Performance of dispersed Rayleigh interferometer on the active cophasing and alignment testbed

We report the laboratory experiment on a segmented mirror testbed that shows the use of a dispersed Rayleigh interferometer to phase segmented mirrors.Segment alignment of tip-tilt is fulfilled by overlapping diffraction pattern centroids of the three individual segments on the focal plane.A spherical interferometer is introduced to evaluate the performance of piston, tip-tilt sensing, and control closed-loop, and finally a total residual root-mean-square (RMS) surface error of about 45 nm is achieved, in which a typical error of about 20 nm is contributed by piston.These results demonstrate that the dispersed Rayleigh interferometer can successfully sense the piston of segmented mirrors and be used in phasing segmented telescopes under extensive studies.     

差动共焦显微成像高稳定三维扫描技术与系统

激光差动共焦显微镜具备高空间分辨率特点,但因其逐点扫描成像方式,扫描时间长,易受三维扫描系统不稳定和环境干扰等影响,产生系统漂移,影响仪器的空间分辨率。利用楔块机构高稳定特点,结合刹车机构的自由抱闸特性,设计了一种新型的轴向升降机构,由此构建了结构更具稳定特性的电动三维扫描系统。稳定性实验验证在搭建的激光差动共焦显微镜上进行,经过监测系统在90min内的轴向位置,轴向漂移小于50nm,与原三维扫描系统漂移140nm对比,漂移速度明显减慢,稳定性有显著提升,进而明显改善了差动共焦显微成像效果。     

Performance of dispersed active cophasing Rayleigh interferometer on the and alignment testbed

We report the laboratory experiment on a segmented mirror testbed that shows the use of a dispersed Rayleigh interferometer to phase segmented mirrors. Segment alignment of tip-tilt is fulfilled by overlapping diffraction pattern centroids of the three individual segments on the focal plane. A spherical interferometer is introduced to evaluate the performance of piston, tip-tilt sensing, and control closed-loop, and finally a total residual root-mean-square （RMS） surface error of about 45 nm is achieved, in which a typical error of about 20 nm is contributed by piston. These results demonstrate that the dispersed Rayleigh interferometer can successfully sense the piston of segmented mirrors and be used in phasing segmented telescopes under extensive studies.     

基于卷积神经网络的高精度分块镜共相检测方法

为获得与单口径望远镜相当的空间分辨率,使成像系统成像质量达到或接近衍射极限,拼接主镜式望远镜的分块子镜应确保实现共相位拼接,本文针对拼接主镜式望远镜高精度平移(piston)误差检测问题,提出了一种基于卷积神经网络的高精度平移误差检测方法.通过在成像系统的出瞳面上设置具有离散孔的光阑,构建了对平移误差极为敏感的点扩散函数图像数据集,根据此数据集的特点搭建了具有高性能的网络模型,并测试得到网络的最佳检测范围.仿真结果表明,在略小于一个波长的捕获范围内,单个网络能够准确地输出一个或多个分块子镜的平移误差;应用于六子镜成像系统时,平移误差检测精度达0.0013λRMS (root mean square),并且方法对残余倾斜(tip-tilt)误差、波前像差、CCD噪声、光源带宽具有良好的鲁棒性.该方法简单快速,可广泛应用于分块镜系统的平移误差检测.     

斩波式自适应移相干涉技术

研究对环境振动和空气扰动所造成的两相干光束间常数项光程变化不敏感的自适应移相干涉系统，利用偏振分光技术，采用闭环控制，并将高频振幅调制与锁相技术相结合，建立一斩波式自适应移相干涉系统，可对环境振动引起的干涉条纹的抖动进行实时探测并予以光程补偿，将干涉条纹依次锁定在与任意相位差相对应的位置,该方法不受两相干光束间光程差大小的限制且具有高信噪比，阐述了该方法的原理，描述了所建立的系统，并给出了实验结果。