The possibility of using Infrared Lock-In Thermography (LIT) to estimate the thickness of a sample was assessed and shown to be accurate up to 1.8mm. LIT is a technique involving heating samples with halogen lamps with varying intensity over time. The intensity is defined by sinusoidal functions. LIT was conducted on samples of varying thickness, gradient, and shape. The Lock-In phase signals were calculated, and a database was then created with the data obtained and was used to estimate the thickness based on the original phase signal. A relationship between gradient and phase signal was also shown based on our data, contrary to current findings in existing literature.
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