Аннотация:Several techniques used to evaluate oil film thickness are discussed in this note. The first technique employ intensity depression of Raman backscattered signal from water under an oil film for the measurement of film thickness, and the second one operates with spectrum normalized to a unit area. However, both are ineffective in some cases. The last approach modelled in laboratory conditions we two Nd:YAG-lasers. Among the three, the last one is found to give better evaluation results.