Possibilities were studied of using a remote laser spectrophotometric method in measuring thickness of oil films on a wavy water surface with utilization of discretely tunable laser source operating at eye-safe narrow spectral range around ~ 2.1 μm. Laser spectrophotometric method is based on measuring reflection coefficient of the water surface on five probing wavelengths and finding thickness of the oil film by the quasisolution search method. It is proposed to use an optical parametric generator tunable along a wavelength in the 1.5--2.6 μm spectral range as a radiation source. Results of mathematical simulation are provided for the optical characteristics of typical oil and pure sea water with a mean square value of measurement noise of 1, 2 and 3 %. Results of mathematical simulation demonstrate that remote laser spectrophotometric method based on the quasisolution selection technique makes it possible to measure oil films with a thickness from several micrometers to ~ 130 μm with an error of no more than 30 % for measurements with noise mean sguare error of 1--3 %
Wall shear stress measurements by white-light oil-film interferometry