铯、钠热管标准黑体辐射源研制及性能评价

介绍了中国计量科学研究院研制的270～1 000 ℃标准黑体辐射源,其中包括270～600 ℃铯热管黑体源和500～1 000 ℃钠热管黑体源、温度标准器和数据采集系统。对铯、钠热管标准黑体辐射源进行性能测试,包括三段控温管式炉温场均匀性,黑体辐射源控温稳定性,黑体空腔轴向温度均匀性,黑体空腔口部辐射温度均匀性和热管测温孔内温度均匀性等。铯、钠热管标准黑体辐射源在整个温度区域内合成标准不确定度为0.09～0.13 ℃（k=2）。     

基于BP神经网络的黑体炉温度时序预测模型的建立

黑体炉作为标准黑体辐射热源,特别适合供多种非接触式测温仪表如光电高温计、光学高温计、辐射高温计等的分度和校验之用.但黑体炉在运行时无法预知温度的具体数值,这为实验和标定带来了诸多不便.文章在神经网络的基础上,建立了黑体炉温度时序预测模型.结果表明:神经网络不但能对黑体炉温度进行预测,而且比实际的测温仪表的精确度高出很多.     

基于神经网络的黑体炉温度时序预测模型的建立

黑体炉作为标准黑体辐射热源,特别适合供多种非接触式测温仪表如光电高温计、光学高温计、辐射高温计等的分度和校验之用,但黑体炉在运行时无法预知温度的具体数值,这为实验和标定带来了诸多不便.本文在神经网络的基础上,建立了黑体炉温度时序预测模型。结果表明:神经网络不但能对黑体炉温度进行预测,而且比实际的测温仪表的精确度高出很多。     

对黑体炉有效发射率值标定的探讨

目前在辐射温度计和热像仪温度的定标上,都缺乏对用于定标黑体的有效发射率的定标,而黑体炉在温度测量及量值传递中处于重要的地位.为了避免温度计量量值的混乱,克服由于没有统一方法及设备造成确定黑体炉有效发射率值不统一的问题,需要尽快明确黑体炉有效发射率定标的问题,以达到规范黑体炉有效发射率确定的目的,确保温度量值的准确可靠.     

改进型封装固定点黑体在辐射测温中的应用

为了延长固定点黑体容器使用寿命和简化使用流程,依据热管黑体和传统石墨坩埚黑体的设计使用经验,研制了改进型封装固定点黑体。针对所研制的锡固定点黑体分别用二等标准铂电阻和传递辐射温度计开展复现测试。改进型封装固定点黑体在经历20余次熔凝循环后,没有出现破裂和金属泄露现象。用标准铂电阻复现多次的平均值为231.909℃,扩展不确定度为0.015℃(k=2);而用固定点黑体校准传递辐射温度计的多次平均值为231.85℃,扩展不确定度为0.096℃(k=2)。     

氟利昂热管黑体辐射源性能实验研究

为了满足机场、车站等红外筛检仪器辐射温度现场校准的要求,文章介绍了一种氟利昂热管黑体辐射源。黑体辐射源空腔形状为圆柱-圆锥形,空腔长100 mm,锥角为120腔,法向平均有效发射率计算值为0.995。利用TRT2辐射温度计对黑体辐射源腔底进行辐射温度测量,对热管进行不同角度的倾斜,测得的黑体辐射源温度稳定性优于0.2℃,氟利昂热管空腔内均匀性优于0.2℃,可以满足现场校准需求。     

等温黑体发射率

黑体发射率的测量和计算,尤其是使用黑体检定辐射温度计时,如何判断和检测黑体的发射率,是人们关注的问题.这里从理论分析出发,应用辐射基本定律,导出了等温黑体发射率的计算公式.同时指出,黑体发射率不仅取决于腔口面积与黑体腔内表面面积之比,同时与黑体腔内表面发射率有关.黑体的发射率可以通过辐射温度反向验证.     

三种典型中温黑体炉述评

一、绪言目前,黑体炉已广泛用于分度各种辐射温度计和作为测量各种物质发射率的标准辐射源。在黑体炉的设计工作中应包括腔体结构的选择、实现腔体等温分布的方法、提高黑体空腔有效发射率的措施以及预期要达到的稳定温度方法等。本文介绍了三种中温体炉的制作、结构和性能,并对各炉的特点及用途作了评述。     

辐射温度计检定中的有关问题

辐射测温仪器包括光学高温计、辐射感温器、光电温度计、红外温度计、比色温度计等。现就1987年颁布的辐射温度计检定规程中的有关问题,作些简单的说明。1.标准器的要求标准器是根据不同热源来选用的,例如900～2000℃辐射源为高温黑体炉时,标准器选为标准光学高温计;300～1200℃辐射源用中温黑体炉,标准器选用二等标准热电偶。     

以钨带灯作为辐射源的标定装置的研究

为保证辐射温度计的准确可靠,需定期对其进行分度和校准。目前使用的装置一般为黑体炉。然而,由于黑体炉体积庞大、价格昂贵、升温时间长,无法满足生产和使用过程中对大量辐射温度计的分度和校准的要求。因此研制一种更为经济简便的标定装置,显得十分必要。     

多波长可视化测温系统标定的实验研究

讨论了一种基于光学的火焰／温度场测量系统的标定方法。借助黑体炉等标定源，利用温控系统提供温度参数，经CCD系统成像得到图像的灰度值，通过函数拟合获得辐射图像灰度与温度之间的关系。通过调整不同的快门速度，扩大了CCD的动态范围，从而扩大测温范围。应用图像处理技术对辐射图像去噪，对标定数据进行了整理和拟合，并对结果进行了分析。     

A Vacuum Infrared Standard Radiation Thermometer at the PTB

A thermal infrared radiation thermometer was jointly developed by the Physikalisch-Technische Bundesanstalt and Raytek GmbH for temperature measurements from − 150°C to 170°C under vacuum. The radiation thermometer is a purpose-built instrument to be operated with the PTB reduced-background infrared calibration facility. The instrument is a stand-alone system with an airtight housing that allows operation inside a vacuum chamber, attached to a vacuum chamber, and in air. The radiation thermometer will serve to calibrate thermal radiation sources, i.e., blackbody radiators, by comparing their radiance temperature to that of a variable-temperature reference blackbody inside the reduced-background calibration facility. Furthermore, since it can be operated under vacuum and in air, the instrument also allows the water- and ammonia-heat-pipe reference blackbodies of the PTB low-temperature calibration facility operated in air to be compared with the variable-temperature blackbody operated under vacuum. Finally, provided that sufficient long-term stability is achieved, the instrument shall be used as a transfer radiation thermometer to carry and compare the temperature scale of PTB by means of radiation thermometry to remote-sensing calibration facilities outside PTB. The mechanical, optical, and electrical designs of the instrument are reported. Results of investigations on the temperature resolution, size-of-source effect, and the reference function are given. The heat-pipe blackbodies operating in air are compared to the variable-temperature blackbody operated under vacuum by using the vacuum radiation thermometer. References to commercial products are provided for identification purposes only and constitute neither endorsement nor representation that the item identified is the best available for the stated purpose.     

Characterization of an Ellipsoidal Radiometer

An ellipsoidal radiometer has been characterized using a 25 mm variable-temperature blackbody as a radiant source. This radiometer is intended for separating radiation from convection effects in fire test methods. The characterization included angular response, responsivity, and purge-gas flow effect studies. The angular response measurements showed that the reflection from the radiometer cavity was higher on one of the cavity halves relative to the other half. Further development work may be necessary to improve the angular response. The responsivity measured with reference to a transfer-standard electrical-substitution radiometer showed dependence on the distance of the radiometer from the blackbody cavity. The purge-gas had the effect of reducing the signal output nearly linearly with flow rate.     

High-temperature effects in fluorine-doped, fused synthetic silica fibers

Effects caused by exposure of large-core, fluorine-doped, step-index silica optical fibers to high temperatures were studied experimentally in controlled laboratory conditions. A fiber was located partially inside a temperature-controlled electric tube furnace and irradiated from the end by a light source. The light source was either an incandescent halogen lamp or a blackbody radiator. The influence of fiber temperature on the angular distribution of the radiation in the fiber and the coupling and propagation of thermal radiation in the fiber was studied. With increasing temperature the profile of the angular distribution of the radiation was transformed irreversibly from a Chinese hat profile to a much flatter one. This effect was pronounced at 1000 degrees C and above. Radiation from the furnace was found to propagate in the fiber as an attenuating mode at temperatures above 800 degrees C. Most of the radiation exited the fiber at angles beyond but close to the acceptance angle. Calculations show that thermal self-radiation of the fiber is negligible. The physical explanations for these effects are discussed and practical conclusions are drawn.     

新型辐射银点炉的研制

介绍了中国计量科学研究院研制的新型银点黑体炉的结构及原理，提出了对复现实验对定点炉性能的要求。对该炉的性能测试及在该炉上进行的复现银点实验表明，该炉完全满足复现实验的要求。文中还给出了荷兰计量研究院使用该炉进行实验研究的结果。     

Copper Fixed-Point Measurements for Radiation Thermometry at National Research Council

Due to its high transition temperature relative to other fixed points defined in the International Temperature Scale of 1990 (ITS-90) and its relatively low cost compared to silver and gold, copper is often chosen as the fixed point used to define the ITS-90 above 1235 K at national measurement institutes. Measurement of the copper freezing point can be done in a variety of furnaces. Although there are a large number of copper fixed-point designs, we expect the freezing temperatures to be the same. The difference between realizing different sized fixed points and the use of different furnaces in which to realize them is explored here. A traditional, large aperture fixed-point containing over 600 g of copper is compared to a hybrid-type fixed point containing only 15 g of copper and a commercial fixed point. Three types of furnaces including a heat-pipe furnace, a compact furnace, and a high-temperature blackbody were used to realize the copper freezing point. Between the fixed-point types, only the length of the plateau differed. However, a significant difference was found between the freezing temperatures determined in the different furnaces, and this difference was independent of cell type.     

Radiation characteristics of a high-emissivity cylindrical-spherical cavity with obscuration

We have calculated, to first order, the apparent emissivity of the bounding diffuse surfaces of a high-emissivity cylindrical-spherical cavity enclosure. Our calculations indicate that to achieve emissivities close to a perfectly absorbing blackbody cavity along the bounding surfaces of the spherical enclosure, the radius of the sphere must be equal to or greater than a factor of 4 times the cylinder radius R(S) > or = 4R(C). Furthermore, to achieve emissivities approaching a blackbody cavity along the lower bounding surfaces of the cylindrical enclosure, the length of the cylinder must be a factor of 4 times greater than the radius of the cylinder L > or = 4R(C). In addition, we present the mathematical framework necessary to calculate radiant transfer within a cavity enclosure that contains obscuration. These results can be applied to the design of high-emissivity blackbody calibration cavities and to the reduction of stray light in terrestrial and spaceborne optical systems.     

Evaluating the Inhomogeneity of Thermocouples Using a Pressure-Controlled Water Heat Pipe

There exists various research reports concerning the evaluation methods for the measurement uncertainty due to inhomogeneity of thermocouples; however, the universal method is still waiting to be established. This article considers the evaluation methods for the measurement uncertainty due to inhomogeneity of thermocouples based on comparison between results of two measurement methods. The first method is to estimate the uncertainty from the immersion characteristics of a thermocouple within a fixed-point furnace during its realization. The second method is to estimate the uncertainty from the immersion characteristics of a thermocouple within a heat-pipe furnace with a long uniform region. A pressure-controlled water heat-pipe furnace with an immersion depth of 1000?mm is developed to enable this work. It overcomes the technical difficulties that existed in applying conventional sealed heat pipes to such applications. From the immersion characteristics of a thermocouple measured by the above two methods, we have introduced three measurement parameters. Estimating the measurement uncertainty due to the inhomogeneity from our measurement results as examples is discussed.