Based on emission spectroscopy flame emission is analysed using spectral imaging. Flame emission imaging is a line-of-sight method like absorption and probes electronically excited species in contrast to LIF which probes ground state species. 2D flame species imaging is carried out with a set of filters mounted in front of the camera lens or 1D using an imaging spectrograph for correlated multi-species detection.
The flame emission (chemiluminescence) of flame radicals like OH*, CH*, C2* is used to e.g. visualize the reaction zone or to monitor flame stoichiometry via emission ratios of such radicals. Infrared emission visualises major flame components like unburnt fuel, CO2 or water.
2-color pyrometry (blackbody radiation) is applied to measure temperature fields in sooty flames. Temporal flame analysis (flame flicker) is measured using statistical information from a time series of flame images. High speed imaging is applied for flame propagation and extinction measurements.