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The adaptive optics (AO) technology without a wave-front sensor is simple and has more application fields than conventional
AO technologies. The theory basis of the AO system based on stochastic parallel gradient descent (SPGD) from the convergence,
the stability, and the averaged convergence rate is analyzed, where SPGD is used to control the AO system. The results show
that the AO system based on SPGD can obtain good convergence and stability, and the fast convergence rate, which is in inverse
proportion to $
\sqrt n
$
\sqrt n
(n is the number of control parameters). 相似文献
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Accurate values of masked detector signal (MDS) is the key to the correction capability of wavefront sensorless (WFSless) model-based adaptive optics (AO) system. However, imaging detectors always carry different kinds of noises in real applications, which make MDS deviate from theoretical results. Calculation errors of MDS suffered from the noise were analyzed through theory and simulation. Additionally, considering the method of threshold is usually used to mitigate the noise, we also discussed the influence of threshold on MDS. Results showed that the simulation is consistent with the theory and there exists an optimal threshold to make the error minimum for different noise. A fitting formula, which can accurately calculate optimal thresholds, was proposed based on the simulated data. Above results can provide a plausible method and theoretical basis to mitigate imaging noise of detectors in real applications. 相似文献
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为了得到结构更合理的汽车散热器的百叶窗翅片结构,采用仿真软件对散热器的翅片进行了仿真模拟.通过改变翅片高度,得到了不同高度下散热器翅片的传热因子j和阻力因子f,并引入无量纲参数j/f13来评价其综合性能.优化结果表明,当翅片高度为7.85mm时,汽车散热器百叶翅片的综合性能最佳. 相似文献
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利用88单元变形镜及电荷耦合器件成像器件,以扩展目标为校正对象,建立了带有噪声的无波前探测自适应光学系统模型。在噪声情况下,验证了扩展目标成像时掩模探测器信号和波前相位的平均梯度平方和之间存在线性关系。将基于此线性关系的算法作为无波前探测自适应光学系统的控制算法,通过仿真,检验了模型式无波前探测自适应光学系统在噪声情况下对扩展目标成像的校正能力。结果表明,相同湍流条件、不同信噪比下的校正效果接近。按照湍流条件从小到大的顺序,与信噪比为20 dB的结果相比,信噪比为5 dB时校正后的平均均方根相对误差分别为3.71%,2.94%和2.42%,说明基于该线性关系的模型控制算法具有较强的抗噪能力。 相似文献
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对于N单元变形镜,模型式无波前探测自适应光学系统只需N+1次远场光斑测量,收敛速度快。使用88单元变形镜、CCD成像器件等建立自适应光学系统仿真平台,分别从理论分析和仿真实验出发探讨模型式无波前探测自适应光学系统在噪声情况下的波前校正性能。结果表明:噪声条件下,基于模型的无波前探测自适应光学系统收敛速度保持不变;相同湍流条件时,不同噪声水平下的校正效果接近。与噪声水平50 dB时的结果相比,按照给定湍流条件从弱到强,噪声水平为30 dB时校正后平均RMS相对误差分别为4.75%、4.04%和2.58%。上述结果验证了基于模型的无波前探测自适应光学系统具有较强的抗噪能力。 相似文献
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3月13日,广西百色供电局团员青年积极响应政府和上级团组织抗旱救灾的号召,组成青年志愿者服务队,参加地方组织的“心系民生、抗旱保苗”青年志愿者助农抗旱活动,为抗旱保春耕贡献自己的一份力量。 相似文献