Surface temperature measurement with contact thermometers
Martin J de Groot
Contact thermometry for measuring surface temperature is generally applied as an alternative to radiation thermometry, often without consideration of the problems involved. Especially when the measurement requirements are restrictive, for example with small measurement uncertainties and/or large thermal gradients, the measurement result is greatly influenced by the measurement technique. Several situations where surface temperatures are to be measured with contact thermometers are discussed. These case studies are used to introduce measurement principles and the relationship between measurement results. Whereas temperature can be defined and measured under strict conditions to within 0.0002 K, surface temperatures very often cannot be measured to better than a few kelvin. The increasing demand for higher quality manufacturing has led to a need for traceability of these measurements. Some projects aimed at achieving this traceability are described.