On-line laser beam characterization

We have developed a system which is capable of measuring the beam parameters of a laser beam in a single camera frame as well as the optics to workpiece distance. A key component is a novel monolithic beam splitter, which generates a 2D array of beam cross-sections on a single camera chip. Each cross-section of the beam corresponds to a different plane along the propagation axis, separated by a well-defined spacing. Using the full area of the camera chip, more than 20 measurement planes can be achieved. This allows a complete beam characterization conforming to ISO 11146 for a broad range of beam parameters of the incoming beam. The optics to workpiece distance is measured with optical means. Using both measurements the focal position relative to the workpiece surface can be calculated.