Development of a New InGaAs Radiation Thermometer at NMIJ

The first InGaAs radiation thermometer at NMIJ was developed more than ten years ago as a standard radiation thermometer operating from 150 to 1,100°C. Its size-of-source effect (SSE) was as large as 1% from 6 mm in diameter to 50 mm in diameter. The new thermometer has an SSE of 0.3%. The reason for the error in measuring the SSE of InGaAs thermometers was also found. The new thermometer at first suffered from nonlinearity and the distance effect (DE). These deficiencies arose from the misalignment of optics inside the thermometer and were solved by increasing the detector size from 1 mm in diameter to 2 mm in diameter. Unfortunately, the detector of 2 mm diameter had a smaller S/N ratio than that of the 1 mm one at the indium (In) point. The final design uses a detector of 1 mm diameter, but the radiation is focussed on a smaller area of the detector. The new thermometer is smaller and lighter than preceding designs and other standard InGaAs radiation thermometers. The temperature of the main part of the instrument, including the filter, the detector, and the preamplifier board, is controlled at 30°C. In addition to the calibration with the six fixed points of copper (Cu), silver (Ag), aluminum (Al), zinc (Zn), tin (Sn), and indium (In), the linearity from the In point to the Cu point, the SSE, the DE, and the spectral responsivity were measured.     

红外辐射温度计的辐射源尺寸效应修正

红外辐射温度计在低温测量的辐射源尺寸效应（SSE） 的规律不同于高温测量。基于以虚拟探测器温度消除背景辐射影响的SSE计算模型,推导了在不同源尺寸和不同背景条件下辐射温度计输出的SSE影响修正公式;得出不同源尺寸条件下辐射温度计温度示值的SSE影响修正的理论解析表达式。在源温度低于或接近背景温度时修正模型与高温测量SSE修正模型有显著差异。所得结果适用于任意温度下对单波段辐射温度计的SSE影响修正。     

红外辐射温度计瞄准的平面辐射源模型

用典型红外辐射温度计的辐射源尺寸效应的实验数据说明不同测量条件下的检定/校准结果的差异可能为其最大允许误差绝对值的数倍。提出具有明确测量条件的平面辐射源瞄准模型和以辐射源前置光阑的方式对于不同空腔黑体辐射源实现相同的等效平面源直径的方法,提出了对光阑的技术特性和放置距离要求,分析表明低温辐射源对光阑的冷却作用可能引起不可忽略的示值降低。采用等效平面源模型的实验结果表明以不同几何条件的空腔黑体辐射源可得到一致的检定结果。讨论了应用平面辐射源模型可能遇到的实际技术问题和解决的对策。     

Calibration of an Absolute Radiation Thermometer for Accurate Determination of Fixed-Point Temperatures

For accurate determinations of thermodynamic temperature, NPL has developed its absolute radiation thermometer (ART), which is calibrated traceably against a cryogenic radiometer. This article reviews some of the potential sources of systematic uncertainty present in the calibration and use of ART. In particular, this article is concerned with the evaluation of the size-of-source effect and the lens transmittance, as well as potential differences in the responsivity of a transfer trap detector when calibrated in terms of radiant power and used in irradiance mode.     

Optical Diffraction Corrections in Radiometric Thermodynamic Temperature Determination

One of the main components of uncertainty in high-temperature thermometry arises because of the size-of-source effect (SSE). This effect makes the temperature measurement sensitive to the geometry of the radiating environment. It is caused by optical diffraction and especially by light scattering off/from, and inter-reflections between, optical components inside the pyrometer. The LNE-INM/CNAM is involved in extending the thermometry temperature scale to very high temperatures (T > 2000 °C) and has developed eutectic-based fixed points (Sadli et al. (in: Zvizdic (ed.) Proceedings of TEMPMEKO 2004, 9th International Symposium on Temperature and Thermal Measurements in Industry and Science, 2004)) and a thermodynamic temperature measurement capability based on absolute radiometric methods (Briaudeau et al. (in: D. Zvizdic (ed.) Proceedings of TEMPMEKO 2004, 9th International Symposium on Temperature and Thermal Measurements in Industry and Science 2004)). A new measurement technique that uses an optical fiber has been developed and tested, allowing the determination of the SSE at any defocusing plane, with high resolution. A model based on optical diffraction has been developed to simulate the SSE in a real situation, considering the contribution to the pyrometer signal of the whole “3D” optical scene inside the blackbody furnace. Using the same approach, it has been demonstrated that optical scattering in a simple radiance meter can be estimated from accurate optical diffraction measurement.     

标准铂电阻温度计自热效应对测量结果的影响

为了研究自热效应对标准铂电阻温度计测量结果的影响,分别从定点法和比较法两方面开展研究.针对定点法,统计中国计量科学研究院近3年检定的标准铂电阻温度计数据,计算不同温区的铂电阻温度计自热效应修正前后的测量结果并进行对比,结果表明,在溯源标准铂电阻温度计时自热效应修正与否对测量结果的影响达到了1.5 mK以上,最大达到了6...     

Acoustic Thermometry Results from 271 to 552 K

The NIST acoustic thermometer determines the thermodynamic temperature from measurements of ratios of the speed of sound of argon in a nearly spherical cavity. We report recent results for T − T ₉₀ on 12 isotherms spanning the range 271–552 K. (T is the thermodynamic temperature and T ₉₀ is the temperature on the International Temperature Scale of 1990.) The results are in excellent agreement with recent acoustic thermometry results reported by Benedetto et al. in the range from 273 to 380 K and with our previously reported results at 303, 430, and 505 K. The combined data sets are sufficiently redundant and sufficiently distributed over the temperature range to support a re-determination of the reference function for standard platinum resistance thermometers for a future temperature scale. The isotherms were analyzed using several methods; the T−T ₉₀ results and related uncertainties are insensitive to the method chosen. The thermal expansion of the stainless-steel resonator was deduced from the frequencies of the microwave resonances of the cavity. To clearly identify two nearly degenerate eigenmodes in our nearly axially symmetric resonator, two phased coupling probes were used to control the azimuthal angle of the microwave excitation.     

环境温度对红外辐射式体温计读数的影响

本简要介绍了所研制的红外辐射式体温计的构成及标定实验方法；研究了环境温度对体温计的影响；并在实验基础上提出了采用分段标定及对环境温度补结果进行修正的方法，提出了测量精度。     

NMIJ Constant-Volume Gas Thermometer for Realization of the ITS-90 and Thermodynamic Temperature Measurement

The constant-volume gas thermometer (CVGT) of the National Metrology Institute of Japan (NMIJ), AIST with ³He as the working gas is used as an interpolating gas thermometer to realize the International Temperature Scale of 1990 (ITS-90) from 3 K to 24.5561 K and as a relative gas thermometer for thermodynamic temperature measurement calibrated at the triple point (TP) of Ne. The standard uncertainties of the realization and measurement are estimated to be 0.58 mK and 0.86 mK at a maximum in the mentioned temperature range, respectively. The maximum difference between both temperatures is about 1 mK. In the calibration of the CVGT, the TP of equilibrium hydrogen (e-H₂) is corrected for isotopic composition as specified in the Technical Annex for the ITS-90. The ambiguity of the TP of Ne due to the variability in isotopic composition is included in the uncertainty. Although the CVGT was also used in 2004 to realize the ITS-90, it was modified for the present experiment to reduce some measurement uncertainty components and the working gas was replaced with a higher-isotopic-purity gas. The results from 2004 were recalculated by correcting for the isotopic composition of e-H₂ and differ insignificantly from the present results, except for a wider scatter.     

较低温度条件下SSE影响红外温度计校准的实验研究

讨论了光源尺寸效应（SSE）现象,并应用SSE系数对红外温度计的SSE特性进行估计。介绍了用于较低温度条件下测量SSE的实验装置,应用该装置对几种红外温度计进行了测试。测试结果表明,当黑体辐射源的光阑孔径大于40 mm时,可以不考虑SSE的影响。该结论适用于大多数工业用温度计的校准。     

Calculated Uncertainty of Temperature Due to the Size-of-Source Effect in Commercial Radiation Thermometers

The article evaluates the uncertainty in the temperature indicated by a radiation thermometer with a direct readout in temperature, due to the uncertainty in measuring the size-of-source effect (SSE) by the so-called “direct method.” Radiation thermometers of this type are the ones most frequently used in practice. The uncertainty of the SSE characteristic is usually not a useful quantity to report to users of commercial radiation thermometers. Instead, they would prefer to know the uncertainty in the measured temperature that results from the uncertainty of the SSE characteristic, and this will be the result of our analysis. The user of a direct reading radiation thermometer will be able to take into account the uncertainty of temperature due to the SSE, if a target with known dimensions is measured. The uncertainty in temperature due to the SSE of analyses based on Planck’s law and its approximation, Wien’s law is compared.     

The VNIIFTRI magnetic temperature scale in the 0.3–3 K range

A thermodynamic temperature scale in the range 0.3–3 K is established by a magnetic method. The results of investigations enable the range of the State Standard of temperature to be extended from 0.8 K to 0.3 K with a simultaneous increase in its accuracy by a factor of 2–3. __________ Translated from Izmeritel’naya Tekhnika, No. 8, pp. 47–53, August, 2007.     

The Influence of Distance and Focus on the Calibration of Infrared Radiation Thermometers

If a radiation thermometer is calibrated by measuring the temperatures of two cavities having different geometries, sometimes discrepancies arise between them, even though their emissivities are close to that of a blackbody. The origin of such discrepancies may result from the size-of-source effect, and in the distance-to-target effect for those thermometers that offer focusing capability. Examples include: (a) out-of-focus image changes the reading: different focus settings produce different results and (b) measurements taken at different distances produce different results. These effects are discussed, their contribution to the measurement uncertainty is evaluated, and some recommendations are made for practical blackbody cavities or radiators to reduce such effects.     

提高辐射温度计检定结果准确度的方法研究

现行的辐射温度计检定规程,概念不够清晰,具体操作步骤描述过于简单,造成检定的实际测量条件有明显的差异,由此导致检定结果的差异。本文从技术角度出发,提出了一种可行的操作方法,力图提高辐射温度计检定结果的准确度。     

基于弹性夹具的辐射温度计检定装置研究

针对目前工作用辐射温度计检定工作存在的问题，提出一种基于弹性夹具的高重复性精度的辐射温度计检定装置。通过介绍装置结构和使用方法，阐明利用弹性夹具固定被检温度计具有更高的灵活性和通用性，以及“一副夹具安装一台被检，共用一个检定台”方式具有更高的机械化程度和工作效率。通过检测和试验结果表明，该装置重复性精度高。     

自校准地表/水表面红外辐射测温仪的研制

研制了一种具有自校准功能的测量地面或水表面辐射温度的仪器,阐述了该仪器的设计原理、具体结构、测试过程及最终的实验结果。为了验证仪器的性能,进行了定标黑体的发射率测量实验,控温稳定性试验,结果表明黑体发射率高于0.996,控温稳定性优于0.04 K;对各个温度传感器进行了标定校准;完成了控制与数据采集程序的编写;进行了样机的辐射测温实验。最后确定出自校准地水表面红外辐射测温仪的测温范围为223～333 K,测温不确定度为0.2 K。     

Middle Temperature Scale for Infrared Radiation Thermometer Calibrated Against Multiple Fixed Points

The NMIJ has established a temperature scale for infrared radiation thermometry from 100 to 420°C consisting of three fixed-point blackbodies at the In, Sn, and Zn points and an InSb detector thermometer at a wavelength of 4.7 μm. The blackbody cavities have large openings of 15 mm diameter. The expanded uncertainties (k = 2) of the In, Sn, and Zn fixed-point radiance temperatures are estimated to be 0.03, 0.03, and 0.05 K, respectively. The expanded uncertainties (k =  2) for the calibration of the infrared radiation thermometer are estimated to be 0.04 K at 157°C (In point), 0.04 K at 232°C (Sn point), and 0.07 K at 420°C (Zn point).     

分度方法对高精度数字温度计测量结果影响的实验研究

铂电阻温度传感器用CVD方程、ITS-90国际温标、多项式方程进行分度,并采用高精度数字温度计显示不同方法的测量结果,以分析不同分度方法对于高精度数字温度计测量结果的影响.在-60～300 ℃进行了实验研究,结果表明,分度方法对于测量结果有一定的影响,在高精度测量条件下可通过方法的选择以提高稳定性和准确度.分度方法的研...     

铂丝位错特性对标准铂电阻温度计稳定性影响的研究

铂丝的位错是影响标准铂电阻温度计性能稳定性的重要因素之一。从微观角度出发,借助X射线衍射(XRD)分析方法,开展了退火时间对铂丝位错密度影响的研究,并利用标准铂电阻温度计退火实验数据进行了验证。结果表明:实际用于标准铂电阻温度计直径为0.07mm的新制铂丝(纯度99.999%)平均位错密度随着退火时间呈指数减小,经过100h退火后位错密度从1012cm^-2下降到1011cm^-2,300h后其位错密度基本保持稳定;新制标准铂电阻温度计在退火前300h其水三相点电阻值明显减小,退火300h后水三相点值变化量小于3mK并趋于平稳,此结果从热处理时间上与铂丝位错实验结果基本吻合。研究结果为标准铂电阻温度计制作工艺的提升及计量检定规程的修订提供技术支撑     

红外辐射温度计专用数字表的研制及评价

日本CHINO公司生产的IR-RST系列标准辐射温度计由于没有设计温度显示装置,无法实时显示温度,针对此类型温度计设计了一款专用的电压测量和温度显示,同时可提供24V直流电压的电测显示仪表。利用高等级的电压源和数字电压表,修正了本专用数字表的误差系数,并考核了稳定性,得到其最大相对误差不超过0.03%。与一款名义波长为0.65 μm的IR-RST辐射温度计配合使用,通过TG HT-9500型高温炉对其组合进行内插分度,实验结果证实分度后校准准确度优于0.03%,1 300 ℃时系统测量结果的扩展不确定度为0.62 ℃。