A new extendable method for the simulation of atmospheric wave-fronts with turbulence intermittency is reported. The purpose is to generate simulations consistent with the distributions observed for the turbulence par...A new extendable method for the simulation of atmospheric wave-fronts with turbulence intermittency is reported. The purpose is to generate simulations consistent with the distributions observed for the turbulence parameters and the seeing, not available with standard methods. The intermittency is included by entering log-normal distributed arrays for the Fried parameter and the spatial coherence outer scale length into an extended form of the phase spectrum. The method is tested on large samples of simulated long-exposure point-source images. The tests show the agreement of the simulations with literature data. The simulations show that the intermittency affects negligibly the long-term median image size but breaks the symmetry of the wave-front phase spectrum, scatters the phase structure function and changes the image profile.展开更多
We developed an adaptive optics system to correct the wave-front distortion of an intense fs laser beam from our multi-TW laser system, Jiguang II. In this paper, the instruments of the adaptive optical system are des...We developed an adaptive optics system to correct the wave-front distortion of an intense fs laser beam from our multi-TW laser system, Jiguang II. In this paper, the instruments of the adaptive optical system are described and the experimental results of the closed-loop wave-front correction are presented. A distorted laser wave-front of 20 wavelengths of P-V values was corrected to 0.15 wavelength of P-V values. The beam quality of the laser system varies from 3.5 diffraction limit to 1.5 diffraction limit.展开更多
In this paper we present the recent research results in the field of vision correction and supernormal vision according to the actual measurements of the wave-front aberrations and the corneal surface topography,the c...In this paper we present the recent research results in the field of vision correction and supernormal vision according to the actual measurements of the wave-front aberrations and the corneal surface topography,the clinical detection of the visual function and the laser corneal refractive surgery,and the optimization of the optical system. These include the features of the aberrations of human eye with different pupil sizes,different fields of view and temporal accommodation,the influence of the polychromatic illumination of the visible wavelength on the supernormal vision,and the effect of the existing laser corneal refractive surgery on the wave-front ab-errations of the eye. It is shown that the wave-front aberration of human eye is of temporal variation and of synthesis with multi impact factors. To achieve super-normal vision,an optimum engineering data for the customized laser corneal sur-gery should be firstly acquired,which may involve the dynamic free-form optical surface. Although the myopia can be corrected by the laser in situ keratomileusis(LASIK) in a certain degree,it brings about negative effects under scotopic condi-tions.展开更多
High-contrast imaging provided by a coronagraph is critical for the direction imaging of the Earth-like planet orbiting its bright parent star.A major limitation for such direct imaging is the speckle noise that is in...High-contrast imaging provided by a coronagraph is critical for the direction imaging of the Earth-like planet orbiting its bright parent star.A major limitation for such direct imaging is the speckle noise that is induced from the wave-front error of an optical system.We derive an algorithm for the wave-front measurement directly from 3 focal plane images.The 3 images are achieved through a deformable mirror to provide specific phases for the optics system.We introduce an extra amplitude modulation on one deformable mirror configuration to create an uncorrelated wave-front,which is a critical procedure for wave-front sensing.The simulation shows that the reconstructed wave-front is consistent with the original wave-front theoretically,which indicates that such an algorithm is a promising technique for the wave-front measurement for the high-contrast imaging.展开更多
面向分布式小型化磁感前端阵列接收长波信号场景,针对长波频段噪声复杂的特性,提出了一种宽带多信号智能联合检测方法。该方法基于已知参考信号样本预训练神经网络,通过神经网络在预训练阶段学习分布式接收样本矢量在各维度上的潜在复...面向分布式小型化磁感前端阵列接收长波信号场景,针对长波频段噪声复杂的特性,提出了一种宽带多信号智能联合检测方法。该方法基于已知参考信号样本预训练神经网络,通过神经网络在预训练阶段学习分布式接收样本矢量在各维度上的潜在复杂关联性规律,进而部署网络后可输出基于输入样本矢量联合概率的置信度量,用于判断当前样本是否存在目标信号从而得到检测结果。基于宽带信号仿真数据集进行实验,结果表明算法可直接对宽带数据进行处理,并能有效完成频谱感知,能够在低信噪比和相关噪声条件下获得接近理论处理增益的检测性能,达到80%以上的检测率。在此基础上,采用中科院空天信息创新研究院布设于内蒙古的超短基线电磁探测阵列(Mini-array by Chinese Academy of Sciences,CASMA)采集的实际长波信号数据进行性能验证,算法性能测试结果同样验证了其有效性。该方法不限于长波信号,也适用于其他具备参考信号条件下的信号盲检测的场景,实现在信道参数未知、信号微弱等盲环境条件下获得更优的目标信号检测性能。展开更多
为高效控制汽车前围板振动噪声,弥补传统材料抑制低频振动性能的不足及易燃、环保性能低的缺陷,设计一种基于Kagome点阵的局域共振型夹芯超材料,建立单胞结构的有限元模型,计算并分析其能带结构、带隙产生机理和弹性波传播特性,以及关...为高效控制汽车前围板振动噪声,弥补传统材料抑制低频振动性能的不足及易燃、环保性能低的缺陷,设计一种基于Kagome点阵的局域共振型夹芯超材料,建立单胞结构的有限元模型,计算并分析其能带结构、带隙产生机理和弹性波传播特性,以及关键几何参数对带隙频段的影响,利用正交实验极差分析法(Statistical Product and Service Software Automatically,SPSSAU)对关键几何参数进行优化,同时开展基于该材料的汽车前围板隔振性能的研究。研究表明,所设计的Kagome点阵夹芯超材料能够实现低频带隙;增加圆块厚度和半径会使带隙频段整体向低频方向移动,且拓宽低频带隙;减小韧带宽度会使带隙频段向低频区域移动,且使带隙宽度减小。将优化后的Kagome点阵夹芯超材料应用于汽车前围板,可明显提高其隔振性能。展开更多
文摘A new extendable method for the simulation of atmospheric wave-fronts with turbulence intermittency is reported. The purpose is to generate simulations consistent with the distributions observed for the turbulence parameters and the seeing, not available with standard methods. The intermittency is included by entering log-normal distributed arrays for the Fried parameter and the spatial coherence outer scale length into an extended form of the phase spectrum. The method is tested on large samples of simulated long-exposure point-source images. The tests show the agreement of the simulations with literature data. The simulations show that the intermittency affects negligibly the long-term median image size but breaks the symmetry of the wave-front phase spectrum, scatters the phase structure function and changes the image profile.
基金This work was partly supported by the National Natural Science Foundation of China(Grant Nos.60225005,60308001)the NKBRSF(Grant No.G1999075202)the National Hi-tech ICF program.
文摘We developed an adaptive optics system to correct the wave-front distortion of an intense fs laser beam from our multi-TW laser system, Jiguang II. In this paper, the instruments of the adaptive optical system are described and the experimental results of the closed-loop wave-front correction are presented. A distorted laser wave-front of 20 wavelengths of P-V values was corrected to 0.15 wavelength of P-V values. The beam quality of the laser system varies from 3.5 diffraction limit to 1.5 diffraction limit.
基金Supported by the National Natural Science Foundation of China (Grant No. 60438030)the Key Research Foundation of Scientific and Technical Committee of Tianjin City of China (Grant No. 033183711)
文摘In this paper we present the recent research results in the field of vision correction and supernormal vision according to the actual measurements of the wave-front aberrations and the corneal surface topography,the clinical detection of the visual function and the laser corneal refractive surgery,and the optimization of the optical system. These include the features of the aberrations of human eye with different pupil sizes,different fields of view and temporal accommodation,the influence of the polychromatic illumination of the visible wavelength on the supernormal vision,and the effect of the existing laser corneal refractive surgery on the wave-front ab-errations of the eye. It is shown that the wave-front aberration of human eye is of temporal variation and of synthesis with multi impact factors. To achieve super-normal vision,an optimum engineering data for the customized laser corneal sur-gery should be firstly acquired,which may involve the dynamic free-form optical surface. Although the myopia can be corrected by the laser in situ keratomileusis(LASIK) in a certain degree,it brings about negative effects under scotopic condi-tions.
基金Supported by the National Natural Science Foundation of China (Grant No. 10873024)
文摘High-contrast imaging provided by a coronagraph is critical for the direction imaging of the Earth-like planet orbiting its bright parent star.A major limitation for such direct imaging is the speckle noise that is induced from the wave-front error of an optical system.We derive an algorithm for the wave-front measurement directly from 3 focal plane images.The 3 images are achieved through a deformable mirror to provide specific phases for the optics system.We introduce an extra amplitude modulation on one deformable mirror configuration to create an uncorrelated wave-front,which is a critical procedure for wave-front sensing.The simulation shows that the reconstructed wave-front is consistent with the original wave-front theoretically,which indicates that such an algorithm is a promising technique for the wave-front measurement for the high-contrast imaging.
文摘面向分布式小型化磁感前端阵列接收长波信号场景,针对长波频段噪声复杂的特性,提出了一种宽带多信号智能联合检测方法。该方法基于已知参考信号样本预训练神经网络,通过神经网络在预训练阶段学习分布式接收样本矢量在各维度上的潜在复杂关联性规律,进而部署网络后可输出基于输入样本矢量联合概率的置信度量,用于判断当前样本是否存在目标信号从而得到检测结果。基于宽带信号仿真数据集进行实验,结果表明算法可直接对宽带数据进行处理,并能有效完成频谱感知,能够在低信噪比和相关噪声条件下获得接近理论处理增益的检测性能,达到80%以上的检测率。在此基础上,采用中科院空天信息创新研究院布设于内蒙古的超短基线电磁探测阵列(Mini-array by Chinese Academy of Sciences,CASMA)采集的实际长波信号数据进行性能验证,算法性能测试结果同样验证了其有效性。该方法不限于长波信号,也适用于其他具备参考信号条件下的信号盲检测的场景,实现在信道参数未知、信号微弱等盲环境条件下获得更优的目标信号检测性能。
文摘为高效控制汽车前围板振动噪声,弥补传统材料抑制低频振动性能的不足及易燃、环保性能低的缺陷,设计一种基于Kagome点阵的局域共振型夹芯超材料,建立单胞结构的有限元模型,计算并分析其能带结构、带隙产生机理和弹性波传播特性,以及关键几何参数对带隙频段的影响,利用正交实验极差分析法(Statistical Product and Service Software Automatically,SPSSAU)对关键几何参数进行优化,同时开展基于该材料的汽车前围板隔振性能的研究。研究表明,所设计的Kagome点阵夹芯超材料能够实现低频带隙;增加圆块厚度和半径会使带隙频段整体向低频方向移动,且拓宽低频带隙;减小韧带宽度会使带隙频段向低频区域移动,且使带隙宽度减小。将优化后的Kagome点阵夹芯超材料应用于汽车前围板,可明显提高其隔振性能。
