A spectrometer comprising - an entry slit configured to receive a one-dimensional image slice of light for spectral analysis along a straight object line shape (A1); - projection optics configured to project a spectrally resolved two-dimensional image (B5) of the straight object line shape (A1) onto a detector array; and - correction optics formed by a monolithic block of material disposed in an optical path directly behind the entry slit and in front of the projection optics, wherein the correction optics comprises ∘ an internal reflection surface forming a cylindrical mirror with its curvature (R12) around a first cylinder axis (C1) in a direction perpendicular to a length (Y) of the entry slit for providing a first reflection of light originating from the entry slit ; ∘ a curved entry surface forming a collimation compensator configured to counteract decollimation of parallel principal light rays (Lc,Le) of the light caused by the first reflection; and ∘ a flat mirror surface extending in a direction parallel (//) to the first cylinder axis (C1) for providing a second reflection of the light, wherein the correction optics is configured to warp the straight object line shape (A1) of the entry slit into a curved object line shape (B1) from a point of view of the projection optics , wherein the warping of the correction optics is configured such that a curvature (R1) of the curved object line shape (B1) counteracts an otherwise distorting curvature (R5) in a projection (A5) of the straight object line shape (A1) by the projection optics without the correction optics , wherein the spectrally resolved image (B5) comprises a plurality of parallel straight projected line shapes formed by spectrally resolved projections of the straight object line shape (A1). - an entry slit configured to receive a one-dimensional image slice of light for spectral analysis along a straight object line shape (A1); - projection optics configured to project a spectrally resolved two-dimensional image (B5) of the straight object line shape (A1) onto a detector array; and - correction optics formed by a monolithic block of material disposed in an optical path directly behind the entry slit and in front of the projection optics, wherein the correction optics comprises ∘ an internal reflection surface forming a cylindrical mirror with its curvature (R12) around a first cylinder axis (C1) in a direction perpendicular to a length (Y) of the entry slit for providing a first reflection of light originating from the entry slit ; ∘ a curved entry surface forming a collimation compensator configured to counteract decollimation of parallel principal light rays (Lc,Le) of the light caused by the first reflection; and ∘ a flat mirror surface extending in a direction parallel (//) to the first cylinder axis (C1) for providing a second reflection of the light, ∘ an internal reflection surface forming a cylindrical mirror with its curvature (R12) around a first cylinder axis (C1) in a direction perpendicular to a length (Y) of the entry slit for providing a first reflection of light originating from the entry slit ; ∘ a curved entry surface forming a collimation compensator configured to counteract decollimation of parallel principal light rays (Lc,Le) of the light caused by the first reflection; and ∘ a flat mirror surface extending in a direction parallel (//) to the first cylinder axis (C1) for providing a second reflection of the light, <EOS>