Synchronous IR photothermal imaging: Absolute temperature variations and phase measurements up to 54 Hz

Lock-in IR thermography is an active method of non destructive testing developed since 1985(1–4). More recently, the commercialization of array cameras allowed the acquisition of images with higher frequencies, thanks to their matrix of detectors. We introduce in this paper a 54 Hz and 27 Hz synchronous detection for infrared thermography using a camera. Information is retrieved about thermal behaviours at these frequencies. Phase results are presented with 20μm scale.