Phosphor thermometry at 5 kHz rate using a high-speed fiber-optic spectrometer

Abstract

A simple kHz-rate spectral phosphor thermometry technique with sub-millisecond temporal resolution for contactless point measurements of short duration transient surface temperature changes was developed by employing a compact high-speed fiber-optic spectrometer, a high repetition rate pulsed green laser, and a fast decaying thermographic phosphor. Temperature changes were determined from the temperature-dependent emission spectra of the YAG:Ce phosphor using a spectral slope method. The precision of single-shot temperature measurements was better than 4% for temperatures up to 700 K. An application of the technique for time-resolved measurements of local transient temperature changes at 5 kHz during repetitive long CO2 laser pulse heating is presented. The measured temperature transients are well-predicted using a two-dimensional axisymmetric heat transfer model.