共查询到19条相似文献,搜索用时 342 毫秒
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提高Hartmann波前传感器质心探测精度的阈值方法 总被引:6,自引:3,他引:3
详细地讨论了Hartmann波前传感器质探测的误差来源。主要讨论了光量子起伏、CCD的背影电子噪声引起的质心探测误差,并对采样阈值对Hartmann波前传感器质心探测精度的影响进行了分析。本文对Hartmann波前传器的经设计以及实际操作提供了一定的理论依据。 相似文献
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人眼像差哈特曼测量仪的重复性测试 总被引:1,自引:1,他引:0
人眼像差哈特曼测量仪利用 Hartmann-Shack 波前传感器探测波前,并用 Zernike 多项式实现波前的重建。测试结果的重复性对该仪器来说是至关重要的。此仪器对模拟人眼静态像差和活体人眼动态像差分别进行单帧采集和连续采集,所得的模拟人眼静态像差 Zernike 系数的标准偏差的最大值,PV 与 RMS 依次为 0.016?,0.061?和 0.006?;活体人眼动态像差 Zernike 系数的标准偏差的最大值,PV 与 RMS 依次为 0.045?,0.167? 和 0.030?,这些指标都小于 ?/5,表明该仪器具有较高的重复性。 相似文献
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精确的测量和控制星载望远镜的波前像差是实现高效空间引力波探测的关键。本文提出了一种基于夏克-哈特曼波前传感器原理的星载望远镜波前像差测量方法,该方法采用经过频域阈值去噪处理后的频域上的互相关算法,使用子孔径数20×16、微透镜尺寸0.279 mm×0.279 mm、焦距34 mm的夏克-哈特曼波前传感器对算法的测量精确度进行验证。对实际点源图像生成已知RMS离焦值(0, 0.22, 0.44, 0.66 nm),从而产生具有偏移量的点源图像。使用模式法进行波前复原后,计算复原波面和残余波面的RMS值,用于比较频域上的互相关算法和传统质心算法的测量精度。结果显示,随着实际离焦值的增加,质心算法的测量误差呈现上升趋势,分别为0.0966 nm, 0.1378 nm,0.1284 nm和0.1463 nm。频域互相关算法可以使夏克-哈特曼波前像差均方根(RMS)误差分别减少13%, 7%, 18%和14%,为空间引力波星载望远镜地面波前像差的高精度测试提供了重要参考。 相似文献
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为了消除或缓解光学相干断层成像方法中散斑等噪声对OCT图像像质退化的影响,提出了基于波原子阈值去噪算法。波原子变换是一种新型的二维多尺度变换,且满足曲线波的抛物比例尺度关系和各向异性征;波原子适用于模式的任意局部方向,能够对轴方向的各向异性模式稀疏展开。本文利用波原子阈值去噪算法,对人眼眼底组织和手指指尖皮肤的OCT图像进行降噪处理,并与传统的小波阈值算法和快速曲波算法对OCT样品图像去噪效果进行对比分析。结果表明,基于波原子阈值去噪方法能够有效地抑制OCT图像散斑噪声,并能保持图像边缘细节特征。 相似文献
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基于绝对差分算法的相关HS波前处理机设计 总被引:2,自引:1,他引:1
在太阳自适应光学系统中,通常采用绝对差分或者互相关因子算法进行哈特曼波前探测.本文给出了一种基于绝对差分算法的相关HS(Hartmann-Shack)波前处理机的设计结果.针对子孔径阵列呈6×6方形排布,单个子孔径大小为32 pixels×32 pixels,参考模板大小为16 pixels×16 pixels的相关HS渡前传感器,采用绝对差分算法在单片FPGA内实现了对波前的实时处理.实验结果表明,该处理机峰值运算量超过230亿次/s,系统延时120μs,能够满足1 000 Hz的CCD采样要求.本设计在单片FPGA内实现,具有成本低、易维护、集成度高的特点. 相似文献
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有结构扩展目标整体倾斜信息提取有效性实验 总被引:1,自引:0,他引:1
根据互相关因子算法和绝对差分算法的基本原理,利用Matlab实现了倾斜信息提取。在此基础上,考察了两种算法的精确性问题,发现绝对差分算法的拟合精度高于互相关算法,其数量级可达到0.0001像素;结合哈特曼波前传感器的测量结果,采用比对的方法,对有结构扩展目标两种算法提取倾斜信息的有效性进行了验证,可以得到,不同倾斜范围时两种算法提取的信息高度吻合,且处理后与哈特曼波前传感器走势一致;经自适应校正后,得到了很好的长曝光像。实验结果表明,这两种算法均可有效地提取出自适应光学所需要的光束波前整体倾斜信息。 相似文献
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Adaptive optics takes its servo feedback error cue from a wavefront sensor. The common Hartmann-Shack spot grid that represents the wavefront slopes is usually analyzed by finding the spot centroids. In a novel application, we used the Fourier decomposition of a spot pattern to find deviations from grid regularity. This decomposition was performed either in the Fourier domain or in the image domain, as a demodulation of the grid of spots. We analyzed the system, built a control loop for it, and tested it thoroughly. This allowed us to close the loop on wavefront errors caused by turbulence in the optical system. 相似文献
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Analysis of Hartmann-Shack wavefront sensors for the eye is traditionally performed by locating and centroiding the sensor spots. These centroids provide the gradient, which is integrated to yield the ocular aberration. Fourier methods can replace the centroid stage, and Fourier integration can replace the direct integration. The two--demodulation and integration--can be combined to directly retrieve the wavefront, all in the Fourier domain. Now we applied this full Fourier analysis to circular apertures and real images. We performed a comparison between it and previous methods of convolution, interpolation, and Fourier demodulation. We also compared it with a centroid method, which yields the Zernike coefficients of the wavefront. The best performance was achieved for ocular pupils with a small boundary slope or far from the boundary and acceptable results for images missing part of the pupil. The other Fourier analysis methods had much higher tolerance to noncentrosymmetric apertures. 相似文献
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Based on the dynamic characteristics of human eye aberration, a microadaptive optics retina imaging system set is established for real-time wavefront measurement and correction. This paper analyzes the working principles of a 127-unit Hartmann-Shack wavefront sensor and a 37-channel micromachine membrane deformable mirror adopted in the system. The proposed system achieves wavefront reconstruction through the adaptive centroid detection method and the mode reconstruction algorithm of Zernike polynomials, so that human eye aberration can be measured accurately. Meanwhile, according to the adaptive optics aberration correction control model, a closed-loop iterative aberration correction algorithm based on Smith control is presented to realize efficient and real-time correction of human eye aberration with different characteristics, and characteristics of the time domain of the system are also optimized. According to the experiment results tested on a USAF 1951 standard resolution target and a living human retina (subject ZHY), the resolution of the system can reach 3.6?LP/mm, and the human eye wavefront aberration of 0.728λ (λ=785?nm) can be corrected to 0.081λ in root mean square (RMS) so as to achieve the diffraction limit (Strehl ratio is 0.866), then high-resolution retina images are obtained. 相似文献