A spectrometer system comprises a housing provided with a window, an illumination source, a spectrometer and a standard for internal recalibration being disposed in said housing. Specific absorption bands of a filling gas present in the housing are identified in a reference spectrum, which was recorded using the standard, wherein a wavelength characterizing the relevant identified specific absorption band is measured in each case such that measured values are obtained for the wavelengths of the absorption bands. A test spectrum is recorded by the spectrometer using the standard. The specific absorption bands of the filling gas are identified in the test spectrum, wherein a wavelength characterizing the relevant identified specific absorption band is measured in each case such that measured values are obtained for the wavelengths of the specific absorption bands.