Fraunhofer-Gesellschaft
What is surface inspection?
Surface inspection is used to check surfaces for defects, irregularities or deviations. On the one hand, fast 2D methods can be used to inspect two-dimensional defects such as soiling, discoloration, gloss level, as well as three-dimensional defects, while losing their height or depth characteristics, as long as they can be displayed with high contrast.
In addition, 3D methods allow the planar recording of the geometric (»three-dimensional«) form of surfaces and their evaluation, down to the nanometer range, which also includes the characterization of three-dimensional defects.
The properties and materials of the surfaces to be tested are constantly increasing. Today, colored, patterned, transparent, reflecting, partially reflecting and fully reflecting surfaces can be inspected with industrial image processing.
How does the surface inspection work?
Simply put, the test specimen is positioned under a camera and suitably illuminated. The camera records the desired sizes or properties of the test specimen ("image acquisition") and in the process of "image data evaluation" the acquired sensor data is evaluated and displayed accordingly.
In the field of surface inspection, the respective system design depends strongly on the properties of the test objects. Depending on whether the component is flat, curved, very shiny, etc., an appropriate system configuration has to be selected, whereby the appropriate illumination is of extreme importance.