ISO/WD 26273

Non-metallic coatings--Measurement of thickness--Terahertz method

Scope

This document specifies a method for measuring the thickness of non-metallic coatings using time domain spectroscopy in the terahertz frequency range.
This method can be used for all coatings that are transparent to electromagnetic waves in the terahertz range, typically from around 10 µm depending on the material. The coatings can be deposited on both metallic and non-metallic base materials. The thickness of all individual layers of a layer stack can also be determined in a single measurement.
This method is also suitable if the layers to be tested are not applied to a substrate but are free-standing. Metallic or generally conductive layers cannot be penetrated by terahertz radiation, but act as a reflector, i.e. their thicknesses cannot be determined using this method.