FIELD: passive methods for remote measuring of thickness of oil or oil product film, elimination of ambiguity at measuring oil product film thickness in millimeter range of wave length values. SUBSTANCE: method comprises steps of measuring at the same frequency vertically polarized electric field components of background non-polarized sky irradiation by two measuring angles ϕ1 and ϕ2 set from direction to zenith; setting angle values satisfying to condition ϕ1<ϕ2, when each angle is not equal to Brewster angle for measured oil product; then alternatively directing measuring device by angle ϕ1 and ϕ2, set from normal line to film surface in direction to film and measuring alternatively for each angle sum of coherent waves of mirror-image and respectively rereflected vertically polarized components while taking into account their phase difference occurred due to different spacing of those components until inlet of measuring device and proportional to doubled film thickness; for each angle calculating film thickness d1 and d2 respectively; determining real thickness of film according to predetermined algorithm on base of comparison of values d1 and d2. EFFECT: elimination of ambiguity at remote measuring of oil product film thickness. 1 dwg
