Digital computed laminography and tomosynthesis - functional principles and industrial applications

X-ray irradiation is well known as a non-destructive testing method for technical components. Unfortunately using simple irradiation technique there is no possibility to get information about the depth of the imaged structures. In 1932 de Plantes performed first experiments to image an object layer by layer. The technique was called laminography and was used in medical diagnostics till the 70th. Furthermore the development of computed tomography (CT) allowed a nondestructive imaging of object slices, but with the restriction that the objects have to be irradiated from the full angular region. Because of high absorption and limited access this is not always possible, e. g. in the case of flat components as multilayer printed circuit boards or welding seams in big components. Laminographic methods are able to overcome these difficulties. They yield images of object slices and allow the determination of the position of the object structures. This article gives a short overview of the existing laminographic methods and the possibilities to use digital laminography for industrial applications. Laminographic methods turn out to be excellent x-ray methods for the inspection of flat components like printed circuit boards or welding seams in big and flat components. Compared with classical laminography, the use of digital x-ray detectors has a lot of advantages and makes it possible to use digital laminography as a modern industrial NDT method.