An apparatus for laser-assisted eye treatment comprises a laser device and first and second accessory modules. The laser device is configured to provide focused laser radiation and has a coupling port. The first accessory module may form a patient interface and has a contact surface for an eye. The second accessory module includes a measuring device that performs measurements of the laser radiation. In certain embodiments, the measurements include the measurement of a pulse duration of the laser radiation using a detector operating on the basis of two-photon absorption. The first and second accessory modules are configured to detachably couple to the laser device at the coupling port. Only one accessory module can be coupled to the coupling port at a time. Therefore, the first accessory module must be removed from the coupling port before the second accessory module can be attached to the coupling port.
