Three types of 2-degree field compensating atmospheric dispersion correctors for prime focus

Three types of prime focus correctors for Chinese 2.16m telescope are introduced in this paper. Each corrector has a 2 degree field and can be used to compensate the atmospheric dispersion of 6″. All the three correctors have excellent image quality and the angles between the principal rays and the optical axes are quite small. There is no special technological difficulty in their fabrication. These designs can not only be used in the 2.16m telescope but also be applied to other large telescopes.     

近地天体望远镜增加卡氏内氏焦点的可行性研究

近地天体望远镜是巡天望远镜, 具有短焦距、大视场、低空间分辨率的光学特点. 望远镜只有一个主焦点, 焦距1.8 m, 底片比例9um/'', 像斑几何能量集中度EE80 ≤2''(像斑环绕能量的80%,即80% encircled energy, 记为EE80), 有效视场直径为4.28-°(14.3deg2), 目前配10k times 10k的STA1600LN CCD (charge-coupled device) camera, 观测视场为9deg2. 通过光学系统设计, 在原光学系统上增加副镜及场改正镜, 获得了焦距9m的卡氏焦点和内氏焦点，底片比例43.6 um /"，在直径15''的可用视场内，像斑EE80≤0.5",为近地天体望远镜实现多终端观测提供了理论依据.     

基于光学遥感影像的2019年加利福尼亚MW7.1和MW6.4双震同震形变测量

利用地震前后的Landsat-8和Sentinel-2光学遥感影像数据,基于频率域互相关算法提取加利福尼亚州MW7.1及MW6.4地震的同震形变场,同时针对形变数据易受轨道误差、条带误差及时间失相干的影响,分别采用最小二乘多项式曲线拟合、改进均值相减等方法去除系统误差项。研究表明,MW7.1主震以右旋走滑为主,地表形变的断层迹线呈NNW走向,长度达55 km,最大滑移量约为2.82 m;MW6.4地震的发震断层迹线呈NE走向,长度达15 km,最大滑移量约为1.05 m,推测2次地震的发震断层分别为NNW向右旋走滑断裂及NE向左旋走滑断裂,二者形成典型的共轭关系。     

面向应用的CBERS-02星高分辨率相机成像数值模拟技术框架

技术框架研究的目标是准确仿真卫星高分辨率相机成像过程中辐射和几何质量的下降情况,从应用方的角度建立评价高分辨率卫星相机在国土资源领域的应用潜力和技术框架,并以CBERS-02B星HR相机在轨成像模拟为例进行了原理验证,同时对今后以国土资源应用评价为目标的高分辨率相机在轨成像模拟改进方案提出了建议。     

巯基棉富集分离—冷原子吸收法测定天然水中痕量汞

用巯基棉富集水中痕量汞,用饱和氯化钠的盐酸溶液解吸,冷原子吸收法测定。当水样取１ Ｌ时,最低检测浓度可达０－００３ μｇ／Ｌ,方法相对标准偏差为３－８ ％ ～６－９ ％ ,巯基棉汞平均回收率为９１－１％ 。该法操作简单、快速、富集倍数大,适用于天然水中痕量汞的分析。     

Late Quaternary fluvial aggradation and incision in the monsoon‐dominated Alaknanda valley,Central Himalaya,Uttrakhand, India

The present study aims to explain the spatial and temporal variability in phases of aggradation/incision in response to changes in climate and seismicity during the late Quaternary in the Alaknanda River valley (a major tributary of the river Ganges or Ganga). Geomorphology, stratigraphy and optical dating of the fluvial sediment reveal that the oldest fluvial landforms preserved in the south of the Main Central Thrust are debris flow terraces developed during the early part of pluvial Marine Isotopic Stage 3. Following this, a period of accelerated incision/erosion owing to an increase in uplift rate and more intense rainfall occurred. In the Lesser Himalaya, three phases of valley fill aggradation around 26 ± 3 ka, 18 ± 2 ka and 15 ± 1 ka and 8 ± 1 ka occurred in response to changes in monsoon intensity and sediment flux. The last phase was regionally extensive and corresponds to a strengthening of the early Holocene Indian Summer Monsoon. A gradual decline in the monsoon strength after 8 ± 1 ka resulted in reduced fluvial discharge and lower sediment transport capacity of the Alaknanda River, leading to valley fill incision and the development of terraces. The study suggests that fluvial dynamics in the Alaknanda valley were modulated by monsoon variability and the role of tectonics was subordinate, limited to providing accommodation space and post‐deposition modification of the fluvial landforms. Copyright © 2010 John Wiley & Sons, Ltd.     

Interpretation of Mauna Loa atmospheric transmission relative to aerosols,using photometric precipitable water amouts

Precipitable water measurements made coincident in time and space with direct broadband solar irradiance measurements are used in conjunction with an atmospheric transmission model to derive a parameter whose major dependence is on total aerosol extinction. Irradiance measurements are used to calculate an atmospheric transmission factor (ATF) that is independent of the instrument calibration and the extraterrestrial solar constant. The dependency of the ATF on precipitable water is determined using LOWTRAN5, an atmospheric transmission model with high spectral resolution. Precipitable water measurements are then used to adjust the measured ATF to correspond to an ATF value obtained for a constant precipitable water amount. The remaining variability in the adjusted ATF is due mostly to aerosol extinction. The technique is applied to a 6-year period (1978–1983) for clear-sky mornings at Mauna Loa, Hawaii (MLO). MLO ATF aerosol residuals are compared with independently measured monochromatic aerosol optical depth. Results show that the ATF aerosol residual is nearly equal to the 500 nm aerosol optical depth prior to the eruption of E1 Chichon, at which time a nonlinear time-dependent relationship between the two quantities is evident. ATF aerosol residuals reflect the spectrally integrated aerosol influence on transmission and, therefore, could indicate better than monochromatic optical depth the radiation balance perturbations due to aerosols. The 6-year precipitable water record for MLO, determined from a dual-channel sunphotometer, has a mean value of 0.3 cm. An annual cycle in precipitable water is evident, as is a 4-month 5-standard-deviation drought from December 1982 through March 1983.     

某些方解石单晶的光学质量评价

本文用光学方法检查了经野外地质工作者挑选过的天然方解石单晶的光学质量。发现部分晶体的光学均匀性很差,晶体中的光散射颗粒很多,不能满足作为光学介质的要求。     

Limestone weathering in Eastern Australia. Part 2: Surface micromorphology study

Results from long term microerosion meter (MEM) studies indicate that microenvironments are characterized by different erosion rates. A complementary study, carried out on the same sites, examines the microscale morphology in each environment. Optical and scanning electron microscopy were used to identify a range of features thought to reflect different processes. Under subaerial conditions micromorphology is dominated by biological weathering features owing to the presence of microflora. Sites permanently covered by soil or stream water have only dissolution etch features, though stream sites may exhibit microfractures. Sites with periodic exposure exhibit both dissolution and biological etch features. The natural environment is more accurately reflected by allowing some microflora colonization of MEM sites rather than preventing colonization by artificial means.