Abstract: 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).

Abstract: The invention relates to a device for the positioning of optical elements with retractable stop enabling accurate positioning of an optical element selected among a plurality of optical elements, including a stand (1); a turret fitted with a element holder and a disc (4), said disc (4) being a ratchet wheel having a peripheral surface (5) fitted with a plurality of blocking means (6), each blocking means (6) corresponding to an optical element, a motor (7) and a crash stop (9) bearing against the peripheral surface of the disc (5). According to the invention the stop (9) contains an anti-friction element (13) in contact with the peripheral surface (5) of the ratchet wheel so that the retractable stop (9) moves according to the contour of the peripheral surface (5) of the ratchet wheel without any friction.