METHOD AND APPARATUS FOR MEASURING THE THICKNESS OF A COATING ON A SUBSTRATE

摘要

PCT No. PCT/GB89/00518 Sec. 371 Date Nov. 13, 1990 Sec. 102(e) Date Nov. 13, 1990 PCT Filed May 12, 1989 PCT Pub. No. WO89/11095 PCT Pub. Date Nov. 16, 1989.A method and apparatus for measuring simultaneously the thickness and the composition of a coating on a metal substrate. A first beam of radiation that produces a primary beam of photons is directed substantially perpendicularly to the surface of the coating. A first detector is positioned substantially perpendicularly to the surface of the coating to receive a first fluoresced beam. The photons having a first energy level representing a higher concentration element of the coating are selected. A first electrical signal is provided that is a function of the intensity of the photons having the first energy level. A second beam of radiation producing a second primary beam of photons is directed at an acute angle to the surface of the coating. A second detector is positioned substantially perpendicularly to the surface of the coating to receive a second fluoresced beam. The photons having a second energy level representing a lower concentration element of the coating are selected. A second electrical signal is provided that is a function of the intensity of the photons having the second energy level. From the first and second electrical signals, the relative composition of the elements of the coating and the thickness of the coating are simultaneously calculated.