环境与灾害监测光学有效载荷发展综述

环境与灾害监测目标具有多样性、定量化要求高等特点,非常适合光学载荷发挥其信息量丰富、种类多、精度高等方面的优势。在国际上,此类光学载荷发展迅速,新技术不断涌现,值得学习借鉴。文章重点阐述了应用于环境与灾害监测民用卫星的光学有效载荷的发展现状和发展趋势,为中国第二代"环境与灾害监测预报小卫星星座"的相关光学有效载荷发展提供参考。     

国外光学遥感成像系统仿真软件发展综述与思考

光学遥感系统仿真是一个复杂的系统工程,涉及多个交叉学科领域。遥感成像仿真需要严格按照成像的物理过程进行模拟,对各关键环节建立精确的模型,设计标准化的技术流程,最终完成基于地学、光学、大气科学、电子学、传感器设计等多学科和多技术领域交叉融合的系统集成。文章通过广泛调研国外光学遥感仿真软件的应用和发展现状,比较3种典型仿真软件的设计框架和技术路线,分析其发展趋势,为自主研发的光学遥感仿真模拟软件提供借鉴。     

小卫星高分辨率成像系统

对小卫星对地观测高分辨率成像系统进行了综述。介绍了国内外有极高分辨率（0．5～1．0m）、高分辨率（1．8～2．5m）和中高分辨率（4-10m）小卫星光学成像系统的性能,并与合成孔径雷达（SAR）成像系统进行了比较。给出了小卫星光学成像系统、SAR高分辨率成像系统和卫星平台的关键技术。讨论了未来小卫星及其高分辨率成像系统技术的发展趋势。     

Feasibility of performing space surveillance tasks with a proposed space-based optical architecture

Under ESA contract an industrial consortium including Aboa Space Research Oy (ASRO), the Astronomical Institute of the University of Bern (AIUB), and the Dutch National Aerospace Laboratory (NLR), proposed the observation concept, developed a suitable sensor architecture, and assessed the performance of a space-based optical (SBO) telescope in 2005. The goal of the SBO study was to analyse how the existing knowledge gap in the space debris population in the millimetre and centimetre regime may be closed by means of a passive optical instrument. The SBO instrument was requested to provide statistical information on the space debris population in terms of number of objects and size distribution. The SBO instrument was considered to be a cost-efficient with 20 cm aperture and 6° field-of-view and having flexible integration requirements. It should be possible to integrate the SBO instrument easily as a secondary payload on satellites launched into low-Earth orbits (LEO), or into geostationary orbit (GEO). Thus the selected mission concept only allowed for fix-mounted telescopes, and the pointing direction could be requested freely. Since 2007 ESA focuses space surveillance and tracking activities in the Space Situational Awareness (SSA) preparatory program. Ground-based radars and optical telescopes are studied for the build-up and maintenance of a catalogue of objects. In this paper we analyse how the proposed SBO architecture could contribute to the space surveillance tasks survey and tracking. We assume that the SBO instrumentation is placed into a circular sun-synchronous orbit at 800 km altitude. We discuss the observation conditions of objects at higher altitude, and select an orbit close to the terminator plane. A pointing of the sensor orthogonal to the orbital plane with optimal elevation slightly in positive direction (0° and +5°) is found optimal for accessing the entire GEO regime within one day, implying a very good coverage of controlled objects in GEO, too. Simulations using ESA’s Program for Radar and Optical Observation Forecasting (PROOF) in the version 2005 and a GEO reference population extracted from DISCOS revealed that the proposed pointing scenario provides low phase angles together with low angular velocities of the objects crossing the field-of-view. Radiometric simulations show that the optimal exposure time is 1–2 s, and that spherical objects in GEO with a diameter of below 1 m can be detected. The GEO population can be covered under proper illumination nearly completely, but seasonal drops of the coverage are possible. Subsequent observations of objects are on average at least every 1.5 days, not exceeding 3 days at maximum. A single observation arc spans 3° to 5° on average. Using a simulation environment that connects PROOF to AIUB’s program system CelMech we verify the consistency of the initial orbit determination for five selected test objects on subsequent days as a function of realistic astrometric noise levels. The initial orbit determination is possible. We define requirements for a correlator process essential for catalogue build-up and maintenance. Each single observation should provide an astrometric accuracy of at least 1”–1.5” so that the initially determined orbits are consistent within a few hundred kilometres for the semi-major axis, 0.01 for the eccentricity, and 0.1° for the inclination.     

长焦距同轴三反空间相机光学系统研究

为了满足空间遥感不同应用的需求,完成了4种型式的长焦距同轴三反光学系统设计。根据同轴三反光学系统设计理论,介绍了同轴三反光学系统设计初始结构设计方法,以工作谱段0．45-0．9μm、F数10、焦距10m为例,对4种型式的长焦距同轴三反光学系统进行优化设计,设计视场内获得接近衍射极限的成像品质,并分析和比较了这几种光学系...     

一种多步的基于切换星间测量的多星自主导航算法

针对基于星间测量的多星自主导航问题,从载荷优化和节约成本考虑,提出了一种单套敏感器切换测量的导航方案。建立了该导航方案下的系统状态空间模型,并基于扩展卡尔曼滤波方程给出了导航估计算法。基于多步卡尔曼滤波方法,将集中的滤波算法解耦为多个平行的子滤波器,使计算量降低到原算法的50%以下,并且在切换测量的导航方案下,部分解耦出的子滤波器可以只预测不更新,能够进一步地降低计算负担。给出了多步滤波算法的推导过程,证明了其与标准卡尔曼滤波的数学等价性,故算法的估计性能及计算结果与标准卡尔曼滤波一致,但计算速度有明显提升。最后,通过具体算例给出了算法的仿真验证。     

Nighttime cloud properties retrieval using MODIS and artificial neural networks

In this work a methodology for inferring water cloud macro and microphysical properties from nighttime MODIS imagery is developed. This method is based on the inversion of a theoretical radiative transfer model that simulates the radiances detected in each of the sensor infrared bands. To accomplish this inversion, an operational technique based on Artificial Neural Networks (ANNs) is proposed, whose main characteristic is the ability to retrieve cloud properties much faster than conventional methods. Furthermore, a detailed study of input data is performed to avoid different sources of errors that appear in several MODIS infrared channels. Finally, results of applying the proposed method are compared with in-situ measurements carried out during the DYCOMS-II field experiment.     

多模光纤强度调制型扰动传感器传感原理

介绍了一种采用"单模光纤-多模光纤-单模光纤"结构的强度调制型扰动传感器,传感光纤为多模光纤.以提高传感灵敏度为目的,对强度调制的传感原理进行研究,并通过仿真及实验验证原理,得出使用相干光源、阶跃折射率多模光纤、对轴熔接单模光纤和多模光纤可以得到传感灵敏度很高的扰动传感器.所述方案结构简单、传感距离长,可应用于各种扰动传感领域,如边界线、军事基地、石油管道等.     

几何代数域内的光流场改进算法

提山了一种新的光流场计算方法：首先,在几何代数域内推导了光流约束方程的新形式;然后,在速度场平滑的基础上,通过求解关于初值问题的热传导方程求解光流场;最后,给出光流场的数值解和仿真结果。实验证明此方法是有效的。     

谐振式科里奥利质量流量计

对谐振式科里奥利质量流量计的基本敏感机理进行了论述.基于典型的U型管敏感结构,建立了谐振式直接质量流量计的数学模型,给出了检测质量流量的信号解算模型,设计了一种信号解算电路并研制了相应的样机.实测结果表明:所研制的信号检测电路的测量误差小于0.1％,具有一定的实用价值,为样机研制提供了具有一定参考意义的理论和实验研究结果.