Light (A) is focussed onto an entrance slit (B) and is collimated by a curved mirror (C). The collimated beam is diffracted from a rotatable grating (D) and the dispersed beam re-focussed by a second mirror (E) at the exit slit (F). Each wavelength of light is focussed to a different position at the slit, and the wavelength which is transmitted through the slit (G) depends on the rotation angle of the grating.
A diagram of a Czerny-Turner monochromator. Light ('''A''') is focussed onto an entrance slit ('''B''') and is collimated by a curved mirror ('''C'''). The collimated beam is diffracted from a rotatable grating ('''D''') and the dispersed beam re-focusse