Numerous experimental studies and numerical models were developed to understand the behavior of gas turbines with LPP technology; in particular, several researches are undergoing to better understand fuel/air interaction in the premixing duct, upstream of the combustion chamber. In this article, studies were performed on kerosene lean premixed flames in a LPP burner by mean of Planar Laser Light Scattering and a new technology such as FAst InfraRed Imaging varying the Air Fuel Ration (AFR). Both techniques evidenced oscillation frequencies around 100Hz both under cold conditions and combustion. Typical frequencies bias toward combustion were identified. The FAIRI technique allowed us to identify frequencies up to several kHz in the 2D dimensions. The investigations also evidenced that the typical frequencies shifted up while increasing AFR. Finally, the analysis of the frequency slope allowed us to characterize the turbulence levels along the flame.