METHOD AND INSTRUMENT FOR MEASURING THE THICKNESS OF A THIN FILM BY INFRARED INTERFERENCE

摘要

P The invention relates to the measurement of the thickness of thin films. /P P An instrument for measuring the thickness of a thin film 5 essentially comprises a source of infrared radiation 1, a semi-transparent mirror 3, a reflecting element 6, an oscillating mirror 7, driven by a device 8, a diffraction grating 9, an infrared detector 12 and a rapid arithmetic unit 18. This instrument makes it possible to accurately measure the thickness of the film 5 based on the infrared interference pattern which results from multiple reflections light at the film to be measured. /P P Application to the control of the production of plastic films. /P