系统为原型的波前校正计算机仿真模型,讨论了系统波前哈特曼探测误差,拟合误差以及变形镜波前复原误差,提出了自适应光学系统在校正大气湍流引直怕波前位相畸变时存在最佳有效孔径的设想。 相似文献
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增量维纳滤波法在波前探测解卷积中的应用 总被引:6,自引:3,他引:3
一个常规的自适应光学系统通常包含三个重要环节:波前探测、波前校正和波前重构。因此对系统的技术要求非常高,造成系统复杂,成本昂贵。基于哈特曼-夏克波前探测的图像解卷积处理就是“事后”处理的一种,它省去了波前校正环节,使常规的自适应光学系统得到简化,降低了系统成本。其基本原理为对瞬时波面进行短时间曝光探测,同时记录相应的短时间曝光图像,来进行解卷积处理。将增量维纳滤波法应用于基于哈特曼-夏克波前探测的解卷积中,并对室内模拟点源情况下的三组畸变光斑图像数据进行了解卷积恢复处理。结果表明,将增量维纳滤波法应用于基于波前探测的解卷积是完全可行的,在室内模拟点源情况下,恢复的图像可以达到衍射极限分辨力。与维纳滤波相比,它扩展了噪声抑制因子的选取范围,在噪声抑制因子选取不正确的情况下,仍能得到比维纳滤波更好的结果。 相似文献
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自适应光学系统中的逢适应控制算法研究 总被引:1,自引:0,他引:1
介绍和分析了一种在自适应光学系统中实用的自适应控制算法。与经典控制算法相比,自适应控制算法调整方便,综合考虑了大气湍流扰动和探测噪声等对系统控制效果的影响,控制参数能适应工作环境的变化,使系统达到最优控制状态。以61单元自适应光学系统上实现的自适应控制算法为例,用经典控制理论的波德(Bode)图、控制带等概念分析了这种算法的特点,并针对算法在实际系统应用中遇到的问题提出了解决的办法。 相似文献
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夏克哈特曼传感器是自适应光学中应用最广泛的波前传感器,它不仅可以测量大气湍流引起的畸变,还可以测量由风、温度变化和机械应力产生的镜面位置误差引起的像差.基于夏克哈特曼传感器,推导了子孔径斜率与装配误差之间的函数关系,提出了一种基于光学系统失调前后点阵光斑质心偏差信息的计算机辅助装调方法,将装配误差求解问题转换成多目标优化问题,可采用多目标智能优化算法进行求解该问题.以某三反光学系统为例,基于Python和Zemax联合仿真进行模拟装调,仿真结果表明,经三次迭代可将失调误差校正到微米级,这可满足实际装调需求,结果验证了所提方法的正确性. 相似文献
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自适应光学系统的控制残余方差分析 总被引:6,自引:4,他引:2
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. 相似文献
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《Journal of Electrostatics》2002,54(3-4):321-332
An electrostatic digital mirror device has been used to replace the lenslet array in a simple adaptive optics system. Clusters of binary pixels define the subapertures of the image plane and direct a small portion of the image onto a detector. The detector measures position shifts in the focused subaperture image caused by optical aberrations. Measurements on a digital mirror-based system and a similar lenslet-based system compare favorably to within a simple scaling factor. A subaperture system designed around a digital mirror device could aid in the development of a sequential subaperturing method that would replace the more complex schemes used in traditional adaptive optics. 相似文献
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Imaging with an array of adaptive subapertures 总被引:2,自引:0,他引:2
An imaging system composed of an array of adaptive optics subapertures referred to as a conformal imaging system is considered. A conformal image of an object viewed through atmospheric turbulence is obtained using the following sequential steps: adaptive compensation of phase distortions through optimization of image quality metrics at each subaperture, measurements of the phase and intensity distributions corresponding to the compensated subaperture images, digital combining and processing of the obtained data, computation of a conformal image using arbitrary phase shifts between subapertures, and correction of these phase shifts through conformal image quality optimization using the stochastic parallel gradient descent algorithm. Numerical simulation results of a dual-star conformal image through atmospheric turbulence are presented. 相似文献
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Hartmann-Shack波前传感器是自适应光学中几种重要的波前传感器之一。本文利用Fourier光学方法分析研究了Hartmann-Shack波前传感器的原理,导出了辐照度分布质心与子孔径波前倾斜的解析表达式,说明了辐照度分布质心及其算法的物理意义,总结了该传感器的若干重要特点。 相似文献
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Laser guide stars (LGSs) aim at increasing the sky coverage of adaptive optics (AO) as this is highly restricted when using only natural guide stars. With such three-dimensional extended objects, spot elongation may limit the measurement accuracy of wavefronts. We evaluate the effect of differential focal anisoplanatism, induced solely by the longitudinal extension of a side-launched LGS, on the slope measurements performed by a Shack-Hartmann for a 40?m class telescope. We also take this effect into account in the wavefront reconstruction and derive estimations of the resulting wavefront error in a multi-LGS AO system. We find an error of 100?nm in the worst case at the subaperture level and a small error of the order of 10?nm for six LGSs after wavefront reconstruction. 相似文献
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We recently introduced matched filtering in the context of astronomical Shack-Hartmann wavefront sensing with elongated sodium laser beacons [Appl. Opt. 45, 6568 (2006)]. Detailed wave optics Monte Carlo simulations implementing this technique for the Thirty Meter Telescope dual conjugate adaptive optics system have, however, revealed frequent bursts of degraded closed loop residual wavefront error [Proc. SPIE 6272, 627236 (2006)]. The origin of this problem is shown to be related to laser guide star jitter on the sky that kicks the filter out of its linear dynamic range, which leads to bursts of nonlinearities that are reconstructed into higher-order wavefront aberrations, particularly coma and trifoil for radially elongated subaperture spots. An elegant reformulation of the algorithm is proposed to extend its dynamic range using a set of linear constraints while preserving its improved noise rejection and Monte Carlo performance results are reported that confirm the benefits of the method. 相似文献
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Maximization of a projected laser beam's power density at a remotely located extended object (speckle target) can be achieved by using an adaptive optics (AO) technique based on sensing and optimization of the target-return speckle field's statistical characteristics, referred to here as speckle metrics (SM). SM AO was demonstrated in a target-in-the-loop coherent beam combining experiment using a bistatic laser beam projection system composed of a coherent fiber-array transmitter and a power-in-the-bucket receiver. SM sensing utilized a 50 MHz rate dithering of the projected beam that provided a stair-mode approximation of the outgoing combined beam's wavefront tip and tilt with subaperture piston phases. Fiber-integrated phase shifters were used for both the dithering and SM optimization with stochastic parallel gradient descent control. 相似文献