Fiber-bundle-based 2D Raman and Rayleigh imaging for major species and temperature measurement in laminar flames

In this Letter, we introduce a novel fiber-bundle-based 2D Raman and Rayleigh imaging system for 2D measurements of major species mole fractions and temperature in flames. A cascade of dichroic mirrors and bandpass filters separate the Raman signal associated with each major species and direct it to a custom-built four-inputs/one-output fiber bundle. The single output of the fiber bundle allows simultaneous detection of four species by using a single back-illuminated CCD camera. The novel imaging system combined with a pulse-burst laser operated at 10 kHz and a 10 kHz optical shutter is characterized from measurements in a Mckenna burner and then applied to a flame stabilized over a Santoro burner. The work is, to the best of our knowledge, the first demonstration of 2D measurements of temperature and major species (i.e., N₂, O₂, H₂, and H₂O) in H₂-air diffusion flames at atmospheric pressure.