What is Laminography?
Laminography is a type of X-Ray inspection used where Computed Tomography is not possible. A laminograph shows a sharp slice through a part with parrallel slices either side shown as blurred. Computed tomography is achieved by rotating a sample through 360 degrees between an x-ray source and an imager. To create a highly accurate scan the part should be placed as close to an x-ray source as possible. While this works well for small volume samples, items such as printed circuit boards (PCBs) can not be rotated close to the source due to the large difference in xyz dimensions. Typically PCBs are very wide and very thin. In cases such as this it is most useful to us laminography.
How is laminography conducted?
Similar to conducting computed tomography the sample is positioned between the x-ray source and the imager. Laminography is often used on parts similar to PCBs, as such it can be said that the part is positioned perpendicular to the x-ray beam and parallel to the imager. During the acquisition the sample moves in a sine wave pattern across the x-ray beam whilst many radiographs are taken. Once the entire sample has been imaged the reconstruction can begin.
Where is laminography used?
A typical case for laminography is the inspection of fibre sheets or PCBs. The information from laminography can be used to clearly see into a large part only a few millimetres thick. This can give the user a greater understanding into how fibres are arranged or if there are any imperfections in the manufacturing process of circuit boards.