A double spectrograph system is disclosed. An entrance slit receives and passes light to be analyzed. A first focusing diffraction grating receives that light. A second focusing diffraction grating receives light reflected by the first focusing diffraction grating. The first and second focusing diffraction gratings both have the characteristic of forming planar substantially anastigmatic spectra. Mounting means keeps the first and second gratings at positions symmetrical about an imaginary plane and with their respective focal planes substantially coincident with each other and the imaginary plane. An exit slit receives the light after it has been reflected by the first grating to the second grating and from the second grating to the exit slit.
