Abstract: The oil fluorescence was measured by laser induced fluorescence (LIF) along with enhanced light excitation. The saturation effects in oil fluorescence spectroscopy were studied at two aspects, namely, the fluorescence intensity and spectral offset. In the experiment, it was shown that the intensity of fluorescence became to worse following the intensity of excitation pulse raised. The characteristics of fluorescence intensity at 430nm in the linear and nonlinear ranges were derived through polynomial nonlinear curve fitting. Furthermore, the three-dimensional oil fluorescence spectra based on the excitation light energy were reconstructed according the nonlinear fitting data derived form the fluorescence intensity in the detection wavelengths. The result demonstrated that the offset of oil fluorescence spectral peak and the nonlinear characteristics of the spectrum intensity with saturated excitation could be used to identify the oil samples which can not be distinguished by the general fluorescence spectroscopy.

Key words: spectroscopy, saturated excitation, laser induced fluorescence, nonlinear characteristics, fluorescence spectrum