Radiation properties of IR calibrators with V-grooved surfaces

ABSTRACT Use of linear or concentric grooves is a well-known approach for increasing the surface emissivity to enable the construction of compact blackbody radiators, improve absorptance of stray radiation traps, baffles and thermal radiation detectors, as well as enhance thermal radiation transfer. Emitters with V-grooved surfaces are widely used as reference sources in radiation thermometry and radiometry. In the design phase of such devices, it is important to predict their performance. Most existing models are devoted to modeling isothermal linear grooves with purely diffuse or specular reflectance. Radiation behavior of concentric grooves differs from linear ones and becomes similar only for large values of the ratio of the radial coordinate to the groove period. This paper covers numerical modeling of isothermal and nonisothermal concentric grooves with mixed specular-diffuse reflection for various viewing conditions using Monte Carlo specialized software. It is shown that the temperature drop towards the peak of a groove might lead to a substantial decrease of the grooves' effective emissivity

Report on the CCT Supplementary Comparison S1 of Infrared Spectral Normal Emittance/Emissivity

open9openHanssen, L; Wilthan, B; Filtz, J -R; Hameury, J; Girard, F; Battuello, M; Ishii, J; Hollandt, J; Monte, CHanssen, L; Wilthan, B; Filtz, J. R; Hameury, J; Girard, Ferruccio; Battuello, Mauro; Ishii, J; Hollandt, J; Monte, C

Materialities and imaginaries of home: geographies of British returnees in later life

This article explores home materialities and home imaginaries in later life, to provide insight into the dialectical relation between the spatial processes of ageing and migration. The article draws on empirical research with British return migrants in older age. The analysis purposively selects four participants from among a wider sample of interviewees to highlight some of the diversity among British returnees and their varied experiences of remaking home upon return. The article explores both the privilege and vulnerabilities of all British returnees as the meaning of home transforms in later life

Learning from a fool: searching for the 'unmanaged' context for radical learning

Drawing on the existing theorizing of organizational learning from a radical perspective, this article attempts to problematize such notion of learning and position it within the existing organizational contexts informed by divergent types of rationality. The study scrutinizes these frameworks with a view to reflect on the potentiality for radical learning to occur within them. In this vein, the conceptual analysis of non-technical and non-marginal notions, namely, ‘spirituality’, ‘luck’ and ‘wisdom’, in different modes of rationality is conducted. This article demonstrates that since the conceptual inclusiveness is entailed by the specificity of sensemaking mechanisms, which these modes employ, the analysed notions can be approached as their litmus paper. The functionalist rationality types are found to be incommensurate with exigencies of the radical context for learning. In pursue of the conducive area for radical learning, the notions of unmanaged organization and the technology of foolishness provide the theoretical frame for the study, and their joint sensemaking context is discussed using examples. This unmanaged space driven by inclusive foolishness is recognized as one that enables the liminal sensemaking processes conducive for radical learning to occur

Infertility and the provision of infertility medical services in developing countries

developing countrie

Test and Assessment of a New Quantum Cascade Laser at 23 μm for Applications in the Longwave Infrared Region

The total outgoing longwave radiation emitted from the earth-atmosphere system to the outer space is in 3 - 100 µm wavelength band. Development of satellite instrumentations for the outgoing longwave radiation depends on material study, sensor research, and instrument tests in the wavelength region of interest. Beyond 20 µm, the availability of a laser source with the average output power \u3e several mW is a challenge in the commercial market. In the presentation, we report the results of testing and assessing a quantum cascade laser (QCL) at 23 µm (430 cm-1) with average power \u3c 1 mW. It operates in a pulsed multimode around LN2 temperature in a cryostat. The QCL at 23 µm has been installed successfully, and was tested using a LiNbO3 pyroelectric detector with some preliminary results. To further stabilize the output of the laser in the cryogenic temperature, a recommended transfer line and a vertical withdrawal container are equipped to the laser cryostat. And a more sensitive and efficient detection is required to measure the output power using a focusing optics for the beam divergence of 60° and 40° in vertical and horizontal directions, respectively. To improve detection, a blocked impurity band (BIB) detector is planning to be applied in the next test, as well as a Deuterium Triglycine Sulfate (DTGS) pyroelectric detector that is recommended by the manufacturer. The test results of the QCL at 23 μm will be compared with that of the power output at the same wavelength from a synchrotron radiation facility. Eventually, it will be integrated with the Complete Hemispherical Infrared Laser-based Reflectometer (CHILR) and the Infrared Laser-based Gonio-reflectometer (ILGR) at NIST to support measurement in the longwave infrared region

Validation of NIST\u27s Low Temperature Infared Spectral Radiance Scale

We have performed measurements of a high emissivity fluid bath variable temperature blackbody source against our reference ammonia heat pipe blackbody from -45 °C to 25 °C. Although the two blackbodies are of very different designs, the spectral radiance results are consistent with calculations based on reference thermometer measurements and effective emissivity data. Both blackbodies employ liquid coolant (ethanol) and two stage refrigeration: internal to the fluid bath LTBB and via an external recirculating bath for the AHPBB. In the case of the AHPBB, the coolant cools the ammonia heat pipe, which provides uniform temperature to the cavity, which it surrounds. The cavity of the LTBB is directly immersed in a bath, which also contains cooling coils for the refrigerant. Temperature uniformity is achieved by stirring the coolant. The radiating cavities are also of different designs. The AHPBB has a typical deep cylinder cavity with a shallow rear cone and is coated with a diffuse black paint, while the LTBB cavity is a trap design with a shorter cylinder section and a longer steeper cone, coated with a specular black paint. In each case, using coating data and cavity modeling, the effective emissivity was calculated to be ≥ 0.9999 from 3.5 µm to 14 µm. We used the Infrared Spectral Emittance Facility (ISEF) to perform a comparison of the two blackbodies across the spectral and temperature ranges previously described. The radiance temperature and effective emissivity results were found to be within the expanded uncertainty of the measurement process, providing validation of the scale

New Capability for Evaluating the Emissivity of Large Aperture Infrared Blackbodies

The Laser Infrared Reflectometry (LIR) laboratory at NIST includes a facility for the measurement of very low reflectance levels of materials and cavities in the infrared such as those used in high accuracy radiometers and blackbody reference sources. The key elements of the facility are integrating sphere systems, which are used to collect the reflected light from the samples and cavities that are measured. For cavity instruments, the effective emissivity or absorptance can be obtained simply by subtraction of the reflectance from unity. The first sphere system, in operation for the last 5 years, the Complete Hemispherical Infrared Laser-based Reflectometer (CHILR), has been used to examine a large number of blackbody and radiometer cavities. However, it is limited to the measurement of cavities with aperture diameters not exceeding 50 mm. There has been an unmet need for the characterization of larger aperture cavities. This presentation reports on the status of a new sphere system designed for accurate measurements of cavities with apertures up to 200 mm in diameter. The core of a new setup is a 50 cm integrating sphere with an integrated substitution / port reduction wheel and means for mapping the spatial distribution of reflectance of the object under test. We describe the concept and performance goals of the new capability. We present the first results of its evaluation, including coating properties and throughput evaluation results, which allow estimates of the signal to noise ratio for different laser sources, as well as the minimum discernable reflectance levels of targets. While full implementation of the new capability may require more time and resources, it is available to support the critical needs of the community. We acknowledge the National Oceanic and Atmospheric Administration (NOAA) Joint Polar Satellite System (JPSS) Program for its support