Analysis of fluorescence simulation and experiments for sea surface oil film based on LIF

In order to effectively analyze the fluorescence distribution of sea surface oil film detected by laser-induced fluorescence (LIF), a novel, to the best of our knowledge, simulation model of the oil film fluorescence was established based on the Monte Carlo method. Using this simulation model, the fluorescence distribution of oil film with different thickness in emission direction and spatial distribution were analyzed. Based on the fluorescence mechanism model of oil film detected by LIF, a criterion for the LIF system calibration, i.e., the fluorescence intensity ratio between oil film and clean seawater (FIR) using the fluorescence collected from clean seawater as a reference was proposed. The validity of the fluorescence simulation model was verified by using the FIR results of theory and simulation. The fluorescence spectra of oil films with different thickness and FIR parameters of corresponding thickness were obtained by experiments. By analyzing the fluorescence spectra of different oil products and oil film thickness, the fluorescence influencing factors of oil film detected by LIF were obtained. The results show that the fluorescence coverage area increases gradually with the increase of oil film thickness. When the incident light is in the same direction as the fluorescence receiving direction, the obtained fluorescence intensity is larger. Moreover, the FIR used as the calibration criterion of the LIF monitoring system can effectively characterize the thickness of oil film on the sea surface for LIF to detect sea surface oil film in real applications.