High-temperature miniature blackbody radiation sources

Various high-temperature blackbody sources for quantitative energy measurements in the IR spectral region are developed. Techniques that ensure a stable operation of the sources at high temperatures are described. The developed blackbody models with maximum temperatures of 2000, 2500, and 3000 K can also operate at other temperatures. Graphite is used as a material for radiators. These blackbodies can be used successfully in radiometric measurements in UV and visible spectral ranges. Blackbodies as high-brightness sources may find wide application in solving the problems of multipass spectroscopy. The blackbody sources developed as rocket engineering has progressed have remained outside the knowledge of foreign scientists.     

Spectral calibration of radiometric detectors using tunable laser sources

This paper describes the analysis of laser-based responsivity measurements using the Tunable Lasers in Photometry setup at the Physikalisch-Technische Bundesanstalt. An approach based on digital signal analysis is proposed to remove interference-caused oscillations in highly resolved spectral data from laser-based measurements, yielding an improved reproducibility and comparability of results. Digital filters are used to selectively suppress the frequency components of interference fringes visible in the measurement data. We describe the algorithm used and discuss the associated uncertainty components of laser-based measurements. Finally, we give examples of the calibration of different detectors with and without interference effects.     

Evaluation of the effective emissivity of reference sources for the radiometric emissivity measurements

The effective emissivity of cavities or interreflecting surfaces is formulated in terms of the effective absorptivity using Kirchhoff s law and the reciprocity of the bidirectional reflectivity distribution function. It is shown that, according to the formulation, the effective emissivity can be evaluated by analyzing absorption processes of radiation. Several types of reference sources are evaluated statistically and analytically: cylindro-cones, lateral holes formed on a sample tube, and opaque samples covered by a hemispherical mirror. The radiative properties of the associated surfaces are characterized by the isotropic specular-diffuse model.Invited paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Application of a radiometric calibration method to lunar Fourier transform IR spectra by using a liquid-nitrogen-cooled high-emissivity blackbody

Since winter 1994/1995 the Moon has been used in addition to the Sun as an IR source of radiation to measure atmospheric absorption spectra with a Bruker IR Fourier transform spectrometer IFS 120M located near Kiruna, Sweden. A two-point radiometric calibration method with blackbody references was applied to lunar spectra in the long-wave detector channel to improve the accuracy of evaluation of the column amounts of different atmospheric trace gases. A new liquid-nitrogen-cooled high-emissivity blackbody without an entrance window is described that is used for this calibration method.     

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.     

Color constancy from blackbody illumination

We present a theoretical analysis of what we believe to be a new color constancy method that inputs two chromaticities of an identical surface taken under two blackbody illuminations. By using the Planck formula for modeling spectra of outdoor illumination and by assuming that a narrowband camera sensitivity function is sufficiently narrow, surface colors can be estimated mathematically. Experiments with simulation and real data have been conducted to evaluate the effectiveness of the method. The results showed that although this method is a perfect vehicle for simulation data, it produces significant errors with real data. A thorough investigation of the cause of errors indicates how important the assumptions on both blackbody illuminations and narrowband camera sensitivities are to the method. Finally, we discuss the robustness of our method and the limitation of solving color constancy using the illumination constraint.     

Geometrical optics and blackbody radiation

Contrary to the customary way, some of the geometrical optics principles in free-space and two dimensions is deduced from blackbody radiation transfer. This is obtained from three hypotheses: (1) a blackbody radiates power proportional to its perimeter, and a convex blackbody does not radiate to itself, (2) reciprocity in radiation transfer, and (3) energy conservation. The analysis of an abstract relay element will lead to deduction of the reflection law in an unconventional form and new properties of the elliptical mirror as an ideal radiation transfer device.     

Aqueous blackbody calibration source for millimeter-wave/terahertz metrology

This paper describes a calibrated broadband emitter for the millimeter-wave through terahertz frequency regime, called the aqueous blackbody calibration source. Due to its extremely high absorption, liquid water is chosen as the emitter on the basis of reciprocity. The water is constrained to a specific shape (an optical trap geometry) in an expanded polystyrene (EPS) container and maintained at a selected, uniform temperature. Uncertainty in the selected radiometric temperature due to the undesirable reflectance present at a water interface is minimized by the trap geometry, ensuring that radiation incident on the entrance aperture encounters a pair of s and a pair of p reflections at 45 degrees. For water reflectance R(w) of 40% at 45 degrees in W-band, this implies a theoretical effective aperture emissivity of (1-R(2)(ws)R(2)(wp))>98.8%. From W-band to 450 GHz, the maximum radiometric temperature uncertainty is +/-0.40 K, independent of water temperature. Uncertainty from 450 GHz to 1 THz is increased due to EPS scattering and absorption, resulting in a maximum uncertainty of -3 K at 1 THz.     

黑体轨迹色温匹配的混光算法

根据实际应用的需求,从格拉斯曼颜色混合定律出发,给出了一种基于混光原理匹配黑体轨迹上色温的算法。该算法已知黑体轨迹上目标色温的色温值和色品坐标,计算出所需红、绿、蓝三原色的亮度,利用该方法可以混合出任意色温的光,实现对黑体轨迹色温的匹配。通过对几种典型色温值进行理论计算以及对可能产生的误差源进行分析,该算法计算精度较高,计算速度较快,在可调标准色温光源的设计中作为理论基础能够很好的满足色温应用的要求。     

Experimental determination of the limits and conditions of applicability of pairwise aggregation of radiometric instruments for the detection of sources of ionizing radiation

The method of pairwise aggregation of radiometric devices for the detection of radioactive substances is studied. The limits of applicability of the method for gamma-neutron fields are determined.     

关于换热器的低温黑体辐射源

介绍一种工作在-80℃～+100℃的基于换热器的新型低温标准黑体辐射源的设计和其发射率的计算.这种黑体辐射源采用液体恒温槽均温致冷和采用气帘隔离法消除低温凝露和结霜,黑体空腔形状为圆锥圆柱型,锥角为120°,空腔内径50mm,腔长为300mm,控温稳定性优于±0.05℃/30min.理论计算的黑体空腔有效发射率为0.998(保留小数点后三位),比对实验测量得到的有效发射率为0.997(保留小数点后三位),二者接近一致.     

深低温星上定标黑体源研究

为匹配红外空间载荷低温光学镜头的光学性能,降低背景噪声,实现载荷高精度星上定标,研制了一种基于制冷机主动制冷的深低温星上定标黑体源装置（低温100 K工作）,该星载黑体源装置由面黑体辐射体、低温制冷机主动制冷系统、冷量传输热管及精密测控温系统组成,通过载荷级真空辐射定标实验校验,最终实现红外遥感器对星上定标黑体源宽光谱（2～16μm）、高发射率（0.987）、深低温（100 K）的高精度定标源需求。该深低温星上定标黑体源可用于对极远极冷极弱目标探测的红外载荷星上辐射定标,其高精度、低功耗、通用性的工程化设计方法,为后续相关研究及推广提供技术支撑。     

Fractional bandwidth normalization for optical spectra with application to the solar blackbody spectrum

Optical spectra are typically normalized per unit wavelength or per unit photon energy, yielding two different expressions or curves. It is advantageous instead to normalize a spectrum to a constant fractional bandwidth, providing a unique expression independent of whether the bandwidth is in dimensions of wavelength or of photon energy. For the Sun, whereas a per-unit-wavelength spectrum peaks in the green and a per-unit-photon-energy spectrum peaks in the IR, when the proposed normalization is used, the output peaks in the red. This approach applies to any spectral source and provides curves of constant spectral resolving power, as produced by many spectrometers.     

High-grade uniform light source for radiometric and photometric applications

Versatile applications in radiometry and photometry require uniform light source systems with a highly Lambertian radiance/luminance output. Examples for this kind of requirements include different applications such as calibration of photometers and radiometers, testing of electronic imaging devices like CCDs or similar array detectors or the use as a homogenous light source in, for instance, gonioreflectometric measurements. At the Physikalisch-Technische Bundesanstalt (PTB) a homogenous sphere radiator consisting of a medium sized integrating sphere (ϕ = 150 mm) with an internal reflector in the equatorial plane was developed. In its first stage of development it was equipped with an internal 250 W quartz tungsten halogen lamp. This sphere radiator had a radiance homogeneity of 99.8% of the emitted radiation measured in the plane of the limiting aperture (ϕ = 40 mm) at the output of the device. In the latest design of the system the radiative output power could be increased by a factor of about 3 by the use of an internal 400 W quartz tungsten halogen lamp while nearly maintaining homogeneity.     

Key areas for adopting international standards in national standards

正SAC issued the 2020 version of the Guide for Adopting International Standards in National Standards in late November of 2020, identifying the key areas where national standards can be scheduled for development and revision based on advanced international standards.