极大望远镜高效率多通道光谱仪的光学系统设计

建立了基于边界限制的宽波段高效率多通道光谱仪快速设计的分析模型,讨论了多通道光谱仪的性能要求、初始结构参数、项目成本、风险之间的相互关系。该模型能够根据给定的系统指标快速计算出多通道光谱仪各子系统的结构参数,能在项目初期对方案的可行性和项目预算给出合理的评估。以4 m级望远镜为平台,设计了基于体位全息光栅的多通道光谱仪,光谱范围为350～1000 nm,每个通道在闪耀波长处的分辨率为5000,光谱仪本体峰值效率大于53%,全工作波段单色像质能量集中度在80%处优于15μm,满足系统的性能要求。     

分块式空间望远镜波前传感及控制方法的仿真研究

分块式空间望远镜的波前传感及控制方法是实现高分辨率成像的关键.空间望远镜在轨展开后,由于空间环境及光学系统本身的特点,存在位置和面形误差,波前误差动态范围大、空间频率覆盖宽,需要采用分级校正的方法逐步减小误差.给出了波前校正流程及相应的波前传感及控制方法.利用Zemax软件建立了同轴偏场三反射镜系统仿真模型,并对主镜进行了分块设计.针对该系统模型,建立了分块式空间望远镜系统波前传感及控制集成仿真软件,通过分析分块主镜的波前误差校正过程验证了算法的可行性.     

高分辨率空间望远镜分块主镜位置误差的在轨校正

针对同轴偏场三反射镜系统用Zemax软件建立了主镜分块模型,提出了基于灵敏度矩阵反演的分块镜位置误差校正方法.对于非圆形的环扇形分块镜,采用环扇域正交的Zernike多项式拟合出瞳波像差.仿真计算了分块镜的灵敏度矩阵,验证了分块镜位置误差和出瞳像差变化量间的线性关系.仿真结果表明,当分块镜具有五个校正自由度时可以将光学系统恢复到设计状态,当分块镜只有三个校正自由度时会有少量剩余误差.     

光学综合孔径望远镜中子望远镜平行性和光程差调整的研究

光干涉技术与天文望远镜技术的结合是提高天文观测分辨率的一种有效方法.采用望远镜阵代替单个大口径望远镜来集光观测,利用最大基线的概念来等效传统光学望远镜的最大口径,很大程度上解决了单个望远镜集光能力不足、角分辨率不高的问题.然而对于光干涉来说,在应用中,只有满足:两束光的相位差δ必须相对稳定、存在相互平行的振动分量、频率相同、两光波在相遇点所产生振动的振幅相差不悬殊和两光波在相遇点的光程差(OPD)应在相干长度之内等这些条件时才能部分相干.光学综合孔径(OAS)望远镜产生干涉条纹的前提条件是子望远镜之间必须两两相干.推导了双光束光干涉的要求,并从双光束干涉的平行性和光程差的要求出发,研究并得出光学综合孔径望远镜子望远镜的平行性和光程差的要求.结合双光束干涉的恒星光干涉仪的光束平行性和光程差的调整方案,研究并得到了光学综合孔径望远镜子望远镜的平行性和光程差调整的光学方案,并讨论了该系统的改进措施.     

Digitalized Mirror Array and Its Application in Large Telescope： Principle and Case Studies

In this article, we report the principle and conceptual design of a fundamentally different technology in fabricating high precision aberration free optical devices. The tip-tilt of facet in a mirror array is produced by digitally controlled line-tilts of rows and columns. It has not only provided a cost-effective designing methodology in optical physics but also led to a much finer precision of 1 mili arc sec or less. As examples of the application of the proposed digitalised optics, two case studies have been given： a 10 m Schmidt telescope （off-axis） and an 8 m Cassegrain telescope （on-axis）.     

卡塞格林望远镜耦合系统锥形导管的仿真与误差分析

为了提高卡塞格林望远镜像斑耦合多模光纤的效率,采用一种在光纤前端放置锥形导管的方法,利用光线在锥形导管中经过多次内全反射耦合进多模光纤中,通过几何光学理论及数值方法分析卡塞格林零视场光束像点的最大耦合角,确定锥形导管初始结构参数。将此参数作为Zemax仿真的初始条件,进行优化仿真计算和误差分析。结果表明:加工误差控制在0.03 mm之内,采用锥形导管后可以使像斑整体耦合效率较直接耦合提高4倍以上。     

中国古代化学的重大科技成就

史前考古学家V.G.Childe认为,哺乳动物以改变自身如长皮毛御寒,长灵牙利爪御敌和捕食以求生存和繁衍,而人则是发展智慧,积累和传递知识,提高能力以求生存和持续发展,并指出:"火、衣服、房屋、火车、飞机、望远镜和枪炮等等,都     

Design of CASSEGRAIN telescope baffles with honeycomb entrance

The stray radiation suppression in Cassegrain family optical system is presented. The design method for ultra-short outer baffle with honeycomb structure is proposed. Meanwhile the constraint formulas for designing the geometries of primary baffle and secondary baffle are deduced when basing the characteristic and taking vignette into account. According to the ray trace simulated data, the point source transmit- tance values of the baffle are less than 10-^10 when incident angles are larger than the rejection angle. The honeycomb-look front baffle guarantees a comparable performance of stray light suppression with traditional tube baffle, while reducing the size greatly.     

基于迭代的傅里叶望远镜图像重构方法

为了提高最终图像的质量,结合传统的直接重构算法和相位重构算法,提出了一种基于迭代的傅里叶望远镜图像重构方法。对反演得到的傅里叶频谱进行逆傅里叶变换得到直接重构图像,取直接重构图像的阈值图像作为相位重构算法的初始输入,通过迭代能够获得质量更高的图像。成像仿真实验结果表明,成像信噪比为50倍时,与直接重构图像相比,迭代重构图像斯特列尔比从0.82提高到0.88,峰值信噪比从17dB提高到19dB;在成像信噪比为100倍时,迭代重构图像斯特列尔比从0.89提高到0.93,峰值信噪比从20dB提高到22dB。     

Hadronic Scenarios for Gamma-Ray Emission from Three Supernova Remnants Interacting with Molecular Clouds

GeV γ-rays detected with the large area telescope on board the Fermi Gamma-ray space telescope in the direc- tion of HB21, MSH 17-39 and G337.0-0.1 have been recently reported. The three supernova remnants （SNRs） show interactions with molecular clouds, and they are effective gamma-ray emitters as the relativistic protons accelerated by the SNR shocks inelastically colliding with the dense gas in the clouds. The origin of the observed γ-rays for the three remnants is investigated in the scenario of the diffusive shock acceleration. In the model, a part of the SNR shock transmits into the nearby molecular clouds, and the shock velocity is greatly reduced. As a result, a shock with a relatively low Alfven Mach number is generated, and the spectra of the accelerated protons and thee＇γ-ray photons produced via proton-proton interaction can be obtained. The results show that the observed γ-ray spectra for the three SNRs interacting with the molecular clouds can be reproduced. It can be concluded that the hadronic origin of the γ-rays for the three SNRs is approved, and the ability of SNR shocks to accelerate protons is also supported.