Method of measuring thickness of an opaque coating using near-infrared absorbance

摘要

The the thickness of an opaque coating may be measured using near-infrared absorbance. One measurement method includes transmitting the near-infrared radiation towards the opaque material and determining relative absorbance levels over a range of near-infrared wavelengths. Absorbance wavelengths having relatively high absorbance and relatively low absorbance are then identified and selected. The selected wavelength values are then correlated with known material thicknesses.