共查询到19条相似文献,搜索用时 109 毫秒
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哈特曼-夏克波前传感器进行波前探测时,用子孔径光斑强度的一阶矩来计算光斑质心位置,子孔径窗口作为探测窗口,但探测时子孔径窗口内噪声对一阶矩有很大的影响,会使质心探测精度产生很大的误差。因此在计算质心位置时探测窗口的选取对探测精度有重要影响,必须选取合适的探测窗口来提高光斑质心探测精度。为此,在传统算法的基础上提出优化探测窗口的方法来提高质心探测精度,仿真和实验结果表明新方法提高了质心探测的精度,未经处理的高噪声恢复波前的波前残差峰谷值是2.851 4λ,均方根值是0.606 3λ,优化探测窗口后波前残差的峰谷值是1.636 2 λ,均方根值是0.367 1 λ,重构误差减小了40%。证明了算法的可行性和稳定性。 相似文献
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哈特曼-夏克波前传感器进行波前探测时,用子孔径光斑强度的一阶矩来计算光斑质心位置,子孔径窗口作为探测窗口,但探测时子孔径窗口内噪声对一阶矩有很大的影响,会使质心探测精度产生很大的误差。因此在计算质心位置时探测窗口的选取对探测精度有重要影响,必须选取合适的探测窗口来提高光斑质心探测精度。为此,在传统算法的基础上提出优化探测窗口的方法来提高质心探测精度,仿真和实验结果表明新方法提高了质心探测的精度,未经处理的高噪声恢复波前的波前残差峰谷值是2.851 4λ,均方根值是0.606 3λ,优化探测窗口后波前残差的峰谷值是1.636 2 λ,均方根值是0.367 1 λ,重构误差减小了40%。证明了算法的可行性和稳定性。 相似文献
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受天光背景、大气湍流强度、信标光回光特性和探测器噪声等因素影响,夏克-哈特曼波前传感器子孔径光斑常存在强度分布不均匀和低信噪比的情况,故子孔径内光斑质心定位不准且波前探测精度下降。提出了一种基于噪声模型变换的子孔径光斑质心提取方法,采用方差稳定变换(VST)将探测引入的泊松-高斯噪声转换为高斯噪声,进一步基于残差反馈优化BM3D策略实现低信噪比子孔径图像的高效去噪。结果显示:所提方法可有效提取低信噪比夏克-哈特曼波前传感器光斑阵列图像中的光斑信号数据,提高了子孔径光斑的质心定位精度和稳定性;相比于传统自适应阈值法等方法,所提方法在子光斑图像峰值信噪比低于6时,可以提升波前复原精度2倍以上。 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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针对夏克-哈特曼波前传感器探测系统中噪声随时间及空间变化频率较快的特点,为了准确估计系统的最优阈值,根据高斯光斑与噪声的分布特性,提出一种以滑动窗口内像素均值及图像信号的局部梯度作为参数,构造关于噪声权重函数的方法,由此获得子孔径阈值的最优估计值,并详细分析了算法的基本原理和实现过程.以典型处理方法获取的阈值与理论最优阈值的误差作为评价标准,仿真和实验结果表明本文提出的阈值估计方法在不同信噪比、不同光斑大小的条件下,均能取得优于典型阈值处理方法获得的结果,且与理论最优阈值的误差小于10%. 相似文献
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Accuracy analysis of centroid calculated by a modified center detection algorithm for Shack-Hartmann wavefront sensor 总被引:1,自引:0,他引:1
The accuracy of the Shack-Hartmann wavefront sensor for measuring the wavefront distortion is mainly dependent upon the measuring accuracy of the centroid of each spot. A modified center detection algorithm, which uses some power from the photon events of each pixel instead of photon events themselves, is analyzed theoretically and the computer simulations are given. The results show that photon noise error and sampling error increases as the power value goes up; and to some powers, the readout noise and background noise error decrease. An experiment is described through which the optimum power can be obtained. 相似文献
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夏克-哈特曼波前传感器的波前相位探测误差 总被引:14,自引:4,他引:10
对夏克-哈特曼(Shack-Hartmann)波前传感器的相位探测误差进行了分析,并分析了它的政论相位探测极限,分析结果表明,夏克-哈特曼波前传感器的相位探测精度与探测器的噪声水平,探测目标的亮度有关,还与被探测对象的特性、孔径波前分割有关。给出了它们的关系表达式。 相似文献
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It is crucial for the wavefront sensor to reduce the influence of noise and enhance the detection accuracy of the centroid, which is also an important step for improving the performances of adaptive optics. In this paper, based on the theoretical analysis and by utilizing the Monte-Carlo simulation (MCS) technology, the results obtained by using the centroid algorithms have been compared in detail for the case, in which centroid of the signal is not at the center of the detection area and it also has a relatively large area. It is shown that the size of the signal spot and its centroid position have considerable influences on the centroid detection accuracy. The numerical results agree well with the theoretical predictions and the optimized parameters for each algorithm have been found. The study will be helpful for further optimizing the optical system and improving the centroid measurement accuracy of the wavefront sensor. 相似文献
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Accuracy analysis on centroid estimation algorithm limited by photon noise for point object 总被引:1,自引:0,他引:1
The variance of the position of point object because of photon noise for centroid estimation algorithm is derived for the first time when the background cannot be eliminated by threshold. On this foundation, the accuracy of centroid estimation algorithm is analyzed by comparing its estimated efficiency (the ratio of the Cramer-Rao lower bound of point object and the variance for centroid algorithm) based on the classic estimation theory. The results indicated that the following factors influence the accuracy of centroid estimation algorithm: SBR (the ratio of the outputs from the signal light and the background), the Gaussian width of signal spot and the size of detected window. The effects of these factors are also described. 相似文献
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We present a Shack-Hartmann wavefront sensor (SHWS) based on a cylindrical microlens array as a device for measuring highly aberrated wavefronts. Instead of the typical spot pattern created by a conventional SHWS, two orthogonal line patterns are detected on a CCD and are superimposed. A processing algorithm uses the continuity of the focal line to extend the dynamic range of measurement by localizing the line, even if it leaves the CCD area confined by the corresponding microcylinder. The measurement of a wavefront from a progressive addition lens with an 80 lambda peak-to-valley value reveals the capabilities of the sensor. 相似文献
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自适应光学系统可以实时测量并校正波前信息,但是系统中大量的噪声严重影响了系统的探测精度.自适应光学系统中一般为加性噪声,本文提出一种全新的变分处理模型去除加性噪声,该模型采用自适应非凸正则项.非凸正则项在保持图像细节上较凸正则项具有更好的效果,能更好地保持点源目标的完整性.另外,根据不同区域的噪声水平自适应地构建正则化参数,使不同区域的像素点受到不同程度的噪声抑制,可以更好地保持目标的边缘细节.在算法实现上,为了解决非凸正则项收敛性较差的缺陷,采用分裂Bregman算法及增广拉格朗日对偶算法进行计算.实验及数值仿真结果都表明,该方法能够较好地去除系统中的加性噪声,且光斑信号保存得较为完整,处理后的质心探测精度及信噪比较高. 相似文献