Simple calibrated nonlinear excitation regime two-line atomic fluorescence thermometry

Nonlinear excitation regime two-line atomic fluorescence (NTLAF) is a promising two-dimensional (2D) thermometry technique for turbulent sooty flames. However, the complexity of calibrating three system parameters and expensive instruments restricts the application of the current NTLAF technique. Here we propose a simple and cheap NTLAF measurement approach based on a one-parameter model and tunable diode laser absorption spectroscopy (TDLAS) calibration. Using this methodology, only one system parameter, instead of three as in traditional NTLAF, is to be calibrated by path-averaged temperature acquired by the TDLAS technique. As a demonstration, instantaneous 2D thermometry data of a homemade burner were acquired using this approach, with measurement uncertainty of ∼4.5% and deviation from both reference TDLAS results and Raleigh scattering measurement results less than 50 K, typically within 20 K. This approach offers a novel simplified NTLAF solution for noncontact, in-suit, high-resolution 2D temperature measurement and is expected to greatly improve the compatibility of the NTLAF technique in scientific research and engineering applications.