Linearly excited indium fluorescence imaging for temporally resolved high-precision flame thermometry.

Two-line atomic fluorescence (TLAF) is a promising technique for two-dimensional (2D) flame thermometry. However, it suffers either from a low signal-to-noise ratio (SNR) when excited in the linear regime or a quenching effect and nonlinear behavior in the nonlinear regime. This work aims to develop a new TLAF modality, which can overcome the aforementioned limitations based on a specifically designed laser source that can generate long pulses (similar to 400 ns) with a moderate energy of similar to 0.9 mu J and. operate at a repetition rate up to similar to 22 kHz. A proof-of-concept experiment was conducted and linearly excited fluorescence images with an SNR up to similar to 14 were obtained within 1 ms acquisition time by synchronizing the laser with the microchannel plate (MCP) of a 10 Hz-rate intensified. camera. The SNR achieved was comparable to that of a traditional nonlinear TLAF implementation and superior to a conventional linear TLAF approach. This approach offers a novel solution for recording linearly excited indium fluorescence images and is expected to make TLAF a temporally resolved and high-precision 2D thermometry for the first time. (C) 2020 Optical Society of America