Coded Excitation for Infrared Non-destructive Testing of Steel Materials

Extensive use of steel materials in numerous applicat-ions necessitates reliable non destructive testing proc-edures for their thorough evaluation. Infrared therm- ography has been proved as a promising evaluation method for characterization of these materials due to its whole field, fast and remote inspection capabilities. But lower power distributed to high frequencies in pulsed thermo-graphy and long repetitive experimentation of lock-in thermography limits conventional thermographic methods, which demands an efficient processing methodology for
detection of subsurface anomalies located at different depths with moderate peak power heat sources in limited span of experimentation time. This paper highlights the applicability of digitized frequency modulated thermal wave imaging for defect detection in mild steel materials and provides a theoretical insight for the proposed
technique. In addition, detection capability of the tech-niques has been compared with conventional phase based approach by taking signal