The invention concerns a spectrograph with a tilted detector window comprising a light source (1), an entrance slit (3), a grating (4), a detector (5) comprising a window through which the light beam diffracted by the grating (4) is transmitted, a part of the diffracted light beam generating reflections on the window or between the window and sensitive surface of the detector (5) and at least a means for inclining able to avoid interference spectra. According to the invention, the at least a means for inclining able to avoid interference spectra comprises the detector window (6, 11) which is an inclined detector window (11).