Device for light structuring by single or multi-photon processes having an autofocus system for detecting reflective interfaces, the autofocus system comprising: a. a radiation source for generating autofocus illumination, b. focusing optics for focusing the autofocus illumination into an interface region of the sample in which the interface is to be detected, c. at least one beam splitter arranged between the radiation source and the focusing optics for irradiating the autofocus illumination into the focusing optics and for coupling out reflected portions of the autofocus illumination into an autofocus beam path, and d. at least one detector (22, 22a, 22b) for detecting an intensity of the reflected portions of the autofocus illumination, said at least one detector (22, 22a, 22b) having a Noise Equivalent Power lying in an interval between 1 fW/Hz 1/2 and 300 pW/Hz 1/2 and by at least one first means (28, 30, 32, 34) arranged to match the intensity of the portions of the autofocus illumination detected by the detector (22, 22a, 22b) with a sensitivity range of the detector (22, 22a, 22b), wherein the detector (22, 22a, 22b) is configured as a point-like detector which comprises a single semiconductor element and detects an integrated intensity as a function of the focus position relative to the interface, and wherein the autofocus device further comprises at least one lens arranged between the beam splitter and the detector (22, 22a, 22b) in the autofocus beam path for focusing the reflected portions of the autofocus illumination into the detector (22, 22a, 22b) such that the available intensity of the reflected radiation is focused onto the single detector (22, 22a, 22b), further comprising a second means for coupling the autofocus illumination into a beam path of a processing radiation of the device for light structuring by single or multi-photon processes, characterised by a plurality of detectors (22a, 22b) having different sensitivity ranges, further comprising third means (28, 34) adapted to select the detector (22a, 22b) used depending on the intensity of the components detected by the detector (22a, 22b). a. a radiation source for generating autofocus illumination, b. focusing optics for focusing the autofocus illumination into an interface region of the sample in which the interface is to be detected, c. at least one beam splitter arranged between the radiation source and the focusing optics for irradiating the autofocus illumination into the focusing optics and for coupling out reflected portions of the autofocus illumination into an autofocus beam path, and d. at least one detector (22, 22a, 22b) for detecting an intensity of the reflected portions of the autofocus illumination, said at least one detector (22, 22a, 22b) having a Noise Equivalent Power lying in an interval between 1 fW/Hz 1/2 and 300 pW/Hz 1/2 and by at least one first means (28, 30, 32, 34) arranged to match the intensity of the portions of the autofocus illumination detected by the detector (22, 22a, 22b) with a sensitivity range of the detector (22, 22a, 22b), wherein the detector (22, 22a, 22b) is configured as a point-like detector which comprises a single semiconductor element and detects an integrated intensity as a function of the focus position relative to the interface, and wherein the autofocus device further comprises at least one lens arranged between the beam splitter and the detector (22, 22a, 22b) in the autofocus beam path for focusing the reflected portions of the autofocus illumination into the detector (22, 22a, 22b) such that the available intensity of the reflected radiation is focused onto the single detector (22, 22a, 22b), further comprising a second means for coupling the autofocus illumination into a beam path of a processing radiation of the device for light structuring by single or multi-photon processes, characterised by a plurality of detectors (22a, 22b) having different sensitivity ranges, further comprising third means (28, 34) adapted to select the detector (22a, 22b) used depending on the intensity of the components detected by the detector (22a, 22b).