Polymer film thickness measurement using laser-ultrasound techniques

The thickness of thin polyester film has been measured using ultrasonic Lamb waves which were generated and detected using noncontacting laser techniques. The uncertainty analysis of such a measurement technique has been examined. Systematic errors in both time of flight and distance between laser generation and detection points were estimated and reduced with the assistance of computerized X-scan translation techniques. Thickness measurements with uncertainties of less than 3% have been achieved.