Apparatus for investigating the surface of fibre composite plastic components, comprising: a radiation source, which is configured to convert at least one non-volatile substance at least partially into gas by irradiating a sample surface of a fibre composite plastic component; a detector unit, which is configured to qualitatively and/or quantitatively detect the at least one substance (22b, 22c, 23) converted into gas, wherein the apparatus also comprises a measuring bell, which is configured to form around the fibre composite plastic component or adjacent to the fibre composite plastic component a measuring volume, which adjoins the sample surface, wherein the measuring bell comprises a seal of a flexible material, which seals the measuring volume at a transition between the measuring bell and the sample surface, wherein the radiation source is configured to irradiate the sample surface through an energy-permeable coupling-in window in the measuring bell, the measuring bell comprises such a coupling-in window, wherein the apparatus comprises a process monitoring unit, which is configured to detect a temperature prevailing at the sample surface, and wherein the radiation source comprises a controller, which is configured to compare the detected temperature with a predetermined threshold value, which implies a risk of thermal degradation of the sample surface, and to end or reduce the intensity of the irradiation if the temperature exceeds the threshold value, comprises, and wherein the radiation source comprises at least one laser and/or at least one plasma emitter, characterized in that the radiation source is configured to initiate a removal of material of the fibre composite plastic component from the sample surface. a radiation source, which is configured to convert at least one non-volatile substance at least partially into gas by irradiating a sample surface of a fibre composite plastic component; a detector unit, which is configured to qualitatively and/or quantitatively detect the at least one substance (22b, 22c, 23) converted into gas, wherein the apparatus also comprises a measuring bell, which is configured to form around the fibre composite plastic component or adjacent to the fibre composite plastic component a measuring volume, which adjoins the sample surface, wherein the measuring bell comprises a seal of a flexible material, which seals the measuring volume at a transition between the measuring bell and the sample surface, wherein the radiation source is configured to irradiate the sample surface through an energy-permeable coupling-in window in the measuring bell, the measuring bell comprises such a coupling-in window, wherein the apparatus comprises a process monitoring unit, which is configured to detect a temperature prevailing at the sample surface, and wherein the radiation source comprises a controller, which is configured to compare the detected temperature with a predetermined threshold value, which implies a risk of thermal degradation of the sample surface, and to end or reduce the intensity of the irradiation if the temperature exceeds the threshold value, comprises, and wherein the radiation source comprises at least one laser and/or at least one plasma emitter, characterized in that the radiation source is configured to initiate a removal of material of the fibre composite plastic component from the sample surface.