二次曲面共形光学整流罩面型设计

椭球形整流罩产生较大的空气阻力,限制了精确制导武器的作战性能。以减小空气阻力为主要目标,针对二次曲面共形光学整流罩进行研究,设计综合性能较为完善的整流罩面型。应用计算流体力学方法,计算了共形整流罩的空气阻力系数,建立了共形整流罩空气阻力评价函数。基于光线追迹理论,以不同目标视场下的平均波前误差作为像质评价指标,构建了共形整流罩像质评价函数。以雷达散射理论为基础,计算了整流罩的雷达散射截面积,给出了共形整流罩雷达散射特性评价函数。结合空气阻力、光学成像质量和雷达散射特性,建立了二次曲面共形整流罩综合性能评价函数,确立了长径比为1.5的抛物线型整流罩具有较好的综合性能。相比椭球形整流罩,该抛物线形整流罩减少了约1/3的空气阻力。     

特殊整流罩窗口的非对称像差研究

分析了居中球形整流罩的波像差和偏心球形整流罩的波像差。为了分析共形整流罩的一般像差特性,建立了不同类型的整流罩模型,重点分析了像散和彗差,讨论了一阶和五阶像差,并与球形整流罩和偏心球形整流罩的相应像差做了比较。分析了长宽比、边缘厚度与顶点厚度比对像差的影响。     

消像差条件在共形光学系统中的应用

根据轴对称光学系统中的消像散条件探讨了共形整流罩结构中消像散万向节点位置的存在性.在此基础上,对共形光学系统中消像差万向节点位置进行了理论推导.软件分析结果表明,轴对称光学系统消像差条件对于共形光学系统的设计仍有良好的指导意义,由此得到的"消像差"共形光学系统的残余像差已处于实际成像系统的像差校正能力范围之内.     

基于反向旋转位相板的共形光学系统设计

在共形光学系统中,椭球形整流罩打破了球形整流罩的旋转对称性,引入了随目标视场变化而变化的动态像差。共形光学设计的主要任务就是消除或者减小椭球形整流罩引入的动态像差,使共形光学系统的成像质量满足使用要求。设计了基于反向旋转位相板的共形光学系统,利用一对反向旋转位相板的反向旋转对目标视场进行动态扫描,利用固定校正器、衍射元件和泽尼克位相板校正了椭球形整流罩引入的动态像差。成像系统采用二次成像的透射式结构,实现了冷光阑效率100%。结果表明:该方法不仅有别于传统扫描方式,而且有效地消除了大长径比的共形光学系统的动态像差。     

基于自由曲面透镜阵列的共形整流罩动态像差校正

为了校正大长径比、大扫描视角共形整流罩引入的动态像差,提出了一种固定自由曲面透镜阵列校正器。通过设计透镜阵列校正器中各透镜自由曲面的面形和旋转角度,校正不同扫描视角大长径比共形整流罩引入的动态像差。实验结果表明,自由曲面透镜阵列校正器可以对长径比为1.2的共形整流罩实现±50°扫描视角的动态像差校正。这种新型校正器具有动态校正器和固定校正器的优点,可适用于扫描视角大、长径比大以及稳定性高的共形整流罩光学系统。     

光刻机投影物镜的像差原位检测新技术

提出了一种新的光刻机投影物镜像差原位检测(AMF)技术。详细分析了该技术利用特殊测试标记检测投影物镜球差、像散、彗差的基本原理,论述了该技术利用对准位置坐标计算像差引起的成像位置偏移量的方法。实验结果表明AMF技术可实现球差、彗差、像散等像差参量的精确测量。AMF技术考虑了光刻胶等工艺因素对像差引起的成像位置偏移量的影响,有效避免了目前基于硅片曝光方式的彗差原位检测技术对离焦量、像面倾斜等像质参量限制的依赖。     

超分辨望远光学系统像差影响及优化设计

针对大口径光学系统中像差影响超分辨效果的问题,开展泽尼克波前像差对望远超分辨成像系统性能和超分辨局部视场影响的研究。设计四区型位相光瞳滤波器,在理想光学系统出瞳处分别加入离焦、像散、彗差和球差像差,逐渐增加幅值,通过分析不同类别和幅度的波前像差下焦面光强分布变化,研究超分辨成像性能和局部视场对不同种类像差的容忍程度。结果表明,离焦可以抑制超分辨旁瓣能量,提高超分辨倍率,但对局部视场影响较大;球差可以抑制超分辨旁瓣能量,增大局部视场;像散和彗差使光斑圆对称性明显下降,其中像散对局部视场的影响较为明显;同时加入适量离焦和球差时,超分辨旁瓣能量下降,超分辨倍率提高,且不影响系统局部视场。据此设计了一个F数为10,焦距为12 m的大口径光学系统,通过合理优化球差和离焦剩余量,实现了超分辨倍率由1.21倍到1.31倍的提升,最大旁瓣峰值由0.33下降到0.30,局部视场为38.28μm。     

共形光学设计研究

符合空气动力学的导引头整流罩都是流线型的面型,由于这些面型破坏了光学系统的对称性,与导引头成像光学配合时会带来严重的像差,使成像质量下降。所谓共形光学设计就是在整流罩和成像光学系统之间加入校正系统,用校正系统校正整流罩所带来的像差,以便获得良好的成像质量。介绍了共形光学设计的概念,讨论了设计原理,分析了热变形的影响,并给出了一个设计实例。     

光学合成孔径成像系统子孔径像差研究

根据波像差理论，推导了光学合成孔径成像系统单个子孔径存在各种像差时波面方差与子孔径数(N)的关系。推导结果表明，piston误差对系统的影响最大，其次是离焦误差、倾斜误差、球差、彗差和像散。运用离焦误差对piston误差、球差和像散进行像差平衡，其效果显著，特别是球差引起的波面方差下降90％。系统各项像差系数随子孔径数的增加而降低;当子孔径数大于6时，各像差系数变化缓慢。根据瑞利判据，计算N(N≤6)个子孔径合成系统的像差允限和相应的3孔径系统的斯特列尔比。     

静态像差对交叉谱相位复原精度的影响及补偿方法

斑点图像重建方法可以有效抑制大气湍流的影响,得到目标衍射极限像。然而系统静态像差破坏了波前的统计信息,降低了相位重建精度。通过理论分析得出在理想情况下,离焦、像散、彗差和球差中只有彗差会在重建结果中引入额外相位值。进一步采用分割光瞳的方式表示交叉谱传递函数与静态像差的关系时,指出通过选择交叉谱的平移向量方向,可以实现在特定方向上静态像差之间的平衡,降低系统像差对相位重建的影响。仿真中球差与离焦像差之间的平衡及离焦像差与像散之间的平衡,都起到了降低相位重建误差的效果。     

Orbital angular momentum crosstalk of single photons propagation in a slant non-Kolmogorov turbulence channel

We analyze the orbital angular momentum (OAM) crosstalk of single photons propagation through low-order atmospheric turbulence. The probability models of the orbital angular momentum crosstalk for single photons propagation in the channel with the non-Kolmogorov turbulence tilt, coma, and astigmatism and defocus aberration have been established. It is found, for α = 11/3, that the turbulent tilt is the dominant aberration which causes the orbital angular momentum crosstalk, the coma is second and the astigmatism is third, but the defocus aberration has no impact on OAM. The results also indicate that the regularities of orbital angular momentum crosstalk caused by the tilt, the coma and the astigmatism are almost the same, respectively. The crosstalk probability of the orbital angular momentum increases as the azimuth mode index p of Laguerre-Gaussian (LG) beam increases, the turbulent strength C_n² enhances, the orbital angular momentum quantum number rises, the diameter of circular sampling aperture D and the channel zenith angle θ increase.     

泽尼克各项像差对人眼光学质量的影响

基于两个人眼光学质量客观评价标准同心相对瞳孔平面(PFWc)和区域调制传递函数(Marea MTF),研究和分析了波前像差均方根值WRMS处于0.05~1.00μm较大范围内泽尼克各项像差对人眼光学质量的影响。分析结果表明,泽尼克各项在WRMS一定时,瞳孔中心区域的光学质量差距明显,离焦(C4)和球差(C12)项的MPFWc值最小,而五叶草(C15、C20)项的MPFWc值最大。五叶草项在WRMS值处于0.05~1.00μm的范围内,其Marea MTF值均大于0.94,表明该像差项对光学质量的影响可以忽略。MPFWc值和Marea MTF值随着WRMS值的增大而减小,但不是简单的线性关系,随着WRMS值的增大,它们的变化趋于平缓。各项泽尼克像差对人眼光学质量的影响存在较大差别,对人眼光学质量的影响从大到小依次为:球差、离焦、散光、彗差、三叶草、四叶草、五叶草等。     

像差及湍流对90°空间光混频器性能的影响研究

光信号在大气湍流中发生畸变,畸变光信号经过有缺陷的光学天线和空间光混频器后,存在混频效率低及抖动的问题。针对空间输出型和单模输出型的90°空间光混频器,推导了带初级像差的90°空间光混频器模型,并研究了湍流对混频效率的影响。仿真结果表明,对于探测器靶面半径为50μm的空间输出型混频器,像差量为0.2λ的倾斜、球差、离焦、彗差和像散分别导致混频效率下降9.8%、0.6%、0.36%、0.02%和0.01%。对于单模输出型混频器,像差量为0.2λ的倾斜、像散、离焦、彗差和球差分别导致混频效率下降14.11%、8.39%、6.35%、2.63%和1.13%。湍流强度Cn²小于6.4×10^-17m^-2/3时,空间输出型比单模输出型混频器的混频效率高19%以上,在湍流强度Cn²大于6.4×10^-16m^-2/3时,两者混频效率接近于0。最后设计加工了空间输出型和单模输出型90°混频器,并搭建性能测试平台。对于探测器靶面半径为50μm的空间输出型混频器,像差量为0.2λ的倾斜、球差和离焦导致混频效率下降52%、10%和6%;对于单模输出型混频器,像差量为0.2λ的倾斜、像散和离焦导致混频效率下降65%、24%和11%,其他像差对混频效率没有影响。湍流对混频器性能影响的实验结果显示,空间输出型光混频器中频信号值的标准差为21.388,该值远低于单模输出型标准差247.442。     

Effects of low-order atmosphere-turbulence aberrations on the entangled orbital angular momentum states

Based on Zernike-model expansion of turbulence phase aberrations and non-Kolmogorov spectrum model of index-of-refraction fluctuation, we analyze the effects of low-order Zernike turbulence aberrations on orbital angular momentum (OAM) entanglement states in a weak fluctuation region. The signal photon detection probability of OAM entanglement states propagating in a slant turbulence channel with non-Kolmogorov turbulence Z-tilt, defocus, astigmatism, and coma aberrations are modeled, respectively. The results demonstrate that turbulence Z-tilt aberration is the dominant aberration, coma is the second, and astigmatism is the third, but that the defocus aberration has no impact on the detection probability. As the power-law exponent of the non-Kolmogorov spectrum increases from 3 to 4, the detection probability decreases.     

Effects of low order atmosphere-turbulence aberrations on the vortex carrying Gaussian beam

The normalized intensity distributions at the focal plane of a vortex carrying Gaussian beam propagating in weak/middle turbulent atmosphere channel with z-tilt aberration, defocus aberration, astigmatism aberration or total turbulent aberration are discussed by numerical calculation. Our results show that the effect of z-tilt aberration on the intensity distribution of optical vortex beam is main effect of total turbulent aberration. In weak turbulent region, the effects of defocus and astigmatism aberration on the intensity distribution of a vortex carrying Gaussian beam can be ignored. In middle turbulent region, the effect of z-tilt aberration is still the most significant, but the effects of defocus and astigmatism aberrations, specially the effect of astigmatism on the center dark core of the intensity distribution at focal plane, can no longer be disregarded. Our results also show that for three low order aberrations, the beam with values of the topological charge, the beam have larger beam-radius and undergo smaller effects of z-tilt turbulent aberration on the doughnut distribution. For defocus aberration, the radius of the center dull of beam intensity increases with the values of topological charges increasing. And for astigmatism aberration, the beam with odd number topological charges, the center dull speck of beam intensity becomes to the bright speck. But for even number topological charges, the center dull speck of beam intensity maintains the dull one.     

A Variation of Schwarzschild Telescope: Golden Section Solution with Two Concentric Spheres and Its Extension to Finite Distance Solutions

Imaging by two concentric spheres is studied by geometrical method. As the system is symmetric with respect to the common center of curvature, peripheral aberrations, namely coma, astigmatism, and distortion, do not appear. The imaging surface is a sphere that shares the center of curvature with two mirrors. As we solve the zero spherical aberration condition for imaging of an object at infinite distance, the golden section number appears as the ratio of the distance between two mirrors and the radius of the primary mirror. For imaging of an object at finite distance, we have to increase the radius of the second mirror. This system also has no peripheral aberrations. Making the object surface spherical, we can obtain a flat image surface. As the spherical aberration is zero in the original system, spherical aberration, coma, and astigmatism remain zero when the object surface is curved.