TWI's patented Thermographic Signal Reconstruction (TSR) method has been widely recognized as a breakthrough in the field of thermography. TSR performance for flaw detection far surpasses that of conventional approaches, which rely on detection of "hot spots" in the IR image sequence. While conventional thermography is adequate for some simple inspection tasks, it often lacks the accuracy, sensitivity and repeatability required to "meet or exceed" the performance of established inspection methods, such as ultrasound. Introduced by TWI in 2001, the TSR method addresses these limitations, and allows an unprecedented degree of sensitivity, depth range and resolution of subsurface defects. The introduction of TSR has played a significant role in the growth of thermography in real-world manufacturing and in-service inspection applications. The in addition to flaw detection, the quantitative nature of TSR enables material characterization, including precise measurement of thickness, defect depth and thermal diffusivity in a wide range of composites, metals, polymers, ceramics and advanced materials.