FLASH THERMOGRAPHY MODELING BASED ON IR CAMERA NOISE CHARACTERISTICS

摘要

Modeling of the flash thermography process typically requires a priori knowledge of the thermophysical properties of the sample and likely defect mechanisms, as well as the amount of energy used to excite the sample. Often, this information is not readily available to the NDT practitioner. Furthermore, since flash thermography is often performed with infrared cameras that do not provide absolute temperature data, it may be difficult to correlate modeling predictions of the surface temperature to experimental results. We have developed a simple model that takes into account the noise characteristics of the camera, and uses that as a basis for predicting camera response. Input energy is expressed as a multiple of noise, and can be measured from the data without the use of additional instrumentation. The method also predicts minimum detectable flaw diameters as a function of depth, noise and input energy, and provides a quantitative basis for the widely used “rule of thumb” used in thermography.