FIELD: optical measurement, contact-free determination of thickness of layers of clear liquids in paint and varnish, chemical and electronic industries, physical and chemical instruments. SUBSTANCE: process employs phenomenon of thermal-capillary convection excited by laser radiation in layer of liquid that leads to dynamic deformation of its free surface in the form axially symmetric depression. Thickness of layer is found by diameter of interference pattern viewed on screen positioned in cross-section of caustic from reflected beam of laser and having form of concentric circumferences. EFFECT: increased measurement accuracy, simplified circuit design and measurement process, expanded range of measurement of layers of optically clear liquids on frosted surface absorbing radiation. 4 dwg
