临边成像光谱仪光谱辐亮度响应度定标研究

基于积分球原理,提出了一种利用积分球进行光谱辐亮度响应度定标的新方法,消除了利用积分球定标的传统方法中由于漫反射板的双向反射率分布函数(BRDF)的测量不确定度大对定标精度的影响,极大地提高了定标精度。利用该方法标定了在研的空间遥感临边成像光谱仪原型样机的光谱辐亮度响应度,分析了定标不确定度,定标合成不确定度为2.6%。将该方法的定标结果与采用标准灯联合漫反射板的定标结果进行了分析比对,结果表明,二者在3%以内相符。引起两种定标结果偏差的主要原因是漫反射板BRDF测量的不确定度。     

CO2探测仪星上辐射定标设计方法的研究

为了使CO2探测仪性能变化得到校正,对CO2探测仪的星上辐射定标方法进行了研究。首先,利用稳定辐射源太阳与漫反射板相结合实现CO2探测仪探测器绝对辐射定标,其次,以定标灯、漫反射板与定标探测器相结合的方法对漫反射板反射率进行监视,实现CO2探测仪的相对辐射定标。最后,采用双定标灯、双定标探测器相互比对的方法对定标灯、定标探测器的性能变化进行校正,进而实现CO2探测仪的高精度星上辐射定标。实验结果表明:星上定标灯稳定性优于1%,星上定标探测器线性度优于0.01%。方案可以实现CO2探测仪绝对辐射定标5%,相对辐射定标3%的精度要求。     

航天遥感器的辐射度精度分析

辐射度精度是评价航天光学遥感器辐射度性能的一个重要指标。针对测量的目标辐射度与目标绝对辐射度之间的差异,建立一种航天遥感器的辐射度精度公式,对航天光学遥感器的辐射度性能进行分析。在辐射度精度的分析过程中,分析了星上定标源的辐射、偏振、杂散辐射、谱段外响应和波长漂移等因素对遥感器辐射度的影响。     

火焰辐射系数对光学测温法的影响与校正研究

研究利用辐射能量测定灰体温度分布的方法在燃烧火焰场分布中的应用问题。通过比较等辐射量的黑体温度，测出灰体的视在亮度温度——辐射温度；并根据灰体辐射系数呶和测定的辐射温度修正灰体的测量温度，获得实际温度。采用特定波长的滤色镜获取窄范围的频谱能量测定温度，避免CCD或其它光电探测器的光谱响应不均匀性对探测的影响；采用等高线划分火焰不同燃烧方式区域，可分区解决辐射能测量中的辐射系数问题，为精确测定火焰辐射温度提供了新思路。     

星载成像光谱仪对地遥感成像的信噪比分析

星载成像光谱仪的高精度反演计算需要正确的估算光谱通道获取信号的能力。针对星载光谱仪光谱通道能量弱,空间背景辐射及杂光强的特点,重新讨论了信噪比模型。新信噪比模型考虑了空间光环境对光谱仪信号通道的影响。针对某型号星载成像光谱仪,使用大气辐射传输软件MODTRAN的大气参数进行了各光谱信道的信噪比计算。同时,充分考虑了大气光环境的影响因素。仿真结果表明,相比于传统信噪比计算模型,实际星载光谱仪在短波光谱获取图像信息时存在更严重的退化现象,即信噪比严重降低。并且随者太阳高度角增加以及大气能见度距离下降,加剧了退化趋势。     

地基微波辐射计自定标的改进算法

微波辐射计的定标精度直接影响其对大气参数的反演精度．基于美国大气辐射测量计划中地基微波辐射计所运用的自定标方法,推导出适用于地基微波辐射计的普遍自定标形式,并针对大气水平不均匀的情况下原始自定标方法的误差,提出一种改进的自定标方法．即原始自定标之后,在不同仰角的定标值附近搜索最佳补偿误差,使回归曲线逼近原点,相关系数接近1,从而修正由水平不均匀大气带来的误差,提高定标精度．利用双通道微波辐射计自定标后的实测数据与探空的仿真结果进行对比,验证了此方法的有效性．     

基于双积分球的光学镜片透反射率测量系统

传统的透反射率测量系统不能同时实现透反射率的高精度测量,并且测量角度固定,测量光学镜片口径较小。为此研制了基于双积分球的透反射率测量系统。系统采用双积分球结构,完成了宽光谱(300nm~1600nm)大角度(0°~90°)范围大口径光学镜片的透反射率测量,采用锁相放大器,有效提取出了微弱信号,抑制了背景光的干扰,实现了亮场环境下的测量,提高了测量精度。最终实验验证以及不确定度分析的结果可以达到:白光透射率测试精度为0.25%,近红外光谱测试精度为0.316%;白光反射率测试精度为0.301%,近红外光谱测试精度为0.381%。     

干涉成像(傅立叶变换)光谱仪发展概述

干涉成像（ 傅叶变换） 光谱仪是八十年代末发展起来的一种较先进的遥感器, 较之色散型成像光谱仪, 它具有光通量大等优点, 适于对可见和红外弱辐射的探测。本文简要回顾了空间遥感技术中的干涉成像光谱仪的发展背景, 并对其主要形式、原理、特点以及目前在国内外的发展、应用状况进行了概要的介绍     

定标噪声源逆向辐射对微波辐射计的精度影响分析

为了提高微波辐射计系统的精度,对微波辐射计接收机反射系数因定标噪声源影响产生的变化进行了研究,并给出了相关的误差公式和系统噪声公式．通过对3165 GHz微波辐射计进行定标噪声源逆向辐射测量实验分析表明,定标噪声源逆向辐射引起的反射系数变化,会使失配因子改变且使系统噪声增加．     

海上飞行目标红外辐射特性测量试验设计

海上的飞行目标的飞行海域环境气象条件比陆地复杂,在进行目标红外辐射特性测量时,大气透过率不确定度增加.本文以海上飞行目标为例,设计了一种基于参考黑体的飞行目标红外辐射特性测量试验,以此提高海上飞行目标红外辐射亮度的测量精度.     

Calibratio performance evaluation of the spaceborne hyperspectral CHRIS imager

The CHRIS (Compact High Resolution Imaging Spectrometer) is a new imaging spectrometer, carried on board a new space platform called PROBA (Project for On Board Autonomy). The satellite was successfully launched in October 2001 by the European Space Agency (ESA). CHRIS operates over the visible/near infrared band (400-1050 nm). It has five work modes and can reach a maximum of 62 spectral bands. In this research, atmospheric correction based on hyperspectral images was performed on CHRIS images by using the popular radiance transfer code ACORN (Atmospheric Correction Now) and empirical algorithms. ACORN was also used to evaluate the calibration performance of CHRIS by the retrieved spectra of typical vegetation and soil. As a result, the maize reflectance spectrum corrected by ACORN could characterize vegetation reflectance in the range of 498-750 nm, but gave a fairly large deviation beyond 750 nm, showing the deficiency of spectral calibration beyond 750 nm. The ACORN-derived soil reflectance decreased beyond 800 nm, which was quite inconsistent with field-spectrum measurement and showed that the calibration accuracy couldn't meet the requirements of ACORN for spectral and radiometric calibration within a certain spectral range. In addition, the stripes on the retrieved water-vapor content map indicated that the radiance-calibration performance of CHRIS is not perfect. As the first spaceborne hyperspectral imager of ESA, the calibration performance of CHRIS needs to be improved.     

Radiometric Calibration Chain Design Based on Uniform Collimated Laser Source

A uniform collimated laser source,composed of the integrating sphere source and the off-axis parabolic,is designed.The calibration process is analyzed theoretically,and Monte Carlo ray tracing method is used to simulate and analyze the design model.The results show that when the calibration source is composed of an 8 cm diameter integral sphere,10 mm diameter exit port,and 1 000 mm focal length,and an off-axis angle 60°parabolic mirror,the maximum divergence angle is 7.5 mrad and the uniformity of irradiance is 99.31%.Finally,the uncertainty of radiometric calibration process is analyzed,and the calibration accuracy of 0.335%for imaging spectrometer can be achieved by using the radiation calibration laser source.     

Estimation of Thermal Imaging System Operating Range Based on Background Radiation

Traditional operating range prediction methods assume that the atmospheric radiances in a target path and a background path are equal.But they are different in a real-world environment.To solve this problem,the influence of atmospheric radiance on operating range prediction is analyzed in this paper.Range estimation model in thermal imaging based on background radiation (REBR) is proposed.Infrared image radiometric calibration is used to calculate the background radiation of a system entrance pupil.The result shows that,compared with traditional operating range prediction methods,the REBR method is more suitable for the actual atmospheric transmission process and the physical process of infrared imaging.     

四象限模拟太阳敏感器的高精度补偿标定方法

为了提高微纳卫星的定姿精度,针对四象限模拟太阳敏感器提出高精度误差补偿方法,设计完整的自动标定流程. 分析四象限硅光电池片光生电流的测量过程,将太阳光入射后的投影关系进行建模,提取主要误差源. 综合考虑各环节,对各路电流测量误差进行单独矫正,对机械加工与安装误差和忽略遮光罩厚度导致误差进行补偿,形成了完备的补偿方法. 实验结果表明,机械加工与安装误差为主要误差源,忽略遮光罩厚度导致误差的影响略大于电流测量误差的影响. 应用该方法在±40°视场范围内补偿前平均精度为3.072°（1σ）,补偿后平均精度为0.177°（1σ）,现有其他方法标定后精度为0.5°（1σ）,提出方法的精度提升了约3倍. 针对标定测试工序,设计全流程自动化标定测试方法,效率明显提高,适合大批量应用.     

陀螺/星敏感器在轨标定算法研究

为确保姿态测量器件长期在轨工作精度,提高三轴稳定卫星的姿态确定精度,针对典型的陀螺/星敏感器联合定姿方案,推导了一种对陀螺和星敏感器进行实时在轨标定的算法.充分考虑卫星姿态测量过程中可能出现的各种误差源,建立陀螺和星敏感器的安装误差和标定因子误差模型,并对可能出现的各种误差进行在轨补偿,与同类算法相比,为卫星姿态确定和校正提供了更加丰富的信息,计算量更小.最后对该算法进行了数学仿真,仿真结果验证了该在轨标定算法的有效性和可靠性.     

基于C#参考式扭矩传感器标定及测试系统的研制

针对扭矩传感器校准测试设备中存在的定位精度不高、对中性较差、测试功能单一等问题,设计了一种参考式扭矩传感器标定及测试系统。系统中对中机构使用锥柄结构,可以提高定位精度和对中性,提高测试的精度,在静态标定和动态测试过程中通过高等级精度扭矩传感器与待测扭矩传感器进行对比。软件部分基于C#语言开发,使用Access数据库存储数据,使用可扩展标记语言(XML)记录传感器初始信息,可实现数据分析、可视化与储存。系统采用多线程技术实现数据采集和硬件控制的协调同步,保证了数据采集精度。结合试验台硬件可以实现系统的静态标定与动态测试两个重要功能。该系统结构简单、实际操作简便、工作效率高。     

Geometric Calibration and Image Quality Assessment of High Resolution Dual-Camera Satellite

The evaluation of geometric calibration accuracy of high resolution satellite images has been increasingly recognized in recent years. In order to evaluate geometric accuracy for dual-camera satellite images based on the ground control points(GCP), a rigorous geometric imaging model,which was based on the collinear equation of the probe directional angle and the optimized tri-axial attitude determination(TRIAD) algorithm, is presented. Two reliable test fields in Tianjin and Jinan(China) were utilized for geometric accuracy validation of Pakistan Remote Sensing Satellite-1. The experimental results demonstrate a certain deviation of the on-orbit calibration result from the initial design values of the calibration parameters. Therefore, on-orbit geometric calibration is necessary for optical satellite imagery. Within this research, the geometrical performances including positioning accuracy without/with GCP and band registration of the dual-camera satellite were analyzed in detail, and the results of geometric image quality are assessed and discussed. As a result, it is feasible and necessary to establish such a geometric calibration model to evaluate the geometric quality of dual-camera satellite.