A spectrometer for examining the spectrum of an optical emission source may include: an optical base body, a light entry aperture connected to the optical base body to couple light into the spectrometer, at least one dispersion element to receive the light as a beam of rays and generate a spectrum, and at least one detector for measuring the generated spectrum. A light path may run from the light entry aperture to the detector. A mirror group with at least two mirrors may be provided in a section of the light path between the light entry aperture and the at least one detector, in which the beam does not run parallel, which may compensate for temperature effects. In the mirror group, at least one mirror or the entire mirror group may be moveable relative to the optical base body and may be coupled to a temperature-controlled drive.