多站观测空间目标可见光散射特性及相关性分析

鉴于空间目标的光散射特性对目标的探测、跟踪与识别等空间突防技术具有十分重要的应用价值,利用双向反射分布函数（BRDF）将光辐射的入射照度和目标的散射亮度联系起来,结合目标的几何建模与轨道理论,计算出某时刻在东北3站观测风云卫星可见光散射亮度变化情况, 其峰值随时间依次达到或接近于7.510-3 W/cm2sr,而新疆阿勒泰散射亮度在东北3站达到峰值时只有3.7510-3 W/cm2sr,得出东北3站点卫星光散射亮度趋势相似,只是由于纬度差异使变化趋势在时间上有所延迟,而在与之经度有很大差别的新疆地区的阿勒泰站点的亮度变化趋势则有很大不同。该方法已经在获取空间目标更多信息选择多站观测中取得应用。     

星载微光遥感器外场辐射定标光源的研制和检测

LED外场辐射定标积分球光源基于辐射通量等效理论,用于星载微光遥感器的在轨辐射定标。该定标光源采用12组峰值波长670 nm的LED密集阵列发光单元,每组最大电功率300 W,辐亮度输出达到5.2×10?2 W·cm?2·sr?1,通过等效辐射通量面积校正后,能够适用于10?9 W·cm?2·sr?1量级的微光通道在轨定标。光源的参数检测结果表明:定标光源角度均匀性在±30°以内优于99.6%,平面均匀性优于99.7%,1 h内稳定性优于99.9%,具有优良的辐射特性。在敦煌中国遥感卫星辐射校正场对VIIRS微光通道进行了在轨实测试验,在轨响应结果为8.27×10?9 W·cm?2·sr?1（含月光贡献和大气影响）,证明了该外场微光定标光源辐射量值设计的合理性。     

临近空间高空气球光学散射特性研究EI北大核心CSCD

基于应用光学中基本辐射理论,研究了临近空间高空气球的光散射特性。利用计算几何学的坐标转换以及网格划分建模思想,对高空气球球面进行网格面元划分。根据高空气球等透明类物体几何结构和物体光学特性,推导出透明类物体双向散射分布函数（BSDF）镜反射/折射、近镜反射/折射、漫反射/折射、理想漫反射/折射相结合的计算模型,最终得出高空气球散射背景辐射在地面产生辐射亮度的计算模型。利用MODTRAN软件在3～5μm和8～14μm波段仿真计算临近空间高空气球的背景辐射亮度,在0.24～2.4μm波段仿真计算气球自身亮度。仿真结果表明：利用BSDF模型计算得到高空气球亮度为2.28×10^-3W/（cm^2·μm·sr）,计算结果误差为10.6%,精度相对双向反射分布函数（BRDF）模型提高2%。在分析高空气球等类透明体散射特性时,可参考此模型来进行计算。     

临近空间高空气球光学散射特性研究

基于应用光学中基本辐射理论,研究了临近空间高空气球的光散射特性。利用计算几何学的坐标转换以及网格划分建模思想,对高空气球球面进行网格面元划分。根据高空气球等透明类物体几何结构和物体光学特性,推导出透明类物体双向散射分布函数(BSDF)镜反射/折射、近镜反射/折射、漫反射/折射、理想漫反射/折射相结合的计算模型,最终得出高空气球散射背景辐射在地面产生辐射亮度的计算模型。利用MODTRAN软件在3~5μm和8~14μm波段仿真计算临近空间高空气球的背景辐射亮度,在0.24~2.4μm波段仿真计算气球自身亮度。仿真结果表明:利用BSDF模型计算得到高空气球亮度为2.28×10-3W/(cm2?μm·sr),计算结果误差为10.6%,精度相对双向反射分布函数(BRDF)模型提高2%。在分析高空气球等类透明体散射特性时,可参考此模型来进行计算。     

200W级高亮度半导体激光器光纤耦合模块

光纤激光器系统需要高可靠性、高亮度、高功率光纤耦合输出二极管激光器模块作为泵浦源。基于mini-bar二极管激光器芯片,采用光束精密准直技术、自由空间合束技术来获得高亮度、高功率光纤耦合输出,针对光纤芯径为200μm、数值孔径为0.22的多模光纤,开展了线偏振二极管激光光纤耦合实验,实验结果表明:光纤稳定输出功率达280 W,对应亮度为5.87 MW/(cm2·sr),电-光效率为45.0%。采用偏振合束技术,光纤预期输出功率可达500 W,对应亮度超过10 MW/(cm2·sr)。该方法可应用于研制数百瓦级高亮度二极管激光光纤耦合输出激光器模块。     

基于双向反射分布函数的空间卫星紫外动态特性研究

根据目标所处的背景辐射环境,对空间卫星的紫外散射特性进行建模方法研究。依据目标表面材料属性与表面状况对目标表面进行区域分解与网格划分。基于辐射理论引入双向反射分布函数模型来描述目标表面网格单元的光散射特性,将目标各个表面所有网格单元散射分量叠加建立了目标紫外散射特性的数学模型。利用给定的目标几何结构尺寸和物性参数仿真获得了目标在轨动态光学特性。在某一观测角度下太阳帆板在探测光学系统入瞳产生的辐照度值与卫星本体接近,最大量级为10-11W/m2。仿真结果表明太阳帆板在目标特性分析时不可忽略。     

基于高次余弦散射分布的空间卫星可见光特性

基于几何光学和辐射理论,研究了空间卫星的可见光散射特性.空间卫星的背景辐射主要包括太阳的直接辐射和地球及大气的散射辐射,根据目标的结构特性与背景特性建立了空间卫星的几何模型和光照模型.分析目标表面状况,入射到目标表面的光线近似服从高次余弦散射分布,根据能量守恒定理及表面材料的高次余弦散射分布特性建立了目标散射特性的数学模型.通过矢量坐标变换确定太阳、地球、观测卫星在目标本体坐标系下的相对位置关系.根据给定的几何尺寸和表面物性参量仿真获得了目标在探测器入瞳处的能量分布及星等特征,目标本体与太阳帆板在探测器入瞳处的辐照度最大量级均为10-12 W/m2.仿真结果表明太阳帆板在目标特性分析时不可忽略,为空间目标的可见光探测提供参考数据.     

基于琼斯法的高亮度积分球定标光源

针对目前光学口径不断增大的空间光学遥感器实验室辐射定标的需求,基于琼斯法设计了一种在400~900 nm波段积分辐亮度为6 800 W/(m2·sr)的高亮度积分球定标光源。对该光源的热设计表明:采用水冷散热的方式能够满足高亮度积分球定标光源的散热需求。实验表明,该定标光源在400~900 nm波段范围内积分辐亮度达到6 714 W/(m2·sr),经过散热后积分球球体温度场分布满足定标要求,可应用于工程实践。     

空间目标观测辐照度特性建模及仿真

为提高对空间目标的探测与识别能力,从电磁散射理论出发,利用基尔霍夫近似法及双向反射分布函数,求出目标面元的辐射亮度,结合空间目标几何外形分析目标的散射特性,从而建立空间目标在天基空间观测系统入瞳处的观测辐照度模型.通过典型实例,仿真分析了某空间目标相对于某天基观测系统的最佳观测部位和弧段.研究结果表明,该方法能够有效地...     

基于光照条件的空间相机增益在轨自动调整

空间相机摄影过程中,通常采用较小的固定增益以避免图像饱和,导致获取的图像存在整体偏暗、图像层次不丰富等问题。提出一种基于光照条件的空间相机增益在轨自动调整方法,根据当前的航天器位置和时间等实时计算星下点处的太阳天顶角,通过非线性拟合建立太阳天顶角与对目标最大反射率对应的地物成像时相机入瞳辐亮度之间的函数关系,进而完成对增益的实时计算和调整。与卫星工具包(STK)仿真和MODTRAN计算结果的对比实验表明,在太阳天顶角取[20°,70°]时辐亮度拟合误差小于等于0.3 W/(m2·sr),相对误差小于等于2.2%。计算和仿真得到太阳天顶角之差约为0.39°(3σ)。在轨成像实验结果表明,太阳天顶角为62.5°时增益调整后图像灰度层次从98提高到183,信息熵提高约19.2%,图像灰度层次更加丰富,使目标更容易辨识。     

Conversion from n bands color space to HSI n color space

This paper presents the method to get the equations that transform a color space of n independent primary colors to the HIS _n color system (H: hue, S: saturation, I: intensity); n indicates the number of bands and the shape of the HIS _n space. For n = 3 the structure is a double triangular pyramid, for n 4 it is the structure of the double pyramid tetrangular, and so on.     

长春光机所航天光学遥感器研制基地建设进展

通过20多年的努力, 中国科学院长春光学精密机械与物理研究所(以下简称长春光机所)现已成为我国航天光学遥感器研制领域的重要基地。本文在回顾其发展历史的基础上, 详实地介绍了近10年来长春光机所在这一领域取得的技术进步, 涵盖了航天光学遥感器研究、设计、制造、装调、检测、试验等各个方面。     

“神舟”四号中的空间环境研究

空间环境 ,特别是日地空间环境是人类航天活动关系极为密切的环境 .文章以“神舟”四号为背景 ,概要介绍了为“神舟”四号飞船所作的空间环境安全保障服务 ,包括在“神舟”四号飞船上进行的空间环境探测、空间环境分布及变化规律的研究、空间环境对人类航天活动及“神舟”飞船的影响 (空间环境效应 ) ,以及为保障“神舟”飞船发射安全、正常运行、顺利返回所作的空间环境预报等 .此外 ,概要评述了国内外上述研究领域的研究现状与进展     

Origin and evolution of MHD turbulence in the solar wind

Summary Solar wind turbulence has both solar and interplanetary sources. Outward travelling waves are generated at the Sun with a spectrum related to the turbulent processes in the solar atmosphere. Instabilities at velocity shears give a local contribution of waves with inward and outward propagation. Nonlinear interactions between the two kinds of waves lead to an energy cascade and to a Kolmogoroff spectrum. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

Debris from comet Halley, comet's mass loss and age

Summary Large particles released from the nucleus of comet Halley, but undetected directly by space probes, seem to affect decisively the mass loss and mass determination of the comet, and consequently its aging. Simultaneous radar meteor observations in 1985–86 at the approaches of the comet emphasize the relatively larger proportion of long-duration echoes with respect to previous years.     

The Hot-Ion Analyzer instrument for the ESA cluster mission

Summary This paper presents the IFSI-CNR activity for the CIS plasma experiment to be flow on the ESA Cluster four-spacecraft mission, see H. Reme (PI)et al., ESA/SP Report 88/1253, September 1988. IFSI contributes to the project by designing and producing part of the experiment,i.e. the sensor of the (0÷40) keV Hot-Ion Analyzer (HIA), its related digital processing unit and its software. This paper summarizes the instrument main features and describes the calibration facility for the first flight unit. Paper presented at the 6th Cosmic Physics National Conference, Palermo, 3–7 November 1992.     

The Ulysses mission: An introduction

Summary On 30 September 1995, Ulysses completed its initial, highly successful, survey of the polar regions of the heliosphere in both southern and northern hemispheres, thereby fulfilling its prime mission. The results obtained to date are leading to a revision of many earlier ideas concerning the solar wind and the heliosphere. Now embarking on the second phase of the mission, Ulysses will continue along its out-of-ecliptic flight path for another complete orbit of the Sun. In contrast to the high-latitude phase of the prime mission, which occurred near solar minimum, the next polar passes (in 2000 and 2001) will take place when the Sun is at its most active. Paper presented at the Special Session on the Ulysses mission of the XXIV International Cosmic-Ray Conference, Rome, August 28–September 8, 1995.     

Overview of the effects of solar-terrestrial phenomena on man and his environment

Summary The effect of solar-terrestrial phenomena on our environment is a rapidly developing science. An overview of this subject is presented including known technological effects, possible effects on ozone depletion, and the much more elusive possibility that solar emissions may be linked to human health. Paper presented at the Special Session on the effects of solar-terrestrial phenomena on man and his environment of the XXIV International Cosmic-Ray Conference, Rome, August 28–September 8, 1995.     

Jets physics in comet P/Halley

Summary CCD images of comet P/Halley taken from Catania Observatory in April 1986 with IHW filters are analysed. On scale distances up to and larger than 200·10³ km these images show the presence of jets in the Cont 6850, H₂O⁺ and C₂ filters. The jet maximum intensity is at <1000 km from the nucleus for dust, at (20÷30)·10³km for H₂O⁺ and at (60÷90)·10³km for C₂, implying 2·10⁴s or 10⁵s formation time for the last two molecules. Comparison of various images shows that H₂O⁺ and C₂ jets are in very different directions, the first one coinciding with the main dust jet, the second one appearing as a continuation in space of a very short dust jet. It is speculated that dust grains have very different sizes and chemical composition from the moment they leave the cometary nucleus, and that grains in the small dust jet undergo fragmentation and chemical reactions to produce C₂ jets.