ISSN: 0090-3973
Page Count: 4

Sources and Magnitude of Errors in the Measurement of Coating Thickness with the Double-Beam Interference Microscope
Saur, RL
Senior physical chemist, General Motors Research Laboratories, Mich.

Abstract

An analysis was made of three factors (fringe width, phase change, and surface roughness) which contribute to errors in measurement of coating thickness with a double-beam interference microscope. Excluding any unpredictable contributions made by surface roughness, a theoretical analysis based on a literature search revealed that the total of the two remaining errors will not exceed ±0.19 μm (±0.0076 mil) if either the coating or its substrate is a metal. If both are metals, the error will not exceed ±0.12 μm (±0.0048 mil). Measurements were made on a few samples of common coating systems. The errors experienced were much less than the above theoretical values, and would not normally contribute significantly to measurements with the double-beam interference microscope.

Keywords:
microscopy, interferometers, dimensional measurement, chromium coatings, anodic coatings, electrodeposited coatings

Paper ID: JTE10080J
DOI: 10.1520/JTE10080J
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