Monochromators
Diffraction gratings are specified by a line density in grooves per millimetre. The higher the density, the greater light is dispersed resulting in a relatively limited spectral extent. Furthermore, in general , the higher line density gratings are optimised for short wavelength use and vice versa. One must take into account the available grating(s) and the operation range of such before deciding how many gratings are required to cover a given range. Where multiple gratings are required, one can opt for a multiple-grating monochromator which would allow performing a spectral measurement over a great range, or whether a single (interchangeable) grating monochromator is used and the measurement performed in two or more parts.
