高精度镜面位置控制的微位移促动器研究

随着光学天文望远镜口径不断增大,望远镜主镜多采用拼接镜面形式,而微位移促动器作为镜面拼接技术的关键部件,始终是研究的热点之一。以双螺旋滚珠丝杆代替传统机械式微位移促动器中减速器加滚珠丝杆结构,利用差动螺旋原理进行微位移输出,使用伺服电机作为驱动电机,并对负载时电机所需的转矩进行分析。微位移促动器的输出位移精度、行程及负载能力是重要技术指标,本文从这三方面的要求出发,开展性能测试。实验结果表明,该微位移促动器总行程为5 mm,理论最大可承载1 200 N,在200 N的负载下实现200 nm的步长分辨率,开环单向位移精度优于0.65μm,闭环单向位移精度优于0.2μm。验证了所提出的微位移促动器具备高精度、大行程和高负载的要求,为我国未来大口径天文望远镜的设计提供技术储备。     

磁致伸缩微位移驱动器性能测试分析

介绍了磁致伸缩微位移驱动器的工作原理,分析了检测方法,设计了使用双频激光干涉仪作为测量基准的测试平台;对该驱动器的位移的输出特性进行了测试,通过拟合处理对测试结果进行数据分析,可提高超磁致伸缩微位移驱动器的线性度和控制精度,使得驱动器性能改善.基于磁致伸缩效应原理研制的微位移驱动器,具有线性好、分辨率高、精度高等优点,经测试,达到了设定的参数指标要求.     

低温微位移促动器的设计与实验

以极地天文望远镜为应用背景,研制了一种低温微位移促动器,并在室温和低温条件下进行性能测试实验,获得了低温微位移促动器的性能指标。分析了3种常见的大行程高精度微位移促动器的结构形式,选择位移缩放式作为低温微位移促动器的基本结构。微位移促动器采用低温步进电机作为驱动元件,以具有特殊消隙结构的螺旋传动作为位移缩放机构,实现了高刚度、耐低温、结构紧凑、密闭性好的微位移促动器的设计。开展了微位移促动器的性能测试实验,结果表明:所设计的低温微位移促动器在室温条件下的步进精度达到1μm±0.082μm,并且满足负载能力的设计要求;低温条件下步进精度可以达到2μm±0.404μm。研制的微位移促动器将为拼接式极地天文望远镜的建设提供重要的技术支持。     

现代望远镜制造中的一些问题

天文学和其他科学技术的发展,不断地要求天文望远镜的改进.最初主要依靠肉眼来进行天文观测,所以当时望远镜的光学性能要求是根据眼睛来提出的.当照相方法在天文上得到应用以后,望远镜的设计制造就从照相的要求上去考虑了.现在光电技术已开始愈来愈多地在天文上应用了,这又对望远镜提出了一些新的要求.目前,大型的天文望远镜主要是用来作照相观测(包括直接照相和光谱照相);光电观     

LAMOST子镜镀膜研究进展

对大口径光学/红外天文望远镜而言,为保障其稳定高效运行,镜面镀膜是重要的维护环节之一.镀膜质量的好坏直接影响镜面光学反射率的高低,也严重影响到天文望远镜的成像质量、观测效率.国家重大科技基础设施—大天区面积多目标光纤光谱天文望远镜(Large Sky Area Multi-Object Fiber Spectroscopic Telescope, LAMOST,又名郭守敬望远镜)自2009年6月通过国家竣工验收并逐步投入巡天观测,目前已进入第2个5 yr巡天计划阶段,取得近两千万的光谱产出和大批高显示度的科学成果. LAMOST共拥有24块施密特改正镜子镜和37块球面主镜子镜,为了确保在野外恶劣观测环境下镜面反射率维持在较高水平,每年要对大批子镜进行镀膜.主要介绍了镀膜需求、镀膜设备,并基于大量实验和多年的完善探索出一套可行的镀膜工艺流程,确保了LAMOST子镜极高的镀膜质量.镀膜后子镜平均反射率高达90%以上,满足了LAMOST光谱巡天的镜面反射率要求.     

天文望远镜子镜超磁致伸缩驱动器驱动模型及参数识别

采用超磁致伸缩驱动器(GMA,Giant Magnetostrictive Actuator)驱动拼接镜面天文望远镜子镜,并建立GMA精密位移驱动准确模型。针对传统遗传算法在辨识GMA位移模型参数时容易过早收敛到次优解的问题,提出了基于分层遗传算法(HGA,HierarchicalGenetic Algorithm)的参数识别方法,其结果在改善驱动位移模拟准确性和提高求解初期种群多样性,相对于其他算法都有较大程度的提高。研究通过与实验结果对比验证了所提出参数辨识方法和建立模型的有效性,位移预测值和实验值的平均偏离值不超过满行程的1.3%。研究还就驱动磁场强度幅值和预应力等因素对滞回、损耗、饱和磁化强度、饱和磁致伸缩量等模型参数的影响进行了分析。     

美国美德(MEADE)系列天文望远镜

美国美德仪器公司是世界级的天文望远镜制造厂家,专业生产高档天文望远镜,其产品光学质量优秀,加工精度高,外形华贵,尤其是它所生产的施密特一卡塞格林折反射式天文望远镜堪称精品,深受天文工作者、学校天文台及天文发烧友的称道。     

享受星空 享受高科技 美国美德ETX系列天文望远镜

1996年,美德公司推出ETX系列天文望远镜,很快引起了业余天文界的革命。第一次有了漂亮外观,便于携带以及卓越的光学分辨率和性能的望远镜。ETX系列天文望远镜已成为最畅销的现代天文望远镜。无论你是刚入门的天文爱好者还是老资格的天文爱好者,ETX系列天文望远镜及Autostar自动寻星控制器都可以让你轻松的定位、探究行星、银河系、星云及星系、小行星和彗星,此外它们还是陆地远距离观察景物、拍摄野生动物的得力工具。     

享受星空 享受高科技 美国美德ETX系列天文望远镜

1996年,美德公司推出ETX系列天文望远镜,很快引起了业余天文界的革命。第一次有了漂亮外观,便于携带以及卓越的光学分辨率和性能的望远镜。ETX系列天文望远镜已成为最畅销的现代天文望远镜。无论你是刚入门的天文爱好者还是老资格的天文爱好者,ETX系列天文望远镜及Autostar自动寻星控制器都可以让你轻松的定位、探究行星、银河系、星云及星系、小行星和彗星,此外它们还是陆地远距离观察景物、拍摄野生动物的得力工具。     

日本天象仪（中）

五藤光学研究所是日本两家主要生产天象仪的厂家之一。1926年五藤齐三以日本惟一的天文仪器制造商的身份,创立了五藤光学研究所。自那以后,五藤光学一直以制造天文望远镜和天象仪为自己的主要业务,赢得日本乃至世界的专业和业余天文学家的极大信任。尤其从1959年起开始生产天象仪,乘着当时的“太空热”,把它的产品从日本推销到海外,占据世界市场的40％。五藤光学的天文望远镜也从面向学校类型发展为超大型反射望远镜、太阳望远镜、移动天文台等。     

Acceleration of Numerical Integration of the Equations of Motion of Asteroids

Solar System Research - Finding and studying possible collisions of asteroids approaching the Earth requires a significant amount of computation. This paper describes the R0 program created to...     

Equation of state and anisotropy of pressure of magnetars

Magnetars are the neutron stars with the highest magnetic fields up to 10¹⁵–10¹⁶ G. It has been proposed that they are also responsible for a variety of extra-galactic phenomena, ranging from giant flares in nearby galaxies to fast radio bursts. Utilizing a relativistic mean field model and a variable magnetic field configuration, we investigate the effects of strong magnetic fields on the equation of state and anisotropy of pressure of magnetars. It is found that the mass and radius of low-mass magnetars are weakly enhanced under the action of the strong magnetic field, and the anisotropy of pressure can be ignored. Unlike other previous investigations, the magnetic field is unable to violate the mass limit of the neutron stars.     

Observations of the intensity of the penumbra of sunspots

Observations of the penumbral intensity of sunspots in 13 wavelength regions are presented. In 4 wavelength regions 54 sunspots are measured. In the other wavelength regions the number of sunspots considered ranges from 3–19.The penumbral intensity alters with position within the spot. This intensity variation is found to be comparable with the change in intensity from one spot to another. The penumbral intensity is found to be independent of spot size in the sample considered.The penumbra model of Kjeldseth Moe and Maltby (1969) with = 0.055 is supported by the measurements.     

A survey of orbits of co-orbitals of Mars

Many asteroids with a semimajor axis close to that of Mars have been discovered in the last several years. Potentially some of these could be in 1:1 resonance with Mars, much as are the classic Trojan asteroids with Jupiter, and its lesser-known horseshoe companions with Earth. In the 1990s, two Trojan companions of Mars, 5261 Eureka and 1998 VF₃₁, were discovered, librating about the L₅ Lagrange point, 60° behind Mars in its orbit. Although several other potential Mars Trojans have been identified, our orbital calculations show only one other known asteroid, 1999 UJ₇, to be a Trojan, associated with the L₄ Lagrange point, 60° ahead of Mars in its orbit. We further find that asteroid 36017 (1999 ND₄₃) is a horseshoe librator, alternating with periods of Trojan motion. This asteroid makes repeated close approaches to Earth and has a chaotic orbit whose behavior can be confidently predicted for less than 3000 years. We identify two objects, 2001 HW₁₅ and 2000 TG₂, within the resonant region capable of undergoing what we designate “circulation transition”, in which objects can pass between circulation outside the orbit of Mars and circulation inside it, or vice versa. The eccentricity of the orbit of Mars appears to play an important role in circulation transition and in horseshoe motion. Based on the orbits and on spectroscopic data, the Trojan asteroids of Mars may be primordial bodies, while some co-orbital bodies may be in a temporary state of motion.     

Graphical representation of periodic motion of the line of nodes of the Moon

In the text-books of astronomy, sections generally related to the Moon deal with the orbital elements of the Earth-Moon system such asa, e, i, , and the time of perigee passage. While the MEAN of the first of the three elements do not vary, mean longitude of the ascending node-mean longitude of the lunar perigee and the time of perigee passage undergoes secular as well as periodic changes due predominantly to the action of the Sun's gravitational attraction. While to a certain degree, explanations related to the calculation of the lunar orbit parameters are given, not a single graphical representation of these short- or long-periodic changes are presented. We allow the number of data related to these periodic changes must cover a large span of time; and if regression of the line of nodes or advances of the line of apses are to be graphically seen, data covering 18.61 and 8.85 yr, respectively, are needed. In this work we particularly aim at the graphical representation of the periodic changes of the line of nodes.