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Self-calibrating Terahertz Technique for Measuring Coating Thickness

This study investigates the applicability of a novel noncontact single-sided terahertz electromagnetic measurement technique for measuring thickness in dielectric coating systems on simulated and realworld coating/substrate systems. The technique does not require knowledge of the velocity of terahertz waves in the coating material. The dielectric coatings ranged from approximately 200 to 1400 μm in thickness. The simulated coating consisted of layered thin paper samples of varying thicknesses on a superalloy substrate and the realworld system consisted of an actual thermal barrier coating on the superalloy substrate. The unique aspects and limitations of this technique for thickness measurements are discussed.

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