Two-colour phosphor thermometry for surface temperature measurement

Thermographic phosphor thermometry enables surface temperatures to be measured over a wide range extending from sub 0 °C to in excess of 1400 °C by utilising the temperature-dependent luminescent properties of lanthanide-doped ceramics. The technique is particularly advantageous where surface temperatures are high due to the difficulty in applying conventional techniques and is therefore particularly well suited to the study of surface temperatures and heat transfer in gas turbines. The paper describes a two-colour implementation of the technique based on the intensity ratio of emissions from two distinct lines in the spectrum. An imaging system based on a single CCD camera has been developed and is described as are the image processing routines. YAG:Dy and YSZ:Dy phosphors were calibrated over a temperature range from 300 to 900 K with a repeatability in the data of around ±0.6%. The response of the phosphors and the performance of the imaging system were demonstrated in a transient heating/cooling study of ceramic and metallic plates.