Method of detecting defects on the surface of a cylindrical object

摘要

An illuminating device is provided that includes, but is not limited to a cylindrical lighting unit with a cylindrical slit diaphragm arranged in the interior thereof. The lighting unit includes, but is not limited to a cylindrical light source with a cylindrical diffusor arranged therein, and the slit diaphragm has a cylinder with axially extending slits that are arranged in such a way that incident beams coupled in perpendicular to the slit diaphragm axis (O) converge in a point (M) that is spaced apart from the cylinder axis in the interior of the slit diaphragm through the slits.