A technique for measuring film thickness on curved substrates

摘要

A technique for measuring the thickness of thin films deposited on curved substrates is described. Conventional multiple beam interferometry with a flat Fizeau plate normally cannot be used with great precision on curved surfaces since the Fizeau fringe spacing is not constant. The technique described in this note takes into consideration the modified Newton's rings which result from such a measurement and gives a precise method of calculating the film thickness.