Sutton, G; Mendieta, A (2023) Imaging luminescence thermometry: Recent developments at NPL. NIST Special Publication, 2100 (05). p. 98.

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Abstract

Accurate, traceable surface temperature measurements are critical in many high value manufacturing applications, particularly at elevated temperatures. Traditionally, surface temperatures are determined by infrared thermometry or sprung-loaded thermocouples. However, these approaches can have large uncertainties, due to unknown surface emissivity and background radiation in the former case and variable contact and heat-sink effects in the latter. Luminescence surface thermometry, where a coating applied to the surface is interrogated optically, has the potential to overcome these limitations and, when correctly applied, is independent of the surface emissivity and unperturbed by strong background thermal radiation. Here we describe two novel imaging luminescence thermometers developed at NPL, utilizing the ubiquitous thermographic phosphor Mg4FGeO6:Mn (MFG), one measuring the luminescence decay time and the other, the spectral intensity ratio. For each instrument, the measurement principles, design, calibration, and measurement uncertainty are presented. Three applications of temperature measurement are then given: resistively heated strips for strain measurements [1], performance evaluation of photovoltaic cells [2], and metals processing with induction heating and comparison with thermal imaging [3]. Fig. 1. shows the spectral intensity ratio thermometer scheme used to measure inductively heated samples, with a comparison between the phosphor derived temperatures and those measured by embedded thermocouples.

Item Type:	Article
Subjects:	Engineering Measurements > Thermal
Divisions:	Thermal & Radiometric Metrology
Identification number/DOI:	10.6028/NIST.SP.2100-05
Last Modified:	06 Jul 2023 13:35
URI:	https://eprintspublications.npl.co.uk/id/eprint/9787