ABSTRACT
This chapter provides an overview of Laser-induced fluorescence (LIF)-based approaches to planar imaging diagnostics, which offer higher sensitivity for species measurements and greater versatility for measuring multiple flow-field parameters than other light-scattering techniques. Laser-induced fluorescence is a well-established, sensitive technique for detecting population densities of atoms and molecules in specific quantum states. Fluorescent light from a segment of the illuminated plane is collected at right angles, passed through a spectral filter, and imaged either directly onto an array detector or onto the front face of an image intensifier. The bulk of fluorescence imaging activity has been concerned with species concentration or mole fraction measurements. In an important extension of gas-phase imaging, it has been shown that organic exciplexes can be used to enable simultaneous imaging of vapor and liquid distributions present in evaporating sprays. Temperature is a critical parameter in many flow fields and so the development of temperature imaging is particularly important.
