CEDIP Infrared Systems is under contract with Framatome, the French manufacturer of nuclear plants, for the development of a new kind of camera, called the flying spot or photothermal camera, that is able to solve the problem of surface crack detection in the nuclear and aviation industries.
The photothermal camera is to be used by Framatome ANP and its subsidiary Intercontrole for the inspection of nuclear pressure vessels in an attempt to replace dye penetration techniques.
The detection of cracks is particularly important for safety in the aviation and nuclear industries. Traditional crack detection methods however are rather slow. Visual testing methods are still the most widely used especially during the processing steps and the maintenance operations. Among them, dye penetration testing is probably the most popular one because of its low cost and high versatility.
Nevertheless, in some cases, this simple technique cannot be used for reasons including surfaces that require non-invasive analysis, surfaces that are unsafe to humans (nuclear vessels), or where high surface roughness can lead to a high risk of false crack measurement. In addition dye penetration techniques do not lend themselves to automation or online measurements.
In the new system, the exterior of a sample under investigation is heated by the absorption of a CW laser scanning the surface. Infrared emissions from the surface are then monitored by an infrared camera.
Based upon this unique and patented adaptation of the active IR thermography technique, the Flying Spot camera permits the detection of surface flaws in metallic materials. This novel system has been proven in field trials to reliably reveal cracks of only a few micrometers width in a contactless way even on rough ‘industrial’ surfaces.
Initial results indicate that the Flying Spot camera may be considered as a true viable industrial alternative to conventional NDE techniques (dye penetration, eddy current, magnetic flux) for fast and remote detection of surface damage.