In certain embodiments, a laser device for laser processing of an eye comprises a source of a pulsed laser beam, a detector system that photodetects partial beams generated from the laser beam, and a control unit that evaluates the detection signals. A first detection element of the detector system provides a first detection signal based on single-photon absorption. A second detection element provides a second detection signal based on two-photon absorption. The control unit puts the measured signal strengths of the two detection signals into a ratio to one another. Variations in the resulting ratio value may be traced back to variations in the pulse duration and/or wave front of the laser beam. The control unit may initiate countermeasures to maintain the beam quality of the laser beam.