Abstract: A method for measuring the penetration depth of a laser beam into a work-piece. A focusing optical unit arranged in a machining head focuses the laser beam in a focal spot. The focal spot produces a vapor capillary in the workpiece. An optical coherence tomograph produces a first and a second measurement beam. The first measurement beam is directed at a first measurement point at the base of the vapor capillary in order to thereby measure a first distance between a reference point and the first measurement point. At the same time, the second measurement beam is directed at a second measurement point on a surface of the workpiece which faces the machining head and which is outside of the vapor capillary measuring a second distance between the reference point and the second measurement point. The depth of penetration of the laser beam is the difference between the second and the first distances.

Abstract: A method for system documentation includes photographing at least part of a system from at least two directions to obtain photographs with a camera having a film plane and a measuring grid plate in front of the film plane. The photographs are digitized. Center lines for individual system parts are separately determined. The digitized photographs are evaluated and a three-dimensional image of the system is prepared with a CAD method from the course of the center lines, for a three-dimensional representation of the system. An apparatus for system documentation includes a camera having a film plane and a measuring grid plate in front of the film plane for taking a photograph of at least part of a system. A digitizing apparatus is provided for the photograph. An apparatus for determining a center line of the system part is connected downstream of the digitizing apparatus. A CAD system is connected downstream of the apparatus for determining the center line.