Laser excitation effects in lifetime-based high-speed phosphor thermometry

With high-speed phosphor thermometry becoming more established follows the need for an improved understanding of laser excitation induced measurement errors. With this aim in mind, the impact of kHz laser excitation on the lifetime method was investigated for the phosphors Mg3FGeO6:Mn (MFG) and YVO4:Tm. The results showed that significant measurement errors can occur for both phosphors. The Maximum Entropy Method (MEM) was utilized to observe changes in the distribution of decay time with changes in laser excitation fluence and repetition rate. In the light of this analysis, it was concluded that the changes in measured decay time and therefore measured temperature cannot be primarily attributed to laser heating for either phosphor. The dominant source of changes in the measured decay time is ascribed to changes in the distributions of decay time with laser fluence for YVO4:Tm and laser irradiance for MFG.

Automated summary

With the advancement of high-speed phosphor thermometry, it is important to understand the measurement errors induced by laser excitation. This study investigated the impact of kHz laser excitation on the lifetime method for phosphors MFG and YVO4:Tm, and found significant measurement errors for both phosphors. The Maximum Entropy Method was used to analyze changes in the distribution of decay time with changes in laser excitation fluence and repetition rate. The results suggest that the changes in measured decay time cannot be primarily attributed to laser heating, but rather to changes in the decay time distributions caused by laser fluence and irradiance.