FIELD: optical measurement methods. SUBSTANCE: technique employs phenomenon of thermocapillary convection which is excited in layer of liquid by laser radiation. Surface of liquid takes form of recess in area of incidence of laser beam. Laser beam reflected from recess forms interference picture. Thickness of layer of liquid is found by minimal diameter of interference picture. EFFECT: raised accuracy, widened range and simplified circuit measuring thickness of layers of optically clear liquid. 2 dwg
