Device and method for laser beam caustic measurement and laser beam system

A device for measuring caustic parameters of a laser beam, the device comprising:

• a beam splitter for splitting the laser beam into at least three spatially separated partial beams, and
• a detection unit for detecting images of the at least three partial beams spatially separated from each other,
• wherein a beam path from an input of the device to the beam splitter defines a beam axis for the laser beam, along which the laser beam propagates until entering the beam splitter,
• wherein the beam splitter comprises at least one optical lens with an optical axis, the at least one optical lens having an entrance refractive surface and an exit refractive surface that are partially reflective, partial reflections at the entrance refractive surface and the exit refractive surface causing the laser beam to be split into the at least three partial beams, and
• wherein the optical lens is positioned off-axis such that the optical axis of the optical lens extends off-axis to the beam axis, and/or the optical lens is tilted such that the optical axis of the optical lens forms an angle with the beam axis that deviates from 0°.