一种发射率测量系统的设计与实现

介绍了一种带有三个黑体空腔的发射率测量系统.该测量系统能在-10²00℃范围内测量多个样品的发射率.测量系统的硬件由三腔黑体辐射源、计算机、红外测温仪和导轨装置组成,可同时测量标准样品、待测样品、标准黑体辐射源三组温度数据,并计算得出待测样品的发射率.同时,应用编程语言进行测量系统的界面设计,结合软件和硬件搭建出了一个自动化、便捷的实验测量系统.     

微小音速喷嘴临界背压比测试装置

音速喷嘴工作时的背压比小于临界背压比是实现并保持临界流的关键。现行国际标准建议,对于喉部雷诺数Red小于2×10⁵的音速喷嘴,需保持0.25的临界背压比或进行临界背压比的实际测量。基于此,建立了一套微小音速喷嘴临界背压比测试装置,该装置能够实现喉径为0.3~3mm,流量范围为0.05~5m³/h音速喷嘴临界背压比的测量,测量结果的扩展不确定度为0.56%(k=2)。     

数学摆台法的超低频加速度校准

建立了基于数学摆台法的超低频加速度校准装置,解决了线振动台超低频加速度信噪比低的问题,对相关校准具有参考价值和借鉴作用。根据低频噪声理论,在建立激光测振仪的功率谱密度模型基础上,提出了位移噪声的定量评价方法,通过实验验证了所提方法的正确性。对数学摆台的虚拟摆臂、激励传递系数进行了实验测量,对校准装置的测量不确定度进行了评定。该装置实现了加速度计在频率范围0.001～0.1Hz、加速度范围5×10^-7 ～1×10^-2m/s² 的绝对法校准。     

基于三维荧光与BLLS/RBL同时检测蜂蜜中3种喹诺酮类抗生素

采用三维荧光光谱法实现对蜂蜜中的3种喹诺酮类抗生素(氟甲喹、恩诺沙星和左氧氟沙星)残留样本的数据测量,对所得光谱消除了二级瑞利散射和拉曼散射的干扰,采用小波优化集合经验模态分解(EEMD)的方法消除光谱噪声,完成了预处理过程。采用双线性最小二乘/残差双线性(BLLS/RBL)算法分别对预处理前后的样本进行定性、定量检测。结果表明:经预处理后可以准确地解析出样本中各组分光谱,且与原光谱有着极高的相似度。定量分析中,氟甲喹、恩诺沙星和左氧氟沙星的预测平均加标回收率RA分别为94.99%,100.20%,103.20%;均方根误差RMSE分别为4.03,0.21,0.29μg/L;灵敏度SL分别为3.2×10³,3.5×10⁴,3.3×10⁴μg/L;检测下限Lout分别为2.08,0.18,0.19μg/L;优于未经预处理的结果。     

燃煤积灰法向光谱发射率的测量

燃煤积灰是超超临界锅炉热量传递链上重要的一环,它的辐射特性对于准确描述热量在锅炉内的传递非常重要。基于傅里叶红外光谱仪（Fourier transform infrared spectroscopy,FTIR）建立了高温法向光谱发射率测量平台。平台测量波长范围3~14μm,温度范围373~873K,采用标准黑漆样片对平台的测量结果进行了校准,对人工积灰样品光谱发射率开展了实验测量。发现人工灰样发射率具有显著的光谱分布特性,在短波段较低而长波段较高;随着温度的上升,人工积灰光谱发射率逐渐上升;随着Fe₂O₃含量的上升,整体人工灰样的光谱发射率在全光谱范围内上升。     

基于空气轴承支撑技术的高准确度大扭矩标准装置研究

介绍了新研制的基于空气轴承支撑技术的20kN·m高准确度扭矩标准装置的工作原理、机械结构、性能试验,评定了该装置的不确定度。该标准装置采用静压空气轴承作为力臂杠杆的支撑部件,力臂系统采用了多部件框架结构,力臂材料采用了低热膨胀系数的因瓦合金材料,砝码加载系统采用了多个砝码组、旋转托盘和升降机构结合的方式,实现了不同量程范围扭矩值测量时加卸荷中不出现逆程。理论分析和性能试验表明:20kN·m扭矩标准装置在100N·m～24kN·m范围内的重复性优于2×10^-5,不确定度优于2×10^-5(k=2)。     

材料光谱发射率测量装置线性度研究

介绍了对中国计量科学研究院建立的材料光谱发射率测量装置关于光谱辐射线性度的研究.本文应用双温黑体法模拟发射率测量的情况,验证了光谱辐射测量的线性度.从而保证发射率测量装置的可靠性,并根据验证中体现出的问题进行分析,也有利于下一步装置改进.     

碲基复合材料薄膜的三阶非线性光学特性

采用电化学诱导溶胶-凝胶法在导电玻璃片上制备了具有三阶非线性光学特性的碲基复合薄膜材料. 采用SEM( 扫描电镜)和EDX( X 光电子能谱)对薄膜的表面形貌和组成进行表征; 应用分光光度计得到薄膜的透射光谱、反射光谱、吸收光谱, 并结合脉冲激光器和 Z 扫描方法测量薄膜的三阶非线性光学特性. 实验结果表明制备的薄膜呈网状结构, 表面组分主要包括Si、Te、O元素; 薄膜在波长为1064nm处呈现负的非线性折射效应和饱和吸收的性质, 其非线性折射系数和非线性吸收系数分别为-4.18×10 ^{- 13} m²/W和-1.6×10 ^{- 6} m/W, 表明了碲基复合薄膜有较强的非线性光学效应, 得到三阶极化率为1.13×10 ^{- 14} (m/V)², 表明复合薄膜具有优良的三阶非线性光学性能.     

100kN·m静重式扭矩标准装置

介绍了中国计量科学研究院研制的100kN·m静重式扭矩标准装置。该装置采用高精度大承载的刀口支承机构,力臂采用单梁结构并配置了力臂限位保护机构,砝码加载系统采用内外圈砝码组和升降机构结合的结构形式,实现了1kN·m～100kN·m范围大扭矩量值的复现。理论分析和性能验证试验表明:100kN·m扭矩装置在1kN·m～100kN·m范围内的重复性优于5×10^-5,相对扩展不确定度优于1×10^-4(k=3)。     

基于电压串联加法的1000kV国家工频电压计量标准

国家高电压计量站使用了特殊设计的准确度达0.01级的1000kV串联式标准电压互感器成功地进行了1000kV工频电压加法试验,比值差和相位差测量不确定度均小于等于2×10^-5和0.06′。所得量值与800kV电容式工频电压比例标准装置测量结果比对,比值差的最大偏差为2.7×10^-5,相位差的最大偏差为0.11′,均没有超出双方的90%置信概率区间。     

Temperature-Resolved Infrared Spectral Emissivity of SiC and Pt–10Rh for Temperatures up to 900°C

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.     

基于激光积分球反射计的集成黑体发射率测量研究

集成黑体发射率是评价其有效光谱辐射亮度不确定度的关键贡献项。建立了激光积分球反射计测量系统,对中国计量科学研究院制备的集成空腔的法向光谱发射率进行了实验研究和模拟验证。在633nm的波长下测量了集成黑体法向光谱发射率,测量结果的标准不确定度优于0.043%。结果表明:集成黑体辐射源在室温条件下的有效发射率高于0.998,与STEEP3蒙特卡罗模拟计算结果偏差在0.04%之内。实验结果与数值模拟的一致性在测量结果不确定度内吻合良好,验证了激光积分球发射计法用于评价集成黑体发射率的可行性。     

Apparatus for Measuring Spectral Emissivity of Solid Materials at Elevated Temperatures

Spectral emissivity measurements at high temperature are of great importance for both scientific research and industrial applications. A method to perform spectral emissivity measurements is presented based on two sample heating methods, the flat plate and tubular furnace. An apparatus is developed to measure the normal spectral emissivity of solid material at elevated temperatures from 1073 K to 1873 K and wavelengths from \(2\,\upmu \hbox {m}\) to \(25\,\upmu \hbox {m}\). Sample heating is accomplished by a torch flame or a high temperature furnace. Two different variable temperature blackbody sources are used as standard references and the radiance is measured by a FTIR spectrometer. Following calibration of the spectral response and background radiance of the spectrometer, the effect of the blackbody temperature interval on calibration results is discussed. Measurements are performed of the normal spectral emissivity of SiC and graphite over the prescribed temperature and wavelength range. The emissivity of SiC at high temperatures is compared with the emissivity at room temperature, and the influence of an oxide layer formed at the surface of SiC on the emissivity is studied. The effect of temperature on the emissivity of graphite is also investigated. Furthermore, a thorough analysis of the uncertainty components of the emissivity measurement is performed.     

Influence of Non-ideal Blackbody Radiator Emissivity and a Method for its Correction

Demands for accurate temperature measurement and calibration are increasing along with the wider use of radiation thermometry in industry. However, the deviation of a ‘blackbody’ radiator emissivity from the emissivity of an ideal blackbody remains one of the main uncertainty contributions in the calibration of radiation thermometers, although the performance of blackbody radiators has been continually improving. Nevertheless, the influence of this deviation was often ignored due to the complexity of the correction. In this paper, general methods to evaluate the influence of the emissivity deviation of a blackbody radiator from unity for typical radiation thermometer models are described. An approximate practical method for wide-band radiation thermometers is proposed. Moreover, the concept of equivalent wavelength and the corresponding calculation method are introduced to simplify the mathematical model. The calculation result and a mathematical expression for the equivalent wavelength applicable to most popular radiation thermometers with a spectral range of 8–14 μm are given. The analysis and calculation show that the influence of blackbody radiator emissivity on longer working-wavelength radiation thermometer calibrations at mid or high temperatures cannot be ignored.     

A dynamic technique for measuring normal spectral emissivity of electrically conducting solids at high temperatures with a high-speed spatial scanning pyrometer

A dynamic (subsecond) technique is described for measuring normal spectral emissivity of electrically conducting solids at high temperatures, primarily in the range 1800 K up to near their melting point. The basic method involves resistively heating a tubular specimen from ambient temperature through the temperature range of interest in less than 1 s by passing an electrical current pulse through it, while using a high-speed spatial scanning pyrometer to measure spectral radiance temperatures along a 25-mm length on the specimen. This portion of the specimen includes a small rectangular hole that approximates a blackbody cavity. Measurements of spectral radiance temperature of the specimen surface as well as specimen true temperature enable the determination of the normal spectral emissivity of the surface via Planck's law. The applicability of the technique is demonstrated by measurements performed on molybdenum in the range 1900–2850 K.     

NIST Radiance Temperature and Infrared Spectral Radiance Scales at Near-Ambient Temperatures

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.     

大口径高发射率面型黑体辐射源的研制

黑体辐射源作为定标标准器,在红外测量设备的辐射定标中具有重要作用。为应对大口径红外测量设备的辐射定标工作需求,设计了1台辐射面积为400mm×400mm的面型黑体辐射源。采用多路控温和连接固定冷源的方式对黑体进行温度控制;通过热仿真确定合适的传热模型,同时结合高发射率涂层工艺与辐射面的结构设计使黑体具备高发射率,辐射面有效发射率可达到0.992;在真空环境下,利用标准铂电阻温度计测量得到黑体辐射面源的温度均匀性偏差最大为0.101K,稳定性平均值为0.018K/10min,该黑体辐射光源能够满足现阶段大口径红外测量设备的使用需求。     

Remote-sensing infrared thermometer with radiation balancing

What is to our knowledge a novel infrared thermometer (IRT) for remote measurement of the temperature rise (-20-100 K) above the variable ambient (270-320 K) of a distant object is described. A radiation-balancing method is successfully extended to the near-ambient temperature range by variation of the temperature of a built-in blackbody, until the radiation from it equals the radiation from the source, so that its temperature is proportional to that of the source. Another feature believed to be novel is simplifying the design by elimination of the need for cooling the blackbody for subambient temperature range by use of a second blackbody, strategically located, which is heated to achieve radiation balance. Detailed theoretical analysis is given, showing that the IRT can measure remotely the total emissivity or even the electric current or voltage. Resistive inserts are proposed for improving the accuracy of current measurement. A method is proposed for simultaneous remote measurement of absolute temperature and emissivity by variation of the heating current and the aperture of the blackbody for radiation balancing in two bands so that prior knowledge of the object's emissivity is not needed.