Polychromator

A prism or diffraction grating can be used to disperse the light.

Unlike a monochromator, it outputs multiple beams over a range of wavelengths simultaneously.

Polychromators have multiple exit slits, each of which allows a different wavelength to pass through it.

Instead, they use a single spatially selective detector (such as photographic film or a charge-coupled device).

Spectrographs are generally used to observe a continuous range of wavelengths, while polychromators are more commonly used to observe several discrete wavelengths, leaving gaps in-between.