Within the TECFLAM group a std. swirl burner is investigated, both exptl. using optical and probe measurements and by simulations by using different modeling attempts. The present study is focused on the laser-based investigation of the NO distribution within the reacting flow field of a strongly swirling, confined 150-kW natural gas flame. Simultaneous quant. measurements of NO and OH concn. fields by laser-induced fluorescence imaging (LIF) and temp. distribution (Rayleigh scattering) are performed. Mixing properties of the unburned gases are investigated for the isothermal and the combusting flow using tetrahydrothiophene (THT) as a new fluorescing tracer. These measurements show which areas are sufficiently mixed allowing for the application of planar Rayleigh thermometry. Areas where THT-LIF interferes with OH-LIF detection are localized and omitted from data evaluation. The data is analyzed yielding global scalar fields for comparison with model simulations and correlations between the different measured scalars are investigated showing an almost linear correlation of NO concn. and temp. within the swirl flame whereas no apparent correlation between NO and OH concn. was found.