Coating thickness gauge using white light interferometer

摘要

The thickness gauge has a wideband light source (1) and a beam splitter, providing a reference beam and a measuring beam, respectively reflected by a reference mirror and at least 2 boundary surfaces (36,38,39,40) of the coated object (37), the reflected beams superimposed on one another at a detector (50). The optical path length of the measuring beam is adjusted via a beam deflector (24), for displacing the focus relative to the boundary surfaces, with evaluation of the position of the interference signals relative to the displacement of the beam deflector, to determine the coating thickness from the spacings between the interference maxima.