共查询到19条相似文献,搜索用时 780 毫秒
1.
2.
3.
为精确获取目标场地的光谱发射率和场地地表温度,研制了具有自校准能力的傅里叶变换红外光谱仪,用于外场地表光谱辐亮度和大气下行辐亮度的测量。开展实验室定标工作,将面源黑体作为标准辐射源,选取观测地面目标热辐射最理想的8~14μm波段,对仪器进行两点法和线性多点法的辐射定标,确定两点法可满足仪器自定标需求。分析光谱仪测量过程中的不确定来源,得到合成不确定度优于0.22 K。开展外场实验,结合光谱迭代平滑温度和发射率分离算法(ISSTES)实现了地表温度和光谱发射率的分离,将获取的光谱发射率与多通道红外辐射计在同一场地下测得的光谱发射率进行比较,进一步验证了自校准红外光谱仪在外场应用时的测量精度和稳定性。 相似文献
4.
发射率分布测量是评价大口径辐射源辐射均匀性的重要基础,但目前针对相关参数的研究较为匮乏。基于全半球激光积分反射方案,设计搭建了基于积分球反射法的红外辐射源发射率分布特征测量系统;开展了测量系统的性能研究,评价了激光光源子系统的稳定性,并在3 W的激光器功率下开展了面辐射源发射率分布特征测量实验。结果表明:建立的测量系统的稳定性良好,以标准金板表面为研究对象,多次测量结果的重复性为0.30%;开展了碳基面辐射源发射率分布实验测量,获得面辐射源发射率的分布云图,发射率的均匀性为98.1%。 相似文献
5.
为了能够实现常温状态下的黑体光谱发射率的准确测量,基于连续可调激光器,搭建了一套中红外波段黑体光谱发射率测量装置。采用自行设计10mA恒流源对MCT探测器进行驱动,测量结果的动态范围从7.29×104提高到4.32×105,有效提升了探测系统的动态范围。该装置实现了覆盖光谱范围7.5~10.6μm,发射率测量量值范围0.01~0.9999的高精度测量,最优不确定度为4.0×10-5(k=2)。 相似文献
6.
7.
介绍了中国计量科学研究院研制的100~400K真空红外亮温标准黑体辐射源的工作原理、结构、性能测试方法及测试结果。黑体辐射源通过液氮制冷与3温区控制实现了100~400K范围内的温度控制。在真空环境下,测试了其在温度范围100~400K轴向温度均匀性、底部温度稳定性等技术指标,结果表明均匀性优于0.120K,控温稳定性优于0.020K/20min;在室温大气环境下,利用基于控制环境辐射的发射率测量方法测量了黑体空腔发射率,空腔法向发射率为0.9998。采用基于蒙特卡罗黑体发射率仿真计算方法分析轴向温度均匀性对空腔发射率的影响,分析了标准黑体辐射源的不确定度来源,在8~16 μm波长亮度温度的合成标准不确定度优于0.030K。 相似文献
8.
作者建立了一套测量300~500 ℃温度区间物体表面法向红外光谱发射率测量装置.在全面了解光电器件、电测设备原理基础上,从发射率定义出发,建立了与装置相对应的测量物体表面光谱发射率的数学(物理)模型,为实验数据的整理和不确定度评估打下了理论基础. 相似文献
9.
激光跟踪仪测量曲面的测量不确定度研究 总被引:4,自引:0,他引:4
针对激光跟踪仪用于曲面轮廓度测量的不确定度评定问题,在论述了激光跟踪仪的标定和面向任务的测量不确定度的基础上,重点研究了Monte-Carlo模拟方法评价面向任务的不确定度的基本思想,并提出了虚拟激光跟踪仪的概念.最后通过实验研究,验证了采用Monte-Carlo模拟方法评价激光跟踪仪测量曲面轮廓度的不确定度是可行的. 相似文献
10.
11.
Thermophysical Properties by a Pulse-Heating Reflectometric Technique: Niobium, 1100 to 2700 K 总被引:3,自引:0,他引:3
F. Righini J. Spišiak G. C. Bussolino M. Gualano 《International Journal of Thermophysics》1999,20(4):1107-1116
Pulse-heating experiments were performed on niobium strips, taking the specimens from room temperature to the melting point is less than one second. The normal spectral emissivity of the strips was measured by integrating sphere reflectometry, and, simultaneously, experimental data (radiance temperature, current, voltage drop) for thermophysical properties were collected with sub-millisecond time resolution. The normal spectral emissivity results were used to compute the true temperature of the niobium strips; the heat capacity, electrical resistivity, and hemispherical total emissivity were evaluated in the temperature range 1100 to 2700 K. The results are compared with literature data obtained in pulse-heating experiments. It is concluded that combined measurements of normal spectral emissivity and of thermophysical properties on strip specimens provide results of the same quality as obtained using tubular specimens with a blackbody. The thermophysical property results on niobium also validate the normal spectral emissivity measurements by integrating sphere reflectometry. 相似文献
12.
13.
14.
Both integrating sphere reflectometry (ISR) as well as laser polarimetry have their advantages and limitations in their ability to determine the normal spectral emissivity of metallic samples. Laser polarimetry has been used for years to obtain normal spectral emissivity measurements on pulse-heated materials. The method is based on the Fresnel equations, which describe reflection and refraction at an ideally smooth interface between two isotropic media. However, polarimetry is frequently used with surfaces that clearly deviate from this ideal condition. Questions arise with respect to the applicability of the simple Fresnel equations to non-specular surfaces. On the other hand, reflectometry utilizing integrating spheres provides a measurement of the hemispherical spectral reflectance, from which the normal spectral emissivity can be derived. ISR provides data on spectral-normal-hemispherical reflectance and, hence, normal spectral emissivity for a variety of surfaces. However, the resulting errors are minimal when both the sample and the reference have a similar bidirectional reflectance distribution function (BRDF). In an effort to explore the limits of polarimetry in terms of surface roughness, room temperature measurements on the same samples with various degrees of roughness were performed using both ISR and a laser polarimeter. In this paper the two methods are briefly described and the results of the comparison are discussed. 相似文献
15.
S. N. Mekhontsev V. B. Khromchenko L. M. Hanssen 《International Journal of Thermophysics》2008,29(3):1026-1040
The realization and the dissemination of spectral radiance and radiance temperature scales in the temperature range of −50
to 250°C and spectral range of 3–13 μm at the National Institute of Standards and Technology are described. The scale is source-based
and is established using a suite of blackbody radiation sources, the emissivity and temperature of which have been thoroughly
investigated. The blackbody emissivity was measured using the complementary approaches of modeling, reflectometry, and the
intercomparison of the spectral radiance of sources with different cavity geometries and coatings. Temperature measurements
are based on platinum resistance thermometers and on the direct use of the phase transitions of pure metals. Secondary sources
are calibrated using reference blackbody sources, a spectral comparator, a controlled-background plate, and a motion control
system. Included experimental data on the performance of transfer standard blackbodies indicate the need for development of
a recommended practice for their specification and evaluation. Introduced services help to establish a nationwide uniformity
in metrology of near-ambient thermal emission sources, providing traceability in spatially and spectrally resolved radiance
temperature, spectral radiance, and background-corrected effective emissivity. 相似文献
16.
Claus P. Cagran Leonard M. Hanssen Mart Noorma Alex V. Gura Sergey N. Mekhontsev 《International Journal of Thermophysics》2007,28(2):581-597
This article reports the first comprehensive results obtained from a fully functional, recently established infrared spectral-emissivity
measurement facility at the National Institute of Standards and Technology (NIST). First, sample surface temperatures are
obtained with a radiometer using actual emittance values from a newly designed sphere reflectometer and a comparison between
the radiometer temperatures and contact thermometry results is presented. Spectral emissivity measurements are made by comparison
of the sample spectral radiance to that of a reference blackbody at a similar (but not identical) temperature. Initial materials
selected for measurement are potential candidates for use as spectral emissivity standards or are of particular technical
interest. Temperature-resolved measurements of the spectral directional emissivity of SiC and Pt–10Rh are performed in the
spectral range of 2–20 μm, over a temperature range from 300 to 900°C at normal incidence. Further, a careful study of the
uncertainty components of this measurement is presented. 相似文献
17.
Accurate measurements of thermophysical properties at high temperatures (above 1000 K) have been obtained with millisecond pulse-heating techniques using tubular specimens with a blackbody hole. In the recent trend toward applications, simpler specimens in the form of rods or strips have been used, with simultaneous measurement of the normal spectral emissivity using either laser polarimetry or integrating sphere reflectometry. In these experiments the estimation of the heat capacity and of the hemispherical total emissivity is based on various computational methods that were derived assuming that the temperature was uniform in the central part of the specimen (long thin-rod approximation). The validity of this approach when using specimens with large cross sections (rods, strips) and when measuring temperature on the specimen surface must be verified. The application of the long thin-rod approximation to pulse-heating experiments is reconsidered, and an analytical solution of the heat equation that takes into account the temperature dependence of thermophysical properties is presented. A numerical model that takes into account the temperature variations across the specimen has been developed. This model can be used in simulated experiments to assess the magnitude of specific phenomena due to the temperature gradient inside the specimen, in relation to the specimen geometry and to the specific thermophysical properties of different materials. 相似文献
18.
V. B. Khromchenko S. N. Mekhontsev L. M. Hanssen 《International Journal of Thermophysics》2009,30(1):9-19
To complement existing water bath blackbodies that now serve as NIST primary standard sources in the temperature range from
15 °C to 75 °C, a gallium fixed-point blackbody has been recently built. The main objectives of the project included creating
an extended-area radiation source with a target emissivity of 0.9999 capable of operating either inside a cryo-vacuum chamber
or in a standard laboratory environment. A minimum aperture diameter of 45 mm is necessary for the calibration of radiometers
with a collimated input geometry or large spot size. This article describes the design and performance evaluation of the gallium
fixed-point blackbody, including the calculation and measurements of directional effective emissivity, estimates of uncertainty
due to the temperature drop across the interface between the pure metal and radiating surfaces, as well as the radiometrically
obtained spatial uniformity of the radiance temperature and the melting plateau stability. Another important test is the measurement
of the cavity reflectance, which was achieved by using total integrated scatter measurements at a laser wavelength of 10.6 μm.
The result allows one to predict the performance under the low-background conditions of a cryo-chamber. Finally, results of
the spectral radiance comparison with the NIST water-bath blackbody are provided. The experimental results are in good agreement
with predicted values and demonstrate the potential of our approach. It is anticipated that, after completion of the characterization,
a similar source operating at the water triple point will be constructed.
Certain commercial equipment, instruments, or material are identified in this paper to specify the experimental procedures
and result adequately. Such identification is not intended to imply recommendation or endorsement by the National Institute
of Standards and Technology, nor is it intended to imply that material or equipment identified are necessarily the best available
for the purpose. 相似文献