The shearography technology is an interferometric test method with which damage or defects can be identified on components under load. This measuring technique even enables detection of deformations of only a few micrometers in size. Already a relatively low component load can thus yield unambiguous measuring results, which are mandatory, particularly for NDT testing.

The test object is illuminated with laser light and observed through a CCD camera equipped with so-called shearing optics. These shearing optics project the object image onto the camera chip twice; each object point is thus represented twice on the CCD chip. When the test object deforms under load, the laser light, reflected by the component, changes.

By superimposing an image showing the unloaded object state with an image taken in the loaded state, the change of any given image point can be determined. The optimum test load type (thermal load or pressure and vacuum load) for the individual component depends on the defect type and defect depth and is ideally determined before serial testing by trial measurements using sample components.