Digitized Frequency Modulated Thermal Wave Imaging for Defect Estimation in Steel

Active InfraRed Thermography (IRT) have gained wide acceptance in the field of Non-Destructive Testing and Evaluation (NDT&E) due to fast, non-contact and wide area inspection supported by various modulated excitation schemes. This paper introduces a novel analytical model for sub-surface defect detection using Digitized Frequency Modulated Thermal Wave Imaging (DFMTWI) technique. The applicability of the proposed technique has been validated over a steel sample containing six square defects located at different depth locations. Further, the defect detection capability of the approach has been assessed by comparing the existing Frequency Domain (FD) and Time Domain (TD) data analysis approach.