辐射测温中环境辐射的影响

在辐射测温中，环境辐射对辐射测温有一定的影响。对于环境辐射的影响，不少参考资料中指出500℃以上可以忽略，经理论分析得出，是否考虑环境辐射的影响，不仅与所测温度有关，同时与辐射温度计的工作波长和所测物体的发射率有关。为了提高测温的准确性，分别对单色、比色测温中环境辐射的影响进行了分析比较。     

辐射测温仪工作波长的选择方法

在辐射测温仪工作波长的选择上,以往一直参照维思位移定律。通过理论分析,发现依照该定律选择测温仪工作彼长是不完善的。为了提高仪表灵敏度和测温准确度,推导出了一种新公式,提出了一种新的工作波长的选择方法,并在理论上证明该方法较目前常用的方法更为理想。     

烟气覆盖表面红外温度测量的实验分析

为了研究辐射参与性烟气对红外测温法金属壁面温度测量的影响,首先根据实验中红外探测器测量得到的表面温度分布的特点,建立了一维表面红外测温模型;然后根据红外热成像测温原理及辐射传输理论,利用源项多流法分析模型计算了烟气覆盖表面在不同烟气厚度和不同表面温度下红外探测器获得的温度;最后利用马弗炉模拟不同温度的表面,振动筛模拟不同浓度和厚度的烟气环境,在实验室条件下设计搭建了模拟烟气覆盖表面的红外测温实验系统,实验验证了源项多流法分析模型,实验测量得到的温度与分析模型预测的温度吻合较好,并提出了利用反演方法修正红外测温的设想。     

基于中波红外热成像的温度场测量技术研究

随着红外探测技术的不断发展,基于中波红外热成像的测温技术得到了越来越广泛的应用。在研究中波红外成像系统测温原理的基础上,探讨了黑体辐射定标技术,以及环境辐射和定标数据处理方法对测温准确度的影响,提出了一系列的处理方法,实现了一套基于红外成像的温度场测量方案,并有效补偿了环境辐射对测量结果的影响,同时降低了定标数据拟合引起的误差,使测温准确度得到了很好保证。     

"詹姆斯·韦伯空间望远镜"开启天文观测的"阿波罗"时代

1 任务背景 早在"哈勃空间望远镜"发射之前,NASA就开始探讨下一代空间望远镜的概念,明确将发展在红外波长范围工作的大型空间望远镜——"下一代天文望远镜"(NGST).2002年,NASA正式选择建造仪器的团队并开始相关指导工作,以领导"阿波罗"计划的NASA第二任局长詹姆斯·韦伯命名了该项任务,将NGST更名为JW...     

热辐射波长测温法的理论研究

从黑体热辐射的普朗克定律出发,导出了热辐射光能量与波长关系中的峰值和拐点位移公式.根据这些公式,提出了热辐射测温技术中的波长测温方法,为热辐射测温传感器的研究提供了一种全新的思路.     

基于双响应波段工作的红外热像仪测温原理与误差分析

为了提高红外热像仪测温的准确性,根据红外辐射理论,从红外热像仪的测温原理出发,分析了基于双响应工作波段的热像仪的测温原理,得出了目标物体的发射率、物体温度计算公式以及相应误差的估算公式,分析了各影响因素对热像仪测量准确度的影响,提供了一种目标物体发射率的测定方法,对利用红外热像仪准确测量内燃机等热能机械表面温度具有重要的意义。     

基于多光谱测温优化的材料光谱发射率测量

针对高温材料红外光谱发射率测量中样品表面温度难以准确测量的问题,提出了直接使用光谱仪测量得出样品表面的光谱辐射能量信息,选取其中合适的光谱波段利用多光谱测温方法得到样品表面温度,进而计算出材料的光谱发射率.分析了多光谱测温中发射率模型的阶次和测量波段选取对测温准确度的影响,给出了温度计算的稳健算法,并对其主要不确定度的来源进行了评定.在1 100 K左右温度下以不锈钢材料进行实验验证,得出温度引起的光谱发射率相对不确定度在2～20 μm范围内低于2%,满足红外隐身和辐射测温等领域的要求,适合于导热性能差的材料或涂层材料的高温光谱发射率测量.     

热象仪简介

热象仪是一种先进的测温仪器,它以红外探测器为敏感元件,把被测物体的辐射热转变为电信号,经过一系列电子仪器在屏幕上显示出热图象,最后用计算机进行图象处理。用它可进行动态温度测量,也可进行温场分布测试;它县有测试温度范围宽、灵敏度高等特点.本文只简述其工作原理、结构特点、标定方法及正确使用等四个方面的内容,供参考。     

落管中双波长测温系统工作波长的优化设计

根据测量所要求的动态范围、线性度、灵敏度 ,通过数值计算得出落管中双波长温度测量中的工作波长及带宽的最佳范围 ,结合实际情况最终确定工作波长为 1 4 μm和 1 5 5 μm ,其带宽均为 0 0 3μm。     

基于蒙特卡罗频率法的葡萄籽总酚含量高光谱测量变量选择

在利用高光谱建立葡萄籽总酚含量的预测模型中,为解决变量过多、模型复杂度高等问题,需依据光谱特点进行有效地数据降维。提出了一种蒙特卡罗频率法（MCF）对高光谱数据进行波长选择,并建立了葡萄籽总酚的支持向量回归（SVR）预测模型。该方法首先采用蒙特卡罗采样（MCS）选择波长子集;然后建立大量SVR子模型,并选出均方根误差（RMSE）较小的子模型,统计每个波长出现的频次;最后根据指数递减函数确定波长个数,选取频次最高的波长子集作为特征波长。结果表明,采用MCF可以在降维的同时提高模型的预测性能,波长数目由原始的196个减少到9个,波长范围均在950~1 400 nm,RMSE值从0.42减少到0.37,预测精度优于SPA等其他波长选择方法。因此,提出的基于MCF在高光谱数据处理中能有效选择特征波长,为准确建立预测模型提供了一种有效的方法。      

Infrared astronomy on the Hubble Space Telescope

The Hubble Space Telescope offers enormous advantages to infrared astronomy in certain situations. The advantages of being above the atmosphere include an increase in spatial resolution, a much wider range of wavelengths available, and lower background radiation. Compared to proposed cooled telescopes, HST offers higher spatial resolution and increased collecting area. HST is particularly well suited to observations at wavelengths less than ～5 μm, where the diffraction limit is less than the seeing limit from the ground and thermal emission does not seriously compromise the sensitivity of the detectors. HST is also favorable for observations requiring high spectral resolution at all wavelengths not accessible from the ground.     

How to achieve diffraction limited resolution with large space telescopes

Large space telescopes cannot be made diffraction-limited at least for short wavelengths. Methods for reconstructing diffraction-limited images are reviewed including active optics, Michelson stellar interferometry, non-redundant aperture arrays, deconvolution and shearing interferometry. Expressions are given for the signal-to-noise ratio in each case and the result of laboratory simulations are presented. It is concluded that diffraction-limited images could be obtained in the visible up to magnitude 21 with large deployable reflectors planned to be used in the far I.R. or millimetric range.     

Submillimeter spectroscopy from space — Missions planned between 1995 and 2005

The submillimeter wavelength range (100 μm ≤ λ ≤ 1 mm) is exceptionally rich in atomic and molecular transitions that provide direct measures of the chemical composition, temperature, density, and cooling of the interstellar medium. In part, this is due to the fact that the most abundant oxygen- and carbon-bearing species as well as the most common hydrides have their lowest lying transitions within this wavelength region. However, because of the great abundance of many of these same species in our own atmosphere (e.g., H₂O and O₂), terrestrial absorption at submillimeter wavelengths is strong, rendering much of the sky inaccessible to ground- and even airborne observing platforms. In recognition of the scientific importance of the submillimeter range to astronomy and the limitations placed on its pursuit by the atmosphere, both NASA and ESA have embarked on ambitious programs to explore these wavelengths from space.     

双波长全息干涉术的实验研究

双波长全息干涉术利用激光器发出的两个或两个以上不同的波长对物体拍摄全息干涉图,相当于用一个等效波长λeq对物体进行干涉测量,从而扩大了测量范围。在改进的泰曼干涉系统中，采用双曝光法双波长全息干涉术对一个抛物面反射镜的面形进行了补偿法检验，最终得到的干涉图样易于分析和判读。实验表明，对于光学元件的面形检验，尤其是非球面元件的面形检验，双波长全息干涉术是一种可行的测量新方法。     

A comparison between CRISTA satellite data and Warner and McIntyre gravity wave parameterization scheme: Horizontal and vertical wavelength filtering of gravity wave momentum flux

An along-track analysis of temperature height profiles measured by the CRISTA satellite instrument was performed to obtain height profiles of absolute values of gravity wave momentum flux. Global distributions of momentum flux from CRISTA are compared to results of the Warner and McIntyre gravity wave parameterization scheme. Only a limited range of horizontal and vertical wavelengths is visible to the CRISTA instrument. Therefore the model results have to be filtered accordingly to make comparisons meaningful. We demonstrate the importance of such a wavelength filtering which significantly increases the correlation of observed and modeled momentum fluxes.     

Retrieval of aerosol optical characteristics from polarization measurements of reflected solar radiation above the oceans

The reflected near infrared solar radiation observed from space above the oceans is due mainly to the atmosphere scattering, as the ocean surface is nearly black. The molecular Rayleigh contribution is also minimized at infrared wavelengths and it can be evaluated. It is shown that the degree of polarization is much more sensitive to the aerosol properties than the radiance. Measurements of polarization at two wavelengths and with an angular scanning are simulated and an inversion algorithm is proposed. It aims at finding an “equivalent aerosol model,” which reproduces the optical thickness and the asymmetry factor of the actual aerosol at all wavelengths in the solar spectrum.     

厘米-分米波段Ⅲ型爆发的统计分析

统计分析了太阳第23周期间(2000年7月至2004年9月)在625~1500,MHz,2600~3800,MHz和5200~7600,MHz范围频谱仪观测到的Ⅲ型射电爆发. 给出了Ⅲ型爆发的分布、寿命、频率漂移率、偏振度和频率带宽. 结果显示, 频率漂移率和频率带宽的平均值随频率的增加而增大, 寿命和偏振度的平均值既不是常数也不是在宽频延伸上保持均匀不变的.最多的Ⅲ型爆发分布在625~3800,MHz范围内, 且随频率的增加而增多. 分析表明, 电子加速和能量释放地点主要是在分米波范围内, 这个频率范围的特征可能与分米波段上的磁位形有关, 并且与主耀斑地点附近磁重联区中的电子加速有关. 然而, 还有相当数量的Ⅲ型爆发发生在5200~7600,MHz范围内, 这个特征表明电子加速的地点是在一个日冕的宽范围中. 关于厘米relax-relax 分米波段Ⅲ型爆发的辐射机制最可能包含相干的等离子体辐射或电子回旋脉泽辐射过程.      

Photochemical growing of complex organics in planetary atmospheres

UV induced syntheses of organic compounds from the main atmospheric constituents can be a very important source of organics in a given planetary environment provided the atmosphere is in a reduced state. The evolution of a CO₂ rich medium only produces very low yields of formaldehyde and related oxygenated compounds. Considering a CO rich atmosphere, the photochemical yield of O-organics formation is much higher, when the synthesis of N-organics remains difficult. The most favourable atmosphere as far as photochemical organic synthesis is concerned is a CH₄ rich milieu.. The photochemical evolution of such a CH₄ atmosphere under UV irradiation leads to a chain of various organics, the complexity of which increases together with the number of pathways involved in their formation. Their complexity also closely correlates with their UV photoabsorption spectrum: the more complex they are, the more shifted is their UV spectrum toward the visible range. Direct photodissociation of methane requires UV photon of wavelengths shorter than about 145 nm. It mainly produces ethane which absorbs UV at wavelengths shorter than about 160 nm, and acetylene, that presents an absorption spectrum extending up to 200 nm. This shift still continuously increases with further increase in number of C atoms. Unsaturated hydrocarbons with 4 and more C atoms have UV absorption characteristics including noticeable band structures in the 250–300 nm range. This trend has very important implication in the photochemical behaviour of a CH₄-rich planetary atmosphere, as it induces many catalytic processes. The occurrence of such processes is closely related to vertical atmospheric and energy deposition profiles. Titan provides a very good example of such a UV-directed organic atmospheric chemistry.     

Far-infrared photometry of comet Halley from NASA''s Kuiper Airborne Observatory

We report the results of 40–160 micron broadband photometry of Comet Halley with apertures of 30–50 arcsecond diameter. Measurements of the spatial distribution of the far-infrared radiation at several wavelengths will also be discussed. A preliminary analysis of the data shows the following conclusions: (1) The brightness of the comet varied by nearly a factor of two on two successive days in 1986 March, during which the visible brightness also changed substantially and in the same sense. (2) The far-infrared energy distribution varied significantly in this period in the sense that the decrease in flux with increasing wavelengths was significantly shallower on the day when the comet was fainter. (3) The spectral slope on both days is considerably shallower than would be expected from an ensemble of grains most of which were much smaller than the observed wavelengths.