Investigation of laser-induced grating spectroscopy of O2 for accurate temperature measurements towards applications in harsh environments

We present an in-depth investigation of laser-induced grating spectroscopy (LIGS) for temperature measurements in practical applications using a narrow-band dye laser with 760 nm wavelength and a pulse duration of 8 ns as the source for the pump beams creating the laser-induced grating. The pump laser wavelength was set to be either resonant with the QR(5) transition from the b1 sigma g+(upsilon '=0 <- X3 sigma g-) open=(upsilon ''=0 band of O-2 for generation of thermal LIGS or nonresonant for generation of purely electrostrictive LIGS. Signals were generated in ambient air as well as in high-pressure or high-temperature dry air mixtures. Pump laser irradiances up to 11 GW/cm(2) were used, which resulted in strong electrostrictive contribution to the overall LIGS signals at atmospheric pressure, with a low thermal contribution due to the weak absorption by the singlet O-2) open=( separators=,b1 sigma g+v '=0. The advantage and disadvantage of thermal or electrostrictive LIGS for temperature measurements are discussed, as well as potential applications in high-pressure environments. Furthermore, the precision of the temperature measurement is discussed by comparing different analysis methods.

Automated summary

This study provides an in-depth investigation of laser-induced grating spectroscopy (LIGS) for temperature measurements in practical applications using a narrow-band dye laser. The advantages and disadvantages of thermal or electrostrictive LIGS for temperature measurements are discussed, as well as potential applications in high-pressure environments. The precision of the temperature measurement is also discussed by comparing different analysis methods.