Introduction to Pyrometry and Comparison of Different Pyrometer Configurations.

For high temperature materials such as thermal protection systems for re-entry vehicles or combustion chambers, the measurement of the surface temperature has been a big challenge for scientists and engineers. Because of chemical reactions between the solid and gas phases at high temperatures, thermocouples only have limited applications. Especially for objects whose surface temperatures are strongly influenced by the flow fields around them non-intrusive temperature measurement techniques are required. These techniques are necessary for applications in rotating systems as well. Besides IR thermography, pyrometry is one of the most efficient non-intrusive measurement techniques. Because of its relatively simpler hardware, pyrometry is very useful for the measurement of local temperatures up to 3000 centigrades. Parallel to the developments in electronics and materials for optic pyrometers with high temperature resolution, quick response and good accuracy have been developed in the last two or three decades. In this lecture, basic relations of thermal radiation as well as the properties of pyrometer components, the differences between spectral and two-color pyrometers and error sources of temperature measurements using pyrometry will be discussed.