Patent ID: 8456523

Claim:
A laser processing head for processing a workpiece by means of a working laser beam, comprising a camera with an imaging optical unit arranged upstream thereof in a beam path and serving for observing a processing region of the workpiece which is processed by means of the working laser beam, a focusing optical unit for focusing the working laser beam with a processing laser light wavelength (λ L ) onto the workpiece surface or onto a position defined relative to the workpiece surface, an illumination device to illuminate the processing region of the workpiece with light having a wavelength (λ K ) of an observation system, an evaluation unit, which is designed to calculate a correction adjustment travel (Δz OS , Δz B ) which compensates for a focal point displacement of the focusing optical unit relative to the workpiece surface or to a position defined relative to the workpiece surface by means of an adjustment travel (Δd KL ) of the imaging optical unit in the direction of the optical axis, which is necessary for focusing the camera image again in the event of a displacement of the focal point of the focusing lens, wherein the evaluation unit is designed, in the calculation of the correction adjustment travel (Δz OS , Δz B ) of the focusing optical unit from the adjustment (Δd KL ) of the imaging optical unit, to include in the calculation focusing differences of the imaging optical unit and of the focusing optical unit on account of the different wavelengths of the observation system (λ K ) and the working laser light wavelength (λ L ).