Optical camera-based Boltzmann luminescent thermometer in dark situations

In this study, a temperature measurement method was proposed that utilizes an optical camera and an AR marker coated with a fluorescence thermometer under low light conditions. A Pr³⁺ activated phosphor is employed as the temperature sensor, and two emissions at 492nm and 535nm originating from 4f -4f transitions are focused on. The emission at 492nm decreases in intensity with increasing temperature, whereas the emission at 535nm may exhibit temperature-independent behavior within a specific wavelength range due to the Boltzmann distribution law. By measuring the intensity ratio of these two emissions, which exhibit different temperature-dependent behaviors, using bandpass filters and an optical camera, a method for temperature estimation is established.