Abstract: A monochromator for examining very narrow band ranges of a light spectrum has a fixed inlet slot, a grid illuminated by said slot and rotatively driven by a grid drive, a fixed outlet slot arranged in the angular area of the generated spectrum and at least one cutoff filter arranged in the path of the rays, continuously and swivelingly driven by the grid drive transversely to the path of the rays for filtering out light of orders other than the observed order. The cutoff filter is coupled to the grid drive in such a way that it is synchronically swiveled over the same angle as the grid, covering the desired spectral range.